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NICMOS ISRs

2010

NICMOS ISR 2010-001: Finesky – removing higher order sky residuals

We report on a new IRAF task called finesky that removes higher order sky residuals in NICMOS images by creating a masked median image of the observed sky. This median sky image is thereafter subtracted from the science images. A residual signal after image processing using the calibration software calnica may be present due to reference files that do not sufficiently match the conditions of the observations. This includes a slight mismatch in the dark current or the flat-field corrections. The task described here can also used to create sky flat-field images.
T. Dahlen, D. Grumm 06 Jul 2010

2009

NICMOS ISR 2009-008: NICMOS Breathing and Focus Field Variations

The focus of the NICMOS cameras is monitored on a regular basis. In order to achieve consistency in the focus determination, several effects have to be taken into consideration. The main ones affecting NICMOS are: (1) thermally induced movement of the secondary mirror (a.k.a. breathing), and (2) a curved focal plane for all three cameras. The latter is known as NICMOS Focus Field Variation and affects both the measurement of the focus and gives a position dependent Point Spread Function. In this Instrument Science Report we discuss the breathing corrections in the context of the NICMOS Focus Monitoring Program, and re-measure the Focus Field Variations.
T. Wiklind 06 Jul 2009

NICMOS ISR 2009-007: CalTempFromBias: Implementation and Testing

This ISR describes the CalTempFromBias program which was developed to estimate the temperature of each of the three NICMOS detectors individually. Unlike previous NICMOS temperature estimates, which are derived from a mounting cup sensor, these temperatures are derived using the bias level of the detectors themselves. The uncertainty associated with these temperature-from-bias values are 0.05K and are the basis for the new temperature-dependent calibration products for NICMOS data. This ISR describes the program CalTempFromBias, its options, and its applications.
N. Pirzkal 09 Jul 2009

NICMOS ISR 2009-006: NICMOS Grism Wavelength Calibration

As part of the Cycle 16 NICMOS calibration program, new observations of planetary nebulae were obtained using all three NICMOS grisms (G096, G141, and G206). The aim of these observations was to re-derive the dispersion relations for the grism modes of NICMOS as well as to examine and parametrize any field dependence of the dispersion relation within the field of view of the instrument. In this ISR, we present updated versions of the dispersion relations of the G096, G141, and G206 grisms. While the field dependence is small (1-2% peak to peak variation), we also compute two dimensional polynomial solutions to compute more exact dispersion relations anywhere in the field of view of NICMOS.
N. Pirzkal 29 Jun 2009

NICMOS ISR 2009-005: NICMOS Temperature Dependent Flat-fields

The bias-derived detector temperature for all three NICMOS cameras showed a variation of about ~2K in both the era before the installation of the NICMOS Cooling System (NCS) 1997-1998, as well as in the post-NCS era, 2002-2008. This temperature variation affected the detector quantum efficiency (DQE) and hence the structure of the flat-fields. In this ISR we discuss the creation of new temperature dependent flat-field reference files that correct for the effect of temperature on the DQE. Temperature dependent flat-fields (*_tdf.fits) populate the keyword TDFFILE in the headers of post-NCS data retrieved after November 19, 2008 and pre-NCS data retrieved after January 23, 2009. The temperature dependent flat-fields are used by the FLATCORR step in calnica version 4.4 and later. For consistency check we also created epoch dependent flatfields for postNCS data and compared them with the temperature dependent flatfields. The result of this analysis is also included here.
D. Thatte 09 Jul 2009

NICMOS ISR-2009-004: NICMOS Photometric Calibration Pipeline

We present the details of the NICMOS Photometric Calibration Pipeline used to generate aperture photometry. We present an overview of the different corrections employed, explain components of the pipeline and also outline the types of photometric and statistical data products created. In de Jong et al. (in preparation) this photometry will be used to determine the photometric calibration constants stored in the PHOTTAB reference files.
A. C. Viana 29 Jun 2009

NICMOS ISR 2009-003: Updates to Calnica: Using Temperature Dependent Reference Files

This report describes how the calnica data reduction software implements temperature dependent reference files in order to correct for temperature dependent variations in the dark current, the flat-fields, and the flux calibration. We describe in detail the logic used by the software to decide when to apply a temperature dependent correction and which temperature to use in that case.
T. Dahlen 29 Jun 2009

NICMOS ISR 2009-002: Temperature Dependent Dark Reference Files: Linear Dark and Amplifier Glow Components

This report describes the investigation of the temperature dependence of the linear dark and amplifier glow components of the NICMOS temperature dependent *_tdd.fits dark reference files in the post-NCS era, 2002-2008. We find a significant temperature dependence of the amplifier glow signal with higher counts at higher temperature when using the bias-derived detector temperature. The linear dark should also be dependent on temperature, however, the expected change in dark current should to be smaller than the scatter introduced from the read noise. This is consistent with what we find. We also describe how the calnica reduction software uses the temperature dependent dark components when calibrating NICMOS images.
T. Dahlen 15 Jun 2009

NICMOS ISR 2009-001: New Bad Pixel Mask Reference Files for the Post-NCS Era

The last determined bad pixel masks for the three NICMOS cameras were made in September 2002. Those masks were created using data from calibration programs following the installation of the NCS and are therefore based on the relatively limited data set available at the time. Since then, the NICMOS calibration monitoring programs have regularly obtained calibration images of both flat-fields and darks, images used to create the mask reference files. With numerous images taken during a long base-line (2002-2008), this data set allows us to create high signal-to-noise reference files, as well as investigate any temporal dependence of the mask files. In this ISR we describe the creation of new mask files based on this extended data set and compare the new masks with the previous versions. The new masks created contain a higher number of bad pixels compared to the old versions, while the number of pixels thought to be affected by “grot” is lower.
E. Barker, T. Dahlen 15 Jun 2009

2008

NICMOS ISR 2008-004: Summary of NICMOS SMOV4 Plans

This ISR outlines the NICMOS plan for Servicing Mission Observatory Verification 4 (SMOV4). It presents the NICMOS requirements, the planned activities to fulfill these requirements and a brief plan for the data reduction and analysis.
T. Wiklind 14 Aug 2008

NICMOS ISR 2008-003: Verifying the NICMOS Count Dependent Non-Linearity Correction

We re-investigate the NICMOS count dependent non-linearity, using the flat field lamps to reach high count regimes. The NICMOS count dependent non-linearity has been previously quantified and is currently corrected in NICMOS pipeline. In this document we show that the count dependent correction is still accurate to within 1.2% of true linearity for counts above 100 ADU independent of filter used. This is a response to the count-rate dependent non-linearity investigations, to eliminate questions about the current count dependent corrections.
B. Shaw, R. S. de Jong 08 Aug 2008

NICMOS ISR 2008-002: Improvements to Calnica

This ISR describes a number of improvements to calnica, the STSDAS task that performs routine instrumental calibration of NICMOS raw images. We report two major and a number of minor updates to the code. The major updates consist of changes in the way the count rate is calculated from up-the-ramp fitting and changes in the cosmic rays rejection algorithm. All updates have been extensively tested and analysis shows improvement in the S/N of output images by 6-15% compared to the previous calnica version. A further improvement is that the error extension in the calibrated images now represents the true errors in a more consistent way compared to the old implementation of the software.
T. Dahlen 06 Jun 2008

NICMOS ISR 2008-001: Bright Earth Persistence in NICMOS

We report the presence of image persistence in NICMOS data due to prior saturation of the array by the bright Earth as well as an algorithm to remove its impact. BEP (Bright Earth Persistence) may occur when ACS and NICMOS are used in parallel, and the data dump of ACS delays the insertion of the NICMOS filter blank as long as 6 minutes beyond the Bright Earth avoidance angle. We have constructed a BEP frame which can be used to model and remove the presence of BEP in NICMOS data. The algorithm is seen to remove 99.5% of the variance in the background of BEP impacted Camera 2 data. Ongoing work involves broadening the applicability of the BEP correction to Camera 1 and 3 and making it available as a pyraf script through STSDAS.
A. Riess, E. Bergeron 20 Mar 2008

2007

NICMOS ISR 2007-004: NICMOS Cycle 15 Baseline Calibration Plans

This document summarizes the NICMOS Calibration Plans for Cycle 15. The monitoring programs from the previous Cycle 13 and 14 are carried out in Cycle 15. Additional calibration is included in order to improve the accuracy of previously archived NICMOS data.
N. Pirzkal 16 Jul 2007

NICMOS ISR 2007-003: NICMOS Focus Update

This ISR will address a number of changes in the way the NICMOS focus is monitored. It will provide a detailed explanation of those changes and a step-by-step description of the new procedure. The ISR also highlights the results of the focus checks after the HST safing event, which caused the NICMOS cooling system (NCS) anomalous shutdown in February of 2007.
H. McLaughlin 29 Jun 2007

NICMOS ISR 2007-002: NICMOS Time Dependent Flat-fields

We use data obtained during the NICMOS flat-field monitoring 2002-2007 to derive a set of time dependent flat-fields. These 'epoch' flat-fields are compared to the current pipeline flat-fields and differences are quantified. Our results are consistent with a decrease in DQE over the five-year period on the order of one per cent. We also find that the spatial structure of the flat-fields change with time. The reasons for these changes are not fully known, but we note that the changes are consistent with a change in detector temperature with time. The order of this effect is generally less than one percent. The 'epoch' flat-fields are available on the NICMOS web page1.
T. Dahlen 29 Jun 2007

NICMOS ISR 2007-001: Removing Post-SAA Persistence in NICMOS Data

A general concern with NICMOS images is the issue of 'persistence', or residual charge from bright sources and cosmic rays that remains trapped in pixels and is gradually released during subsequent exposures. This is particularly noticeable after HST transits of the South Atlantic Anomaly (SAA), where the cosmic ray rate is so high that their residual flux contributes a significant noise component to many subsequent exposures. We describe the 'SAAclean' task which can be run on post-SAA NICMOS images to identify the amount of charge in each pixel that can be attributed to persistent flux from SAA cosmic rays, and apply a correction based on an SAA persistence model to remove this flux from the data. This task has so far been tested on a variety of NICMOS data, and this represents the most recent update of this task in the PyRAF/STSDAS environment to the HST observer community.
E. Barker 15 May 2007

2006

NICMOS ISR 2006-004: Temperature Monitoring of NICMOS

NICMOS observations are dependent on a cold and stable thermal environment. In this ISR we describe the temperature monitoring and how a stable thermal environment for the NICMOS detectors is achieved. A comparison between the thermal properties of the cryogenically cooled dewar during Cycle 7 and the present cooling using using the NICMOS Cooling System, is presented. A complete thermal history from the start in 1997 up to January 2006 is presented.
T. Wiklind 26 Jul 2006

NICMOS ISR 2006-003: Correcting the NICMOS count-rate dependent non-linearity

We describe a routine to correct NICMOS imaging data for the NICMOS count-rate dependent non-linearity recently discovered by Bohlin et al. (2005) and quantified by de Jong et al. (2006) and Bohlin et al. (2006). The routine has been implemented in the python scripting language and is callable from the shell command line and from iraf. The routine corrects NICMOS count-rate images assuming the non-linearity follows a powerlaw behavior. The wavelength dependence of the non-linearity is interpolated between the measured points of de Jong et al. (2006) and Bohlin et al. (2006) if necessary. The count rates in the output images are modified and hence the standard NICMOS calibration zero-points are no longer valid. New calibration zero-points have been derived from standard star images corrected with the routine. The routine was tested on the lamp-on/off data used in de Jong et al. (2006) to measure the non-linearity effect. We apply the correction to the NGC1850 stellar cluster field and the Hubble Ultra Deep Field (HUDF) to show the magnitude offsets expected due to the non-linearity on objects with a range in luminosity and surface brightness.
R. de Jong 29 Mar 2006

NICMOS ISR 2006-002: NICMOS Count Rate Dependent Non-Linearity in G096 and G141

Since the discovery of the NICMOS count rate dependent non-linearity documented in NICMOS ISR 2005-002, additional tests have been conducted to further understand and quantify the effect. Long integrations of up to 25 minutes exhibited the same level of non-linearity as the original 1-3 minute integrations. Observations of the star P041C on high background from an internal flat field lamp provides another measure of the wavelength dependence of the nonlinearity to compliment the measures based on pure hydrogen WD models.
R. Bohlin 15 Feb 2006

NICMOS ISR 2006-001: NICMOS Count-rate Dependent Non-linearity Tests using Flatfield Lamps

We investigate the recently discovered NICMOS count-rate dependent non-linearity (Bohlin et al. 2005) using the flatfield lamps to artificially increase the count rate. A star cluster field was imaged in a lamp off-on-off sequence in all cameras in a selected set of filters, followed by a series of darks to investigate persistence and to clean the images from any remaining charge for the next orbit. Subtracting the lamp-off images from the lamp-on images clearly shows residual ADUs at the star positions, indicating that a higher background (and thus total) count rate increases the number of ADUs registered from an object. We model the non-linearity with a power law (count-rate å fluxƒŋ) and fit this model to the data. Both NIC1 and NIC2 (NIC3 was not tested in this program) show non-linearity, becoming stronger at shorter wavelengths, but with larger amplitude than predicted by the Bohlin et al. NIC3 measurements. The non-linearity in NIC1 and NIC2 amounts to 0.06-0.10 mag offset per factor ten change in incident flux for the shortest wavelength (F090M and F110W), about 0.03 mag/dex at F160W, and less at longer wavelengths. Archival data from Cycle 7 are also analyzed, showing that the nonlinearity has not changed in NIC2 F110W, and suggesting that this effect is independent of detector temperature.
R. de Jong 15 Feb 2006

2005

NICMOS ISR 2005-005: NICMOS Cycles 13 and 14 Calibration Plans

This document summarizes the NICMOS Calibration Plans for Cycles 13 and 14. These plans complement the SMOV3b, the Cycle 10 (interim), and the Cycles 11 and 12 (regular) calibration programs executed after the installation of the NICMOS Cooling System (NCS).. These previous programs have shown that the instrument is very stable, which has motivated a further reduction in the frequency of the monitoring programs for Cycle 13. In addition, for Cycle 14 some of these programs were slightly modified to account for 2 Gyro HST operations. The special calibrations on Cycle 13 were focussed on a follow up of the spectroscopic recalibration initiated in Cycle 12. This program led to the discovery of a possible count rate non-linearity, which has triggered a special program for Cycle 13 and a number of subsequent tests and calibrations during Cycle 14. At the time of writing this is a very active area of research. We also briefly comment on other calibrations defined to address other specific issues like: the autoreset test, the SPAR sequences tests, and the low-frequency flat residual for NIC1. The calibration programs for the 2-Gyro campaigns are not included here, since they have been described somewhere else. Further details and updates on specific programs can be found via the NICMOS web site.
S. Arribas 02 Dec 2005

NICMOS ISR 2005-004: NICMOS Small deltaT Dewar/NCS PID Model for Orbit Night Power Reduction

Without SM4 and the installation of new Ni-HB2B batteries, HST is facing a future with decreasing battery capacity. This ISR explores one option for reducing HST's battery load during orbit night while maintaining the science capability of the NICMOS. Modulating the NCS setpoint temperature, i.e., increasing it during orbit night and decreasing it during orbit day, can accomplish this. A linear NICMOS small deltaT thermal model was developed based on flight data serendipitously obtained during Proposal 10097, NICMOS Temperature Setpoint Darks, to predict camera one's temperature, NCS compressor speed, and total NCS power for modulations of +/-1, +/-2, and +/-3K. The results are presented.
T. Wheeler and M. Robinson 05 Oct 2005

NICMOS ISR 2005-003: A Test of Possible NICMOS Non-linearity

Observations of standard stars with NICMOS grism (G096), when compared with the same standards taken by STIS (G750L), show a disagreement over the wavelength range 0.8 to 1 micron. Further comparison with ACS F850LP data confirms thisnon-linearity to be due to NICMOS in the sense that fainter stars in NICMOS appear too faint relative to a brighter normalisation. We investigate this over a wide magnitude range by compiling samples of stars (over the range 8 < J < 17) and galaxies (spanning the range 17 < J < 25), with available data with both NICMOS (F110W and F160W) and ground-based JHbands. We find no difference between the NICMOS F160W and ground-based H-band magnitudes. However, in the case of NICMOS F110W and J-band filters, allowing for differences in the filter response functions, we find a trend at the bright-end (J < 17), confirming a non-linearity but smaller than that was seen in Bohlin effect by a factor of 2-3. No significant slope is seen at the faint-end. This non-linearity is interpreted as being due to trapping and the difference in exposure times between the bright and faint objects (Riess 2005). We conclude that most of the observations will not be strongly affected by this effect as the source count rates are sufficiently high so that the fraction of charge lost to traps is negligible. The most affected observations are for faint sources with relatively short exposures.
B. Mobasher and A. Riess 15 Aug 2005

NICMOS ISR 2005-001: NICMOS Two Gyro Mode Coronagraphic Performance

In preparation for the Hubble Space Telescope (HST) entry into Two Gyro Mode (TGM) operations, the NICMOS coronagraphic performance was assessed during the February 21, 2005 TGM on orbit test (ID: 10448) in two filter bands (F110W and F160W). The gyroscope pair 2-4 was used for the TGM test. Observations were obtained of a previously observed calibration target (GJ517; sp.type=K5Ve) coronagraphically and with direct imaging. The F110W filter performance very closely tracks the three gyro mode (ID: 10177) results. The observed jitter of ~6.2 mas had little effect on the 1.1 ėm coronagraphy. This result clearly shows that 1.1 ėm coronagraphy is robust against the observed TGM jitter. The NICMOS coronagraph inner working angle (IWA) is 3.2 ë/D at 1.1 ėm. Consequently, there is sufficient performance compliance to target decentering of these RMS amplitudes within the coronagraphic hole. There was a slight decline in performance with the F160W filter with respect to three gyro mode which may be due to imaging systematics; i.e., breathing and jitter. The 1.6 ėm coronagraphy is more susceptible to imaging systematics primarily due its broader PSF (IWA=2.2 ë/D). At r=10 pixels, the coronagraphic diffracted and scattered light suppression factor is ~3 compared to direct imaging, while it is a factor of 4 in three gyro mode. The observed coronagraphic performance is essentially unaffected at 1.1 ėm with TGM operations, while there is a marginal decline at 1.6 ėm of similar amplitude to that arising from other well-known HST/NICMOS orbit-driven instabilities. The improvement in image contrast (and dynamic range) with coronagraphy and TGM is still substantial over direct imaging.
G. Schneider, A. Schultz, S. Malhotra & I. Dashevsky 08 Jul 2005

NICMOS ISR 2005-002: Grism Sensitivities and Apparent Non-Linearity

Recent grism observations using the NICMOS instrument on HST have extended the spectrophotometric wavelength coverage of a subset of 16 STIS standard stars to ~2ėm. These observations include the three primary WD standards that are used to establish the absolute sensitivities of the three grism modes. However in their overlap region at 0.8-1.0ėm, the ratios of the STIS and NICMOS fluxes for brightest/faintest stars disagree by almost 25%. ACS spectrophotometry for two of the same stars in the same wavelength band agrees with STIS to 2%. A comparison of the grism spectrophotometry directly with ACS F850LP and F892N photometry for eight stars again verifies the need to correct the NICMOS grism data for non-linearity. After correction, the NICMOS grism fluxes have uncertainties ranging up to ~3% at 1.7ėm. The possible effect of this newly discovered apparent non-linearity on NICMOS photometry is being investigated with new NICMOS photometric observations and by comparisons with independent IR data sets.
R. Bohlin, D. Lindler, & A. Riess 10 May 2005

2004

NICMOS ISR 2004-002: New Exposure Time Calculator for NICMOS (imaging): Features, Testing and Recommendation

A new NICMOS ETC for imaging mode has been developed as part of the Astronomer's Proposal Toolkit (APT) project. This new tool fully updates the NICMOS performance for Cycles 11+, expands the funtionality of the previous ETC, providing the user more options, and homogenizes the non-instrument specific parameters (i.e. sky background, extinction laws) with other HST-ETCs. This report summarizes its main characteristics, and gives some recommendations to potential users. Details about the tool itself can be found in the documentation linked to the ETC user interface, which can be accessed from the NICMOS web site at STScI.
S. Arribas 26 Feb 2004

NICMOS ISR 2004-001: NICMOS Coronagraphic Calibration

The NICMOS coronagraphic imaging mode has been fully reactivated following SM3B, performing slightly better than during Cycle 7. The diffractive rejection is essentially unchanged (to first order) from Cycle 7 except there is a shift in the mean position of the cold mask which gives better second-order rejection on the downsloping diffraction spikes and slightly worse on the upsloping diffraction spikes. A target can be positioned within ~0.08 pixel (~5.8 mas) of the coronagraphic hole low-scatter position, with a repeatability of ~0.04 pixel (~2.9 mas) for two visits executed within the same orbit, with a roll between visits. The coronagraphic focus was checked and no adjustment was needed. The Cycle 7 coronagraphic focus position is still the best focus. A slight adjustment was made to the PAMC tilt to remove some coma that was not present during Cycle 7. The "hole 32x32 pixel subarray" field-of-regard (FOR) was adjusted by a few pixels in each direction due to displacement of the hole image on the detector caused by the warm up at the end of Cycle 7 and subsequent cool down following SM3B. A new ACQ FOR "gain" table (flat field) was installed to handle hot and cold pixels, allowing Mode-2 acquisitions for targets from H=4 to 17. The coronagraphic hole low scatter point, the "sweet spot," was checked and a slight adjustment was required to achieve light suppression about the coronagraphic hole comparable to or slightly better than that achieved during Cycle 7.
A. Schultz 30 Jan 2004

2003

NICMOS ISR 2003-011: NICMOS Cycle 12 Calibration Plan

This document summarizes the NICMOS Calibration Plan for Cycle 12. (CPC12). The plan complements the SMOV3b, the Cycle 10 (interim), and the Cycle 11 calibration programs. These previous programs have shown that the instrument is very stable, which has motivated a reduction in the frequency of the monitoring programs for CPC12. Because this stable behavior, systematic errors in the calibration become more important. For this reason CPC12 includes two programs aimed at reducing such errors: the photometric and spectroscopic recalibrations. The CPC12 also includes an outsourced calibration to enable coronagraphic + polarimetric observations.
S. Arribas 11 Nov 2003

NICMOS ISR 2003-010: Removal of Cosmic Ray persistence From Science Data using the Post-SAA Darks

Latent or persisten images of cosmic ray hits following HST transits of the South Atlantic Anomaly (SAA) can signicantly increase the noise in subsequent NICMOS science images. By taking a pair of DARK exposures immediately following the exit of the SAA, a map of the persistent signal can be made and then used to subtract this signal from the impacted images in that orbit, thereby recovering much of the original S/N. We here describe an algorithm to do this
E. Bergeron and M. Dickenson 07 Oct 2003

NICMOS ISR 2003-009: NICMOS IntraPixel Sensitivity

A study of the NICMOS (Camera 3) intrapixel sensitivity is carried out after installation of cryo-cooler in Cycle 11. The consistency of the procedure adopted here is tested by applying it to the data in Cycle 7, as analyzed by Storrs et al (1999), and reproducing their results. The intrapixel sensitivity in Cycle 11 is then measured and compared to that in Cycle 7 (before the installation of the NICMOS cryo-cooler). We find 27% decrease in the intrapixel sensitivity from Cycle 7 to Cycle 11 for both F110W (J-band) and F160W (Hband) filters. The possibility of this effect being due to an increase in the stellar PSF over this period is considered and discarded, as we only find 5% change in the PSF between the two cycles. .
C. Xu and B. Mobasher 23 Sep 2003

NICMOS ISR 2003-008: NICMOS Temperature Table

Nine NICMOS Cooling System (NCS) mnemonics and five temperature sensors are extracted from the engineering telemetry and bundled together into an STSDAS FITS table, the NICMOS Temperature Table. The FITS binary table has the same ipppssoot as the corresponding science observation with a file name extension of "epc". The table is created by the Engineering Data Processing System (EDPS) and can be retrieved with the science data from the HST Archive for which OTFR has been requested. The table is provided as an aid for use in calibration, temperature monitoring, and as a convenience to science data users.The table will be available following installation OPUS 14.4.
A.B. Schultz 02 Sep 2003

NICMOS ISR 2003-007:Analysis of the HST Thermal Background as Seen by NICMOS and NCS

This report describes the results from the SMOV3b and Cycle 11 thermal background calibration programs for NICMOS. The HST aft shroud is warmer due to ongoing degradation of the external MLI and increased power of the instruments installed during SM3B (ACS and the Nicmos Cooling System (NCS)). This warms the NICMOS fore-optics, affecting the thermal background in long wavelength camera 2 and camera 3 filters by approximately 20% beyond the increase due to DQE alone. This should be taken into account when planning observations with these cameras in filters longward of 1.9 microns, or in especially broad filters such as F175W in camera 3. Since camera 1 has no filters with a central wavelength longward of 1.9 microns, thermal emission effects in this camera are not an issue, and have not been studied.
M. Sosey 14 May 2003

NICMOS ISR 2003-006: A Test of non-Standard Gain Settings for the NICMOS Detectors

We report on the results of a test program to explore the potential scientific benefit of using non-standard gain settings in NICMOS observations. While this capability had originally been included in the NICMOS design, it has never been used on orbit. We present our analysis of the test data, discuss the potential scientific benefits, and outline the necessary modifications to planning, implementation, and pipeline calibration of NICMOS data taken with non-standard gain settings.
C. Xu & T. Boeker 13 May 2003

NICMOS ISR 2003-005: NICMOS Focus Monitoring in the Year Following SMOV 3b

Monthly monitoring of the NICMOS focus since SMOV 3b, following the installation of the NICMOS Cooling System (NCS) has revealed stable and consistent focus measurements in all three cameras. The focus values for each camera, which were measured and uplinked to the Telescope during SMOV 3b are accurate and have not required any revision.
E. Roye 23 Apr 2003

NICMOS ISR 2003-004: Measuring the Cold Mask Offset

An unexpected increase in measured thermal background during the Cycle 11 early calibration program caused speculation that the cold mask position could have shifted since Cycle 7. To address this concern, a single orbit NICMOS program was executed (Program ID: 9704) to obtain deep PSF images of the star LHS1846 in all three cameras. Analysis of this data using the Phase Retrieval software package revealed a minimal amount of cold mask shift since Cycle 7 and provided new, more accurate cold mask values for the Tiny Tim PSF modeling software. It was concluded that the cold mask position was not the cause of increased thermal background observed during the Cycle 11 early calibration program. Increased thermal background has since been determined to be the result of increased thermal load on the HST aft shroud due to the addition of ACS and NCS during SM3b.
E. Roye 23 Apr 2003

NICMOS ISR 2003-003: NICMOS Monitoring Stability

A review of the NICMOS monthly flat field monitoring data (program IDs: 9326, 9640) indicates that the NICMOS cameras are functioning as expected due in large part to the stable temperature provided by the NICMOS Cooling System (NCS). The flat field data (lamp-on) filter count rates have remained constant following SM3B/SMOV indicating that detector sensitivity and the lamps fluxes have remained constant. Additionally, pixel saturation levels have essentially remained unchanged since SMOV. The number of grot affected pixels has not changed since SMOV indicating stability within the dewar. Note that there was an increase in the number of grot affected pixels following Cycle 7 & 7N with the addition of a large chunk in the lower right quadrant of NIC1. Dithering to remove the affects of grot is recommended. A check of the NIC2 coronagraphic hole image location shows hole motion similar to what was observed during Cycle 7 & 7N. Coronagraphic observers should taylor their observations to minimize the effects of hole motion on their data. Incremental monthly and super flat field reference files have been created and delivered to the HST Archive for user support.
A.B. Schultz 02 Apr 2003

NICMOS ISR 2003-002: NICMOS Memory/Hardware Anamolies

NICMOS has experienced Error Detection and Correction (EDAC) single-bit EDAC errors, TPG resets, and Intel Exception problems. Except for the last error, the EDAC errors have been specific to the same memory address location. They are handled by software. A Timing Pattern Generator (TPG) reset occurs when a spurious signal is generated caused by a high energy particle event. The NICMOS flight software (FSW) was modified to handle TPG resets. An Intel Exception will suspend the instrument. There is all likelihood that additional similar EDAC errors, TPG resets, and suspends due to an Intel Exception problem will occur during the on-orbit life time of NICMOS. This ISR is intended to document the hardware errors and to be a resource when additional errors occur.
A.B. Schultz 03 Feb 2003

NICMOS ISR 2003-001: High Signal-to-Noise, Differential NICMOS Spectrophotometry

We report analysis for NICMOS CAL/9642, High S/N Capability Characterization.The purpose of this three orbit test was to establish NICMOS time domain stability in a domain not previously tested for NICMOS. Observations of the bright (H = 6.13) G0 V star HD 209458 were obtained using 1.8 second MULTIACCUMs with G141 on NIC3. Exposure-to-exposure stability summed over the full spectrum provides S/N of 2000, i.e. we demonstrated 0.5 mmag photometric precision treating the observations simply as broad-band, time-series photometry. Orbit-to-orbit means in a 0.2 micron band taken in ratio to neighboring continuum, without applying any corrections for correlated variations in contemporaneous auxiliary parameters, differed by only 3x10-4. A much better result was obtained with application of such corrections, but the result cannot be considered secure with comparison of only two orbits data. There is an excellent chance that in applications with sufficient flux to generate the required Poisson limit, that well planned NICMOS observations can provide differential spectrophotometric stability better than 1 part in 10,000 if not even significantly better.
R.L. Gilliland and S. Arribas 08 Jan 2003

2002

NICMOS ISR 2002-005: Implementation of the Temperature-Dependent Dark Correction in CalnicA

The pipeline implementation of the temperature-dependent dark correction, previously only available to users as a WWW tool, is described. The algorithm used to generate the darks is described, along with a description of how the IDL code and data that are used in the WWW tool were incorporated into the usual HST pipeline model of code+reference files. This implementation necessitated the creation of a new reference file type: the Temperature- Dependent Dark (TDD) file. The design of this file type allowed many of the hard constants to be removed from the code and put into the reference files, allowing more convenient and flexible updating of the calibration parameters, if necessary.
R. Jedrzejewski 15 Jun 2009

NICMOS ISR 2002-004: SM3b Science Flats

This report describes the results from the NICMOS pointed flat-field calibration program for SM3B. During programs 8998, 9557, and 9327, multiple sky background and lamp-on exposures were obtained for all filters with all cameras. Analysis of the DQE reveals that the relative countrates are at expected levels with respect to the operating temperature of 77K and are all within 8% of the ratio of modeled QE at 77K-to-62K performed during the 1997/1998 warm-up program. The resulting lamp-on minus background images were normalized to create the final calibration reference files.
L. Mazzuca 17 Oct 2002

NICMOS ISR 2002-003: NICMOS Cycle 11 Calibration Plan

This document describes the NICMOS calibration activities for Cycle 11. It complements the SMOV3b and the NICMOS Cycle 10 interim calibration programs. These activities cover a period of 13 months and pursue the following major objectives: i) to monitor the main instrument properties, ii) to test the model for generating darks, iii) to analyze in detail the intra-pixel sensitivity effects for cameras 2 and 3, iv) to calibrate the polarimetry mode, and v) to establish NICMOS stability when tracking differential (spectrophotometric) changes over time. In addition, a contingency program (‘Pupil Transfer Function’) will be activated if differential photometry over the chips obtained from SMOV data does not reach the required levels of accuracy.
S. Arribas 16 Jul 2002

NICMOS ISR 2002-002b: SM3B NICMOS Focus Check

We report determinations of the NICMOS foci following cool down of the NICMOS detectors after installation and activation of the NICMOS Cooling System (NCS). A focus sweep in all three cameras executed on May 3, 2002 (program ID: 8977). Visual inspection of the data indicated that a small amount of coma had been introduced since January 1999. Phase retrieval (STScI) and encircled energy (University of Arizona) measurements were used to determine the best focus positions. The results of the two methods compared quite favorably with each other. Adjustments to the current Pupil Alignment Mechanism (PAM) positions were implemented on May 9, 2002 for Camera 1 & 2 (PAM1 & PAM2). No focus adjustments were implemented for Camera 3 (PAM3) or for the Camera 2 coronagraphic focus (PAMC). Adjustment of the intermediate focus position between Camera 1 & 2 (PAMI) will be managed starting during week 2002.133 by SMS.
A. B. Schultz 12 Jun 2002

NICMOS ISR 2002-002: NICMOS Cycle 10 Interim Calibration Plan

This document describes the NICMOS calibration activities for cycle 10 which will execute after the completion of the SMOV3b program and before the start of the routine Cycle 11 calibration program. These activities cover a period of approximately 5 months and pursue the following objectives: i) enable calibration of the imaging mode for the three cameras and all the spectral elements, ii) complete the calibrations of the spectroscopic mode, iii) monitor during this period key aspects of the instrument (optics stability, detectors properties, scientific capability), and iv) to perform special calibrations (i.e. ‘gain test’; accum-darks to support post-SAA observations) which were not implemented in the SMOV3b program .
S. Arribas 14 Mar 2002

NICMOS ISR 2002-001: Bad Pixel Masks

A study of the frequency and location of the NICMOS bad pixels in each of the three cameras had not been undertaken since the instrument was commissioned on-board HST in 1997. The original MASKFILEs located in the calibration database (CDBS) were compiled with data taken during Systems Level Thermal Vacuum (SLTV) ground testing in August 1996. This analysis examined dark frames taken during the initial lifetime of NICMOS, March 1997 - January 1999, and details the creation of new bad pixel masks for each camera. Updated flat field reference files were also created as a result of this analysis.
M. Sosey 14 Feb 2002

2001

NICMOS ISR-1997-026: Characteristics of NICMOS Detector Dark Observations

This ISR describes the characteristics of the dark current for the NICMOS detectors. We then describe a recipe for generating `synthetic' dark current calibration reference files, which could be used to generate darks for any arbitrary sequence of MULTIACCUM reads, and present results of a comparison of such a synthetic dark with observed data.
NICMOS Group 09 Apr 2012

NICMOS ISR-026: Characteristics of NICMOS Detector Dark Observations

This ISR describes the characteristics of the dark current for the NICMOS detectors. We then describe a recipe for generating `synthetic' dark current calibration reference files, which could be used to generate darks for any arbitrary sequence of MULTIACCUM reads, and present results of a comparison of such a synthetic dark with observed data.
NICMOS Group 09 Apr 2012

NICMOS ISR 2001-002: NICMOS OTFR: A Feasibility Study for Improved Scientific Return

We examine the feasibility and utility of performing bias drift corrections to NICMOS data in a pipeline environment, with a specific eye towards the use of these routines in an “On The Fly Reprocessing” (OTFR) system. We have investigated the feasibility of the required calibration software implementation, as well as the scientific quality of the data that would be produced by such a system. Our results indicate that the implementation would be quite straight-forward, and that the calibrated data products would offer a vast improvement over the currently-available products and would be immediately usable for scientific analysis with little or no further post-pipeline processing.
H. Bushouse 14 Nov 2001

NICMOS ISR 2001-001: Performance of the NICMOS ETC Against Archived Data

A robust test of the newest version of the NICMOS Exposure Time Calculator (ETC) was conducted in order to assess its performance against actual NICMOS datasets in predicting an accurate Signal - to - Noise ratio for observation planning. All available signal regimes were explored and the results show good agreement with the ETC for all cases.
M. Sosey 14 Nov 2001

2000

NICMOS ISR 2000-005: The new NICMOS Exposure Time Calculator: Software and Installation

This report describes the latest version of the NICMOS Imaging Exposure Time Calculator (ETC) from a software developer and instrument support point of view. This ETC uses STScI Calibration Data Base tables for instrument and telescope data, and STSDAS.SYNPHOT for its throughput engine. It uses a self-contained library to calculate thermal background due to telescope and instrument optics. We describe technical details of the software in case observers wish to extend the capabilities of the ETC.
A. Sivaramakrishnan 14 Nov 2001

NICMOS ISR-2000-003 Results of the June 2000 NICMOS-NCS EMI Test

We summarize the findings of the NICMOS+NCS EMI Tests conducted at Goddard Space Flight Center in June 2000. No NCS-induced noise was detected over a wide range of read-out sequences and compressor speeds. The sensitivity of the test data was close to on-orbit performance, thus the improved NCS design appears well suited for restoring NICMOS capabilities without degrading its sensitivity.
S. Holfeltz 14 Nov 2001

NICMOS ISR-2000-004 NICMOS Warm Darks

NICMOS was commanded to Observe on June 19, 2000 and on June 30, 2000. A series of MULTIACCUM and ACCUM darks were executed as part of the flight software (FSW 4.0C) installation. As expected, the darks were saturated at the current temperature of ~230o K. Real-time monitoring of the instrument during the dark observations indicates that NICMOS is healthy and functioning as expected.
A. Schultz 14 Nov 2001

NICMOS ISR-00-001: The NICMOS Exposure Time Calculator: Algorithms and User Interface

This report describes the latest version of the NICMOS Exposure Time Calculator (ETC) developed to support NCS-era HST NICMOS planning. We added a thermal optics library to the ETC, and model various detector behaviors seen during the NICMOS end-of-life period. There are no ad-hoc parameter values in the thermal optics library describing the telescope and the NICMOS camera. This ETC supports imaging through all filters except the grisms.
A. Sivaramakrishnan 14 Nov 2001

NICMOS ISR 00-002: NICMOS Dark Current Anomaly: Test Results

We report on the results of a laboratory test program to investigate the nature of the NICMOS dark current anomaly. The test was designed to investigate one proposed mechanism of signal electrons - excited into the conduction band by infrared photons - being stored at low temperatures in charge traps throughout the detector material and released during warmup. The test did not reproduce the bump, and the proposed scenario could not be confirmed. The nature of the anomaly thus remains unexplained. We discuss this result with regard to possible alternative explanations and options for testing them.
Boker, T. 25 Sep 2007

1999

george test

this is a test
L. Mazzuca 14 Nov 2001

1997

NICMOS ISR -1997-025: NICMOS Pointed Thermal Background: Results from On-Orbit data

This ISR presents the results of the analysis of NICMOS pointed thermal background data taken as part of the Servicing Mission Orbital Verification (SMOV).
D. Daou 14 Nov 2001

NICMOS ISR-1997-027: Camera 3 Performance

We present information on the curent optical performance of NICMOS camera 3 (NIC3) at J, H, and K, obtained without moving the HST secondary mirror, i.e. the performance obtainable today, outside a NIC3 'campaign'. We also assess the performance that can be expected if the HST secondary is refocused to bring NIC3 into focus.
A. Storrs 14 Nov 2001

1996

NICMOS ISR 1996-019: Cosmic Rays on NICMOS: Results from Thermal Vacuum Data

The analysis of NICMOS data obtained during the System Level Thermal Vacuum Test in August 1996 has yielded some information on the sensitivity of the NICMOS detectors to cosmic ray hits.
D. Calzetti 14 Nov 2001

2010

NICMOS ISR 2010-001: Finesky – removing higher order sky residuals

We report on a new IRAF task called finesky that removes higher order sky residuals in NICMOS images by creating a masked median image of the observed sky. This median sky image is thereafter subtracted from the science images. A residual signal after image processing using the calibration software calnica may be present due to reference files that do not sufficiently match the conditions of the observations. This includes a slight mismatch in the dark current or the flat-field corrections. The task described here can also used to create sky flat-field images.
T. Dahlen, D. Grumm 06 Jul 2010

2009

NICMOS ISR 2009-008: NICMOS Breathing and Focus Field Variations

The focus of the NICMOS cameras is monitored on a regular basis. In order to achieve consistency in the focus determination, several effects have to be taken into consideration. The main ones affecting NICMOS are: (1) thermally induced movement of the secondary mirror (a.k.a. breathing), and (2) a curved focal plane for all three cameras. The latter is known as NICMOS Focus Field Variation and affects both the measurement of the focus and gives a position dependent Point Spread Function. In this Instrument Science Report we discuss the breathing corrections in the context of the NICMOS Focus Monitoring Program, and re-measure the Focus Field Variations.
T. Wiklind 06 Jul 2009

NICMOS ISR 2009-007: CalTempFromBias: Implementation and Testing

This ISR describes the CalTempFromBias program which was developed to estimate the temperature of each of the three NICMOS detectors individually. Unlike previous NICMOS temperature estimates, which are derived from a mounting cup sensor, these temperatures are derived using the bias level of the detectors themselves. The uncertainty associated with these temperature-from-bias values are 0.05K and are the basis for the new temperature-dependent calibration products for NICMOS data. This ISR describes the program CalTempFromBias, its options, and its applications.
N. Pirzkal 09 Jul 2009

NICMOS ISR 2009-006: NICMOS Grism Wavelength Calibration

As part of the Cycle 16 NICMOS calibration program, new observations of planetary nebulae were obtained using all three NICMOS grisms (G096, G141, and G206). The aim of these observations was to re-derive the dispersion relations for the grism modes of NICMOS as well as to examine and parametrize any field dependence of the dispersion relation within the field of view of the instrument. In this ISR, we present updated versions of the dispersion relations of the G096, G141, and G206 grisms. While the field dependence is small (1-2% peak to peak variation), we also compute two dimensional polynomial solutions to compute more exact dispersion relations anywhere in the field of view of NICMOS.
N. Pirzkal 29 Jun 2009

NICMOS ISR 2009-005: NICMOS Temperature Dependent Flat-fields

The bias-derived detector temperature for all three NICMOS cameras showed a variation of about ~2K in both the era before the installation of the NICMOS Cooling System (NCS) 1997-1998, as well as in the post-NCS era, 2002-2008. This temperature variation affected the detector quantum efficiency (DQE) and hence the structure of the flat-fields. In this ISR we discuss the creation of new temperature dependent flat-field reference files that correct for the effect of temperature on the DQE. Temperature dependent flat-fields (*_tdf.fits) populate the keyword TDFFILE in the headers of post-NCS data retrieved after November 19, 2008 and pre-NCS data retrieved after January 23, 2009. The temperature dependent flat-fields are used by the FLATCORR step in calnica version 4.4 and later. For consistency check we also created epoch dependent flatfields for postNCS data and compared them with the temperature dependent flatfields. The result of this analysis is also included here.
D. Thatte 09 Jul 2009

NICMOS ISR-2009-004: NICMOS Photometric Calibration Pipeline

We present the details of the NICMOS Photometric Calibration Pipeline used to generate aperture photometry. We present an overview of the different corrections employed, explain components of the pipeline and also outline the types of photometric and statistical data products created. In de Jong et al. (in preparation) this photometry will be used to determine the photometric calibration constants stored in the PHOTTAB reference files.
A. C. Viana 29 Jun 2009

NICMOS ISR 2009-003: Updates to Calnica: Using Temperature Dependent Reference Files

This report describes how the calnica data reduction software implements temperature dependent reference files in order to correct for temperature dependent variations in the dark current, the flat-fields, and the flux calibration. We describe in detail the logic used by the software to decide when to apply a temperature dependent correction and which temperature to use in that case.
T. Dahlen 29 Jun 2009

NICMOS ISR 2009-002: Temperature Dependent Dark Reference Files: Linear Dark and Amplifier Glow Components

This report describes the investigation of the temperature dependence of the linear dark and amplifier glow components of the NICMOS temperature dependent *_tdd.fits dark reference files in the post-NCS era, 2002-2008. We find a significant temperature dependence of the amplifier glow signal with higher counts at higher temperature when using the bias-derived detector temperature. The linear dark should also be dependent on temperature, however, the expected change in dark current should to be smaller than the scatter introduced from the read noise. This is consistent with what we find. We also describe how the calnica reduction software uses the temperature dependent dark components when calibrating NICMOS images.
T. Dahlen 15 Jun 2009

NICMOS ISR 2009-001: New Bad Pixel Mask Reference Files for the Post-NCS Era

The last determined bad pixel masks for the three NICMOS cameras were made in September 2002. Those masks were created using data from calibration programs following the installation of the NCS and are therefore based on the relatively limited data set available at the time. Since then, the NICMOS calibration monitoring programs have regularly obtained calibration images of both flat-fields and darks, images used to create the mask reference files. With numerous images taken during a long base-line (2002-2008), this data set allows us to create high signal-to-noise reference files, as well as investigate any temporal dependence of the mask files. In this ISR we describe the creation of new mask files based on this extended data set and compare the new masks with the previous versions. The new masks created contain a higher number of bad pixels compared to the old versions, while the number of pixels thought to be affected by “grot” is lower.
E. Barker, T. Dahlen 15 Jun 2009

2008

NICMOS ISR 2008-004: Summary of NICMOS SMOV4 Plans

This ISR outlines the NICMOS plan for Servicing Mission Observatory Verification 4 (SMOV4). It presents the NICMOS requirements, the planned activities to fulfill these requirements and a brief plan for the data reduction and analysis.
T. Wiklind 14 Aug 2008

NICMOS ISR 2008-003: Verifying the NICMOS Count Dependent Non-Linearity Correction

We re-investigate the NICMOS count dependent non-linearity, using the flat field lamps to reach high count regimes. The NICMOS count dependent non-linearity has been previously quantified and is currently corrected in NICMOS pipeline. In this document we show that the count dependent correction is still accurate to within 1.2% of true linearity for counts above 100 ADU independent of filter used. This is a response to the count-rate dependent non-linearity investigations, to eliminate questions about the current count dependent corrections.
B. Shaw, R. S. de Jong 08 Aug 2008

NICMOS ISR 2008-002: Improvements to Calnica

This ISR describes a number of improvements to calnica, the STSDAS task that performs routine instrumental calibration of NICMOS raw images. We report two major and a number of minor updates to the code. The major updates consist of changes in the way the count rate is calculated from up-the-ramp fitting and changes in the cosmic rays rejection algorithm. All updates have been extensively tested and analysis shows improvement in the S/N of output images by 6-15% compared to the previous calnica version. A further improvement is that the error extension in the calibrated images now represents the true errors in a more consistent way compared to the old implementation of the software.
T. Dahlen 06 Jun 2008

NICMOS ISR 2008-001: Bright Earth Persistence in NICMOS

We report the presence of image persistence in NICMOS data due to prior saturation of the array by the bright Earth as well as an algorithm to remove its impact. BEP (Bright Earth Persistence) may occur when ACS and NICMOS are used in parallel, and the data dump of ACS delays the insertion of the NICMOS filter blank as long as 6 minutes beyond the Bright Earth avoidance angle. We have constructed a BEP frame which can be used to model and remove the presence of BEP in NICMOS data. The algorithm is seen to remove 99.5% of the variance in the background of BEP impacted Camera 2 data. Ongoing work involves broadening the applicability of the BEP correction to Camera 1 and 3 and making it available as a pyraf script through STSDAS.
A. Riess, E. Bergeron 20 Mar 2008

2007

NICMOS ISR 2007-004: NICMOS Cycle 15 Baseline Calibration Plans

This document summarizes the NICMOS Calibration Plans for Cycle 15. The monitoring programs from the previous Cycle 13 and 14 are carried out in Cycle 15. Additional calibration is included in order to improve the accuracy of previously archived NICMOS data.
N. Pirzkal 16 Jul 2007

NICMOS ISR 2007-003: NICMOS Focus Update

This ISR will address a number of changes in the way the NICMOS focus is monitored. It will provide a detailed explanation of those changes and a step-by-step description of the new procedure. The ISR also highlights the results of the focus checks after the HST safing event, which caused the NICMOS cooling system (NCS) anomalous shutdown in February of 2007.
H. McLaughlin 29 Jun 2007

NICMOS ISR 2007-002: NICMOS Time Dependent Flat-fields

We use data obtained during the NICMOS flat-field monitoring 2002-2007 to derive a set of time dependent flat-fields. These 'epoch' flat-fields are compared to the current pipeline flat-fields and differences are quantified. Our results are consistent with a decrease in DQE over the five-year period on the order of one per cent. We also find that the spatial structure of the flat-fields change with time. The reasons for these changes are not fully known, but we note that the changes are consistent with a change in detector temperature with time. The order of this effect is generally less than one percent. The 'epoch' flat-fields are available on the NICMOS web page1.
T. Dahlen 29 Jun 2007

NICMOS ISR 2007-001: Removing Post-SAA Persistence in NICMOS Data

A general concern with NICMOS images is the issue of 'persistence', or residual charge from bright sources and cosmic rays that remains trapped in pixels and is gradually released during subsequent exposures. This is particularly noticeable after HST transits of the South Atlantic Anomaly (SAA), where the cosmic ray rate is so high that their residual flux contributes a significant noise component to many subsequent exposures. We describe the 'SAAclean' task which can be run on post-SAA NICMOS images to identify the amount of charge in each pixel that can be attributed to persistent flux from SAA cosmic rays, and apply a correction based on an SAA persistence model to remove this flux from the data. This task has so far been tested on a variety of NICMOS data, and this represents the most recent update of this task in the PyRAF/STSDAS environment to the HST observer community.
E. Barker 15 May 2007

2006

NICMOS ISR 2006-004: Temperature Monitoring of NICMOS

NICMOS observations are dependent on a cold and stable thermal environment. In this ISR we describe the temperature monitoring and how a stable thermal environment for the NICMOS detectors is achieved. A comparison between the thermal properties of the cryogenically cooled dewar during Cycle 7 and the present cooling using using the NICMOS Cooling System, is presented. A complete thermal history from the start in 1997 up to January 2006 is presented.
T. Wiklind 26 Jul 2006

NICMOS ISR 2006-003: Correcting the NICMOS count-rate dependent non-linearity

We describe a routine to correct NICMOS imaging data for the NICMOS count-rate dependent non-linearity recently discovered by Bohlin et al. (2005) and quantified by de Jong et al. (2006) and Bohlin et al. (2006). The routine has been implemented in the python scripting language and is callable from the shell command line and from iraf. The routine corrects NICMOS count-rate images assuming the non-linearity follows a powerlaw behavior. The wavelength dependence of the non-linearity is interpolated between the measured points of de Jong et al. (2006) and Bohlin et al. (2006) if necessary. The count rates in the output images are modified and hence the standard NICMOS calibration zero-points are no longer valid. New calibration zero-points have been derived from standard star images corrected with the routine. The routine was tested on the lamp-on/off data used in de Jong et al. (2006) to measure the non-linearity effect. We apply the correction to the NGC1850 stellar cluster field and the Hubble Ultra Deep Field (HUDF) to show the magnitude offsets expected due to the non-linearity on objects with a range in luminosity and surface brightness.
R. de Jong 29 Mar 2006

NICMOS ISR 2006-002: NICMOS Count Rate Dependent Non-Linearity in G096 and G141

Since the discovery of the NICMOS count rate dependent non-linearity documented in NICMOS ISR 2005-002, additional tests have been conducted to further understand and quantify the effect. Long integrations of up to 25 minutes exhibited the same level of non-linearity as the original 1-3 minute integrations. Observations of the star P041C on high background from an internal flat field lamp provides another measure of the wavelength dependence of the nonlinearity to compliment the measures based on pure hydrogen WD models.
R. Bohlin 15 Feb 2006

NICMOS ISR 2006-001: NICMOS Count-rate Dependent Non-linearity Tests using Flatfield Lamps

We investigate the recently discovered NICMOS count-rate dependent non-linearity (Bohlin et al. 2005) using the flatfield lamps to artificially increase the count rate. A star cluster field was imaged in a lamp off-on-off sequence in all cameras in a selected set of filters, followed by a series of darks to investigate persistence and to clean the images from any remaining charge for the next orbit. Subtracting the lamp-off images from the lamp-on images clearly shows residual ADUs at the star positions, indicating that a higher background (and thus total) count rate increases the number of ADUs registered from an object. We model the non-linearity with a power law (count-rate å fluxƒŋ) and fit this model to the data. Both NIC1 and NIC2 (NIC3 was not tested in this program) show non-linearity, becoming stronger at shorter wavelengths, but with larger amplitude than predicted by the Bohlin et al. NIC3 measurements. The non-linearity in NIC1 and NIC2 amounts to 0.06-0.10 mag offset per factor ten change in incident flux for the shortest wavelength (F090M and F110W), about 0.03 mag/dex at F160W, and less at longer wavelengths. Archival data from Cycle 7 are also analyzed, showing that the nonlinearity has not changed in NIC2 F110W, and suggesting that this effect is independent of detector temperature.
R. de Jong 15 Feb 2006

2005

NICMOS ISR 2005-005: NICMOS Cycles 13 and 14 Calibration Plans

This document summarizes the NICMOS Calibration Plans for Cycles 13 and 14. These plans complement the SMOV3b, the Cycle 10 (interim), and the Cycles 11 and 12 (regular) calibration programs executed after the installation of the NICMOS Cooling System (NCS).. These previous programs have shown that the instrument is very stable, which has motivated a further reduction in the frequency of the monitoring programs for Cycle 13. In addition, for Cycle 14 some of these programs were slightly modified to account for 2 Gyro HST operations. The special calibrations on Cycle 13 were focussed on a follow up of the spectroscopic recalibration initiated in Cycle 12. This program led to the discovery of a possible count rate non-linearity, which has triggered a special program for Cycle 13 and a number of subsequent tests and calibrations during Cycle 14. At the time of writing this is a very active area of research. We also briefly comment on other calibrations defined to address other specific issues like: the autoreset test, the SPAR sequences tests, and the low-frequency flat residual for NIC1. The calibration programs for the 2-Gyro campaigns are not included here, since they have been described somewhere else. Further details and updates on specific programs can be found via the NICMOS web site.
S. Arribas 02 Dec 2005

NICMOS ISR 2005-004: NICMOS Small deltaT Dewar/NCS PID Model for Orbit Night Power Reduction

Without SM4 and the installation of new Ni-HB2B batteries, HST is facing a future with decreasing battery capacity. This ISR explores one option for reducing HST's battery load during orbit night while maintaining the science capability of the NICMOS. Modulating the NCS setpoint temperature, i.e., increasing it during orbit night and decreasing it during orbit day, can accomplish this. A linear NICMOS small deltaT thermal model was developed based on flight data serendipitously obtained during Proposal 10097, NICMOS Temperature Setpoint Darks, to predict camera one's temperature, NCS compressor speed, and total NCS power for modulations of +/-1, +/-2, and +/-3K. The results are presented.
T. Wheeler and M. Robinson 05 Oct 2005

NICMOS ISR 2005-003: A Test of Possible NICMOS Non-linearity

Observations of standard stars with NICMOS grism (G096), when compared with the same standards taken by STIS (G750L), show a disagreement over the wavelength range 0.8 to 1 micron. Further comparison with ACS F850LP data confirms thisnon-linearity to be due to NICMOS in the sense that fainter stars in NICMOS appear too faint relative to a brighter normalisation. We investigate this over a wide magnitude range by compiling samples of stars (over the range 8 < J < 17) and galaxies (spanning the range 17 < J < 25), with available data with both NICMOS (F110W and F160W) and ground-based JHbands. We find no difference between the NICMOS F160W and ground-based H-band magnitudes. However, in the case of NICMOS F110W and J-band filters, allowing for differences in the filter response functions, we find a trend at the bright-end (J < 17), confirming a non-linearity but smaller than that was seen in Bohlin effect by a factor of 2-3. No significant slope is seen at the faint-end. This non-linearity is interpreted as being due to trapping and the difference in exposure times between the bright and faint objects (Riess 2005). We conclude that most of the observations will not be strongly affected by this effect as the source count rates are sufficiently high so that the fraction of charge lost to traps is negligible. The most affected observations are for faint sources with relatively short exposures.
B. Mobasher and A. Riess 15 Aug 2005

NICMOS ISR 2005-001: NICMOS Two Gyro Mode Coronagraphic Performance

In preparation for the Hubble Space Telescope (HST) entry into Two Gyro Mode (TGM) operations, the NICMOS coronagraphic performance was assessed during the February 21, 2005 TGM on orbit test (ID: 10448) in two filter bands (F110W and F160W). The gyroscope pair 2-4 was used for the TGM test. Observations were obtained of a previously observed calibration target (GJ517; sp.type=K5Ve) coronagraphically and with direct imaging. The F110W filter performance very closely tracks the three gyro mode (ID: 10177) results. The observed jitter of ~6.2 mas had little effect on the 1.1 ėm coronagraphy. This result clearly shows that 1.1 ėm coronagraphy is robust against the observed TGM jitter. The NICMOS coronagraph inner working angle (IWA) is 3.2 ë/D at 1.1 ėm. Consequently, there is sufficient performance compliance to target decentering of these RMS amplitudes within the coronagraphic hole. There was a slight decline in performance with the F160W filter with respect to three gyro mode which may be due to imaging systematics; i.e., breathing and jitter. The 1.6 ėm coronagraphy is more susceptible to imaging systematics primarily due its broader PSF (IWA=2.2 ë/D). At r=10 pixels, the coronagraphic diffracted and scattered light suppression factor is ~3 compared to direct imaging, while it is a factor of 4 in three gyro mode. The observed coronagraphic performance is essentially unaffected at 1.1 ėm with TGM operations, while there is a marginal decline at 1.6 ėm of similar amplitude to that arising from other well-known HST/NICMOS orbit-driven instabilities. The improvement in image contrast (and dynamic range) with coronagraphy and TGM is still substantial over direct imaging.
G. Schneider, A. Schultz, S. Malhotra & I. Dashevsky 08 Jul 2005

NICMOS ISR 2005-002: Grism Sensitivities and Apparent Non-Linearity

Recent grism observations using the NICMOS instrument on HST have extended the spectrophotometric wavelength coverage of a subset of 16 STIS standard stars to ~2ėm. These observations include the three primary WD standards that are used to establish the absolute sensitivities of the three grism modes. However in their overlap region at 0.8-1.0ėm, the ratios of the STIS and NICMOS fluxes for brightest/faintest stars disagree by almost 25%. ACS spectrophotometry for two of the same stars in the same wavelength band agrees with STIS to 2%. A comparison of the grism spectrophotometry directly with ACS F850LP and F892N photometry for eight stars again verifies the need to correct the NICMOS grism data for non-linearity. After correction, the NICMOS grism fluxes have uncertainties ranging up to ~3% at 1.7ėm. The possible effect of this newly discovered apparent non-linearity on NICMOS photometry is being investigated with new NICMOS photometric observations and by comparisons with independent IR data sets.
R. Bohlin, D. Lindler, & A. Riess 10 May 2005

2004

NICMOS ISR 2004-002: New Exposure Time Calculator for NICMOS (imaging): Features, Testing and Recommendation

A new NICMOS ETC for imaging mode has been developed as part of the Astronomer's Proposal Toolkit (APT) project. This new tool fully updates the NICMOS performance for Cycles 11+, expands the funtionality of the previous ETC, providing the user more options, and homogenizes the non-instrument specific parameters (i.e. sky background, extinction laws) with other HST-ETCs. This report summarizes its main characteristics, and gives some recommendations to potential users. Details about the tool itself can be found in the documentation linked to the ETC user interface, which can be accessed from the NICMOS web site at STScI.
S. Arribas 26 Feb 2004

NICMOS ISR 2004-001: NICMOS Coronagraphic Calibration

The NICMOS coronagraphic imaging mode has been fully reactivated following SM3B, performing slightly better than during Cycle 7. The diffractive rejection is essentially unchanged (to first order) from Cycle 7 except there is a shift in the mean position of the cold mask which gives better second-order rejection on the downsloping diffraction spikes and slightly worse on the upsloping diffraction spikes. A target can be positioned within ~0.08 pixel (~5.8 mas) of the coronagraphic hole low-scatter position, with a repeatability of ~0.04 pixel (~2.9 mas) for two visits executed within the same orbit, with a roll between visits. The coronagraphic focus was checked and no adjustment was needed. The Cycle 7 coronagraphic focus position is still the best focus. A slight adjustment was made to the PAMC tilt to remove some coma that was not present during Cycle 7. The "hole 32x32 pixel subarray" field-of-regard (FOR) was adjusted by a few pixels in each direction due to displacement of the hole image on the detector caused by the warm up at the end of Cycle 7 and subsequent cool down following SM3B. A new ACQ FOR "gain" table (flat field) was installed to handle hot and cold pixels, allowing Mode-2 acquisitions for targets from H=4 to 17. The coronagraphic hole low scatter point, the "sweet spot," was checked and a slight adjustment was required to achieve light suppression about the coronagraphic hole comparable to or slightly better than that achieved during Cycle 7.
A. Schultz 30 Jan 2004

2003

NICMOS ISR 2003-011: NICMOS Cycle 12 Calibration Plan

This document summarizes the NICMOS Calibration Plan for Cycle 12. (CPC12). The plan complements the SMOV3b, the Cycle 10 (interim), and the Cycle 11 calibration programs. These previous programs have shown that the instrument is very stable, which has motivated a reduction in the frequency of the monitoring programs for CPC12. Because this stable behavior, systematic errors in the calibration become more important. For this reason CPC12 includes two programs aimed at reducing such errors: the photometric and spectroscopic recalibrations. The CPC12 also includes an outsourced calibration to enable coronagraphic + polarimetric observations.
S. Arribas 11 Nov 2003

NICMOS ISR 2003-010: Removal of Cosmic Ray persistence From Science Data using the Post-SAA Darks

Latent or persisten images of cosmic ray hits following HST transits of the South Atlantic Anomaly (SAA) can signicantly increase the noise in subsequent NICMOS science images. By taking a pair of DARK exposures immediately following the exit of the SAA, a map of the persistent signal can be made and then used to subtract this signal from the impacted images in that orbit, thereby recovering much of the original S/N. We here describe an algorithm to do this
E. Bergeron and M. Dickenson 07 Oct 2003

NICMOS ISR 2003-009: NICMOS IntraPixel Sensitivity

A study of the NICMOS (Camera 3) intrapixel sensitivity is carried out after installation of cryo-cooler in Cycle 11. The consistency of the procedure adopted here is tested by applying it to the data in Cycle 7, as analyzed by Storrs et al (1999), and reproducing their results. The intrapixel sensitivity in Cycle 11 is then measured and compared to that in Cycle 7 (before the installation of the NICMOS cryo-cooler). We find 27% decrease in the intrapixel sensitivity from Cycle 7 to Cycle 11 for both F110W (J-band) and F160W (Hband) filters. The possibility of this effect being due to an increase in the stellar PSF over this period is considered and discarded, as we only find 5% change in the PSF between the two cycles. .
C. Xu and B. Mobasher 23 Sep 2003

NICMOS ISR 2003-008: NICMOS Temperature Table

Nine NICMOS Cooling System (NCS) mnemonics and five temperature sensors are extracted from the engineering telemetry and bundled together into an STSDAS FITS table, the NICMOS Temperature Table. The FITS binary table has the same ipppssoot as the corresponding science observation with a file name extension of "epc". The table is created by the Engineering Data Processing System (EDPS) and can be retrieved with the science data from the HST Archive for which OTFR has been requested. The table is provided as an aid for use in calibration, temperature monitoring, and as a convenience to science data users.The table will be available following installation OPUS 14.4.
A.B. Schultz 02 Sep 2003

NICMOS ISR 2003-007:Analysis of the HST Thermal Background as Seen by NICMOS and NCS

This report describes the results from the SMOV3b and Cycle 11 thermal background calibration programs for NICMOS. The HST aft shroud is warmer due to ongoing degradation of the external MLI and increased power of the instruments installed during SM3B (ACS and the Nicmos Cooling System (NCS)). This warms the NICMOS fore-optics, affecting the thermal background in long wavelength camera 2 and camera 3 filters by approximately 20% beyond the increase due to DQE alone. This should be taken into account when planning observations with these cameras in filters longward of 1.9 microns, or in especially broad filters such as F175W in camera 3. Since camera 1 has no filters with a central wavelength longward of 1.9 microns, thermal emission effects in this camera are not an issue, and have not been studied.
M. Sosey 14 May 2003

NICMOS ISR 2003-006: A Test of non-Standard Gain Settings for the NICMOS Detectors

We report on the results of a test program to explore the potential scientific benefit of using non-standard gain settings in NICMOS observations. While this capability had originally been included in the NICMOS design, it has never been used on orbit. We present our analysis of the test data, discuss the potential scientific benefits, and outline the necessary modifications to planning, implementation, and pipeline calibration of NICMOS data taken with non-standard gain settings.
C. Xu & T. Boeker 13 May 2003

NICMOS ISR 2003-005: NICMOS Focus Monitoring in the Year Following SMOV 3b

Monthly monitoring of the NICMOS focus since SMOV 3b, following the installation of the NICMOS Cooling System (NCS) has revealed stable and consistent focus measurements in all three cameras. The focus values for each camera, which were measured and uplinked to the Telescope during SMOV 3b are accurate and have not required any revision.
E. Roye 23 Apr 2003

NICMOS ISR 2003-004: Measuring the Cold Mask Offset

An unexpected increase in measured thermal background during the Cycle 11 early calibration program caused speculation that the cold mask position could have shifted since Cycle 7. To address this concern, a single orbit NICMOS program was executed (Program ID: 9704) to obtain deep PSF images of the star LHS1846 in all three cameras. Analysis of this data using the Phase Retrieval software package revealed a minimal amount of cold mask shift since Cycle 7 and provided new, more accurate cold mask values for the Tiny Tim PSF modeling software. It was concluded that the cold mask position was not the cause of increased thermal background observed during the Cycle 11 early calibration program. Increased thermal background has since been determined to be the result of increased thermal load on the HST aft shroud due to the addition of ACS and NCS during SM3b.
E. Roye 23 Apr 2003

NICMOS ISR 2003-003: NICMOS Monitoring Stability

A review of the NICMOS monthly flat field monitoring data (program IDs: 9326, 9640) indicates that the NICMOS cameras are functioning as expected due in large part to the stable temperature provided by the NICMOS Cooling System (NCS). The flat field data (lamp-on) filter count rates have remained constant following SM3B/SMOV indicating that detector sensitivity and the lamps fluxes have remained constant. Additionally, pixel saturation levels have essentially remained unchanged since SMOV. The number of grot affected pixels has not changed since SMOV indicating stability within the dewar. Note that there was an increase in the number of grot affected pixels following Cycle 7 & 7N with the addition of a large chunk in the lower right quadrant of NIC1. Dithering to remove the affects of grot is recommended. A check of the NIC2 coronagraphic hole image location shows hole motion similar to what was observed during Cycle 7 & 7N. Coronagraphic observers should taylor their observations to minimize the effects of hole motion on their data. Incremental monthly and super flat field reference files have been created and delivered to the HST Archive for user support.
A.B. Schultz 02 Apr 2003

NICMOS ISR 2003-002: NICMOS Memory/Hardware Anamolies

NICMOS has experienced Error Detection and Correction (EDAC) single-bit EDAC errors, TPG resets, and Intel Exception problems. Except for the last error, the EDAC errors have been specific to the same memory address location. They are handled by software. A Timing Pattern Generator (TPG) reset occurs when a spurious signal is generated caused by a high energy particle event. The NICMOS flight software (FSW) was modified to handle TPG resets. An Intel Exception will suspend the instrument. There is all likelihood that additional similar EDAC errors, TPG resets, and suspends due to an Intel Exception problem will occur during the on-orbit life time of NICMOS. This ISR is intended to document the hardware errors and to be a resource when additional errors occur.
A.B. Schultz 03 Feb 2003

NICMOS ISR 2003-001: High Signal-to-Noise, Differential NICMOS Spectrophotometry

We report analysis for NICMOS CAL/9642, High S/N Capability Characterization.The purpose of this three orbit test was to establish NICMOS time domain stability in a domain not previously tested for NICMOS. Observations of the bright (H = 6.13) G0 V star HD 209458 were obtained using 1.8 second MULTIACCUMs with G141 on NIC3. Exposure-to-exposure stability summed over the full spectrum provides S/N of 2000, i.e. we demonstrated 0.5 mmag photometric precision treating the observations simply as broad-band, time-series photometry. Orbit-to-orbit means in a 0.2 micron band taken in ratio to neighboring continuum, without applying any corrections for correlated variations in contemporaneous auxiliary parameters, differed by only 3x10-4. A much better result was obtained with application of such corrections, but the result cannot be considered secure with comparison of only two orbits data. There is an excellent chance that in applications with sufficient flux to generate the required Poisson limit, that well planned NICMOS observations can provide differential spectrophotometric stability better than 1 part in 10,000 if not even significantly better.
R.L. Gilliland and S. Arribas 08 Jan 2003

2002

NICMOS ISR 2002-005: Implementation of the Temperature-Dependent Dark Correction in CalnicA

The pipeline implementation of the temperature-dependent dark correction, previously only available to users as a WWW tool, is described. The algorithm used to generate the darks is described, along with a description of how the IDL code and data that are used in the WWW tool were incorporated into the usual HST pipeline model of code+reference files. This implementation necessitated the creation of a new reference file type: the Temperature- Dependent Dark (TDD) file. The design of this file type allowed many of the hard constants to be removed from the code and put into the reference files, allowing more convenient and flexible updating of the calibration parameters, if necessary.
R. Jedrzejewski 15 Jun 2009

NICMOS ISR 2002-004: SM3b Science Flats

This report describes the results from the NICMOS pointed flat-field calibration program for SM3B. During programs 8998, 9557, and 9327, multiple sky background and lamp-on exposures were obtained for all filters with all cameras. Analysis of the DQE reveals that the relative countrates are at expected levels with respect to the operating temperature of 77K and are all within 8% of the ratio of modeled QE at 77K-to-62K performed during the 1997/1998 warm-up program. The resulting lamp-on minus background images were normalized to create the final calibration reference files.
L. Mazzuca 17 Oct 2002

NICMOS ISR 2002-003: NICMOS Cycle 11 Calibration Plan

This document describes the NICMOS calibration activities for Cycle 11. It complements the SMOV3b and the NICMOS Cycle 10 interim calibration programs. These activities cover a period of 13 months and pursue the following major objectives: i) to monitor the main instrument properties, ii) to test the model for generating darks, iii) to analyze in detail the intra-pixel sensitivity effects for cameras 2 and 3, iv) to calibrate the polarimetry mode, and v) to establish NICMOS stability when tracking differential (spectrophotometric) changes over time. In addition, a contingency program (‘Pupil Transfer Function’) will be activated if differential photometry over the chips obtained from SMOV data does not reach the required levels of accuracy.
S. Arribas 16 Jul 2002

NICMOS ISR 2002-002b: SM3B NICMOS Focus Check

We report determinations of the NICMOS foci following cool down of the NICMOS detectors after installation and activation of the NICMOS Cooling System (NCS). A focus sweep in all three cameras executed on May 3, 2002 (program ID: 8977). Visual inspection of the data indicated that a small amount of coma had been introduced since January 1999. Phase retrieval (STScI) and encircled energy (University of Arizona) measurements were used to determine the best focus positions. The results of the two methods compared quite favorably with each other. Adjustments to the current Pupil Alignment Mechanism (PAM) positions were implemented on May 9, 2002 for Camera 1 & 2 (PAM1 & PAM2). No focus adjustments were implemented for Camera 3 (PAM3) or for the Camera 2 coronagraphic focus (PAMC). Adjustment of the intermediate focus position between Camera 1 & 2 (PAMI) will be managed starting during week 2002.133 by SMS.
A. B. Schultz 12 Jun 2002

NICMOS ISR 2002-002: NICMOS Cycle 10 Interim Calibration Plan

This document describes the NICMOS calibration activities for cycle 10 which will execute after the completion of the SMOV3b program and before the start of the routine Cycle 11 calibration program. These activities cover a period of approximately 5 months and pursue the following objectives: i) enable calibration of the imaging mode for the three cameras and all the spectral elements, ii) complete the calibrations of the spectroscopic mode, iii) monitor during this period key aspects of the instrument (optics stability, detectors properties, scientific capability), and iv) to perform special calibrations (i.e. ‘gain test’; accum-darks to support post-SAA observations) which were not implemented in the SMOV3b program .
S. Arribas 14 Mar 2002

NICMOS ISR 2002-001: Bad Pixel Masks

A study of the frequency and location of the NICMOS bad pixels in each of the three cameras had not been undertaken since the instrument was commissioned on-board HST in 1997. The original MASKFILEs located in the calibration database (CDBS) were compiled with data taken during Systems Level Thermal Vacuum (SLTV) ground testing in August 1996. This analysis examined dark frames taken during the initial lifetime of NICMOS, March 1997 - January 1999, and details the creation of new bad pixel masks for each camera. Updated flat field reference files were also created as a result of this analysis.
M. Sosey 14 Feb 2002

2001

NICMOS ISR-1997-026: Characteristics of NICMOS Detector Dark Observations

This ISR describes the characteristics of the dark current for the NICMOS detectors. We then describe a recipe for generating `synthetic' dark current calibration reference files, which could be used to generate darks for any arbitrary sequence of MULTIACCUM reads, and present results of a comparison of such a synthetic dark with observed data.
NICMOS Group 09 Apr 2012

NICMOS ISR-026: Characteristics of NICMOS Detector Dark Observations

This ISR describes the characteristics of the dark current for the NICMOS detectors. We then describe a recipe for generating `synthetic' dark current calibration reference files, which could be used to generate darks for any arbitrary sequence of MULTIACCUM reads, and present results of a comparison of such a synthetic dark with observed data.
NICMOS Group 09 Apr 2012

NICMOS ISR 2001-002: NICMOS OTFR: A Feasibility Study for Improved Scientific Return

We examine the feasibility and utility of performing bias drift corrections to NICMOS data in a pipeline environment, with a specific eye towards the use of these routines in an “On The Fly Reprocessing” (OTFR) system. We have investigated the feasibility of the required calibration software implementation, as well as the scientific quality of the data that would be produced by such a system. Our results indicate that the implementation would be quite straight-forward, and that the calibrated data products would offer a vast improvement over the currently-available products and would be immediately usable for scientific analysis with little or no further post-pipeline processing.
H. Bushouse 14 Nov 2001

NICMOS ISR 2001-001: Performance of the NICMOS ETC Against Archived Data

A robust test of the newest version of the NICMOS Exposure Time Calculator (ETC) was conducted in order to assess its performance against actual NICMOS datasets in predicting an accurate Signal - to - Noise ratio for observation planning. All available signal regimes were explored and the results show good agreement with the ETC for all cases.
M. Sosey 14 Nov 2001

2000

NICMOS ISR 2000-005: The new NICMOS Exposure Time Calculator: Software and Installation

This report describes the latest version of the NICMOS Imaging Exposure Time Calculator (ETC) from a software developer and instrument support point of view. This ETC uses STScI Calibration Data Base tables for instrument and telescope data, and STSDAS.SYNPHOT for its throughput engine. It uses a self-contained library to calculate thermal background due to telescope and instrument optics. We describe technical details of the software in case observers wish to extend the capabilities of the ETC.
A. Sivaramakrishnan 14 Nov 2001

NICMOS ISR-2000-003 Results of the June 2000 NICMOS-NCS EMI Test

We summarize the findings of the NICMOS+NCS EMI Tests conducted at Goddard Space Flight Center in June 2000. No NCS-induced noise was detected over a wide range of read-out sequences and compressor speeds. The sensitivity of the test data was close to on-orbit performance, thus the improved NCS design appears well suited for restoring NICMOS capabilities without degrading its sensitivity.
S. Holfeltz 14 Nov 2001

NICMOS ISR-2000-004 NICMOS Warm Darks

NICMOS was commanded to Observe on June 19, 2000 and on June 30, 2000. A series of MULTIACCUM and ACCUM darks were executed as part of the flight software (FSW 4.0C) installation. As expected, the darks were saturated at the current temperature of ~230o K. Real-time monitoring of the instrument during the dark observations indicates that NICMOS is healthy and functioning as expected.
A. Schultz 14 Nov 2001

NICMOS ISR-00-001: The NICMOS Exposure Time Calculator: Algorithms and User Interface

This report describes the latest version of the NICMOS Exposure Time Calculator (ETC) developed to support NCS-era HST NICMOS planning. We added a thermal optics library to the ETC, and model various detector behaviors seen during the NICMOS end-of-life period. There are no ad-hoc parameter values in the thermal optics library describing the telescope and the NICMOS camera. This ETC supports imaging through all filters except the grisms.
A. Sivaramakrishnan 14 Nov 2001

NICMOS ISR 00-002: NICMOS Dark Current Anomaly: Test Results

We report on the results of a laboratory test program to investigate the nature of the NICMOS dark current anomaly. The test was designed to investigate one proposed mechanism of signal electrons - excited into the conduction band by infrared photons - being stored at low temperatures in charge traps throughout the detector material and released during warmup. The test did not reproduce the bump, and the proposed scenario could not be confirmed. The nature of the anomaly thus remains unexplained. We discuss this result with regard to possible alternative explanations and options for testing them.
Boker, T. 25 Sep 2007

1999

george test

this is a test
L. Mazzuca 14 Nov 2001

1997

NICMOS ISR -1997-025: NICMOS Pointed Thermal Background: Results from On-Orbit data

This ISR presents the results of the analysis of NICMOS pointed thermal background data taken as part of the Servicing Mission Orbital Verification (SMOV).
D. Daou 14 Nov 2001

NICMOS ISR-1997-027: Camera 3 Performance

We present information on the curent optical performance of NICMOS camera 3 (NIC3) at J, H, and K, obtained without moving the HST secondary mirror, i.e. the performance obtainable today, outside a NIC3 'campaign'. We also assess the performance that can be expected if the HST secondary is refocused to bring NIC3 into focus.
A. Storrs 14 Nov 2001

1996

NICMOS ISR 1996-019: Cosmic Rays on NICMOS: Results from Thermal Vacuum Data

The analysis of NICMOS data obtained during the System Level Thermal Vacuum Test in August 1996 has yielded some information on the sensitivity of the NICMOS detectors to cosmic ray hits.
D. Calzetti 14 Nov 2001