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Hubble Space Telescope
COS Instrument Science Reports

2018

ISR 2018-22: Improvements to the COS FUV G130M and G160M Wavelength Solutions at Lifetime Position 1

The wavelength dispersion coefficients and zero points of the COS FUV G130M and G160M gratings at each lifetime position (LP1, LP2, LP3, LP4) have been re-derived. In this document we present the analysis behind the improvements of the wavelength solutions for data obtained at LP1 (i.e., before July 2012). Discussions of the methodology used to derive updated wavelength solutions at lifetime positions 2, 3, and 4 are presented in separate documents. In this analysis, we have used archival data of objects that were observed with both COS and an overlapping STIS echelle mode to determine the dispersion coefficient and an initial measurement of the zero point for each standard cenwave setting. The zero points were then refined using archival COS programs where multiple cenwaves were used within a single visit, which provided a better relative alignment between COS modes. The wavelength solution accuracy has been improved from ~15 km/s (1 resolution element) to ~7.5 km/s (0.5 resolution element), with the greatest correction occurring for each grating at the longest cenwaves (i.e., 1327 and 1623).
R. Plesha 20 Nov 2018

ISR 2018-20: Flat Fields and Flux Calibrations for the COS FUV Channel at Lifetime Position 4

As part of the calibration of the fourth lifetime position (LP4) of the Cosmic Origins Spectrograph (COS) Far-Ultraviolet (FUV) detector, we derived low-order flat fields (L flats) and sensitivities. To do this, spectra of the star WD 0308-565 were obtained with the G130M, G160M, and G140L gratings, and spectra of the star GD 71 were obtained with the G160M grating, all through the Primary Science Aperture (PSA). Observations were executed with all cenwaves and all FP-POS with the exception of G130M/1055 and G130M/1096, which remained at LP2. The L flats and sensitivities at LP4 were derived with the same method as at LP3. The L flats at LP4 agree with those at LP3 to within ~2%, depending on grating and detector position. The sensitivities at LP4 are as expected after accounting for the previously characterized time-dependent sensitivity of the FUV detector. The relative and absolute flux calibration accuracies at LP4 are within the specifications of 2% and 5%.
W. Fischer 25 Sep 2018

ISR 2018-19: On-orbit comparison of the emission line intensities of the COS Pt-Ne Calibration Lamps

There are two platinum-neon (Pt-Ne) hollow cathode lamps on the COS calibration platform that are used for wavelength calibration and target acquisition purposes. Due to differences in optical paths and operating currents the fluxes provided by these lamps (P1 and P2) are not the same. We analyze images and spectra taken with both Pt-Ne lamps to determine the ratio of the lamp fluxes as a function of wavelength. The results are used to compute recommended lamp flash durations should P1 be used for a task normally done with P2, and vice versa. In the event that either Pt-Ne lamp should fail, this analysis provides the starting point for continuing operations with a single working lamp.
N. Indriolo 31 Aug 2018

ISR 2018-18: Verification of COS/FUV Bright Object Aperture (BOA) Operations at Lifetime Position 4

We report the results of the COS/FUV calibration program, 15368, designed to verify operations of the Bright Object Aperture (BOA) at the fourth Lifetime Position (LP4). The bright standard star G191-B2B was observed with the G130M/1291, G160M/1623, and G140L/1280 settings with one lamp exposure taken with the G130M/1291 setting to test a complete set of operations. The spectral resolution was measured for G130M/1291, and cross-dispersion (XD) profiles were constructed and compared to those from LP3 and LP2. We show that the LP4 XD profiles are nearly identical to those at LP3 and the resolving power of G130M is R ~ 4500.
J. White 15 Aug 2018

ISR 2018-17: COS FUV Aperture and Spectrum Placement at LP4

Program 14875 was executed to determine the spacecraft pointing offset and aperture offset needed for the fourth COS FUV Lifetime Position (LP4). The spectrum was shifted approximately -2.52 arcseconds in the cross-dispersion direction, then the aperture was scanned across the stationary spectrum in both directions to identify the optimum location of the aperture, along with the entries in the Science Instrument Aperture File at LP4.
D. Sahnow 15 Aug 2018

ISR 2018-16: COS2025: A New Strategy to Prolong the Lifetime of the COS/FUV Detector to 2025

The efficiency of the COS FUV microchannel plate detector at converting incoming photons into detectable electrons decreases with usage. This depletion of the detector's gain, i.e., gain sag, results in un-usable regions of the FUV detector. Over the past few years a number of strategies have been employed to mitigate the effects of gain sag, from periodically raising the high voltage to periodically moving science spectra to a pristine lifetime position. However, the strategies that have been employed up to now do not allow the FUV detector to continue operating into 2025 without a significant impact of the scientific capabilities. The COS2025 strategy, presented here, is a new strategy that was developed to continue operating COS FUV into 2025 while retaining full science capabilities.
C. Oliveira 01 Aug 2018

ISR 2018-14: Exploratory Phase for Optimizing Lifetime Position 4 of the COS/FUV Detector

In order to mitigate gain-sag effects, COS/FUV science spectra are periodically moved to pristine locations of the detector, i.e. different lifetime positions (LP). This ISR describes the LP4 exploratory phase, during which the feasibility of placing LP4 at -2.5'' below LP3 (-5'' below LP1) was examined, the effects of the LP4 move on the science quality and calibration accuracy of spectra were investigated, and the final location of LP4 (- 2.5'' below LP3) was determined. We describe in detail the strategy adopted for the LP4 exploratory phase to ensure that all potential issues were identified and resolved well in advance of the LP4 move.
J. Roman-Duval 05 Jun 2018

ISR 2018-12: Cycle 24 HST+COS Target Acquisition Monitor Summary

HST/COS calibration program 14847 (P14857) was designed to verify that all three COS Target Acquisition (TA) modes were performing nominally during Cycle 24. The program was designed not only to determine if any of the COS TA flight software (FSW) patchable constants need updating but also to determine the values of any required parameter updates. All TA modes were determined to be performing nominally during the Cycle 24 calendar period of October 1, 2016 – October 1, 2017. No COS SIAF, TA subarray, or FSW parameter updates were required as a result of this program.
S. Penton 01 Jun 2018

ISR 2018-11: Cycle 24 COS/NUV Spectroscopic Sensitivity Monitor

Time-dependent sensitivity (TDS) monitoring is necessary for accurate flux calibration of the COS NUV MAMA. Regular calibration observations monitor the decline in sensitivity for all 4 NUV gratings: G185M, G225M, G285M, and G230L. Results from the Cycle 24 NUV TDS program show the reflectivity of the G225M and G285M gratings, which are coated in bare-aluminum, exhibit a steep time-dependent degradation at a rate of -3 to -2.5%/year and -11.3 to -10.3%/year respectively. The G185M and G230L gratings, which are coated in MgF2 over aluminum, are declining at rates of -0.2 to +0.6%/year and -0.2 to +0.8%/year respectively.
J. Taylor 30 May 2018

ISR 2018-10: Testing the Linearity of the Cosmic Origins Spectrograph FUV Channel Thermal Correction

The Far Ultraviolet Cross Delay Line (FUV XDL) detector on the Cosmic Origins Spectrograph (COS) is subject to temperature-dependent distortions. The correction performed by the COS calibration pipeline (CalCOS) assumes that these changes are linear across the detector. In this report we evaluate the accuracy of the linear approximations using data obtained on orbit. Our results show that the thermal distortions are consistent with our current linear model.
M. Fix 04 May 2018

ISR 2018-09: Cycle 24 COS/FUV Spectroscopic Sensitivity Monitor

We summarize the Cycle 24 COS/FUV spectroscopic sensitivity monitor that ran from November 2016 to October 2017. We give an overview of the program and a summary of the analysis of the data.
G. De Rosa 04 May 2018

ISR 2018-08: The Spatial Resolution of the COS FUV channel at Lifetime Position 4

We report on the COS FUV spatial resolution at Lifetime Position 4 (LP4), as determined via analysis of the cross-dispersion spread functions (XDSFs). The XDSFs are predicted by the Code V optical model of the COS system and validated via high-S/N observations taken at LP4. We present analysis of the XDSFs in multiple central wavelength settings of the three COS FUV gratings, deriving the dependence of the width (FWHM) of the XDSFs vs. wavelength. We find good agreement (RMS<1 pixel) between the predictions and the models on the FUVB segment, but in several settings the data are broader than the models by 1-2 pixels on FUVA.
A. Fox 16 Feb 2018

ISR 2018-07: The Spectral Resolution of the COS FUV channel at Lifetime Position 4

We report on the COS FUV spectral resolution at Lifetime Position 4 (LP4). We show that a high-resolution STIS spectrum convolved with the COS line spread functions (LSFs) generated by Code V optical models can successfully reproduce the observed COS line profiles at LP4. The spectral resolution at LP4 has degraded by ~10-15% relative to LP3, as expected from the models. The highest resolution achievable is on the FUVA segment of the G160M cenwaves, where it reaches R=19,700 (FWHM=15.2 km/s). The resolution of the workhorse cenwave G130M/1291 varies from R=12,100 (24.8 km/s) to R=16,900 (17.7 km/s).
A. Fox 16 Feb 2018

ISR 2018-06: Cycle 24 COS FUV Internal/External Wavelength Scale Monitor

We report on the monitoring of the COS FUV wavelength scale zero-points during Cycle 24 in program 14855. Select cenwaves were monitored for all FUV gratings at Lifetime Position 3. All measured offsets are within the error goals, although the G140L cenwaves show offsets at the short-wavelength end of segment A that are approaching the tolerance.
W. J. Fischer 15 Feb 2018

ISR 2018-05: Cycle 24 COS NUV Internal/External Wavelength Scale Monitor

We report on the monitoring of the COS NUV wavelength scale zero-points during Cycle 24 in program 14859. Select cenwaves were monitored for all NUV gratings. With minor exceptions, measured offsets are within the error goals. The declining sensitivity of the G285M grating is beginning to present a challenge for precise cross-correlation.
W. J. Fischer 15 Feb 2018

ISR 2018-04: Cycle 24 COS FUV Dark Monitor Summary

We summarize the Cycle 24 FUV Dark Monitoring Program for the Cosmic Origin Spectrograph (COS) on the Hubble Space Telescope (HST) covering dates November 2016 to October 2017. We give an overview of the calibration plan and summary for this calibration program.
M. Fix 13 Feb 2018

ISR 2018-03: Cycle 24 COS NUV Dark Monitor Summary

We summarize the Cycle 24 NUV Dark Monitoring Program for the Cosmic Origin Spectrograph (COS) on the Hubble Space Telescope (HST) covering dates November 2016 to October 2017. We give an overview of the calibration plan and summary for this calibration program.
M. Fix 13 Feb 2018

ISR 2018-02: Cycle 24 COS/NUV Fold Distribution

We summarize the Cycle 24 COS/NUV Fold Distribution for the Cosmic Origins Spectrograph's (COS) MAMA detector on the Hubble Space telescope. The detector micro-channel plate's health state is determined and the results presented.
T. Wheeler 13 Feb 2018

ISR 2018-01: Cycle 24 COS FUV Detector Gain Maps

Program 14519 used the onboard deuterium lamp to illuminate the LP2 and LP3 regions of the COS FUV detector before and after high voltage changes. The pulse height information obtained was used to create gain maps in order to monitor the detector gain sag and to determine when high voltage changes and Lifetime Position changes were needed.
D. Sahnow 13 Feb 2018

2017

ISR 2017-23: Summary of Cycle 24 Program- COS Pure Parallel Observations of Geocoronal Lyα

In this report we summarize the Cycle 24 program that obtained geocoronal Lyα observations with the FUV detector of the Cosmic Origin Spectrograph (COS).
J. White 05 Dec 2017

ISR 2017-22: COS NUV Focus Sweep

Program 13530 performed an NUV focus sweep during Cycle 21 in order to determine whether the COS focus has changed since it was originally measured in Program 11469 during SMOV. Nineteen NUV exposures of NGC188-41 were obtained during a single orbit while the OSM1 focus was moved over the range from -200 to +200 steps. The focus was found to be close to the initial value.
D. Sahnow 31 Aug 2017

ISR 2017-21: Characterization of the COS FUV Detector Modal Gain at LP4

Program 14525 used the onboard deuterium lamp to illuminate the LP2 and LP4 regions of the COS FUV detector in order to obtain gain maps where the LP4 science and wavelength calibration spectra will fall. These gain maps have been used to determine the initial high voltage values after the move to LP4, and to use as an initial point in the monitoring of gain vs. time that will be done after the move.
D. Sahnow 28 Aug 2017

ISR 2017-20: Quick-check of the COS/FUV G130M Spectral Resolution at Lifetime Position 4

Optimization program PID14842 was primarily designed to determine the impact of the move of COS/FUV operations to Lifetime Position 4 (LP4; -5.02" from LP1 in cross-dispersion direction) on the G130M spectral resolution and to generate new LSFs at LP4.
P. Sonnentrucker 28 Aug 2017

ISR 2017-19: Optimization of COS/FUV Spectrum Placement at Lifetime Position 4

We give a summary of the rationale, structure and preliminary analysis of the Lifetime Position 4 (LP4) special calibration program 14841, aimed at determining the optimal placement of the spectra at LP4.
G. De Rosa 28 Aug 2017

ISR 2017-18: Cycle 23 COS Target Acquisition Monitor Summary

COS program 14440 was designed to verify that COS Target Acquisitions (TA) were performing nominally during Cycle 23, and to check if any of the TA patchable constants present in the COS flight software (FSW) need updating. All FUV observations in 14440 were performed at LP3, and at the nominal (LP1) NUV position.
S. Penton 28 Aug 2017

ISR 2017-17: Focusing the COS/FUV G160M and G140L Gratings at Lifetime Position 4

In December 2016 focus sweeps were performed at the fourth lifetime position (LP4) of the COS/FUV detector with the G160M and G140L gratings. In this ISR we present the results. The focus sweeps involved observations of the stars Feige 48 and AzV75 at a range of focus settings. This is a partner ISR to 2017-16.
A. Fox 28 Aug 2017

ISR 2017-16: FUV Focus Sweep Exploratory Program for COS at LP4

As part of the exploratory phase of the move of COS/FUV operations to Lifetime Position 4 (LP4), we designed program 14527 to measure changes in the focus offsets required to optimize spectral resolution at the prospective LP4 position (-5.02" from LP1 in cross-dispersion direction). Following the successful strategy established in program LENA2 (P13635, LP3 move), we executed one focus sweep using the G130M/1222 configuration (FUVB only) and two sweeps using the G130M/1309 configuration (FUVA and FUVB treated separately). This is a partner ISR to 2017-17.
P. Sonnentrucker 28 Aug 2017

ISR 2017-15: Summary of Cycle 23 Program- COS Pure Parallel Observations of Geocoronal Lyα

In this report we summarize the Cycle 23 geocoronal Lyα observations for the Cosmic Origin Spectrograph (COS).
J. White 18 Aug 2017

ISR 2017-14: Cycle 23 COS FUV Detector Gain Maps

Program 14439 used the onboard deuterium lamp to illuminate the LP3 region of the COS FUV detector immediately before and after the nominal high voltage on Segment B was changed on January 18, 2016. Exposures were also taken at LP2 approximately one year after the previous LP2 gain maps were obtained. The pulse height information obtained was used to create gain maps in order to monitor the detector gain sag and to determine when high voltage changes and Lifetime Position changes were needed.
D. Sahnow 07 Aug 2017

ISR 2017-13: Cycle 23 COS/NUV Spectroscopic Sensitivity Monitor

Observations of HST spectrophotometric standard stars show that there is a time dependence of the COS NUV MAMA sensitivity. Time-dependent sensitivity (TDS) monitoring is necessary for accurate flux calibration. Regular calibration observations monitor the decline in sensitivity for all 4 NUV gratings: G185M, G225M, G285M, and G230L.
J. Taylor 02 Aug 2017

ISR 2017-12: Cycle 23 COS NUV Dark Monitor Summary

Here we summarize the Cycle 23 NUV Dark Monitoring Program for the Cosmic Origin Spectrograph (COS) on the Hubble Space Telescope (HST) covering dates November 2015 to October 2016. We give an overview of the calibration plan and summary for this calibration program.
M. Fix 31 Jul 2017

ISR 2017-11: Cycle 23 COS FUV Dark Monitor Summary

Here we summarize the Cycle 23 FUV Dark Monitoring Program for the Cosmic Origin Spectrograph (COS) on the Hubble Space Telescope (HST) covering dates November 2015 to October 2016. We give an overview of the calibration plan and summary for this calibration program.
M. Fix 31 Jul 2017

ISR 2017-10: Cycle 23 COS/FUV Spectroscopic Sensitivity Monitor

We summarize the Cycle 23 COS/FUV spectroscopic sensitivity monitor that ran from November 2015 to October 2016. We give an overview of the program and a summary of the analysis of the data.
G. DeRosa 31 Jul 2017

ISR 2017-09: Cycle 23 COS/NUV Fold Distribution

We summarize the Cycle 23 COS/NUV Fold Distribution for the Cosmic Origins Spectrograph's (COS) MAMA detector on the Hubble Space telescope. The detector mirco-channel plate's health state is determined and the results presneted.
T. Wheeler 21 Jul 2017

ISR 2017-08: Cycle 23 COS NUV Internal/External Wavelength Scale Monitor

We report on the results of the monitoring of the COS NUV wavelength scale zero-points during Cycle 23 in PID14443. Select cenwaves for all NUV gratings were monitoring in this program with a structure that remained unchanged since Cycle 21. The program was reduced from 3 to 2 visits per year in Cycle 23.
P. Sonnentrucker 21 Jul 2017

ISR 2017-07: Cycle 23 COS FUV Internal/External Wavelength Scale Monitor

We report on the results of the monitoring of the COS FUV wavelength scale zero-points during Cycle 23 with program PID1443. The full monitoring sequence includes the G130M/1096-1222-1291-1317, the G160M/1577-1623 and the G140L/1105-1280 configurations. All data were taken at LP3.
P. Sonnentrucker 21 Jul 2017

ISR 2017-06: Spectral Resolution of COS/FUV at Lifetime Position 3

In this ISR, we characterize the spatial and spectral resolution at the third COS FUV lifetime position.
J. Roman-Duval 20 Jun 2017

ISR 2017-05: Recommended CENWAVE Settings for NUV COS ACQ/PEAKXD Procedure

This ISR discusses recommended cenwaves used for NUV COS ACQ/PEAKXD procedures and the motivation behind the selected cenwaves. The following are the appendices for 2017-05:
Appendix A
Appendix B
Appendix C
Appendix D
Appendix E
Appendix F
N. Indriolo 16 May 2017

ISR 2017-04: The Hubble Spectroscopic Legacy Archive

The goal of the Hubble Spectroscopic Legacy Archive (HSLA) is to provide to the community new science-grade combined spectra for all publicly available data obtained by the Cosmic Origins Spectrograph (COS) and the Space Telescope Imaging Spectrograph (STIS). These data are packaged into “smart archives” according to target type and scientific themes to facilitate the construction of archival samples for common science uses. A new “quick look” capability makes the data easy for users to quickly access, assess the quality of, and download for archival science.
M. Peeples 28 Apr 2017

ISR 2017-03: Analysis of the COS/NUV Extraction Box Heights

We present a diagnostic test of the extraction box heights (EBHs) used when extracting NUV spectroscopic data. This study was motivated by a discrepancy between the EBH used by the COS Exposure Time Calculator during observation planning (8 pixels) and the COS calibration pipeline (CALCOS) during the creation of the final spectra (57 pixels). In this Instrument Science Report, we study the effects of decreasing the EBH on the net counts and signal-to-noise ratio for CALCOS-reduced spectra of many different targets. We also provide detailed instructions for users who wish to perform a custom extraction for their data.
E. Snyder 16 Aug 2017

ISR 2017-02: Updates to the COS/NUV Dispersion Solution Zero-points

In order to update the zero-points of 66 NUV settings, three special calibration programs were executed during Summer 2016. These three calibration programs obtained data with COS (PID 14503) and STIS (PID 14504 & 14505). Here we report on the analysis performed on these data to determine the updates to the NUV zero-points. A new NUV wavelength dispersion reference file was delivered to CRDS in February 2017 as a result of this effort.
R. Plesha 10 Aug 2017

ISR 2017-01: Bright Object Protection (BOP) Considerations for M Dwarf Flare Events

We provide clear and concise guidance for Guest Observers and Contact Scientists to evaluate the health and safety of the instrument when observing M dwarfs, taking into consideration current scientific research about the frequency with which large flare events occur, and a risk tolerance level for causing an inadvertent detector shutdown due to overlight conditions from a large flare during an observation.
R. Osten 16 Feb 2017

2016

ISR 2016-15: Third COS FUV Lifetime Calibration Program: Flatfield and Flux Calibrations

The derivation of the L-flats and sensitivities at LP3 differed from their LP1 and LP2 counterparts in a few key ways, which we describe in this report. Firstly, we quantified a cut-off in spatial frequency that we assigned to the L-flats. Secondly, we derived a new method for simultaneously fitting both the L-flats, pixel-to-pixel flats (P-flats), and sensitvities which we compared to our previous method of separately fitting L-flats and sensitivities. These new methods produce comparable results, but provide us with an external test on the robustness of each approach individually.
J. Debes 04 Oct 2016

ISR 2016-14: Cycle 22 COS/NUV Fold Distribution

We summarize the Cycle 22 COS/NUV Fold Distribution for the Cosmic Origins Spectrograph's (COS) MAMA detector on the Hubble Space Telescope. The detector micro-channel plate's health state is determined and the results are presented.
T. Wheeler 22 Sep 2016

ISR 2016-13: Cycle 22 COS/FUV Spectroscopic Sensitivity Monitor

We summarize the Cycle 22 COS/FUV spectroscopic sensitivity monitor that ran from November 2014 to October 2015. We give an overview of the program and a summary of the analysis of the data.
G. DeRosa 22 Sep 2016

ISR 2016-12: Cycle 22 COS NUV Internal/External Wavelength Scale Monitor

We report on the results of the monitoring of the COS NUV wavlength scale zero-points during Cycle 22. Select cenwaves for all NUV gratings were monitoring in this program with a structure that remained unchanged since Cycle 21.
P. Sonnentrucker 22 Sep 2016

ISR 2016-11: Cycle 22 COS NUV Dark Monitor Summary

Here we summarize the Cycle 22 NUV Dark Monitoring Program for COS covering dates November 2014 to October 2015. We give an overview of the calibration plan and summary for this calibration program.
M. Fix 22 Sep 2016

ISR 2016-10: Cycle 22 COS/NUV Spectroscopic Sensitivity Monitor

Results from the cycle 22 NUV TDS program show the reflectivity of the G225M and G285M gratings, which are coated in bare-aluminum, declines at a rate of -3 to -2.5%/year and -10.6 to -11.8%/year, respectively. The G185M and G230L gratings, which are coated in MgF2 over aluminum, show a decline of -0.3 to +0.6%/year and -0.4 to +0.9%/year, respectively.
J. Taylor 22 Sep 2016

ISR 2016-09: Cycle 22 COS Target Acquisition Monitor

COS program 13972 was designed to verify that COS Target Acquisitions (TA) were performing nominally during Cycle 22, and to check if any of the TA patchable constants present in the COS flight software (FSW) need updating. COS exposures obtained in HST program 14035 (HST Cycle 22 Focal Plane Calibration [SI-FGS Alignment]) were also used in this analysis. This program verified that all three TA modes were behaving nominally in Cycle 22, and determined that no SIAF, subarray, or FSW parameter updates were required at this time.
COS 22 Sep 2016

ISR 2016-08: Cycle 22 Characterization of HV Change Effect on the COS/FUV Sensitivity

Program 13971 was a special calibration program executed in Cycle 22 in order to characterize the effect of the COS FUV detector high voltage on the sensitivity. Previous changes to the high voltage settings led us to believe that an increase in the high voltage values caused an increase in sensitivity in addition to the expected increase in gain. This program was designed to measure that effect and determine whether it is a function of incident wavelength and/or position on the detector.
D. Sahnow 22 Sep 2016

ISR 2016-07: Cycle 22 COS FUV Detector Gain Maps

Program 13970 used the onboard deuterium lamp to illuminate the LP2 and LP3 regions of the COS FUV detector at the time of the Lifetime 3 move. The pulse height information obtained was used to create gain maps in order to monitor the detector gain sag and to determine when high voltage changes and Lifetime Position changes were needed.
D. Sahnow 21 Sep 2016

ISR 2016-06: Cycle 22 COS FUV Internal/External Wavelength Scale Monitor

We report on the results of the monitoring of the COS FUV wavlength scale zero-points during Cycle 22. Only the G130M/1096 and G140L/1105-1280 configurations were monitored in this program. Monitoring of the standard G130M and G160M modes was part of the calibration phase associated with the move of COS FUV operations to LP3 and will be presented in a separate ISR.
P. Sonnentrucker 21 Sep 2016

ISR 2016-05: Cycle 22 COS FUV Dark Monitor Summary

Here we summarize the Cycle 22 FUV Dark Monitoring Program for COS covering dates November 2014 to October 2015. We give an overview of the calibration plan and summary for this calibration program.
M. Fix 22 Sep 2016

ISR 2016-04: Summary of COS Cycle 23 Calibration Plan

We summarize the calibration activities for the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope during Cycle 23 which ran from November 2015 through October 2016. We give an overview of the COS calibration plan, COS usage statistics and we briefly describe major changes with respect to the previous cycle. High-level executive summaries for each calibration program comprising Cycle 23 are also given here. Results of the analysis attached to each program are published in separate ISRs.
P. Sonnentrucker 22 Sep 2016

ISR 2016-03: Summary of the COS Cycle 22 Calibration Program

We summarize the calibration activities for the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope during Cycle 22 which ran from November 2014 through October 2015. We give an overview of the COS calibration plan, COS usage statistics and we briefly describe major changes with respect to the previous cycle. High-level executive summaries for each calibration program comprising Cycle 22 are also given here. Results of the analysis attached to each program are published in separate ISRs.
P. Sonnentrucker 21 Sep 2016

ISR 2016-02: Characterizing the COS OSM1 Drift in the Dispersion Direction

In this ISR, we analyze the OSM drift on finer time-scales than the TAGFLASH intervals to determine if the current CalCOS correction is sufficient.
J. White 25 Aug 2016

ISR 2016-01: Optimization of Lifetime Position 3 of the COS/FUV Detector

In this ISR, we describe the process for selecting the LP3 location, and the subsequent requirements for the new extraction algorithm supporting science at LP3.
J. Roman-Duval 25 Feb 2016

2015

ISR 2015-05: Verification of COS/FUV Bright Object Aperture (BOA) Operations at Lifetime Position 3

We report the results of the COS/FUV calibration program LCAL4, designed to verify operations and performance of the bright object aperture (BOA) at the third lifetime position (LP3).
A. Fox 10 Dec 2015

ISR 2015-06: Summary of the COS Cycle 21 Calibration Program

We summarize the Cycle 21 calibration program for the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope, covering the time period from November 2013 through October 2014. We give an overview of the Calibration plan and status summaries for each of the individual proposals comprising the C21 Calibration program.
H. Sana 25 Sep 2015

ISR 2015-04: Does Not Exist

An ISR with this number does not exist
04 Oct 2016

ISR 2015-03: Changes to the COS Extraction Algorithm for Lifetime Position 3

The COS FUV Detector Lifetime Position 3 (LP3) has been placed only 2.5” below the original lifetime position (LP1). This is sufficiently close to gain-sagged regions at LP1 that a revised extraction algorithm is needed to ensure good spectral quality. We provide an overview of this new “TWOZONE” extraction algorithm, discuss its strengths and limitations, describe new output columns in the X1D files that show the boundaries of the new extraction regions, and provide some advice on how to manually tune the algorithm for specialized applications.
C. Proffitt 25 Sep 2015

ISR 2015-02: Summary of the COS Cycle 20 Calibration Program

We summarize the Cycle 20 calibration program for the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope, covering the time period from November 2012 through October 2013. We give an overview of the Calibration plan and status summaries for each of the individual proposals comprising the C20 Calibration program.
J. Roman-Duval 11 Jun 2015

ISR 2015-01: The COS/FUV Focus Sweep Program at Lifetime Position 3 (LENA2/13635)

We present the results from the focus sweeps performed in July 2014 in preparation for the move to lifetime position 3 with the G130M, G160M, and G140L gratings using the bright stars Feige 48 and AzV75 as targets.
A. Fox 20 May 2015

2014

ISR 2013-13: COS/FUV Characterization of Optical Effects at Potential Lifetime Positions

In this document we provide a summary of the analysis performed on data obtained as part of program 12678, "COS/FUV Characterization of Optical Effects". Changes to throughput, resolution and gain as a function of position were evaluated and compared to raytrace models.
D. Sahnow 24 Apr 2015

ISR 2014-01: Summary of the Cycle 19 COS Calibration Program

We summarize the Cycle 19 calibration program for the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope, covering the time period from November 2011 through October 2012. We give an overview of the Calibration Plan and status summaries for each of the individual proposals comprising the C19 Calibration program.
J. Roman-Duval 16 Jul 2014

ISR 2013-09: Updated Absolute Flux Calibration of the COS FUV Modes

We present newly derived point source absolute flux calibrations for the COS FUV modes at both the original and second lifetime positions.
D. Massa 14 Mar 2014

2013

ISR 2013-16: Summary of Results from the First Move to a New COS FUV Lifetime Position

We summarize the results of the enabling and calibration activities involved in the first COS FUV move to a new lifetime position, which occurred on July 23, 2012.
R. Osten 08 Oct 2013

ISR 2013-08: Characterization of the COS FUV Detectors

This document describes the results derived from the COS calibration Program 12676, "COS/FUV Characterization of Detector Effects".
D. Massa 01 Oct 2013

ISR 2013-07: COS/FUV Spatial and Spectral Resolution at the new Lifetime Position

In this ISR we characterize the spatial and spectral resolution at the second COS FUV lifetime position.
J. Roman-Duval 10 Jun 2013

ISR 2013-06: COS FUV Dispersion Solution Verification at the New Lifetime Position

In this report, we describe the analysis we performed to verify the dispersion solutions of the M gratings using data collected in 12805 and of the L grating using data obtained in enabling program 12796 (FENA3:“Second COS FUV Lifetime Position: Focus Sweep Enabling Program”; Oliveira et al. 2013).
P. Sonnentrucker 10 Jun 2013

ISR 2013-05: Second COS FUV Lifetime Position: Verification of FUV Bright Object Aperture (BOA) Operations (FCAL4)

The document describes the analysis of data taken as part of the second lifetime calibration program 12807. This program was designed to characterize the BOA spectroscopic performance at the second lifetime position.
J. H. Debes 22 May 2013

ISR 2013-04: Summary of COS Cycle 18 Calibration Programs

This document summarizes the status of the calibration programs for COS during Cycle 18.
G. Kriss 26 Apr 2013

ISR 2013-03: Second COS FUV Lifetime Position: Verification of Aperture and FUV Spectrum Placement (FENA2)

This document describes the analysis of the data obtained for proposal 12795 which determined the exact updates for the Science Instrument Aperture File (SIAF) and for the COS aperture block positioning needed to implement routine science operations at COS FUV Lifetime Position 2.
C. Proffitt 08 Apr 2013

ISR 2013-02: COS/FUV Mapping of Stray PtNe Lamp Light Through the FCA

This ISR reviews the causes of the shutdown program 12096 and how program 12677 was crafted to avoid a similar shutdown. The document presents results from program 12677 and their impact on future lifetime position is discussed.
C. Oliveira 07 Feb 2013

ISR 2013-01: Second COS FUV Lifetime Position Results from the Focus Sweep Enabling Program, FENA3 (12796)

This document describes the results from the second lifetime position focus sweep with COS/FUV G130M, G160M, and G140L gratings as part of the programs executed to enable COS/FUV science at the second lifetime position.
C. Oliveira 06 Feb 2013

2012

ISR 2012-02: Summary of COS Cycle 17 Calibration Program

This document summarizes the status of the calibration programs for COS during Cycle 17.
R.Osten 29 Nov 2012

ISR 2012-01: COS FUV Focus Determination for the G140L Grating

Describes the procedures for determining the COS FUV fine-focus for the G140L grating.
P. Ghavamian 03 Oct 2012

2011

ISR 2010_11: COS FUV Detector Dark Rates During SMOV and Cycle 17

This ISR describes the behavior and characteristics of the COS FUV detector dark rate during SMOV and Cycle 17.
D. Sahnow 07 Oct 2011

ISR 2011-05: Gain sag in the FUV detector of the Cosmic Origins Spectrograph

SPIE paper describing the characteristics and mitigation strategies of gain sag in the FUV detector.
David J. Sahnow, Cristina Oliveira, Alessandra Aloisi, Philip E. Hodge, Derck Massa, Rachel Osten, Charles Proffitt, Azalee Bostroem, Jason B. McPhate, Stéphane Béland, Steven N. Osterman and Steven V. Penton, "Gain sag in the FUV detector of the Cosmic Origins Spectrograph", Proc. SPIE 8145, 81450Q (2011); http://dx.doi.org/10.1117/12.893989
Copyright 2011 Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.

D. Sahnow 26 Sep 2011

ISR 2011-04: Details of COS TAGFLASH Execution

Describes the characteristics of COS TAGFLASH exposures.
T. Keyes 07 Sep 2011

ISR 2011-03: COS FUV Gridwire Flat Field Template

Results of the FUV Gridwire Flat Field Development and Testing.
J. Ely 05 Aug 2011

ISR 2011-02: Updated Results from the COS Spectroscopic Sensitivity Monitoring Program

Updated Results from the COS Spectroscopic Sensitivity Monitoring Program.
R. Osten 28 Jun 2011

ISR 2010_13: SMOV: COS FUV and NUV On-Orbit Structural and Thermal Stability

This ISR provides a description and analysis of the structural and thermal stability of the COS instrument.
T. Ed Smith 12 Jul 2011

ISR 2010_12: COS NUV Detector Dark Rates During SMOV and Cycle 17

This ISR describes the behavior and characteristics of the COS NUV detector dark rate during SMOV and Cycle 17.
D. Sahnow 12 Jul 2011

ISR 2011-01: Improved Medium Resolution Line Spread Function for the COS FUV Spectrum

We have developed an improved line spread function (LSF) for the medium resolution far- ultraviolet gratings (G130M and G160M) of the Cosmic Origins Spectrograph (COS) by taking into account scattering in the far wings due to microroughness on the HST primary mirror.
G. Kriss 18 Mar 2011

2010

ISR 2010-10: SMOV: COS NUV Imaging Performance

Presenting data analysis to describe NUV Imaging Performance for COS after SM4. Revised 10/6/2010
P. Goudfrooij 11 Mar 2010

ISR 2010-08: SMOV: COS NUV External Spectroscopic Performance

Describes the external spectroscopic performance of the COS NUV detector
S. Béland 30 Sep 2010

ISR 2010-09: COS FUV External Spectroscopic Performance

A description of the External Spectroscopic Performance of the FUV Channel on COS
P. Ghavamian 30 Sep 2010

ISR 2010-15: Early Results from the COS Spectroscopic Sensitivity Monitoring Programs

We report initial results from the Cosmic Origins Spectrograph spectroscopic sensitivity monitoring calibration programs.
R. Osten 02 Aug 2010

ISR 2010-14: COS Target Acquisition Guidelines, Recommendations, and Interpretation

This ISR provides an overview of COS TA and updates, expands, and supersedes information in the COS IHB(v2)
T. Keyes 15 Jun 2010

ISR 2010-07: SMOV: COS FUV Focus Determination

The procedures for determining the COS FUV fine-focus are described
D. Lennon 04 Mar 2010

ISR 2010-06: SMOV: COS FUV Wavelength Calibration

Update to the FUV wavelength calibration from SMOV data
C. Oliveira 19 Feb 2010

ISR 2010-05: SMOV: COS NUV Wavelength Calibration

Update to the NUV wavelength calibration from SMOV
C. Oliveira 19 Feb 2010

ISR 2010-04: SMOV: COS NUV On-orbit Optical Alignment

SMOV NUV optical alignment process description
G. Hartig 12 Feb 2010

ISR 2010-03: COS Near-UV Flat Fields and High S/N Determination from SMOV Data

Describes the process of determining and results of the COS NUV high S/N flat field reference files from data taken during SMOV4
T. Ake 04 Feb 2010

ISR 2010-02: SMOV Absolute Flux Calibration of the COS FUV Modes

Describes the processes used to determine the absolute flux calibration of COS FUV point source spectra
D. Massa 28 Jan 2010

ISR 2010-01: SMOV Absolute Flux Calibration of the COS NUV Modes

Describes the processes used to determine the absolute flux calibration of COS NUV point source spectra
D. Massa 28 Jan 2010

2009

ISR 2009-01(v1): Preliminary Characterization of the Post-Launch Line Spread Function of COS

Description of the COS Line Spread Function (LSF) as determined by post-launch testing.
P. Ghavamian 01 Oct 2009

2008

COS ISR 08-01: Phase II Update and Guidelines for Cycle 17 Users of COS

Summary of recommended practice and suggestions for observers preparing their Phase II COS program submissions for Cycle 17.
D. Soderblom 06 Jun 2008

2002

COS ISR 02-01: COS Bright Object Protection

COS Bright Object Protection
C. Leitherer 07 Mar 2006

1999

COS ISR 99-01: COS Design Reference Mission and Ground System Volume Requirements

COS Design Reference Mission and Ground System Volume Requirements
Charles (Tony) Keyes 07 Mar 2006