2012
Charge Transfer Efficiency Correction: WFC Dark Files
In May of 2012, a new version of the calibration pipeline for ACS on the Hubble Space Telescope, CALACS 2012.2, was released. One of the major improvements in the new CALACS is the incorporation of the algorithm created by Anderson and Bedin (2010) to correct for the charge transfer efficiency (CTE) losses in WFC1 and WFC2. This algorithm is a pixel specific correction that is applied as one of the first steps in CALACS, before the subtraction of the dark reference file. In order to properly reduce any raw science images it was necessary to correct all the WFC dark reference files used in CALACS for CTE loss, about 1,600 files.
S. Ogaz et al.
07 Aug 2012
Bias and Dark Calibration of ACS/WFC Data: Post-SM4 Automated Pipeline
We describe the post-SM4 automated pipeline that creates reference files for bias and
dark calibration of ACS/WFC data. This document is intended for those who would like
to adopt our pipeline or understand the technical details of its implementation.
Lim, P. et al
19 Apr 2012
2008
ACS-R Multi-Parameter Optimization Constraints (TIR 08-04
Abstract
The repaired ACS WFC will undergo a three-week Optimization Campaign during early SMOV with read noise being the primary target for improvements through testing adjustments of a large number of detector control, voltage and timing patterns. A large number of factors, in addition to read noise, contribute to the utility of science data from ACS WFC. In this TIR we enumerate several such factors including Charge Transfer Efficiency (CTE), Full Well Depth (FWD), Linearity, Cross talk, gain stability and bias drift. For each we quantify values that existed when WFC was last used in January 2007 and provide extrapolation that we believe would have existed with a continuously operable instrument to May 2009. For each factor we provide qualitative discussion of how changes would impact science in order to provide a framework for considering changes that may arise during the Optimization Campaign.
In many cases, e.g. for CTE, significant deterioration of performance from nominal expectations as a result of changes during the optimization campaign would provide support for adjusting the optimization to lessen this, even at the cost of some increase of read noise.
R. L. Gilliland
03 Dec 2008
ACS-R SMOV Optimization Plan-I. Rationale and Strategy (TIR-08-03)
The document provides the optimization plan for the HST/ACS Replacement (ACS-R) flight hardware. It specifies the rationale for and types of activities required during SMOV to optimize the on-orbit performance of the hardware. The new flight hardware uses internal interfaces of the instrument that were not described or characterized in detail during the original build of the ACS. This optimization is planned in order to mitigate the risk of the ground (test) hardware not emulating these flight instrument interface well enough.
Edward S. Cheng
26 Aug 2008
Delivery of a new ACS SBC throughput curve for Synphot (TIR 2008-002)
On November 12th, 2007 a new ACS SBC throughput curve was implemented in CDBS, OPUS and DADS. This new curve is an improved version and accounts for SBC red leak. The red leak portion is based on a spectrum of HD 209458 prepared by Paul Goudfrooij.
Boffi, F.R.
21 Apr 2008
2007
We describe a revised set of procedures and software for creating finding charts and object catalogues which can be used to assess the risk to the STIS MAMA and ACS SBC detectors from bright blue objects in the vicinity of proposed planetary observations. These charts show the path of given planet, moon or comet across the background of stars, down to magnitude limit of the GSC2 digital sky survey plates. Associated object catalogues and color-magnitude diagrams are also produced showing which stars may violate bright object limits for the selected instrument mode.
Charles Proffit et. al.
11 Jun 2007
2006
Quantum Yield Correction for ACS/HRC and ETC implementation(ACS TIR 06-03)
In the ACS/HRC CCD a single UV photon may generate more than one photo-electron. We calculate the theoretical quantum yield and discuss the impact on the calculation of the S/N ratio for an observation in the UV. Without such correction the S/N can be overestimated up to ~18% in the F220W and ~26% at the bluest edge of PR200L. The implementation of the quantum yield correction in the ACS Exposure Time Calculator (ETC) is also described.
M. Sirianni, C. Pavlovsky
07 Nov 2006
The ACS Side-2 Switch: An Opportunity to Adjust the WFC CCD Temperature Setpoint (ACS TIR 06-02)
This TIR describes the rationale for the WFC CCD temperature setpoint change from -77C to -81C that occurred concurrent with the switchover to Side 2 electronics in July 2006.
M. Sirianni, R. Gilliland, K. Sembach
06 Sep 2006
2004
Revision of the Advanced Camera for Surveys Filter Throughputs
Filter Throughput revision
F.R.Boffi
01 Jul 2004
2001
Scatter from the ACS/WFC inter-chip gap
A brief investigation was made to assess the scatter properties of the gap between the two WFC
chips. The geometry of this gap is complex and composed of materials,
which present diffusive surfaces that might potentially scatter light in an undesired fashion.
Nevertheless,
this gap could provide a useful dump for the unwanted light from a bright point source in a field
of fainter sources under study, minimizing the area of the image affected by blooming (along the
CCD columns).
George Hartig
27 May 2003
Related TIRs from the Telescopes Branch
2012
Charge Transfer Efficiency Correction: WFC Dark Files
In May of 2012, a new version of the calibration pipeline for ACS on the Hubble Space Telescope, CALACS 2012.2, was released. One of the major improvements in the new CALACS is the incorporation of the algorithm created by Anderson and Bedin (2010) to correct for the charge transfer efficiency (CTE) losses in WFC1 and WFC2. This algorithm is a pixel specific correction that is applied as one of the first steps in CALACS, before the subtraction of the dark reference file. In order to properly reduce any raw science images it was necessary to correct all the WFC dark reference files used in CALACS for CTE loss, about 1,600 files.
S. Ogaz et al.
07 Aug 2012
Bias and Dark Calibration of ACS/WFC Data: Post-SM4 Automated Pipeline
We describe the post-SM4 automated pipeline that creates reference files for bias and
dark calibration of ACS/WFC data. This document is intended for those who would like
to adopt our pipeline or understand the technical details of its implementation.
Lim, P. et al
19 Apr 2012
2008
ACS-R Multi-Parameter Optimization Constraints (TIR 08-04
Abstract
The repaired ACS WFC will undergo a three-week Optimization Campaign during early SMOV with read noise being the primary target for improvements through testing adjustments of a large number of detector control, voltage and timing patterns. A large number of factors, in addition to read noise, contribute to the utility of science data from ACS WFC. In this TIR we enumerate several such factors including Charge Transfer Efficiency (CTE), Full Well Depth (FWD), Linearity, Cross talk, gain stability and bias drift. For each we quantify values that existed when WFC was last used in January 2007 and provide extrapolation that we believe would have existed with a continuously operable instrument to May 2009. For each factor we provide qualitative discussion of how changes would impact science in order to provide a framework for considering changes that may arise during the Optimization Campaign.
In many cases, e.g. for CTE, significant deterioration of performance from nominal expectations as a result of changes during the optimization campaign would provide support for adjusting the optimization to lessen this, even at the cost of some increase of read noise.
R. L. Gilliland
03 Dec 2008
ACS-R SMOV Optimization Plan-I. Rationale and Strategy (TIR-08-03)
The document provides the optimization plan for the HST/ACS Replacement (ACS-R) flight hardware. It specifies the rationale for and types of activities required during SMOV to optimize the on-orbit performance of the hardware. The new flight hardware uses internal interfaces of the instrument that were not described or characterized in detail during the original build of the ACS. This optimization is planned in order to mitigate the risk of the ground (test) hardware not emulating these flight instrument interface well enough.
Edward S. Cheng
26 Aug 2008
Delivery of a new ACS SBC throughput curve for Synphot (TIR 2008-002)
On November 12th, 2007 a new ACS SBC throughput curve was implemented in CDBS, OPUS and DADS. This new curve is an improved version and accounts for SBC red leak. The red leak portion is based on a spectrum of HD 209458 prepared by Paul Goudfrooij.
Boffi, F.R.
21 Apr 2008
2007
We describe a revised set of procedures and software for creating finding charts and object catalogues which can be used to assess the risk to the STIS MAMA and ACS SBC detectors from bright blue objects in the vicinity of proposed planetary observations. These charts show the path of given planet, moon or comet across the background of stars, down to magnitude limit of the GSC2 digital sky survey plates. Associated object catalogues and color-magnitude diagrams are also produced showing which stars may violate bright object limits for the selected instrument mode.
Charles Proffit et. al.
11 Jun 2007
2006
Quantum Yield Correction for ACS/HRC and ETC implementation(ACS TIR 06-03)
In the ACS/HRC CCD a single UV photon may generate more than one photo-electron. We calculate the theoretical quantum yield and discuss the impact on the calculation of the S/N ratio for an observation in the UV. Without such correction the S/N can be overestimated up to ~18% in the F220W and ~26% at the bluest edge of PR200L. The implementation of the quantum yield correction in the ACS Exposure Time Calculator (ETC) is also described.
M. Sirianni, C. Pavlovsky
07 Nov 2006
The ACS Side-2 Switch: An Opportunity to Adjust the WFC CCD Temperature Setpoint (ACS TIR 06-02)
This TIR describes the rationale for the WFC CCD temperature setpoint change from -77C to -81C that occurred concurrent with the switchover to Side 2 electronics in July 2006.
M. Sirianni, R. Gilliland, K. Sembach
06 Sep 2006
2004
Revision of the Advanced Camera for Surveys Filter Throughputs
Filter Throughput revision
F.R.Boffi
01 Jul 2004
2001
Scatter from the ACS/WFC inter-chip gap
A brief investigation was made to assess the scatter properties of the gap between the two WFC
chips. The geometry of this gap is complex and composed of materials,
which present diffusive surfaces that might potentially scatter light in an undesired fashion.
Nevertheless,
this gap could provide a useful dump for the unwanted light from a bright point source in a field
of fainter sources under study, minimizing the area of the image affected by blooming (along the
CCD columns).
George Hartig
27 May 2003