We are proposing a calibration for a known systematic on WFC3, a new instrument. We do not need any specific images for this calibration and thus we chose to submit an archival proposal. When I tried to submit the proposal I received an error that presented submission because I hadn’t chose any specific data sets for archival retrieval. I cannot choose WFC3 data sets because there are none ion the archive yet and thus this is not an option in APT. After talking with help@stsci.edu (Brett), I decided to indicate WFPC2 on the submission form for datasets in order to allow me to submit the proposal. I obviously don’t need any WFPC2 data sets for this proposal so I hope the appropriate changes will be made. We have already talked with several members of the WFC3 team and they were supportive of this proposal. In the proposal we make it clear that we don’t need any special observations to perform this calibration. All of the images we need will be taken as part of normal calibration and science observation programs in Cycle 17. Assigned ID: 723 ----- Attempting Submission 1 (Fri Mar 07 23:08:50 GMT 2008) ----- Phase I Proposal 723 (persistence.apt) successfully submitted. ----- Attempting Submission 2 (Fri Mar 07 23:14:24 GMT 2008) ----- ----- Attempting Submission 3 (Tue Mar 11 17:53:56 GMT 2008) ----- WFC3 ARchival proposal with no datasets for a calibration Weak gravitational lensing, the slight distortion of the shapes of background galaxies by foreground dark matter, has become an important tool in precision cosmology. With the addition of the of the near infrared (NIR) WFC3 channel later this year, there will be NIR surveys in which weak lensing will be a primary or secondary science goal. We have identified an important instrumental systematic effect, image persistence, or ghosting, that is present in HgCdTe NIR detectors such as WFC3. This effect will cause non-negligible shape distortions that mimic a weak lensing signal and prevent precise weak lensing measurements. We have outlined a mitigation strategy that entials quantifying the effect and then removing the effect from the data as the first stage in image processing. We have all the necessary tools, including two HgCdTe detectors in our labs undergoing persistence characterization, an existing image simulation pipeline, and well-tested weak lensing shape measurement software. Using science and calibration imaging data taken during the normal course of Cycle 17 operations, we will develop a model of persistence in WFC3, produce a removal algorithm, and deliver the results to STScI for dissemination to the community. We will also monitor WFC3 over the course of Cycle 17 to see if the persistence worsens due to charged particle radiation damage.

COSMOLOGY 12 70000 true 0.0 0.0 false false false false false SUPPORTED