WFC3/IR Persistence as Measured in Cycle 17 using Tungsten Lamp Exposures
Abstract
Like most IR arrays, the IR detector incorporated into WFC3 exhibits persistence, an afterglow in science pixels that have been saturated in earlier exposures. Here we report on the results of an attempt to characterize the persistence in the WFC3/IR detector using the internal Tungsten flat field lamp to illuminate the array. We find that the persistence is well described by a power law as a function of time with a slope of -0.9. Ignoring one anomalous visit, the average persistence persistence 1000 s after the end of a saturated exposure rises from 0.33 to 0.52 e s-1 as the fluence increases from 2x to 20x saturation. Unfortunately, one visit with a mean fluence of 2x saturation, or 140,000 e, showed much more persistence (0.65 e s-1 at 1000 s) than two other nearly identical visits executed several months later (0.32-0.34 e s-1). It is unclear why the first visit was anomalous. Partially as a result, a much more extensive set of observations to characterize persistence will be carried out in Cycle 18.
- Publication:
-
Space Telescope WFC Instrument Science Report
- Pub Date:
- November 2010
- Bibcode:
- 2010wfc..rept...17L
- Keywords:
-
- Hubble Space Telescope;
- HST;
- Space Telescope Science Institute;
- WFC3;
- Wide Field Camera 3