WFC3 IR Gain from 2010-2015
Abstract
The conversion from electronic analog data units (ADUs) to electrons is one of the fundamental parameters needed to characterize the IR channel of WFC3. The IR detector on WFC3 has four quadrants, each with a separate amplifier chain. Here we report measurements of the gain of each of the amplifiers using a set of internal flat fields (F126N, SPARS50, 13 reads, ~600 sec). We find the gain values to be 2.27, 2.21, 2.20, 2.28 ± 0.02 e-/ADU for quadrants 1, 2, 3, 4, respectively. The flat field observations were taken from Oct. 2010 to June 2015 at a nominal gain setting of 2.5 e-/ADU. Persistence seems to have had little effect on our gain measurement, although it emerged unexpectedly at just half full-well in some of our flat fields (~14,000 DN/pix). Finally we compare the gain values computed from data calibrated with the current pipeline (2008) non-linearity correction to those computed from data calibrated with the new 2014 correction and find the difference, <1%, is negligible.
- Publication:
-
Space Telescope WFC Instrument Science Report
- Pub Date:
- September 2015
- Bibcode:
- 2015wfc..rept...14G
- Keywords:
-
- Hubble Space Telescope;
- Space Telescope Science Institute;
- STScI;
- HST;
- WFC3;
- flat fields