WFC3/UVIS: 2018 Superbias Reference File
Abstract
Here we discuss the 2018 superbias reference file for the Wide Field Camera 3 (WFC3) UVIS channel. We analyze the 2018 superbias for the average pixel value per chip and and compare it to the 2017 superbias. We analyze all 11 superbias files from 2009-2018 for temporal variations in the average bias level across chip 1 and 2. We investigate charge transfer efficiency effects by calculating the average value for 200 rows of pixels closest and furthest from the CCD amplifiers. We have determined the average 2018 superbias level is 0.29 ± 0.65 e-, which is 0.030 ± 0.91 e- higher compared to the 2017 superbias. Our analysis of all 11 superbias files shows the average pixel level has been increasing since 2009 at a rate of 0.014 ± 0.001 e-/year and 0.033 ± 0.002 e-/year for chip 1 and 2 respectively. We have determined that the 2018 average superbias level is 0.21 ± 0.69 e- above the 2009 level. The 2018 superbias has been delivered to the Calibration Reference Data System and observers with science images taken after 2018-01-01 may request the improved products of their data through the Mikulski Archive for Space Telescopes.
- Publication:
-
Space Telescope WFC Instrument Science Report
- Pub Date:
- August 2019
- Bibcode:
- 2019wfc..rept...11K
- Keywords:
-
- HST;
- Hubble Space Telescope;
- Space Telescope Science Institute;
- STScI;
- WFC3;
- Wide Field Camera 3;
- UVIS;
- Bias;
- Superbias