UVIS Flat Fields Affected by Shutter-Induced Vibration
Abstract
Image ratios of short internal tungsten flat fields exhibit faint diagonal striping along a direction coincident with the shutter edge travel. We investigate the phenomenon using additional archival data, both internal and external, and develop a model to quantify the amount of variation observed across the field of view. We find 1) no evidence for striping in external images, 2) the stripes are limited to short (<10s) internal exposures and 3) the stripes' amplitude is noticeably higher in images taken with the B shutter blade. Specifically, blade A image striping is typically 0.1% or less peak to peak while the blade B striping is typically 0.5% or higher peak to peak for 1 s exposures. We interpret the lack of striping in external images as an indication that the effect is not directly related to the low-level blurring of the PSF observed in short (<10s) external exposures that has been attributed to shutter-induced vibrations of the WFC3 pick-off mirror or the M1 mirror. Instead, we interpret the striping effect as a shutter-induced vibration of an optical element in the internal light path of the calibration subsystem.
- Publication:
-
Space Telescope WFC Instrument Science Report
- Pub Date:
- August 2018
- Bibcode:
- 2018wfc..rept...11K
- Keywords:
-
- Hubble Space Telescope;
- HST;
- Space Telescope Science Institute;
- STScI;
- WFC3;
- Wide Field Camera 3;
- Shutter;
- UVIS