Instrument Science Report 2009-05:
Bandwidth Stability of the WFPC2 Narrow Band and Linear Ramp Filters
P. L. Lim and J. Biretta
May 18, 2009
As part of the WFPC2 close-out calibrations, we examine the stability of the bandwidths of the narrow band and linear ramp filters. We measure the FWHM of the spots produced by VISFLAT exposures using linear ramp filters crossed with narrow band filters. We do this for eight different pairings of narrow band and linear ramp filters. We then compare results from 1995 and 2008, and find negligible change in the bandpass FWHM for all eight filter pairs tested. Any change in the combined bandwidth is less than about 1% of the bandwidth. Our constraints on any changes in the narrow band filters (taken alone) are less strong, but we can rule out bandwidth changes larger than about 5% for typical narrow band filters (16% for the narrowest filter, F656N).
The Complete Paper (PDF 0.14 MB) is available.