Instrument Science Report 2009-01:
Rapid Pinhole Growth in the F160BW Filter
J. Biretta and K. Verner
March 25, 2009
The WFPC2 Filter F160BW, also known as the Wood's filter, was designed to transmit UV emission around 150nm and strongly block all other wavelengths. The filter has a unique construction where a thin film of sodium metal serves as the spectral element. However, sodium is a highly unstable and reactive metal, which makes the filter susceptible to changes over time. Herein we report a rapidly growing pinhole in the filter located in the field of view of the WF2 CCD. Observers requiring a high rejection of out-of-band light (i.e. red leak) should take note of this feature, and avoid the affected region in the field-of-view.
The Complete Paper (PDF 1.0 MB) is available.