WFPC2 Filters after 16 Years on Orbit P. L. Lim 1, M. Quijada 2, S. Baggett 1, J. Biretta 1, J. MacKenty 1, R. Boucarut 2, S. Rice 2, & J. del Hoyo 2 STScI Calibration Workshop Space Telescope Science Institute 2 Goddard Space Flight Center

Motivations Over 180k datasets during on-orbit operation Improve science calibrations –In-band, red/blue leaks –Change in transmission, bandpass wavelength Distribute new filter transmissions on WFPC2 website (approx. Oct 2010) Publish results in Instrument Science Report STScI Calibration Workshop 2010

Known Changes F122M –20-25% throughput drop (Biretta & Gonzaga 2008; private communications) F160BW –Pinhole growth (WFPC2 ISR ) F343N –50% throughput drop (WFPC2 ISR ) Most filter changes expected to be less than a few percent STScI Calibration Workshop 2010

Filters of Interest Known on-orbit changes –F122M, F160BW, F343N High utilization –F300W, F450W, F555W, F606W, F675W, F702W, F814W, F850LP Regular utilization –F255W, F336W, F439W, F502N, F656N, F658N, F673N UV filters (red leak, pinholes) –F170W, F185W, F218W Others –F130LP, F160AW, F165LP, F375N, F380W, F390N, F437N, F467M, F469N, F487N, F1042M, ramp filters STScI Calibration Workshop 2010

Methods Cosmetic inspections (completed) –Stains, spots, pinholes Scan filter transmissions with spectrophotometer at GSFC –λ > 2000Å, Δλ ~ Å Compare with pre- and in-flight data STScI Calibration Workshop 2010

Five-Point Scan STScI Calibration Workshop 2010

F343N Confirms photometry results (Gonzaga & Biretta 2009) λ peak ~ 2Å redder, FWHM ~ 3Å wider, uniform change 3432Å 3434Å

F160AW, F160BW STScI Calibration Workshop 2010 AW → Not used in-flight due to pinholes BW → Pinholes now worse than AW, spatially dependent Will investigate when BW changes happened (Log scale)

F450W STScI Calibration Workshop 2010 Consistent with pre- and in-flight data (Log scale)

F170W STScI Calibration Workshop 2010 Red leak consistent with pre- and in-flight (Log scale)

Summary Goal is to improve science calibrations Inspections and scans are performed Early results are presented here –F343N, F160AW, F160BW, F450W, F170W Work is on-going and expected to be published in Oct 2010 STScI Calibration Workshop 2010 Thank you