June 8, 2009
Charles Proffitt and the STIS
Team

• Completed final visit of MAMA FUV Recovery
11350 last night
• All currents and voltages within the expected range
• Fold test l ooks fine with no significant shift towards the higher fold numbers
• Flat field brightness consistent with previous trends
• Dark rate of 6.6 c/s consistent with expectations

• Slow decline usually attributed to lamp fading
• NUV HITM2 spectrum shows at most 2% change
• Need more detailed comparison of HITM2 at FUV wavelengths.

• Phase Retrivial to determine focus using 24 STIS F28X50OII narrow band images
• CR-SPLIT=2, 4 point subsampled dither

• STIS “best” focus is defined at the aperture plane
– Determined by maximizing throughput of 0.1x0.09
aperture with G230LB
– Routine monitor GRW+70 5824, V=12.7 hot DA
• Produces about 4e5 counts in 20 s
• However, actual monitor had some issues
– Bias level in early ACQ/Peaks too low, clipped flux
– Later fluctuations in background subtraction caused intermittent poor centering
– On-orbit flux number subtracts pedestal from faintest dwell point, underestimating total flux

• Re-analyzed historical data to allow comparison with a different brighter star
• Use detailed flux + background extraction from ACQ/PEAK confirmation image to remeasure flux
– Scale by synphot predicted flux, include:
• expected CTE losses
• time dependent sensitivity changes.
• For SMOV used even brighter star to mitigate centering problems

• FUV Dark Check 11390
– Watch how dark rate increases as function of time since HV on.
• NUV MAMA Recovery
– Visit 1 June 8, 19:55 UT
– Visit 2 June 9, 21:40 UT
– Visit 3 June 11, 17:22 UT
– Visit 4 June 13, 17:15 UT
• + ongoing CCD Darks and Biases