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Space Telescope Imaging Spectrograph

ACTIVITY TITLE: CCD Optical Format Verification



DESCRIPTION: For each CCD spectral optical element in the MSM (G230LB, G230MB, G430L, G430M, G750L, and G750M), a HITM1 lamp spectrum will be taken to match selected observations that were done as part of the cycle 11 STIS/CAL program 9617. The new observations need only be done for one CENWAVE value of each grating. These observations will verify the optical paths and MSM positioning used for each of these modes, and will also allow a check of the spectral resolution. Note that the spectral format of CCD imaging modes will be verified by activity STIS-08 and STIS-09.


DEPENDENCIES: Should be sequenced after STIS-08, but if necessary can be done any time after the initial CCD anneal (STIS-05) is completed.

DURATION: 30 minutes (one 1800 s internal visit)


ANALYSES & EXPECTED RESULTS: For each lamp spectrum obtained, compare the position of the spectral lines and the locations masked by the aperture bars to corresponding observations from program 9617. Look for any unexpected or operationally significant shifts in how the spectrum is projected onto the detector. Also, compare the line profiles for selected spectral lines to check for any changes in spectral resolution or focus across the detector. Look especially for any changes that are significant enough to affect operations or science data quality, or which might require table or database updates.

COMMENTS: Program 9617 switched to using the HITM1 in place of the LINE lamp for CCD dispersion solution checks, because the HITM1 lamp gives much better illumination at the E1 aperture positions. Program 9617 was also executed after the switch to side-2 operations for STIS, and as such may provide a better comparison to SMOV4 data than would earlier programs. Suggested exposures are as follows. All use the 52X0.1 aperture and the HITM1 lamp at the medium setting. G230LB 214s; G430L 10s; G750L 6.2s; G230MB CENWAVE=2697 14s; G430M CENWAVE=4451 18s; G750M CENWAVE=7795 29s.

AUTHOR/telephone/email: Charles Proffitt/410-338-4938/

DATE: September 7, 2007