Index A ACCUM mode 1, 2 Doppler correction pulse-height data acquisitions 1, 2, 3 ACQ/IMAGE ACQ/PEAKD ACQ/PEAKXD ACQ/SEARCH spiral pattern centering accuracy and photometry early (preliminary images) exposure time dispersed-light imaging extended or multiple targets offset target overhead times recommended parameters (table) airglow - see background rates airglow emission - see background rates apertures 1, 2 BOA FCA PSA table WCA ApM - see mechanisms, ApM B background rates 1, 2 airglow 1, 2 detector Earthshine geocoronal Moon second-order light tables zodiacal light 1, 2 BOA - see apertures, BOA bright-object protection 1, 2 BUFFER-TIME estimation C calibration accuracies calibration observations 1, 2 Cycle 17 Cycle 18 Cycle 19 Cycle 20 FUV lifetime positions ground testing SMOV Cardelli extinction model COS compared to STIS 1, 2 focal plane schematic optical design 1, 2 team members Cycle 17 calibration observations Cycle 18 calibration observations Cycle 19 calibration observations Cycle 20 calibration observations D dark rate 1, 2 data products 1, 2 dead time FUV NUV detector non-linear effects - see dead time detector plate scale Doppler correction ACCUM mode TIME-TAG mode E Earthshine - see background rates effective area FUV point source NUV imaging NUV point source ETC 1, 2 examples observing sequences 1, 2 using the ETC 1, 2 exposure time acquisitions dispersed-light imaging estimating with ETC 1, 2 valid values wavecal exposures Exposure Time Calculator - see ETC EXTENDED optional parameter extinction Cardelli model F FCA - see apertures, FCA flat-field quality flux precision FP-POS optional parameter Frequently-Asked Questions FUV channel detector 1, 2 bright-object protection procedures characteristics (table) count-rate limits dark rate 1, 2 dead time dead-time constant format gain sag photocathode pulse-height distribution quantum efficiency segment gap coverage sensitivity adjustments single-segment observations stim pulses walk effect effective area grating parameters lifetime positions calibration optical design spatial variation of dark rate wavelength settings and ranges G G130M grating CENWAVE=1055 or 1096 CENWAVE=1222 G140L grating G160M grating G185M grating G225M grating G230L grating G285M grating Gain sag Galactic extinction - see extinction grating parameters ground testing H HST apertures and focal plane 1, 2 wavefront errors I Instrument Development Team (IDT) members L line-spread function 1, 2 M mechanisms ApM OSM1 OSM2 1, 2 shutter MIRRORB N Number_of_Iterations optional parameter NUV channel detector 1, 2 bright-object protection procedures characteristics (table) count-rate limits dark rate 1, 2 dead time dead-time constant format MAMA properties photocathode point-spread function quantum efficiency spectral gap coverage effective area grating parameters imaging 1, 2 optical design vignetting wavelength settings and ranges O OSM1 - see mechanisms, OSM1 OSM2 - see mechanisms, OSM2 overhead times 1, 2 acquisitions first-exposure adjustment generic observatory times OSM1 movements OSM2 movements Phase I estimates science exposures P photometric precision plate scale - see detector plate scale point-spread function 1, 2 of NUV MAMA PSA - see apertures, PSA pulse-height distribution R resolution imaging spatial spectroscopic 1, 2 (table) temporal (TIME-TAG mode) resolution element (resel) resolving power S Scattered light, internal second-order light SEGMENT optional parameter sensitivity shutter - see mechanisms, shutter signal-to-noise ratio estimating improving plots see also exposure time, estimating SMOV calibration observations SNAP programs spectrograph design parameters 1, 2 spectroscopic modes - see grating parameters stim pulses STIS compared to COS 1, 2 STMAG system STScI Help Desk T TAGFLASH exposure durations target acquisitions - see acquisitions TIME-TAG mode 1, 2 BUFFER-TIME estimation Doppler correction pulse-height data U units and conventions User Support W wavecal - see wavelength calibration wavelength accuracy specifications wavelength calibration 1, 2 AUTO TAGFLASH user-specified wavelength settings and ranges (table) wavelengths, units and convention WCA - see apertures, WCA X XDL - see FUV channel Z zodiacal light - see background rates ΜΙΡΡΟΡΑ