12081( 4) - 16-Apr-2010 18:03:53 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 12081 Version: 4 Check-in Time: 16-Apr-2010 18:03:53 STScI Edit Number: 0 Title COS Flux Calibration Below 1150 Angstroms with G140L/1280 ------------------------------------------------------------------------------------ Type Cycle CAL/COS 17 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Derck L. Massa Space Telescope Science Institute CoI: Dr. Steven V. Penton University of Colorado at Boulder N CoI: Dr. Steven Osterman University of Colorado at Boulder N CoI: Dr. Ralph Bohlin Space Telescope Science Institute N CoI: Dr. Pierre Chayer The Johns Hopkins University N ------------------------------------------------------------------------------------ Abstract We currently have a fairly accurate (10%) estimate of the G140L FUVB FUV sensitivity. This is based on low S/N data of a faint standard star and a set of relatively high S/N spectra of a bright wd which cannot be accurately modelled. The former have an accuracy worse than 20%, and the latter had to rely on FUSE absolute fluxes, which are only good to about 10%. Since this setting is now available to GOs, we should obtain an accurate (2-3%) charaterization of the FUV G140L sensitivity. To do this, we intend to observe the hot wd GD50. This star has high S/N IUE, FUSE and EUVE observations. Further, it has been observed from the ground and its atmospheric parameters are reasonably well determined. Both Pierre Chayer and Ralph Bolhin have agreed to produce the models needed to use it as a high quality FUV flux calibration source. In addition, the existance a good GD50 EUVE spectrum means that the same observations can be used to characterize the EUV sensitivity to 10% accuracy, if estimates of the COS EUV sensitivity are correct. ------------------------------------------------------------------------------------ Observations Description ------------------------ GD 50 was selected for observaiton because it is the the brightest EUVE source that is faint enough to be observed with COS. We will obtain G140L CENWAVE=1230 FP-POS=4 observations to place as much of the long wavelength flux off of the FUVB as possible. FUVA must be off, since COS is much more sensitive at those wavelengths and GD 50 would be over bright there. Ninety minutes of observing time is required to obtain a S/N = 50/1 for a 20 pixel bin -- appropriate for accurate flux calibration. Three orbits gives about 93 min of time on target. FUVA must be off.. ETC COS.A287428 shows that the source flux 1150 and shortward violates the local count rate limit of 7.0 by 10% ( 0.769). However, since this occurs at 1150, where the target is well calibrated, this should not be a concern. Will use FP-POS positions to minimize fixed pattern noise, which is unknown in 12081( 4) - 16-Apr-2010 18:03:53 - [ 2] this region of the FUVB. Moving to longer wavelengths onto the detector should not be an issue since the maximum count rate is expected to occur near 1155. Real Time Justification ----------------------- Calibration Justification ------------------------- Measure the COS FUV (900 - 1150Ang) G140L sensitivity to 2% and obtain a rough measure of its EUV (300-700) sensitivity. This S/N can be obtained over 20 pixel bins using FP-POS observartions of 90 min or longer -- the proposed program has 93 min of exposures. Additional Comments ------------------- ------------------------------------------------------------------------------------ 12081( 4) - 16-Apr-2010 18:03:53 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 GD50 CALIBRATION, THROUGHPUT RA=03H48M50.2000S +/- 0.1", J2000 V = 13.98 +/- 0.01 TEST DEC=-00D58'31.20" +/- 0.1" Reference Frame: ICRS Comments: Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.0043 -0.1610 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 12081( 4) - 16-Apr-2010 18:03:53 - [ 4] Visit: 01 Visit Requirements: SCHED 90% On Hold Comments: Additional Comments: FUVA must be off.. ETC COS.A287428 shows that the source flux 1150 and shortward violates the local count rate limit of 7.0 by 10% ( 0.769). However, since this occurs at 1150, where the target is well calibrated, this shyould not be a concern. Will use FP-POS positions to minimize fixed pattern noise, which is unknown in this region of the FUVB. Moving longer wavelengths onto the detector should not be an issue since the maximum count rate is expected to occur at 1155. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 GD50 COS/NUV ACQ/SEA BOA MIRRORA SCAN-SIZE=3, STEP-SIZE=1.767 1 20 S RCH ------------------------------------------------------------------------------------------------------------------------------------ 2 GD50 COS/NUV ACQ/IMA BOA MIRRORA 1 20 S GE ------------------------------------------------------------------------------------------------------------------------------------ 3 GD50 COS/FUV TIME-TA PSA G140L 1280 SEGMENT=B, FLASH=YES, 1 1500 S G FP-POS=4, BUFFER-TIME=140 ------------------------------------------------------------------------------------------------------------------------------------ 4 GD50 COS/FUV TIME-TA PSA G140L 1280 SEGMENT=B, FLASH=YES, 1 1500 S G FP-POS=3, BUFFER-TIME=140 ------------------------------------------------------------------------------------------------------------------------------------ 5 GD50 COS/FUV TIME-TA PSA G140L 1280 FLASH=YES, SEGMENT=B, 1 1000 S G FP-POS=2, BUFFER-TIME=140 ------------------------------------------------------------------------------------------------------------------------------------ 6 GD50 COS/FUV TIME-TA PSA G140L 1280 FLASH=YES, SEGMENT=B, 1 750 S G FP-POS=2, BUFFER-TIME=140 ------------------------------------------------------------------------------------------------------------------------------------ 7 GD50 COS/FUV TIME-TA PSA G140L 1280 SEGMENT=B, BUFFER-TIME=140, 1 1700 S G FLASH=YES, FP-POS=1 ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ GD50 1 COS/NUV ACQ/SEA BOA MIRRORA none none none none 1 N/A RCH GD50 2 COS/NUV ACQ/IMA BOA MIRRORA none none none none 1 N/A GE GD50 3 COS/FUV TIME-TA PSA G140L 1280 none none none none 1 N/A G GD50 4 COS/FUV TIME-TA PSA G140L 1280 none none none none 2 N/A G 12081( 4) - 16-Apr-2010 18:03:53 - [ 5] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ GD50 5 COS/FUV TIME-TA PSA G140L 1280 none none none none 2 N/A G GD50 6 COS/FUV TIME-TA PSA G140L 1280 none none none none 3 N/A G GD50 7 COS/FUV TIME-TA PSA G140L 1280 none none none none 3 N/A G 12081( 4) - 16-Apr-2010 18:03:53 - [ 6] Summary Form for Proposal 12081 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures BOA, PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV, COS/NUV ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/IMAGE, ACQ/SEARCH, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=140, FLASH=YES, FP-POS=1, FP-POS=2, FP-POS=3, FP-POS=4, SCAN-SIZE=3, SEGMENT=B, STEP-SIZE=1.767 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements SCHED 90% ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G140L, MIRRORA ------------------------------------------------------------------------------------------------------------------------------------ Target Names GD50 ------------------------------------------------------------------------------------------------------------------------------------