6938( 6) - 08/26/97 11:10 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6938 Version: 6 Check-in Date: 26-Aug-1997 11:09:22 1.Proposal Title: PSF Characterization ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle CAL/WF2 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: ANDREW FRUCHTER SPACE TELESCOPE SCIENCE INSTITUTE CoI: Chris O'dea STScI N ------------------------------------------------------------------------------------ 6. Abstract Provide a subsampled PSF over the full field to allow PSF fitting photometry, test PSF subtraction as well as dithering techniques (cf. effects of the OTA breathing and CCD gain). ------------------------------------------------------------------------------------ 6938( 6) - 08/26/97 11:10 - [ 2] Observations Description ------------------------ Measure PSF over full field in photometric filters in order to update the TIM and TINYTIM models and to allow accurate empirical PSFs to be derived for PSF fitting photometry. These observations will also be useful in order to test PSF subtraction and dithering techniques at various locations on the CCD chips. With one orbit per photometric filter, a spatial scan is performed over a 4X4 grid on the CCD. The step size is 0.025 arcseconds. This gives a critically sampled PSF over most of the visible range. The crowded Omega Cen field is used. 40 (with gain = 15) sec images are taken through each of the photometric filters (F336W, F439W, F555W, F675W and F814W). Effects of the OTA breathing (1 additional orbit) and CCD gain (1 additional orbit) onto the dithering and PSF subtraction techniques will also be investigated. Based partially on cycle 4 program 5575 and cycle 5 program 6193 which used a similar field. Note however that most observations in this program use the same specially chosen field in Omega Cen as the cycle 5 proposal 6193, but with a few arcsec shift in order to better map the PSF variation across the field. The proposal also allows a check for subpixel phase effects on the integrated photometry. Output -- Subsampled PSFs for photometry codes. Data for comparison with PSF and dithering codes. Provides measurement of pixel phase effect on photometry (sub pixel QE variations exist). The chosen field will have tens of well exposed stars in each chip. Each star will be measured 16 times per filter at different pixel phase. The proposal therefore provides, in principle, a high signal to noise, critically sampled PSF. This will leave PSF fitting photometrists in a much better position than now, where pixel undersampling clearly limits the results. The result will be largely limited by breathing variations in focus. It is hard to judge the PSF accuracy that will result. If breathing is less than 5 microns peak to peak, the resulting PSFs should be good to about 10% in each pixel. Breathing effects will be investigated (1 additional orbit) as well as the gain dependence (1 additional orbit). PSF fitting results using this calibration would of course be much more accurate. In addition, the test gives a direct measurement of sub-pixel phase effects on photometry, which should be measured to better than 1%. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- SCHEDULING COMMENTS: - Proposal currently written as several single visits requiring in total 7 orbits for easier scheduling (same orientation should of course be maintai- ned for all visits except F336W). Because of a desirable comparison between the PSFs derived for the different filters, we should like the entire proposal to be executed within 2 weeks. This is necessary to minimize the spacecraft temperature differences t hat result from orbital precession effects. ------------------------------------------------------------------------------------ 6938( 6) - 08/26/97 11:10 - [ 3] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: ------------------------------------------------------------------------------------ 6938( 6) - 08/26/97 11:10 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 OMEGA-CEN-A CALIBRATION,PHOTOMETRIC RA = 13H 26M 41.48S +/- 0.1S, 2000 V = 20.0+/-1.2 DEC = -47D 31' 7.4" +/- 1",PLATE B-V = -0.4+/-0.2 -ID=ZZZR Comments: target position from dataset u2ssa203t (proposal 6053) 2 OMEGA-CEN-B CALIBRATION,PHOTOMETRIC RA=13H 25M 31.5S +/- 0.1S, DEC=- J2000 V = 16.4 47D 35' 33.6" +/- 1.00" Comments: target position from dataset u3890401t (proposal 6193) 3 OMEGA-CEN-C CALIBRATION,PHOTOMETRIC XI-OFF=0.25" +/- 0.01",ETA- J2000 V = 16.4 OFF=0.25" +/- 0.01",FROM 2 Comments: position offset to study effects of breathing 6938( 6) - 08/26/97 11:10 - [ 5] Visit: 01 Visit Requirements: ORIENT 5D TO 75D; GROUP 1-7 WITHIN 14D On Hold Comments: Additional Comments: orient 185d to 255d also acceptable. Orient based on pa_v3=217 for u2ssa203t, +/-35d Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 OMEGA-CEN-A WFPC2 IMAGE WFALL-F F336W CR-SPLIT=NO,ATD-GAIN=15, 1 40 S SPATIAL SCAN 1 IX SCAN-READ=ALL Comments: UV PSF observations, rich field in prop 6053 ------------------------------------------------------------------------------------------------------------------------------------ 6938( 6) - 08/26/97 11:10 - [ 6] Visit: 02 Visit Requirements: ORIENT 45D TO 115D On Hold Comments: Additional Comments: orient 225d to 295d also acceptable. Orient based on pa_v3=263d for u3890401t (from cyc 5 psf proposal 6193), +/- 35d Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 20 OMEGA-CEN-B WFPC2 IMAGE PC1 F439W CR-SPLIT=NO,ATD-GAIN=15, 1 40 S SPATIAL SCAN 1 SCAN-READ=ALL Comments: same field as prop 6193, same orient (+/- 35d) ------------------------------------------------------------------------------------------------------------------------------------ 6938( 6) - 08/26/97 11:10 - [ 7] Visit: 03 Visit Requirements: SAME ORIENT AS 02 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 30 OMEGA-CEN-B WFPC2 IMAGE PC1 F555W CR-SPLIT=NO,ATD-GAIN=15, 1 40 S SPATIAL SCAN 1 SCAN-READ=ALL Comments: same field as prop 6193, same orient (+/- 35D) ------------------------------------------------------------------------------------------------------------------------------------ 6938( 6) - 08/26/97 11:10 - [ 8] Visit: 04 Visit Requirements: SAME ORIENT AS 02 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 40 OMEGA-CEN-B WFPC2 IMAGE PC1 F675W CR-SPLIT=NO,ATD-GAIN=15, 1 40 S SPATIAL SCAN 1 SCAN-READ=ALL Comments: same field as prop 6193, same orient (+/- 35D) ------------------------------------------------------------------------------------------------------------------------------------ 6938( 6) - 08/26/97 11:10 - [ 9] Visit: 05 Visit Requirements: SAME ORIENT AS 02 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 50 OMEGA-CEN-B WFPC2 IMAGE PC1 F814W CR-SPLIT=NO,ATD-GAIN=15, 1 40 S SPATIAL SCAN 1 SCAN-READ=ALL Comments: same field as prop 6193, same orient (+/- 35D) ------------------------------------------------------------------------------------------------------------------------------------ 6938( 6) - 08/26/97 11:10 - [ 10] Visit: 06 Visit Requirements: SAME ORIENT AS 02; GROUP 6-7 WITHIN 2D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 60 OMEGA-CEN-C WFPC2 IMAGE PC1 F814W CR-SPLIT=NO,ATD-GAIN=15, 1 40 S SPATIAL SCAN 1 SCAN-READ=ALL Comments: To study breathing effects ------------------------------------------------------------------------------------------------------------------------------------ 6938( 6) - 08/26/97 11:10 - [ 11] Visit: 07 Visit Requirements: SAME ORIENT AS 02 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 70 OMEGA-CEN-B WFPC2 IMAGE PC1 F814W CR-SPLIT=NO,ATD-GAIN=7, 1 40 S SPATIAL SCAN 1 SCAN-READ=ALL Comments: To study gain=7 effects ------------------------------------------------------------------------------------------------------------------------------------ 6938( 6) - 08/26/97 11:10 - [ 12] Scan Paramters Form ------------------------------------------------------------------------------------------------------------------------------------ Data ID: 1 Exposure Logsheet lines: 1.010,2.020,3.030,4.0 FGS Scan: D Dwell Only: dwell points/line: 4 Seconds per dwell: 40.00 Scan width (arc-secs): 0.3750 Scan length (arc-secs): 0.3750 Angle between sides (degrees) 90.00 Number of lines: 4 Scan rate (arc-sec/sec): 0.0000 PA of first scan line (degrees) 270.000 Scan frame (CEL or S/C): S/C Length Offset (arc-sec): 0.0 Width Offset (arc-sec): 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 6938( 6) - 08/26/97 11:10 - [ 13] Summary Form for Proposal 6938 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO ATD-GAIN=15 SCAN-READ=ALL ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category CAL/WF2 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 5D TO 75D; GROUP 1-7 WITHIN 14D SPATIAL SCAN 1 ORIENT 45D TO 115D SAME ORIENT AS 02 SAME ORIENT AS 02; GROUP 6-7 WITHIN 2D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F336W F439W F555W F675W F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names OMEGA-CEN-A OMEGA-CEN-B OMEGA-CEN-C ------------------------------------------------------------------------------------------------------------------------------------