9255( 3) - 06/12/01 08:03 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 9255 Version: 3 Check-in Date: 12-Jun-2001 08:02:50 1.Proposal Title: Cycle 10 WFPC2 Astrometric Effects of CTE ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle CAL/WF2 10 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: John Biretta Space Telescope Science Institute CoI: Sylvia Baggett STScI N ------------------------------------------------------------------------------------ 5. Abstract This proposal attempts to quantify the astrometric effects of CTE by measuring (1) the relative separation of a bright source vs. a faint target at different positions on the PC1 CCD, and (2) the relative motion of a source on the CCD compared to very precise slews performed with the FGSs. These tests will be conducted for point and extended targets at several different intensity levels. ------------------------------------------------------------------------------------ 9255( 3) - 06/12/01 08:03 - [ 2] Observations Description ------------------------ While the photometric effects of CTE have been well studied, and correction algorithms have been developed, very little is known about the astrometric effects of CTE. Riess (2000; WFPC2 ISR 00-04) has shown that extended sources suffer some degree of distortion due to CTE, indicating that the astrometry of sources must also be affected. E.g., the relative separation of a faint source from a bright source may depend on all the factors that influence CTE (position on detector, observing epoch, brightness in electrons, and image background). Targets will be observed in PC, 2x2 grid, 20" on a side, in the first orbit; the second orbit is a repeat with a small pointing offset (dither of N+1/2 PC pixels). The 2-orbit sequence will be done at different background light levels, using exposures from 100s in F450W to 1200s in F622W, repeated three times for two targets (total ~12 orbits). Targets will be the dense star field in Omega Cen, and a field of faint galaxies (from extended target CTE proposal 8456). Both fields in both targets will be chosen to have a bright star surrounded by fainter objects. While most of the test is performed on the PC, the WFC CCDs will also be important, as they can provide a sanity check on the motions made with the FGSs. The motions on the WFC CCDs will be a smaller number of pixels, and hence less subject to CTE variations. (Though the larger WFC pixels will make astrometry more difficult). Hence some care should be taken to have stars available on the WFC CCDs, though PC1 is the detector of primary interest. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 9255( 3) - 06/12/01 08:03 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC5139 CALIBRATION, RA=13H 27M 15.6S +/- 0.1S, DEC=- J2000 V = 16.4 PHOTOMETRIC 47D 29' 36.3" +/- 1.00", PLATE- ID=02EX Coordinate Source: HST_IMAGE Comments: target position measured from u40x0103m.c0h[1][485, 485] (prop 6941) 2 A1689-10 CALIBRATION, RA=13H 11M 30.38S +/- 0.1S, DEC= J2000 V = 19 PHOTOMETRIC -01D 21' 10.8" +/- 0.1", PLATE- ID=012I Coordinate Source: HST_IMAGE Comments: rich galaxy cluster; target measured on u5kl0101r.c0h wmosaic 955, 1279, % DGESTAR=0495800683F3. For completeness, the dominant guidestar ID listed in the measured omega Cen image (u40x0103m) was 3994304477; the secondary GS was 3994300327. 9255( 3) - 06/12/01 08:03 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type WFPC2-LINE SPIRAL Pattern_Purpose DITHER OTHER Number_Of_Points 2 4 Point_Spacing 0.3535 20 Coordinate_Frame POS-TARG POS-TARG Pattern_Orient 45 0. Center_Pattern NO YES ------------------------------------------------------------------------------------------------------------------------------------ 9255( 3) - 06/12/01 08:03 - [ 5] Visit: 01 Visit Priority: Visit Requirements: SEQ 1-3 WITHIN 8 H On Hold Comments: Additional Comments: USE SAME GUIDE STAR THROUGHOUT VISIT. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC5139 WFPC2 IMAGE PC1 F606W ATD-GAIN=7,CR-SPLIT=NO 1 10 S PATTERN 1 10 NO SPLIT ------------------------------------------------------------------------------------------------------------------------------------ 9255( 3) - 06/12/01 08:03 - [ 6] Visit: 02 Visit Priority: Visit Requirements: SAME ORIENT AS 01 On Hold Comments: Additional Comments: USE SAME GUIDE STAR THROUGHOUT VISIT. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC5139 WFPC2 IMAGE PC1 F606W ATD-GAIN=7,CR-SPLIT=NO 1 100 S PATTERN 1 20 NO SPLIT ------------------------------------------------------------------------------------------------------------------------------------ 9255( 3) - 06/12/01 08:03 - [ 7] Visit: 03 Visit Priority: Visit Requirements: SAME ORIENT AS 01 On Hold Comments: Additional Comments: USE SAME GUIDE STAR THROUGHOUT VISIT. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 30 NGC5139 WFPC2 IMAGE PC1 F606W ATD-GAIN=7,CR-SPLIT=NO 1 800 S PATTERN 1 30 NO SPLIT Comments: No CR-SPLIT since need high background. ------------------------------------------------------------------------------------------------------------------------------------ 9255( 3) - 06/12/01 08:03 - [ 8] Visit: 04 Visit Priority: Visit Requirements: SEQ 4-5 WITHIN 7.5 H ORIENT 70D TO 110D On Hold Comments: Additional Comments: USE SAME GUIDE STAR THROUGHOUT VISIT. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 40 A1689-10 WFPC2 IMAGE PC1 F606W ATD-GAIN=7,CR-SPLIT=NO 1 100 S PATTERN 1 40 NO SPLIT ------------------------------------------------------------------------------------------------------------------------------------ 9255( 3) - 06/12/01 08:03 - [ 9] Visit: 05 Visit Priority: Visit Requirements: SAME ORIENT AS 04 On Hold Comments: Additional Comments: USE SAME GUIDE STAR THROUGHOUT VISIT. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 50 A1689-10 WFPC2 IMAGE PC1 F606W ATD-GAIN=7,CR-SPLIT=NO 1 100 S PATTERN 1 50 NO SPLIT ------------------------------------------------------------------------------------------------------------------------------------ 9255( 3) - 06/12/01 08:03 - [ 10] Visit: 06 Visit Priority: Visit Requirements: SAME ORIENT AS 04 On Hold Comments: Additional Comments: USE SAME GUIDE STAR THROUGHOUT VISIT. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 60 A1689-10 WFPC2 IMAGE PC1 F606W ATD-GAIN=7,CR-SPLIT=NO 1 800 S PATTERN 1 60 Comments: No CR-SPLIT since need high background. ------------------------------------------------------------------------------------------------------------------------------------ 9255( 3) - 06/12/01 08:03 - [ 11] Summary Form for Proposal 9255 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PC1 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ATD-GAIN=7 CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category CAL/WF2 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements SEQ 1-3 WITHIN 8 H PATTERN 1 10 NO SPLIT SAME ORIENT AS 01 PATTERN 1 20 NO SPLIT PATTERN 1 30 NO SPLIT SEQ 4-5 WITHIN 7.5 H ORIENT 70D TO 110D PATTERN 1 40 NO SPLIT SAME ORIENT AS 04 PATTERN 1 50 NO SPLIT PATTERN 1 60 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F606W ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC5139 A1689-10 ------------------------------------------------------------------------------------------------------------------------------------