10136( 2) - 05/19/04 08:34 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 10136 Version: 2 Check-in Date: 19-May-2004 12:32:32 1.Proposal Title: Post-AGB Stars in the Halo of M81 ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle 4. Parallel Pointing Tolerance GO 13 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Dr. Howard E. Bond Space Telescope Science Institute CoI: Dr. Michael H. Siegel Space Telescope Science Institute N ------------------------------------------------------------------------------------ 6. Abstract Post-asymptotic-giant-branch (PAGB) stars of spectral types A-F are the brightest members of Population II. We have shown, using ground-based observations, that PAGB stars have tremendous potential as highly efficient standard candles and as tracers of halo populations and late stellar evolution. Our analysis of PAGB stars in archival HST images of M32, based on the equivalent of one orbit of HST time, precisely reproduces the accepted distance. We propose to obtain ACS/WFC and WFPC2 images of fields in the halo of M81, as another test of the PAGB method. We show that 4 orbits of HST data will produce a distance of comparable accuracy to the much more laborious Cepheid technique. If successful on M81, we will propose in the next cycle to measure the distance to Virgo using our method, a distance ladder that has only two rungs (trigonometric parallaxes of subdwarfs to calibrate PAGB stars in globular clusters, and then PAGB stars in Virgo). ------------------------------------------------------------------------------------ 10136( 2) - 05/19/04 08:34 - [ 2] Observations Description ------------------------ We will obtain WFPC2 frames in u, V, I (F336W, F555W, F814W) in a field in the halo of M81, for the purpose of identifying post-AGB stars with large Balmer jumps. We will also use ACS/WFC in parallel in another, adjacent halo field, in V and I (F606W, F814W). Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 10136( 2) - 05/19/04 08:34 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 M81-HALO- GALAXY, HALO, SPIRAL RA=09H54M32.9S +/- 0.1", J2000 V = 24.5+/-0.1 FIELD DEC=+69D00'0.00" +/- 0.1", PLATE-ID=00M9 Coordinate Source: IMAGE_TIED_TO_GSC_FRAME 10136( 2) - 05/19/04 08:34 - [ 4] Visit: 01 Visit Priority: Visit Requirements: SCHED 30%; ORIENT 107.0D TO 117.0 D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 M81-HALO-FI WFPC2 IMAGE WFALL F555W ATD-GAIN=7,CR-SPLIT=NO 1 1200 S POS TARG 0, 0; PAR 2 WITH ELD 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 ANY ACS/WFC ACCUM WFC F606W CR-SPLIT=NO 1 500 S ------------------------------------------------------------------------------------------------------------------------------------ 3 M81-HALO-FI WFPC2 IMAGE WFALL F555W ATD-GAIN=7,CR-SPLIT=NO 1 1200 S POS TARG 0.25, 0.25; PAR ELD 4 WITH 3 ------------------------------------------------------------------------------------------------------------------------------------ 4 ANY ACS/WFC ACCUM WFC F606W CR-SPLIT=NO 1 500 S ------------------------------------------------------------------------------------------------------------------------------------ 5 M81-HALO-FI WFPC2 IMAGE WFALL F814W ATD-GAIN=7,CR-SPLIT=NO 1 1200 S POS TARG 0, 0; PAR 6 WITH ELD 5 ------------------------------------------------------------------------------------------------------------------------------------ 6 ANY ACS/WFC ACCUM WFC F814W CR-SPLIT=NO 1 500 S ------------------------------------------------------------------------------------------------------------------------------------ 7 M81-HALO-FI WFPC2 IMAGE WFALL F814W ATD-GAIN=7,CR-SPLIT=NO 1 1200 S POS TARG 0.25, 0.25; PAR ELD 8 WITH 7 ------------------------------------------------------------------------------------------------------------------------------------ 8 ANY ACS/WFC ACCUM WFC F814W CR-SPLIT=NO 1 500 S ------------------------------------------------------------------------------------------------------------------------------------ 9 M81-HALO-FI WFPC2 IMAGE WFALL F336W ATD-GAIN=7,CR-SPLIT=NO 1 1200 S POS TARG 0, 0; PAR 10 ELD WITH 9 ------------------------------------------------------------------------------------------------------------------------------------ 10 ANY ACS/WFC ACCUM WFC F814W CR-SPLIT=NO 1 500 S ------------------------------------------------------------------------------------------------------------------------------------ 11 M81-HALO-FI WFPC2 IMAGE WFALL F336W ATD-GAIN=7,CR-SPLIT=NO 1 1200 S POS TARG 0.5, 0.25; PAR ELD 12 WITH 11 ------------------------------------------------------------------------------------------------------------------------------------ 12 ANY ACS/WFC ACCUM WFC F814W CR-SPLIT=NO 1 500 S ------------------------------------------------------------------------------------------------------------------------------------ 13 M81-HALO-FI WFPC2 IMAGE WFALL F336W ATD-GAIN=7,CR-SPLIT=NO 1 1200 S POS TARG 0.75, 0.75; PAR ELD 14 WITH 13 ------------------------------------------------------------------------------------------------------------------------------------ 14 ANY ACS/WFC ACCUM WFC F606W CR-SPLIT=NO 1 500 S ------------------------------------------------------------------------------------------------------------------------------------ 15 M81-HALO-FI WFPC2 IMAGE WFALL F336W ATD-GAIN=7,CR-SPLIT=NO 1 1200 S POS TARG 0.25, 0.5; PAR ELD 16 WITH 15 ------------------------------------------------------------------------------------------------------------------------------------ 16 ANY ACS/WFC ACCUM WFC F606W CR-SPLIT=NO 1 500 S ------------------------------------------------------------------------------------------------------------------------------------ 10136( 2) - 05/19/04 08:34 - [ 5] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Visit Id| Exp Id |Primary |Secondary |Iteration |CR-SPLIT |Orbit Num |Duration | |Pattern Pos |Pattern Pos |Num |Num | | ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Visit Id| Exp Id |Primary |Secondary |Iteration |CR-SPLIT |Orbit Num |Duration | |Pattern Pos |Pattern Pos |Num |Num | | ------------------------------------------------------------------------------------------------------------------------------------ 01 1 none none none none 1 1200.0 01 2 none none none none 1 1282.0 01 3 none none none none 1 1200.0 01 4 none none none none 1 1349.0 01 5 none none none none 2 1300.0 01 6 none none none none 2 1369.0 01 7 none none none none 2 1300.0 01 8 none none none none 2 1354.0 01 9 none none none none 3 1300.0 01 10 none none none none 3 1424.0 01 11 none none none none 3 1300.0 01 12 none none none none 3 1354.0 01 13 none none none none 4 1300.0 01 14 none none none none 4 1369.0 01 15 none none none none 4 1300.0 01 16 none none none none 4 1354.0 10136( 2) - 05/19/04 08:34 - [ 6] Summary Form for Proposal 10136 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures WFALL WFC ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ACS/WFC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ATD-GAIN=7 CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements SCHED 30%; ORIENT 107.0D TO 117.0 D POS TARG 0, 0; PAR 2 WITH 1 POS TARG 0.25, 0.25; PAR 4 WITH 3 POS TARG 0, 0; PAR 6 WITH 5 POS TARG 0.25, 0.25; PAR 8 WITH 7 POS TARG 0, 0; PAR 10 WITH 9 POS TARG 0.5, 0.25; PAR 12 WITH 11 POS TARG 0.75, 0.75; PAR 14 WITH 13 POS TARG 0.25, 0.5; PAR 16 WITH 15 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F555W F606W F814W F336W ------------------------------------------------------------------------------------------------------------------------------------ Target Names M81-HALO-FIELD ANY ------------------------------------------------------------------------------------------------------------------------------------