6779( 14) - 02/18/97 14:26 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6779 Version: 14 Check-in Date: 18-Feb-1997 14:23:24 1.Proposal Title: Photometry for M28 and NGC 5286 ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle STELLAR POPULATIONS GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: CARL GEBHARDT UNIVERSITY OF MICHIGAN CoI: Carlton Pryor Rutgers University N CoI: Ted Williams Rutgers University N CoI: James Hesser DAO N ------------------------------------------------------------------------------------ 6. Abstract We propose to obtain V and I photometry for the centrally- concentrated Galactic globular clusters M28 and NGC 5286 extending to slightly below the main-sequence turnoff. These data will yield color-magnitude diagrams and accurate stellar positions which we will use to precisely determine the radial and azimuthal structure of the clusters and to search for exotic stellar populations. The HST stellar positions will also increase the size, improve the accuracy, and eliminate several kinds of contamination from our large samples of ground-based Fabry-Perot stellar velocities for the two clusters. Combining the structure and kinematic data will allow us to derive accurate mass profiles for the two clusters, thus testing key predictions of the dynamical models for core collapse and constraining the population of heavy stellar objects in the clusters. Comparing the measured cluster rotation with flattening of star-count isopleths will let us search for changes in the axis of rotation with radius such as we have found in M15. M28 is of particular interest for dynamical studies because pulsar timing measurements suggest that it has a large mass-to-light ratio in its central region. NGC 5286 has a collapsed core and is rapidly rotating. ------------------------------------------------------------------------------------ 6779( 14) - 02/18/97 14:26 - [ 2] Observations Description ------------------------ We desire exposures which will reach at least one magnitude below the faintest star observable in the Fabry-Perot observations. This is about V=19.5. For both M28 and NGC 5286, this is more than adequate to measure the horizontal branch and the blue stragglers. To reach fainter than 19.5 in V and 18.5 in I, we desire five exposures of 6s with both the F555W and F814W filters. With this exposure time, the brightest stars will not saturate. We will dither to oversample the PSF. Real Time Justification ----------------------- Intensive ground-based Fabry-Perot observations have been and are being obtained at CTIO and CFHT. Both M28 and NGC 5286 have been studied and, combined with HST images, the data will yield approximately 700 stellar velocities in both M28 and NGC 5286. Future observations to obtain a larger velocity dataset and repeat measurements are likely. We already have obtained a large database of stellar velocities with the Fabry-Perot, and have and will combine these data with existing and planned HST images to measure the central dynamics. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 6779( 14) - 02/18/97 14:26 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC6626 STELLAR CLUSTER, RA=18H 24M 32.9S +/- 0.1S,DEC=- 2000 V = 13.5+/-0.2 GLOBULAR CLUSTER 24D 52' 12" +/- 1" B-V = 1.0+/-0.2 E(B-V) = 0.4+/-0.2 2 NGC5286 STELLAR CLUSTER, RA=13H 46M 26.5S +/- 0.1S,DEC=- 2000 V = 14.2+/-0.2 GLOBULAR CLUSTER 51D 22' 24" +/- 1" B-V = 0.9+/-0.2 E(B-V) = 0.2+/-0.2 6779( 14) - 02/18/97 14:26 - [ 4] Visit: 01 Visit Requirements: PCS MODE FINE ORIENT 100D TO 260D 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC6626 WFPC2 IMAGE PC1-FIX F555W DITHER-TYPE=LINE, 1 140 S DITHER-LINE-STEPS=3, DITHER-LINE-SPACING=0.236 ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC6626 WFPC2 IMAGE PC1-FIX F555W 1 4.0 S ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC6626 WFPC2 IMAGE PC1-FIX F814W DITHER-TYPE=LINE, 1 140 S DITHER-LINE-STEPS=3, DITHER-LINE-SPACING=0.236 ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC6626 WFPC2 IMAGE PC1-FIX F814W 1 3.0 S ------------------------------------------------------------------------------------------------------------------------------------ 6779( 14) - 02/18/97 14:26 - [ 5] Visit: 02 Visit Requirements: PCS MODE FINE 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC5286 WFPC2 IMAGE PC1-FIX F555W DITHER-TYPE=LINE, 1 140 S DITHER-LINE-STEPS=3, DITHER-LINE-SPACING=0.236 ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC5286 WFPC2 IMAGE PC1-FIX F555W 1 100 S ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC5286 WFPC2 IMAGE PC1-FIX F555W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC5286 WFPC2 IMAGE PC1-FIX F814W DITHER-TYPE=LINE, 1 140 S DITHER-LINE-STEPS=3, DITHER-LINE-SPACING=0.236 ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC5286 WFPC2 IMAGE PC1-FIX F814W 1 7 S ------------------------------------------------------------------------------------------------------------------------------------ 6779( 14) - 02/18/97 14:26 - [ 6] Summary Form for Proposal 6779 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters DITHER-TYPE=LINE DITHER-LINE-STEPS=3 DITHER-LINE-SPACING=0.236 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category STELLAR POPULATIONS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PCS MODE FINE ORIENT 100D TO 260D PCS MODE FINE ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F555W F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC6626 NGC5286 ------------------------------------------------------------------------------------------------------------------------------------