6832( 7) - 05/06/97 12:55 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6832 Version: 7 Check-in Date: 06-May-1997 11:32:57 1.Proposal Title: Imaging of a Protogalaxy at z=2.7 Discovered by its Young Stellar Population ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle COSMOLOGY GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Howard Yee UNIVERSITY OF TORONTO CoI: Erica Ellingson University of Colorado Y CoI: Ray Carlberg University of Toronto N CoI: David Schade University of Toronto N CoI: Jill Bechtold Steward Observatory N ------------------------------------------------------------------------------------ 6. Abstract A protogalaxy candidate at z=2.7 has been discovered serendipitously by the CNOC cluster redshift survey. The candidate is a very bright (V=20.5 mag, absolute mag -- 28), resolved (2''*4''), disk-like galaxy with a strong absorption line spectrum indicative of young O, B, and A stars. The most likely interpretation of this object is that it is an early- type galaxy observed within 0.5 Gyr since its initial burst of star formation which produced most of its stellar mass. We propose to obtain HST images in 3 filters (F814W, F555W, and F300W) to study its structure and morphology in detail. These data will enable us to confirm our interpretation that the continuum arises from young stars, and to investigate the dynamical and evolutionary state of the protogalaxy and the uniformity of the star forming prcoess. The high resolution images will allow us to set stringent limits on the size of the bulge, the existence of a hidden quasar and gravitational lensing, if any. The nature, spatial distribution, and age of the stars can be studied using spatially resolved colors from these images. We estimate that the F555W-F814W color will allow us to discriminate age since star formation to an accuracy of ~0.1 Gyr. The F300W filter images the galaxy below the Ly limit, providing important proof of the stellar origin of the continuum and additional constraints on the existence of on-going star formation. Furthermore, these observations will also allow us to study the possible existence of a group or cluster associated with this object. ------------------------------------------------------------------------------------ 6832( 7) - 05/06/97 12:55 - [ 2] Observations Description ------------------------ The observation will consist of WFPC2 imaging using 3 filters (F814W, F555W, and F300W) on the field around the protogalaxy, with the protogalaxy on the PC quadrant. In a relative short ground-based exposure, the protogalaxy can be seen to the 24 mag/square arcsec isophot. The galaxy basically has a flat spectrum in the AB system between V and I. We expect that obtaining a S/N of 3 per pixel at 24 mag/sq arcsec will be sufficient for us to examine the structure of the object in detail. Using the tables and formulae in the WFPC2 handbook, we obtain integration times of ~ 200 and 440 mins for the F555W and F814W filters. Hence the request of 4 and 9 orbits for these filters, respectively. For the F300W filter, we wish to be able to detect objects with an AB magnitude of 27 covering about 1 sq arc at S/N~5. This requires about 120 min, hence the request of 3 orbits. The I band image and ground-based spectroscopy of the PG will allow us to correct for the red leak in the F300W filter. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: E. Ellingson, CASA CB 389, U. Colorado, Boulder CO*80309 Ship Via: UPS Email: e.elling@casa.colorado.edu ------------------------------------------------------------------------------------ 6832( 7) - 05/06/97 12:55 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 MS1512+37- GALAXY, High Redshift RA=15H 12M 25.7S +/- 0.2S, DEC= 1950.0 Z=2.72 V = 20.88 GAL Galaxy 36D 47' 31.1" +/-3" V-R = 0.72 Comments: galaxy 6 arcsec NW of cluster cD galaxy 6832( 7) - 05/06/97 12:55 - [ 4] Visit: 01 Visit Requirements: ORIENT 135D TO 165D 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 MS1512+37-G WFPC2 IMAGE PC1 F814W DITHER-TYPE=LINE,CR-SPLIT=NO 1 1100 S AL ------------------------------------------------------------------------------------------------------------------------------------ 2 MS1512+37-G WFPC2 IMAGE PC1 F814W DITHER-TYPE=LINE,CR-SPLIT=NO 1 1200 S AL ------------------------------------------------------------------------------------------------------------------------------------ 3 MS1512+37-G WFPC2 IMAGE PC1 F814W CR-TOLERANCE=0.2,DITHER-TYPE=LINE 1 45 M AL ,CR-SPLIT=DEF ------------------------------------------------------------------------------------------------------------------------------------ 4 MS1512+37-G WFPC2 IMAGE PC1 F814W CR-TOLERANCE=0.2,DITHER-TYPE=LINE 1 45 M AL ,CR-SPLIT=DEF ------------------------------------------------------------------------------------------------------------------------------------ 5 MS1512+37-G WFPC2 IMAGE PC1 F814W CR-TOLERANCE=0.2,DITHER-TYPE=LINE 1 45 M AL ,CR-SPLIT=DEF ------------------------------------------------------------------------------------------------------------------------------------ 6832( 7) - 05/06/97 12:55 - [ 5] Visit: 02 Visit Requirements: SAME ORIENT AS 1 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 MS1512+37-G WFPC2 IMAGE PC1 F814W DITHER-TYPE=LINE,CR-SPLIT=NO 1 1100 S AL ------------------------------------------------------------------------------------------------------------------------------------ 2 MS1512+37-G WFPC2 IMAGE PC1 F555W CR-TOLERANCE=0.2,DITHER-TYPE=LINE 1 45 M AL ,CR-SPLIT=DEF ------------------------------------------------------------------------------------------------------------------------------------ 3 MS1512+37-G WFPC2 IMAGE PC1 F555W CR-TOLERANCE=0.2,DITHER-TYPE=LINE 1 45 M AL ,CR-SPLIT=DEF ------------------------------------------------------------------------------------------------------------------------------------ 4 MS1512+37-G WFPC2 IMAGE PC1 F300W CR-TOLERANCE=0.2,DITHER-TYPE=LINE 1 45 M AL ,CR-SPLIT=DEF ------------------------------------------------------------------------------------------------------------------------------------ 5 MS1512+37-G WFPC2 IMAGE PC1 F300W DITHER-TYPE=LINE,CR-SPLIT=NO 1 1200 S AL ------------------------------------------------------------------------------------------------------------------------------------ 6832( 7) - 05/06/97 12:55 - [ 6] Summary Form for Proposal 6832 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters DITHER-TYPE=LINE CR-SPLIT=NO CR-SPLIT=DEF CR-TOLERANCE=0.2 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category COSMOLOGY ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 135D TO 165D SAME ORIENT AS 1 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F814W F555W F300W ------------------------------------------------------------------------------------------------------------------------------------ Target Names MS1512+37-GAL ------------------------------------------------------------------------------------------------------------------------------------