6564( 5) - 09/22/98 09:25 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6564 Version: 5 Check-in Date: 22-Sep-1998 09:24:04 1.Proposal Title: DETAILED MORPHOLOGY OF A LYMAN-ALPHA GALAXY AT Z=2.3 ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 6 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: James Lowenthal University of Massachusetts CoI: BRUCE WOODGATE NASA/GSFC N ------------------------------------------------------------------------------------ 5. Abstract The identification and detailed study of galaxies at high redshift remains the most direct path to understanding galaxy formation and evolution, yet there are only a handful of radio quiet galaxies known in emission at z>1.5. By using HST and WFPC2 to image the Coup Fourre Galaxy -- the first Lyman-alpha emission galaxy discovered near a high-redshift damped Ly- alpha\ absorption line cloud-- at z=2.3 in Ly-alpha\ and broad-band V and I, I will discriminate between star formation and nuclear activity as the source of Ly-alpha\ emission and will be able to test for evidence of galaxy mergers or interaction, and of the clumpy star formation sites thought to accompany young, coalescing galaxies. This source is a viable candidate for a primeval galaxy, the Rosetta Stone of cosmology, and detailed morphological study on kpc scales is crucial to compare the light profile to current-day disk or bulge systems, to relate the galaxy's characteristics directly to theories of galaxy formation, and to help clarify the relation between absorbing and emitting galaxies. Multi-band photometry will allow direct comparison to spectral synthesis models of galaxy evolution to estimate the galaxy's age and star formation history. We will also search the field for additional compact galaxies or protogalaxies physically associated with the absorber/emitter pair, using the Ly-alpha\ and broad-band filters to select candidates via their colors, sizes, and morphologies. ------------------------------------------------------------------------------------ 6564( 5) - 09/22/98 09:25 - [ 2] Observations Description ------------------------ There very fortunately happens to be on WFPC2 a 147A-wide filter, F410M, that includes Lyman-Alpha for z=2.3128 at 4027A. We request 16 orbits with this filter in order to reach an estimated signal-to-noise ratio S/N = 3 for a point source with emission line flux 1e-17 erg/s/cm^2, corresponding to the Lyman- Alpha flux from an unobscured galaxy at z=2.3 undergoing star formation at the rate of 1 Msun/yr. Such a source will provide an estimated signal of about 3e-3 e-/s, compared with an estimated background rate on the PC of 4e-4 e\s\pixel, which dominates the noise. We are assuming here a sky brightness of 22.3 mag/arcsec^2 based on an ecliptic latitude of 5 deg, and 2940 sec of usable integration time per orbit, after allowing for instrument overhead and Earth occulation. If our main target, the Coup Fourre galaxy, were a point source, it would appear at S/N~168, ensuring adequate signal-to-noise even if it were extended over 1 arcsec^2. We are also requesting 3 orbits of integration with the F555W = V and 2 orbits with the F814W = I filters. This will allow us to detect point sources of V=28.1 and I=27.5 with S/N=3, corresponding to two magnitudes fainter than an L* Sa galaxy at z=2.3 assuming passive evolution. These filters were chosen to provide a spectrally close comparison to the Lyman -Alpha images (V), to provide as long a spectral baseline as possible to aid in the identification of additional z=2.3 candidate sources via their broad-band colors (I), and to maintain consistency with the recommended WFPC2 filter selection policy. We intend to place the Lyman-Alpha galaxy on the WF3 chip, with the V=16.6 image of the QSO PHL 957, 47 arcsec away, ideally falling on PC1, (but possibly on WF1-3, if orientation constraints so dictate). This will ensure high S/N for our main target and maximum sensitivity to faint sources within 250 h^-1 kpc of the damped Lyman-Alpha cloud, while helping to alleviate saturation and providing maximum resolution for the QSO PSF region, which may show faint Lyman-Alpha emission from the Damped Lyman-Alpha Clouds itself. There is no overall ORIENT constraint, but we prefer the 3 visits to be at the same orient, and have so specified. This provides maximum field overlap and depth to these prime observations, and allows parallel data to be on the same field in each visit, providing maximum depth for them. We have use POS_TARGs to dither the exposures, rather than DITHER_BOX, to allow application of the STIS G430L slitless parallels for these z=2.3 observations according to the agreements of the Parallel Working Group. We have used CR-Splits within each orbit in order to begin the CR-reject process without sub-pixel blurring and to allow parallels to be inserted without motions in the middle of the orbits. The POS_TARGs in Visit 2 are slightly different from those of Visit 1 to provide more independent pointings for optimal rejection of hot pixels. Half-pixel offsets are provided within the POS_TARGs to improve the resolution of the WF images. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 6564( 5) - 09/22/98 09:25 - [ 3] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 6564( 5) - 09/22/98 09:25 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 PHL957-GAL GALAXY, LYMAN ALPHA RA=01H 3M 8.44S +/- 0.06S, 2000.0 Z=2.313 V = 23.6+/-0.5 CLOUD, QSO DEC=13D 16' 40.92" +/- 1.0" B-V = 0.6+/-0.5 Comments: Main object of interest is "Coup Fourre Galaxy" at z=2.313, a Lyman-alpha galaxy 47 arcsec to the northwest of the QSO PHL 957 line of sight. QSO is V=16.5. With galaxy on WF3, desire QSO on PC1 (ORIENT=120), but QSO on WF1, WF2, or WF3 is acceptable, so we specify no ORIENT constraint overall, only that the ORIENTs of each visit be the same. 6564( 5) - 09/22/98 09:25 - [ 5] Visit: 01 Visit Priority: Visit Requirements: On Hold Comments: Additional Comments: It is crucial to image BOTH the Galaxy and the QSO. Original ORIENT = 120.0D +/- 70D has been abandoned. Instead we specify location of galaxy on WF3, so that any ORIENT will image QSO somewhere on PC, WF1, WF2, or WF3. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 PHL957-GAL WFPC2 IMAGE WF3-FIX F410M CR-SPLIT=0.5,CR-TOLERANCE=0.0 1 2550 S POS TARG 21.5, 21.5 ------------------------------------------------------------------------------------------------------------------------------------ 20 PHL957-GAL WFPC2 IMAGE WF3-FIX F410M CR-SPLIT=0.5,CR-TOLERANCE=0.0 1 2600 S POS TARG 22.5, 22.5 ------------------------------------------------------------------------------------------------------------------------------------ 30 PHL957-GAL WFPC2 IMAGE WF3-FIX F410M CR-SPLIT=0.5,CR-TOLERANCE=0.0 1 2600 S POS TARG 23.05, 21.5 ------------------------------------------------------------------------------------------------------------------------------------ 40 PHL957-GAL WFPC2 IMAGE WF3-FIX F410M CR-SPLIT=0.5,CR-TOLERANCE=0.0 1 2600 S POS TARG 24.05, 22.5 ------------------------------------------------------------------------------------------------------------------------------------ 50 PHL957-GAL WFPC2 IMAGE WF3-FIX F410M CR-SPLIT=0.5,CR-TOLERANCE=0.0 1 2600 S POS TARG 23.05, 23.05 ------------------------------------------------------------------------------------------------------------------------------------ 60 PHL957-GAL WFPC2 IMAGE WF3-FIX F410M CR-SPLIT=0.5,CR-TOLERANCE=0.0 1 2600 S POS TARG 24.05, 24.05 ------------------------------------------------------------------------------------------------------------------------------------ 70 PHL957-GAL WFPC2 IMAGE WF3-FIX F410M CR-SPLIT=0.5,CR-TOLERANCE=0.0 1 2600 S POS TARG 21.5, 23.05 ------------------------------------------------------------------------------------------------------------------------------------ 80 PHL957-GAL WFPC2 IMAGE WF3-FIX F410M CR-SPLIT=0.5,CR-TOLERANCE=0.0 1 2600 S POS TARG 22.5, 24.05 ------------------------------------------------------------------------------------------------------------------------------------ 6564( 5) - 09/22/98 09:25 - [ 6] Visit: 02 Visit Priority: Visit Requirements: SAME ORIENT AS 01 On Hold Comments: Additional Comments: Same orient maximizes the common area between visits, allowing the narrow band and wide band to cover the same area, and allows the STIS G430L generic parallels to be applied to be uniquely deep. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 PHL957-GAL WFPC2 IMAGE WF3-FIX F410M CR-SPLIT=0.5,CR-TOLERANCE=0.0 1 2500 S POS TARG 19.5, 19.5 ------------------------------------------------------------------------------------------------------------------------------------ 20 PHL957-GAL WFPC2 IMAGE WF3-FIX F410M CR-SPLIT=0.5,CR-TOLERANCE=0.0 1 2600 S POS TARG 20.5, 20.5 ------------------------------------------------------------------------------------------------------------------------------------ 30 PHL957-GAL WFPC2 IMAGE WF3-FIX F410M CR-SPLIT=0.5,CR-TOLERANCE=0.0 1 2600 S POS TARG 21.05, 19.5 ------------------------------------------------------------------------------------------------------------------------------------ 40 PHL957-GAL WFPC2 IMAGE WF3-FIX F410M CR-SPLIT=0.5,CR-TOLERANCE=0.0 1 2600 S POS TARG 22.05, 20.5 ------------------------------------------------------------------------------------------------------------------------------------ 50 PHL957-GAL WFPC2 IMAGE WF3-FIX F410M CR-SPLIT=0.5,CR-TOLERANCE=0.0 1 2600 S POS TARG 21.05, 21.05 ------------------------------------------------------------------------------------------------------------------------------------ 60 PHL957-GAL WFPC2 IMAGE WF3-FIX F410M CR-SPLIT=0.5,CR-TOLERANCE=0.0 1 2600 S POS TARG 22.05, 22.05 ------------------------------------------------------------------------------------------------------------------------------------ 70 PHL957-GAL WFPC2 IMAGE WF3-FIX F410M CR-SPLIT=0.5,CR-TOLERANCE=0.0 1 2600 S POS TARG 19.5, 21.05 ------------------------------------------------------------------------------------------------------------------------------------ 80 PHL957-GAL WFPC2 IMAGE WF3-FIX F410M CR-SPLIT=0.5,CR-TOLERANCE=0.0 1 2600 S POS TARG 20.5, 22.05 ------------------------------------------------------------------------------------------------------------------------------------ 6564( 5) - 09/22/98 09:25 - [ 7] Visit: 03 Visit Priority: Visit Requirements: SAME ORIENT AS 01 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 PHL957-GAL WFPC2 IMAGE WF3-FIX F555W CR-SPLIT=0.5,CR-TOLERANCE=0.0 1 2500 S POS TARG 21.5, 21.5 ------------------------------------------------------------------------------------------------------------------------------------ 20 PHL957-GAL WFPC2 IMAGE WF3-FIX F555W CR-SPLIT=0.5,CR-TOLERANCE=0.0 1 2600 S POS TARG 22.55, 22.55 ------------------------------------------------------------------------------------------------------------------------------------ 30 PHL957-GAL WFPC2 IMAGE WF3-FIX F555W CR-SPLIT=0.5,CR-TOLERANCE=0.0 1 2600 S POS TARG 23.05, 22.5 ------------------------------------------------------------------------------------------------------------------------------------ 40 PHL957-GAL WFPC2 IMAGE WF3-FIX F814W CR-SPLIT=0.5,CR-TOLERANCE=0.0 1 2600 S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 50 PHL957-GAL WFPC2 IMAGE WF3-FIX F814W CR-SPLIT=0.5,CR-TOLERANCE=0.0 1 2600 S SAME POS AS 20 ------------------------------------------------------------------------------------------------------------------------------------ 6564( 5) - 09/22/98 09:25 - [ 8] Summary Form for Proposal 6564 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures WF3-FIX ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=0.5 CR-TOLERANCE=0.0 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements POS TARG 21.5, 21.5 POS TARG 22.5, 22.5 POS TARG 23.05, 21.5 POS TARG 24.05, 22.5 POS TARG 23.05, 23.05 POS TARG 24.05, 24.05 POS TARG 21.5, 23.05 POS TARG 22.5, 24.05 SAME ORIENT AS 01 POS TARG 19.5, 19.5 POS TARG 20.5, 20.5 POS TARG 21.05, 19.5 POS TARG 22.05, 20.5 POS TARG 21.05, 21.05 POS TARG 22.05, 22.05 POS TARG 19.5, 21.05 POS TARG 20.5, 22.05 POS TARG 22.55, 22.55 POS TARG 23.05, 22.5 SAME POS AS 10 SAME POS AS 20 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F410M F555W F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names PHL957-GAL ------------------------------------------------------------------------------------------------------------------------------------