7449( 4) - 05/29/97 10:07 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 7449 Version: 4 Check-in Date: 29-May-1997 10:04:29 1.Proposal Title: H-alpha Imaging of an Elusive Damped Ly- alpha cloud at z=0.6 ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle QUASAR ABSORPTION LIN GO 7 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: JAMES LOWENTHAL Lick Observatory CoI: Jane Charlton The Pennsylvania State University N CoI: Matthew Bershady The Pennsylvania State University N CoI: Chris W. Churchill The Pennsylvania State University N CoI: Charles C. Steidel California Institute of Technology N ------------------------------------------------------------------------------------ 6. Abstract The line of sight to QSO 3C 336 (z_em = 0.927) is one of the richest and best- studied available for absorption line investigation. Despite intensive ground-based and HST imaging and spectroscopy, however, the galaxy responsible for the highest column density system -- a damped Ly-alpha cloud at z=0.656 -- remains unidentified. The spectra imply a low metal enrichment for the cloud, with Fe/H~-1.2, in conflict with the general scenario that damped Ly-alpha clouds progressively turn gas into stars over cosmic time. We propose deep narrowband NICMOS imaging of the QSO line of sight using the F108N filter, which fortuitously includes H-alpha at z=0.656, to attempt to detect the putative absorbing galaxy. With its excellent resolution and dynamic range, this observing combination affords the best opportunity available to find the elusive source. Imaging the absorber directly is crucial to constrain its size, morphology, and star formation activity. With 4 orbits in the narrow-band filter and 1 in a broad-band comparison (plus 1 orbit for PSF calibration), our observations should be sensitive (5-sigma) to any compact galaxy with a star formation rate greater than 1 M_sun up to within 0.2 arcsec, or 0.9 h_100^-1 kpc, of the QSO sightline. If the absorber is indeed a dwarf galaxy almost exactly superposed on the QSO image, then NICMOS + redshifted H-alpha filter provides the only way to image the system directly. This is important for interpretation of the extensive spectroscopic information already gathered on this absorption cloud, including from HST. ------------------------------------------------------------------------------------ 7449( 4) - 05/29/97 10:07 - [ 2] Observations Description ------------------------ A galaxy forming stars at the rate of 1 M_sun/yr with a Salpeter IMF will produce an H-alpha luminosity L_Alpha~ 1.1x10^41 ergs/sec (Kennicutt 1983), corresponding at z=0.656 to an observed flux F(H-alpha) = 1.25 * 10^-16 ergs/sec/cm^2 (for q_0=0.05) or 1.7 * 10^-16 ergs/sec/cm^2 (for q_0=0.5). A dwarf galaxy with core radius 1 kpc will subsume <0.25 h_100 arcsec, so for the purposes of these calculations we will assume a point source. We have used the NICMOS exposure time calculator and the information in the NICMOS handbook to estimate that to achieve SNR = 4 in the F108N filter with Camera 1 for the conservative case (F(H-alpha) = 1.25 * 10^-16 ergs/sec/cm^-2 ) would require 10,000 s, assuming the SNR to be limited by read noise at this short wavelength. This translates into (3.5*47m), where 47 minutes is the available visibility per orbit (except the first orbit) minus estimated overhead and guide star acquisition time. Therefore the desired narrow- band sensitivity can be achieved in just under 4 orbits, using MULTIACCUM mode with multiple non- destructive readouts to maximize the SNR. We have verified that the QSO, with J~16.5 or F(1.1 micron)~4.2*10^-4 Jy, will not saturate the detector for t<10^5 sec. We will shift positions between orbits to facilitate cosmic ray removal. The comparison broad-band observations should sample the continuum region as close as possible to the expected emission line; therefore we have selected the F110M filter for that purpose. In order to verify that any flux detected in the narrow-band filter is indeed line emission and not continuum flux, the continuum observations need to be sufficiently deep that a minimum equivalent width limit is satisfied. For >= 1 M_sun/yr of star formation and nominal extinction, we expect W_em~10 Angstrom, or W_obs~16 Angstrom at z=0.656. This translates into a continuum level F(1.1 micron)~4.2*10^-5 Jy or J~19. The exposure time estimator indicates that with the F110M filter we can reach SNR ~100 for that level in ~ 30 m, guaranteeing that any excess flux in the narrow- band filter will be a robust detection of line emission. Again, the QSO will not saturate the detector until 4000 sec, well above our integration time. The limiting continuum sensitivity (5-sigma) will correspond to J~22.25, as much as a magnitude deeper than the Keck + NIRC K-band images. Because of the unforeseen need to obtain PSF calibration observations, we will devote one of our six allotted orbits to those calibrations, and will limit all of our science integrations to five orbits. Each of those five orbits will be split into one 2048-sec F108N H-alpha integration and one 512-sec F110M continuum integration at the same position. For this revised Phase II submission following the 5 May 1997 update on NICMOS performance, we have eliminated Camera 3 from our observing plan, since its out-of-focus images in attached parallel mode are useless to us. Camera 2 lacks the narrow-band filter matching H-alpha at z=0.656; with this camera in Attached Parallel mode, we propose to enhance the existing ground-based near-IR photometry of galaxies close to the QSO sight line with deep imaging in the recommended F160W filter. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 7449( 4) - 05/29/97 10:07 - [ 3] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 7449( 4) - 05/29/97 10:07 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 3C336.0 EXT-MEDIUM, Damped RA=16H 24M 39.076S +/-0.07S, 2000.0 Z=0.927 V = 17.47+/-0.5 Lyman Alpha Cloud, DEC= +23D 45' 12.2" +/-1.0" B-V = 0.44 Absorption Line System - Extragalactic, 2 GSC2044.810 CALIBRATION, Point RA=16H 30M 22.91S +/-0.01S, DEC= 2000.0 V = 12.71 Spread Function +23D 45' 07.9" +/-0.2" B-V = 1.05 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1982.38 0.0 0.0 0.0 7449( 4) - 05/29/97 10:07 - [ 5] TARGET LIST c)Generic Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Selection Criteria | Flux data No | Name | Description | | ------------------------------------------------------------------------------------------------------------------------------------ 3C336.NIC2 EXT-MEDIUM, Damped RA=16H 25M,DEC=23D,R=10D V = 20.0 Lyman Alpha Cloud, B-V = 0.0 Absorption Line System Comments: F <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< ield near 3C336 to be imaged in parallel by NIC2 ------------------------------------------------------------------------------------------------------------------------------------ 7449( 4) - 05/29/97 10:07 - [ 6] Visit: 01 Visit Requirements: SEQ 1-2 WITHIN 10H 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 3C336.0 NIC1 MULTIAC NIC1 F108N SAMP-SEQ=MIF2048,NSAMP=25 1 DEF PAR 3-4 WITH 1-2 CUM ------------------------------------------------------------------------------------------------------------------------------------ 2 3C336.0 NIC1 MULTIAC NIC1 F110M SAMP-SEQ=MIF512,NSAMP=25 1 DEF CUM ------------------------------------------------------------------------------------------------------------------------------------ 3 3C336.NIC2 NIC2 MULTIAC NIC2 F160W SAMP-SEQ=SPARS256,NSAMP=10 1 DEF CUM ------------------------------------------------------------------------------------------------------------------------------------ 4 3C336.NIC2 NIC2 MULTIAC NIC2 F160W SAMP-SEQ=SPARS256,NSAMP=4 1 DEF CUM ------------------------------------------------------------------------------------------------------------------------------------ 5 3C336.0 NIC1 MULTIAC NIC1 F108N SAMP-SEQ=MIF2048,NSAMP=25 1 DEF POS TARG +1.0105,+1.0105; CUM PAR 7-8 WITH 5-6 ------------------------------------------------------------------------------------------------------------------------------------ 6 3C336.0 NIC1 MULTIAC NIC1 F110M SAMP-SEQ=MIF512,NSAMP=25 1 DEF POS TARG +1.0105,+1.0105 CUM ------------------------------------------------------------------------------------------------------------------------------------ 7 3C336.NIC2 NIC2 MULTIAC NIC2 F160W SAMP-SEQ=SPARS256,NSAMP=10 1 DEF CUM ------------------------------------------------------------------------------------------------------------------------------------ 8 3C336.NIC2 NIC2 MULTIAC NIC2 F160W SAMP-SEQ=SPARS256,NSAMP=4 1 DEF CUM ------------------------------------------------------------------------------------------------------------------------------------ 9 3C336.0 NIC1 MULTIAC NIC1 F108N SAMP-SEQ=MIF2048,NSAMP=25 1 DEF POS TARG -1.0105,+1.0105; CUM PAR 11-12 WITH 9-10 ------------------------------------------------------------------------------------------------------------------------------------ 10 3C336.0 NIC1 MULTIAC NIC1 F110M SAMP-SEQ=MIF512,NSAMP=25 1 DEF POS TARG -1.0105,+1.0105 CUM ------------------------------------------------------------------------------------------------------------------------------------ 11 3C336.NIC2 NIC2 MULTIAC NIC2 F160W SAMP-SEQ=SPARS256,NSAMP=10 1 DEF CUM ------------------------------------------------------------------------------------------------------------------------------------ 12 3C336.NIC2 NIC2 MULTIAC NIC2 F160W SAMP-SEQ=SPARS256,NSAMP=4 1 DEF CUM ------------------------------------------------------------------------------------------------------------------------------------ 13 3C336.0 NIC1 MULTIAC NIC1 F108N SAMP-SEQ=MIF2048,NSAMP=25 1 DEF POS TARG -1.0105,-1.0105; CUM PAR 15-16 WITH 13-14 ------------------------------------------------------------------------------------------------------------------------------------ 14 3C336.0 NIC1 MULTIAC NIC1 F110M SAMP-SEQ=MIF512,NSAMP=25 1 DEF POS TARG -1.0105,-1.0105 CUM ------------------------------------------------------------------------------------------------------------------------------------ 15 3C336.NIC2 NIC2 MULTIAC NIC2 F160W SAMP-SEQ=SPARS256,NSAMP=10 1 DEF CUM ------------------------------------------------------------------------------------------------------------------------------------ 7449( 4) - 05/29/97 10:07 - [ 7] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 16 3C336.NIC2 NIC2 MULTIAC NIC2 F160W SAMP-SEQ=SPARS256,NSAMP=4 1 DEF CUM ------------------------------------------------------------------------------------------------------------------------------------ 17 3C336.0 NIC1 MULTIAC NIC1 F108N SAMP-SEQ=MIF2048,NSAMP=25 1 DEF POS TARG +1.0105,-1.0105; CUM PAR 19-20 WITH 17-18 ------------------------------------------------------------------------------------------------------------------------------------ 18 3C336.0 NIC1 MULTIAC NIC1 F110M SAMP-SEQ=MIF512,NSAMP=25 1 DEF POS TARG +1.0105,-1.0105 CUM ------------------------------------------------------------------------------------------------------------------------------------ 19 3C336.NIC2 NIC2 MULTIAC NIC2 F160W SAMP-SEQ=SPARS256,NSAMP=10 1 DEF CUM ------------------------------------------------------------------------------------------------------------------------------------ 20 3C336.NIC2 NIC2 MULTIAC NIC2 F160W SAMP-SEQ=SPARS256,NSAMP=4 1 DEF CUM ------------------------------------------------------------------------------------------------------------------------------------ 7449( 4) - 05/29/97 10:07 - [ 8] Visit: 02 Visit Requirements: 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 GSC2044.810 NIC1 MULTIAC NIC1 F108N SAMP-SEQ=STEP16,NSAMP=25 1 DEF CUM ------------------------------------------------------------------------------------------------------------------------------------ 2 GSC2044.810 NIC1 MULTIAC NIC1 F108N SAMP-SEQ=STEP16,NSAMP=25 1 DEF POS TARG +1.0105,+1.0105 CUM ------------------------------------------------------------------------------------------------------------------------------------ 3 GSC2044.810 NIC1 MULTIAC NIC1 F108N SAMP-SEQ=STEP16,NSAMP=25 1 DEF POS TARG -1.0105,+1.0105 CUM ------------------------------------------------------------------------------------------------------------------------------------ 4 GSC2044.810 NIC1 MULTIAC NIC1 F108N SAMP-SEQ=STEP16,NSAMP=25 1 DEF POS TARG -1.0105,-1.0105 CUM ------------------------------------------------------------------------------------------------------------------------------------ 5 GSC2044.810 NIC1 MULTIAC NIC1 F108N SAMP-SEQ=STEP16,NSAMP=25 1 DEF POS TARG +1.0105,-1.0105 CUM ------------------------------------------------------------------------------------------------------------------------------------ 6 GSC2044.810 NIC1 MULTIAC NIC1 F110M SAMP-SEQ=STEP1,NSAMP=25 1 DEF POS TARG +1.0105,-1.0105 CUM ------------------------------------------------------------------------------------------------------------------------------------ 7 GSC2044.810 NIC1 MULTIAC NIC1 F110M SAMP-SEQ=STEP1,NSAMP=17 1 DEF CUM ------------------------------------------------------------------------------------------------------------------------------------ 8 GSC2044.810 NIC1 MULTIAC NIC1 F110M SAMP-SEQ=STEP1,NSAMP=25 1 DEF CUM ------------------------------------------------------------------------------------------------------------------------------------ 9 GSC2044.810 NIC1 MULTIAC NIC1 F110M SAMP-SEQ=STEP1,NSAMP=17 1 DEF POS TARG +1.0105,+1.0105 CUM ------------------------------------------------------------------------------------------------------------------------------------ 10 GSC2044.810 NIC1 MULTIAC NIC1 F110M SAMP-SEQ=STEP1,NSAMP=25 1 DEF POS TARG +1.0105,+1.0105 CUM ------------------------------------------------------------------------------------------------------------------------------------ 11 GSC2044.810 NIC1 MULTIAC NIC1 F110M SAMP-SEQ=STEP1,NSAMP=17 1 DEF POS TARG -1.0105,+1.0105 CUM ------------------------------------------------------------------------------------------------------------------------------------ 12 GSC2044.810 NIC1 MULTIAC NIC1 F110M SAMP-SEQ=STEP1,NSAMP=25 1 DEF POS TARG -1.0105,+1.0105 CUM ------------------------------------------------------------------------------------------------------------------------------------ 13 GSC2044.810 NIC1 MULTIAC NIC1 F110M SAMP-SEQ=STEP1,NSAMP=17 1 DEF POS TARG -1.0105,-1.0105 CUM ------------------------------------------------------------------------------------------------------------------------------------ 14 GSC2044.810 NIC1 MULTIAC NIC1 F110M SAMP-SEQ=STEP1,NSAMP=25 1 DEF POS TARG -1.0105,-1.0105 CUM ------------------------------------------------------------------------------------------------------------------------------------ 15 GSC2044.810 NIC1 MULTIAC NIC1 F110M SAMP-SEQ=STEP1,NSAMP=17 1 DEF POS TARG +1.0105,-1.0105 CUM ------------------------------------------------------------------------------------------------------------------------------------ 7449( 4) - 05/29/97 10:07 - [ 9] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 16 GSC2044.810 NIC1 MULTIAC NIC1 F110M SAMP-SEQ=STEP1,NSAMP=25 1 DEF POS TARG +1.0105,-1.0105 CUM ------------------------------------------------------------------------------------------------------------------------------------ 7449( 4) - 05/29/97 10:07 - [ 10] Summary Form for Proposal 7449 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations NIC1 NIC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SAMP-SEQ=MIF2048 NSAMP=25 SAMP-SEQ=MIF512 NSAMP=10 NSAMP=4 SAMP-SEQ=SPARS256 SAMP-SEQ=STEP16 SAMP-SEQ=STEP1 NSAMP=17 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category QUASAR ABSORPTION LINES ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements SEQ 1-2 WITHIN 10H PAR 3-4 WITH 1-2 POS TARG +1.0105,+1.0105; PAR 7-8 WITH 5-6 POS TARG +1.0105,+1.0105 POS TARG -1.0105,+1.0105; PAR 11-12 WITH 9-10 POS TARG -1.0105,+1.0105 POS TARG -1.0105,-1.0105; PAR 15-16 WITH 13-14 POS TARG -1.0105,-1.0105 POS TARG +1.0105,-1.0105; PAR 19-20 WITH 17-18 POS TARG +1.0105,-1.0105 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F108N F110M F160W ------------------------------------------------------------------------------------------------------------------------------------ Target Names 3C336.0 3C336.NIC2 GSC2044.810 ------------------------------------------------------------------------------------------------------------------------------------