5948( 9) - 11/22/95 13:14 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 5948 Version: 9 Check-in Date: ********** 1.Proposal Title: Damped Lyman-alpha Absorption Lines from Moderate-Redshift Galaxies ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Quasars GO 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Kenneth Lanzetta State University of New York at Stony Brook CoI: Arthur Wolfe University of California, San Diego N CoI: David Turnshek University of Pittsburgh N ------------------------------------------------------------------------------------ 6. Abstract We will obtain intermediate-resolution spectroscopy of nine moderate-redshift (0.05 < z < 1.6) candidate damped Ly-alpha absorption features that were detected toward higher-redshift background QSOs in an exhaustive search of the IUE archival data base. This search forms a systematic, unbiased survey for moderate-redshift damped Ly-alpha absorbers. Accurate spectra of the candidate features will allow us to confirm (or otherwise) the damped nature of the absorption profiles and to determine the H I column densities. By combining the results of this ultraviolet survey with those derived from existing optical surveys we will determine the redshift evolution of the rate of incidence, cosmological mass density, and column density distribution of damped Ly-alpha absorbers over a redshift baseline spanning 0.05 < z < 4.0. We will furthermore secure a sample of moderate-redshift damped Ly- alpha absorbers for further detailed study. These results will constrain theories of galaxy formation and evolution and will help to determine the type or types of galaxies responsible for the absorption. This proposal was awarded medium priority status in Cycle 3 but was not completed due to the short duration of Cycle 3. ------------------------------------------------------------------------------------ 5948( 9) - 11/22/95 13:14 - [ 2] Observations Description ------------------------ We require observations of nine candidate damped Ly-alpha absorption features toward seven background QSOs in order to generate a statistically complete sample of absorption systems. Based on our experience with similar spectra obtained at optical wavelengths and on simulations of the planned HST observations, we estimate that in order to unambiguously confirm (or otherwise) the damped nature of the candidate damped Ly-alpha absorption features and to determine accurate H I column densities we require signal-to-noise ratios (in the continuum) of S/N ~ 15 per diode with the GHRS and grating G140L or the FOS and gratings G130H, G190H, or G270H. For two features with Lambda = 1341 Angstrom and Lambda = 1464 Angstrom we will use the GHRS with G140L and the LSA aperture to obtain spectra of spectral resolution FWHM ~ 150 km s^-1 and of signal-to-noise ratio S/N ~ 15 per diode. Exposure times of 1694 s and 1530 s will be required. For one feature with Lambda = 1551 Angstrom we will use the FOS with G130H and the 1'' aperture to obtain spectra of spectral resolution FWHM ~ 330 km s^-1 and of signal-to-noise ratio S/N ~ 15 per diode. An exposure time of 1890 s will be required. For one feature with Lambda = 1847 Angstrom we will use the FOS with G190H and the 1'' aperture to obtain spectra of spectral resolution FWHM ~ 330 km s^-1 and of signal-to-noise ratio S/N ~ 15 per diode. An exposure time of 1731 s will be required. For five features (toward three background QSOs) with Lambda = 2394 Angstrom, Lambda = 2880 Angstrom, and Lambda = 3010 Angstrom we will use the FOS with G270H and the 1'' aperture to obtain spectra of spectral resolution FWHM ~ 330 km s^-1 and of signal-to-noise ratio S/N ~ 15 per diode. Exposure times of 234 s, 188 s, and 469 s will be required. To estimate the exposure times required to obtain these signal-to-noise ratios, we determined actual ultraviolet fluxes from the IUE spectra and used the sensitivity curves and aperture throughputs quoted in the Faint Object Spectrograph Instrument Handbook, Version 5.0 and the Goddard High Resolution Spectrograph (GHRS) Instrument Handbook, Version 5.0. At the wavelengths of interest, ultraviolet fluxes of the background QSOs in our sample range from 0.1 * 10^-14 through 1.4 * 10^-14 erg s^-1 cm^-2 AA^-1, with 0.3 * 10^-14 erg s^-1 cm^-2 AA^-1 being typical. As an example, consider an object observed at Lambda = 2400 Angstrom with f_Lambda = 0.3 * 10^-14 erg s^-1 cm^-2 AA^-1 using the FOS with G270H and the red detector. Scaling from Figure 1.2.3 of the Faint Object Spectrograph Instrument Handbook yields a count rate of 1 count s^-1 diode^-1. This count rate greatly exceeds the dark count rate of 0.01 count s^-1 diode^-1, and the background is negligible, so dark and background counts may be neglected. A total of 225 counts per diode (i.e. a signal-to-noise ratio of S/N = 15 per diode) may therefore be obtained in an exposure time of 225 s. In most cases we can easily fit the guide star acquisition, the target acquisition, and the science exposure into one orbit. (NOTE: We have padded, or in a few cases trimed, exposure times as necessary to fill orbits.) But in one case we require a PEAK acquisition with FOS, so the observation will require two orbits. NOTE: For the two observations to be obtained with the GHRS, we have found that an FOS acquisition of the target is required to complete the observation in one orbit. We have discussed this acquisition strategy in detail with Anuradha Koratkar and with Claus Leitherer, who are aware of the details of the strategy. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 5948( 9) - 11/22/95 13:14 - [ 3] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 5948( 9) - 11/22/95 13:14 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 PHL909 GALAXY,QSO RA = 00H 57M 09.97S +/- 0.005S, 2000 Z = V = 16.7 +/- 1.0 DEC = +14D 46' 10.3" +/- 0.05", 0.171 B-V = -0.10 +/- 0.10 PLATE-ID=028Y U-B = -0.40 +/- 0.10 F-CONT(1340) = 6.0 +/- 1.0 E-15 4 FBS1047+550 GALAXY,QSO RA = 10H 50M 45.79S +/- 0.005S, 2000 Z = V = 16.5 +/- 0.5 DEC = +54D 47' 19.07" +/- 0.05", 2.165 F-CONT(3010) = 1.0 +/- 0.3 E-15 PLATE-ID = 01AM 5 PG1329+412 GALAXY,QSO RA = 13H 31M 41.14S +/- 0.005S, 2000 Z = V = 16.3 +/- 0.5 DEC = +41D 01' 58.71" +/- 0.05", 1.937 F-CONT(1850) = 2.0 +/- 0.6 E-15 PLATE-ID = 00XY 6 PG1451-375 GALAXY,QSO RA = 14H 54M 27.36S +/- 0.005S, 2000 Z = V = 16.7 +/- 0.1 DEC = -37D 47' 34.23" +/- 0.05", 0.314 B-V = 0.09 +/- 0.10 PLATE-ID = 00AP F-CONT(1550) = 1.0 +/- 0.2 E-14 7 PG2112+059 GALAXY,QSO RA = 21H 14M 52.58S +/- 0.005S, 2000 Z = V = 15.52+/- 0.1 DEC = +06D 07' 42.24" +/- 0.05", 0.466 F-CONT(1460) = 1.0 +/- 0.2 E-14 PLATE-ID=02V8 5948( 9) - 11/22/95 13:14 - [ 5] Visit: 01 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 PHL909 FOS/BL ACQ/BIN 4.3 MIRROR 1 57.3S ONBOARD ACQ FOR 2 ARY ------------------------------------------------------------------------------------------------------------------------------------ 2 PHL909 HRS ACCUM 2.0 G140L 1341.0 4 300S ------------------------------------------------------------------------------------------------------------------------------------ 5948( 9) - 11/22/95 13:14 - [ 6] Visit: 04 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 FBS1047+550 FOS/RD ACQ/PEA 4.3 MIRROR SCAN-STEP- 1 0.8S ONBOARD ACQ FOR 2 K Y=1.204, SEARCH -SIZE-X=1, SEARCH-SIZE-Y=3 ------------------------------------------------------------------------------------------------------------------------------------ 2 FBS1047+550 FOS/RD ACQ/PEA 1.0 MIRROR SCAN-STEP- 1 0.8S ONBOARD ACQ FOR 3 K X=0.602, SCAN- STEP-Y=0.602, SEARCH-SIZE- X=6, SEARCH- Comments: SIZE-Y=2 ------------------------------------------------------------------------------------------------------------------------------------ 3 FBS1047+550 FOS/RD ACQ/PEA 0.3 MIRROR SCAN-STEP- 1 0.8S ONBOARD ACQ FOR 4 K X=0.172, SCAN- STEP-Y=0.172, SEARCH-SIZE- X=5, SEARCH- Comments: SIZE-Y=5 ------------------------------------------------------------------------------------------------------------------------------------ 4 FBS1047+550 FOS/RD ACCUM 1.0 G270H 3010.0 1 469S MIN DUR 80%; MAX DUR 1000% ------------------------------------------------------------------------------------------------------------------------------------ 5948( 9) - 11/22/95 13:14 - [ 7] Visit: 05 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 PG1329+412 FOS/RD ACQ/BIN 4.3 MIRROR 1 6.6S ONBOARD ACQ FOR 2 ARY ------------------------------------------------------------------------------------------------------------------------------------ 2 PG1329+412 FOS/RD ACCUM 1.0 G190H 1846.0 1 1550S MIN DUR 80%; MAX DUR 1000% ------------------------------------------------------------------------------------------------------------------------------------ 5948( 9) - 11/22/95 13:14 - [ 8] Visit: 06 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 PG1451-375 FOS/BL ACQ/BIN 4.3 MIRROR 1 57.3S ONBOARD ACQ FOR 2 ARY ------------------------------------------------------------------------------------------------------------------------------------ 2 PG1451-375 FOS/BL ACCUM 1.0 G130H 1551.0 1 1400S MIN DUR 80%; MAX DUR 1000% ------------------------------------------------------------------------------------------------------------------------------------ 5948( 9) - 11/22/95 13:14 - [ 9] Visit: 07 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 PG2112+059 FOS/BL ACQ/BIN 4.3 MIRROR 1 19.3S ONBOARD ACQ FOR 2 ARY ------------------------------------------------------------------------------------------------------------------------------------ 2 PG2112+059 HRS ACCUM 2.0 G140L 1464.0 4 300S ------------------------------------------------------------------------------------------------------------------------------------ 5948( 9) - 11/22/95 13:14 - [ 10] Summary Form for Proposal 5948 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/BL HRS FOS/RD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/BINARY ACCUM ACQ/PEAK ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SCAN-STEP-Y=1.204 SEARCH-SIZE-X=1 SEARCH-SIZE-Y=3 SEARCH-SIZE-Y=2 SEARCH-SIZE-Y=5 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Quasars ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 2 ONBOARD ACQ FOR 3 ONBOARD ACQ FOR 4 MIN DUR 80%; MAX DUR 1000% ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G140L G270H G190H G130H ------------------------------------------------------------------------------------------------------------------------------------ Target Names PHL909 FBS1047+550 PG1329+412 PG1451-375 PG2112+059 ------------------------------------------------------------------------------------------------------------------------------------