! Proposal 5948, submission 1 ! PI: Kenneth Lanzetta ! Received Tue Mar 28 12:02:16 EST 1995 ! From: lanzetta@sbastc.ess.sunysb.edu Proposal_Information Title: Damped Lyman-alpha Absorption Lines from Moderate-Redshift Galaxies Proposal_Category: GO Scientific_Category: Quasars Cycle: 5 Investigators PI_name: Kenneth Lanzetta PI_Institution: State University of New York at Stony Brook CoI_Name: Arthur Wolfe CoI_Institution: University of California, San Diego Contact: N CoI_Name: David Turnshek CoI_Institution: University of Pittsburgh Contact: N 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. Questions Observing_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. Fixed_Targets Target_Number: 1 Target_Name: PHL909 Alternate_Names: 0054+144 Description: GALAXY,QSO Position: RA = 00H 57M 09.97S +/- 0.005S, DEC = +14D 46' 10.3" +/- 0.05", PLATE-ID=028Y Equinox: 2000 RV_or_Z: Z = 0.171 Flux: V = 16.7 +/- 1.0, B-V = -0.10 +/- 0.10, U-B = -0.40 +/- 0.10, F-CONT(1340) = 6.0 +/- 1.0 E-15 Comments: Target_Number: 4 Target_Name: FBS1047+550 Alternate_Names: 1047+550 Description: GALAXY,QSO Position: RA = 10H 50M 45.79S +/- 0.005S, DEC = +54D 47' 19.07" +/- 0.05", PLATE-ID = 01AM Equinox: 2000 RV_or_Z: Z = 2.165 Flux: V = 16.5 +/- 0.5, F-CONT(3010) = 1.0 +/- 0.3 E-15 Comments: Target_Number: 5 Target_Name: PG1329+412 Alternate_Names: 1329+412 Description: GALAXY,QSO Position: RA = 13H 31M 41.14S +/- 0.005S, DEC = +41D 01' 58.71" +/- 0.05", PLATE-ID = 00XY Equinox: 2000 RV_or_Z: Z = 1.937 Flux: V = 16.3 +/- 0.5, F-CONT(1850) = 2.0 +/- 0.6 E-15 Comments: Target_Number: 6 Target_Name: PG1451-375 Alternate_Names: 1451-375 Description: GALAXY,QSO Position: RA = 14H 54M 27.36S +/- 0.005S, DEC = -37D 47' 34.23" +/- 0.05", PLATE-ID = 00AP Equinox: 2000 RV_or_Z: Z = 0.314 Flux: V = 16.7 +/- 0.1, B-V = 0.09 +/- 0.10, F-CONT(1550) = 1.0 +/- 0.2 E-14 Comments: Target_Number: 7 Target_Name: PG2112+059 Alternate_Names: 2112+059 Description: GALAXY,QSO Position: RA = 21H 14M 52.58S +/- 0.005S, DEC = +06D 07' 42.24" +/- 0.05", PLATE-ID=02V8 Equinox: 2000 RV_or_Z: Z = 0.466 Flux: V = 15.52+/- 0.1, F-CONT(1460) = 1.0 +/- 0.2 E-14 Comments: Visits Visit_Number: 1 Exposure_Number: 1 Target_Name: PHL909 Config: FOS/BL Opmode: ACQ/BINARY Aperture: 4.3 Sp_Element: MIRROR Number_of_Iterations: 1 Time_Per_Exposure: 57.3S Special_Requirements: ONBOARD ACQ FOR 2 Comments: Exposure_Number: 2 Target_Name: PHL909 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: G140L Wavelength: 1341.0 Number_of_Iterations: 4 Time_Per_Exposure: 300.0S Comments: Visit_Number: 4 Exposure_Number: 1 Target_Name: FBS1047+550 Config: FOS/RD Opmode: ACQ/PEAK Aperture: 4.3 Sp_Element: MIRROR Optional_Parameters: SCAN-STEP-Y=1.204, SEARCH-SIZE-X=1, SEARCH-SIZE-Y=3 Number_of_Iterations: 1 Time_Per_Exposure: 0.8S Special_Requirements: ONBOARD ACQ FOR 2 Comments: Exposure_Number: 2 Target_Name: FBS1047+550 Config: FOS/RD Opmode: ACQ/PEAK Aperture: 1.0 Sp_Element: MIRROR Optional_Parameters: SCAN-STEP-X=0.602, SCAN-STEP-Y=0.602, SEARCH-SIZE-X=6, SEARCH-SIZE-Y=2 Number_of_Iterations: 1 Time_Per_Exposure: 0.8S Special_Requirements: ONBOARD ACQ FOR 3 Comments: Exposure_Number: 3 Target_Name: FBS1047+550 Config: FOS/RD Opmode: ACQ/PEAK Aperture: 0.3 Sp_Element: MIRROR Optional_Parameters: SCAN-STEP-X=0.172, SCAN-STEP-Y=0.172, SEARCH-SIZE-X=5, SEARCH-SIZE-Y=5 Number_of_Iterations: 1 Time_Per_Exposure: 0.8S Special_Requirements: ONBOARD ACQ FOR 4 Comments: Exposure_Number: 4 Target_Name: FBS1047+550 Config: FOS/RD Opmode: ACCUM Aperture: 1.0 Sp_Element: G270H Wavelength: 3010.0 Number_of_Iterations: 1 Time_Per_Exposure: 469.0S Special_Requirements: MIN DUR 80%; MAX DUR 1000% Comments: Visit_Number: 5 Exposure_Number: 1 Target_Name: PG1329+412 Config: FOS/RD Opmode: ACQ/BINARY Aperture: 4.3 Sp_Element: MIRROR Number_of_Iterations: 1 Time_Per_Exposure: 6.6s Special_Requirements: ONBOARD ACQ FOR 2 Comments: Exposure_Number: 2 Target_Name: PG1329+412 Config: FOS/RD Opmode: ACCUM Aperture: 1.0 Sp_Element: G190H Wavelength: 1846.0 Number_of_Iterations: 1 Time_Per_Exposure: 1550.0S Special_Requirements: MIN DUR 80%; MAX DUR 1000% Comments: Visit_Number: 6 Exposure_Number: 1 Target_Name: PG1451-375 Config: FOS/BL Opmode: ACQ/BINARY Aperture: 4.3 Sp_Element: MIRROR Number_of_Iterations: 1 Time_Per_Exposure: 57.3S Special_Requirements: ONBOARD ACQ FOR 2 Comments: Exposure_Number: 2 Target_Name: PG1451-375 Config: FOS/BL Opmode: ACCUM Aperture: 1.0 Sp_Element: G130H Wavelength: 1551.0 Number_of_Iterations: 1 Time_Per_Exposure: 1400.0S Special_Requirements: MIN DUR 80%; MAX DUR 1000% Comments: Visit_Number: 7 Exposure_Number: 1 Target_Name: PG2112+059 Config: FOS/BL Opmode: ACQ/BINARY Aperture: 4.3 Sp_Element: MIRROR Number_of_Iterations: 1 Time_Per_Exposure: 19.3S Special_Requirements: ONBOARD ACQ FOR 2 Comments: Exposure_Number: 2 Target_Name: PG2112+059 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: G140L Wavelength: 1464.0 Number_of_Iterations: 4 Time_Per_Exposure: 300.0S Comments: Data_Distribution Medium: 8MM Blocking_Factor: 10 Ship_To: PI_address Ship_Via: UPS Recipient_Email: !lanzetta@sbastc.ess.sunysb.edu