! Proposal 6612, submission 1 ! PI: Kenneth M. Lanzetta ! Received Wed Feb 21 12:10:48 EST 1996 ! From: lanzetta@sbast3.ess.sunysb.edu Proposal_Information Title: Damped Lyman-alpha Absorption Lines from Moderate-Redshift Galaxies Proposal_Category: GO Scientific_Category: QSO Absorption Lines Cycle: 6 Investigators PI_name: Kenneth M. Lanzetta PI_Institution: State University of New York at Stony Brook CoI_Name: Arthur M. Wolfe CoI_Institution: University of California, San Diego Contact: N Abstract: We propose to obtain intermediate-resolution spectroscopy of eight moderate-redshift (0.05 < z < 0.8) candidate damped Ly- alpha\ absorption features that were detected toward higher- redshift background QSOs in an exhaustive search of the HST 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 neutral hydrogen 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. Questions Observing_Description: We require observations of eight candidate damped LyAlpha absorption features toward six 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 LyAlpha absorption features and to determine accurate neutral hydrogen 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 grating G190H. To estimate the exposure times required to obtain these signal-to-noise ratios, we determined actual ultraviolet fluxes from the HST spectra and used the sensitivity curves and aperture throughputs quoted in the Faint Object Spectrograph Instrument Handbook, Version 6.0 and the Instrument Handbook for the Goddard High Resolution Spectrograph (GHRS), Version 6.0. At the wavelengths of interest, ultraviolet fluxes of the background QSOs in our sample range from 0.15 * 10^-14 through 1.0 * 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 = 1850 Angstrom\ with f_Lambda = 0.3 * 10^-14 erg s^-1 cm^-2 AA^-1 using the FOS with G190H and the red detector. From Table 1--7 of the Faint Object Spectrograph Instrument Handbook, the count rate is found to be 0.2 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 1125 s. We will adopt FOS-assisted target acquisition for the GHRS exposures and PEAKUP target acquisition for the FOS exposures. In most cases we can easily fit the guide star acquisition, the target acquisition, and the science exposure into two orbits, although in one case we require one orbit and in one case we require three orbits. (We will pad, or in a few cases trim, exposure times as necessary to fill orbits.) Real_Time_Justification: Calibration_Justification: Additional_Comments: Fixed_Targets Target_Number: 1 Target_Name: UM301 Description: GALAXY,QSO Position: RA = 01H 03M 12.960S +/- 0.07S, DEC = +02D 21' 10.70" +/- 0.1", PLATE-ID=04YD Equinox: 2000 RV_or_Z: Z=0.39 Flux: V = 17.7 +/- 0.5 Target_Number: 2 Target_Name: 3C95 Description: GALAXY,QSO Position: RA = 03H 51M 28.55S +/- 0.07S, DEC = -14D 29' 09.0" +/- 0.1", PLATE-ID=029R Equinox: 2000 RV_or_Z: Z=0.616 Flux: V = 16.22 +/- 0.5, B-V = 0.33 +/- 0.1, U-B = -0.56 +/- 0.1 Target_Number: 3 Target_Name: US1867 Description: GALAXY,QSO Position: RA = 08H 53M 34.20S +/- 0.07S, DEC = +43D 49' 0.20" +/- 0.1", PLATE-ID=00XV Equinox: 2000 RV_or_Z: Z=0.513 Flux: V = 16.4 +/- 0.5 Target_Number: 4 Target_Name: PG1338+416 Description: GALAXY,QSO Position: RA = 13H 41M 0.770S +/- 0.07S, DEC = +41D 23' 13.50" +/- 0.1", PLATE-ID=00XY Equinox: 2000 RV_or_Z: Z=1.219 Flux: V = 16.08 +/- 0.5 Target_Number: 5 Target_Name: PG1352+011 Description: GALAXY,QSO Position: RA = 13H 54M 58.670S +/- 0.07S, DEC = +00D 52' 10.10" +/- 0.1", PLATE-ID=014F Equinox: 2000 RV_or_Z: Z=1.121 Flux: V = 16.03 +/- 0.5 Target_Number: 6 Target_Name: 4C11.72 Description: GALAXY,QSO Position: RA = 22H 54M 10.43S +/- 0.07S, DEC = +11D 36' 39.00" +/- 0.1", PLATE-ID=00JD Equinox: 2000 RV_or_Z: Z=0.323 Flux: V = 15.77 +/- 0.5, B-V = 0.17 +/- 0.1, U-B = -0.87 +/- 0.1 Visits Visit_Number: 1 Exposure_Number: 1 Target_Name: UM301 Config: FOS/BL 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: 2.34s Special_Requirements: ONBOARD ACQUISITION FOR 2 Comments: Exposure_Number: 2 Target_Name: UM301 Config: FOS/BL 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: 2.34S Special_Requirements: ONBOARD ACQUISITION FOR 3 Comments: Exposure_Number: 3 Target_Name: UM301 Config: FOS/BL Opmode: ACQ/PEAK Aperture: 0.5 Sp_Element: MIRROR Optional_Parameters: SCAN-STEP-X=0.29, SCAN-STEP-Y=0.29, SEARCH-SIZE-X=3, SEARCH-SIZE-Y=3 Number_of_Iterations: 1 Time_Per_Exposure: 2.34S Special_Requirements: ONBOARD ACQUISITION FOR 4 Comments: Exposure_Number: 4 Target_Name: UM301 Config: FOS/BL Opmode: ACQ/PEAK Aperture: 0.3 Sp_Element: MIRROR Optional_Parameters: SCAN-STEP-X=0.172, SCAN-STEP-Y=0.172, SEARCH-SIZE-X=3, SEARCH-SIZE-Y=3 Number_of_Iterations: 1 Time_Per_Exposure: 10S Special_Requirements: ONBOARD ACQUISITION FOR 5-7 Comments: Exposure_Number: 5 Target_Name: UM301 Config: FOS/BL Opmode: ACCUM Aperture: 1.0 Sp_Element: G190H Wavelength: 1628.8 Number_of_Iterations: 1 Time_Per_Exposure: 180.0S Special_Requirements: MIN DUR 80%; MAX DUR 1000% Comments: Exposure_Number: 6 Target_Name: UM301 Config: FOS/BL Opmode: ACCUM Aperture: 1.0 Sp_Element: G190H Wavelength: 1628.8 Number_of_Iterations: 1 Time_Per_Exposure: 2400.0S Special_Requirements: MIN DUR 80%; MAX DUR 1000% Comments: Exposure_Number: 7 Target_Name: UM301 Config: FOS/BL Opmode: ACCUM Aperture: 1.0 Sp_Element: G190H Wavelength: 1628.8 Number_of_Iterations: 1 Time_Per_Exposure: 2401.0S Special_Requirements: MIN DUR 80%; MAX DUR 1000% Comments: Visit_Number: 2 Exposure_Number: 1 Target_Name: 3C95 Config: FOS/BL Opmode: ACQ/BINARY Aperture: 4.3 Sp_Element: MIRROR Number_of_Iterations: 1 Time_Per_Exposure: 8.9S Special_Requirements: ONBOARD ACQUISITION FOR 2 Comments: Exposure_Number: 2 Target_Name: 3C95 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: G140L Wavelength: 1303.8 Optional_Parameters: STEP-PATT=DEF, FP-SPLIT=NO, COMB=FOUR Number_of_Iterations: 15 Time_Per_Exposure: 299.2S Comments: Visit_Number: 3 Exposure_Number: 1 Target_Name: US1867 Config: FOS/BL Opmode: ACQ/BINARY Aperture: 4.3 Sp_Element: MIRROR Number_of_Iterations: 1 Time_Per_Exposure: 13.1S Special_Requirements: ONBOARD ACQUISITION FOR 2 Comments: Exposure_Number: 2 Target_Name: US1867 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: G140L Wavelength: 1409.7 Optional_Parameters: STEP-PATT=DEF, FP-SPLIT=NO, COMB=FOUR Number_of_Iterations: 16 Time_Per_Exposure: 299.2S Comments: Visit_Number: 4 Exposure_Number: 1 Target_Name: PG1338+416 Config: FOS/RD Opmode: ACQ/BINARY Aperture: 4.3 Sp_Element: MIRROR Number_of_Iterations: 1 Time_Per_Exposure: 3.4S Special_Requirements: ONBOARD ACQUISITION FOR 2 Comments: Exposure_Number: 2 Target_Name: PG1338+416 Config: FOS/RD Opmode: ACCUM Aperture: 1.0 Sp_Element: G190H Wavelength: 1945.0 Number_of_Iterations: 1 Time_Per_Exposure: 1690.0S Special_Requirements: MIN DUR 80%; MAX DUR 1000% Comments: Exposure_Number: 3 Target_Name: PG1338+416 Config: FOS/RD Opmode: ACCUM Aperture: 1.0 Sp_Element: G190H Wavelength: 1945.0 Number_of_Iterations: 1 Time_Per_Exposure: 2500.0S Special_Requirements: MIN DUR 80%; MAX DUR 1000% Comments: Visit_Number: 5 Exposure_Number: 1 Target_Name: PG1352+011 Config: FOS/RD Opmode: ACQ/BINARY Aperture: 4.3 Sp_Element: MIRROR Number_of_Iterations: 1 Time_Per_Exposure: 3.3S Special_Requirements: ONBOARD ACQUISITION FOR 2 Comments: Exposure_Number: 2 Target_Name: PG1352+011 Config: FOS/RD Opmode: ACCUM Aperture: 1.0 Sp_Element: G190H Wavelength: 1852.3 Number_of_Iterations: 1 Time_Per_Exposure: 1580.0S Special_Requirements: MIN DUR 80%; MAX DUR 1000% Comments: Visit_Number: 6 Exposure_Number: 1 Target_Name: 4C11.72 Config: FOS/BL 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: 1S Special_Requirements: ONBOARD ACQUISITION FOR 2 Comments: Exposure_Number: 2 Target_Name: 4C11.72 Config: FOS/BL 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: 1S Special_Requirements: ONBOARD ACQUISITION FOR 3 Comments: Exposure_Number: 3 Target_Name: 4C11.72 Config: FOS/BL Opmode: ACQ/PEAK Aperture: 0.5 Sp_Element: MIRROR Optional_Parameters: SCAN-STEP-X=0.29, SCAN-STEP-Y=0.29, SEARCH-SIZE-X=3, SEARCH-SIZE-Y=3 Number_of_Iterations: 1 Time_Per_Exposure: 10s Special_Requirements: ONBOARD ACQUISITION FOR 4 Comments: Exposure_Number: 4 Target_Name: 4C11.72 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: G140L Wavelength: 1313.0 Number_of_Iterations: 10 Time_Per_Exposure: 299.2S Comments: Data_Distribution Medium: 8MM Blocking_Factor: 10 Ship_To: Kenneth M. Lanzetta Department of Earth and Space Sciences State University of New York at Stony Brook Stony Brook, NY 11794-2100 Ship_Via: UPS Recipient_Email: lanzetta@sbastc.ess.sunysb.edu