! $Id: 6712,v 11.1 1996/08/14 22:17:35 pepsa Exp $ Proposal_Information Title: The Gaseous Extent of Galaxies: How Far is Too Far? Proposal_Category: GO Scientific_Category: QSO ABSORPTION LINES Cycle: 6 Investigators PI_name: John K. Webb PI_Institution: University of New South Wales CoI_Name: Kenneth M. Lanzetta CoI_Institution: State University of New York at Stony Brook Contact: N CoI_Name: Robert F. Carswell CoI_Institution: Institute of Astronomy Contact: N CoI_Name: Xavier Barcons CoI_Institution: Instituto de Fisica de Cantabria Contact: N Abstract: The origin of the Lyman-Alpha clouds has been a subject of intense recent activity. The launch of HST made it possible for the first time to make direct identification of objects at low/intermediate redshift which give rise to Lyman-Alpha absorption towards a bright background QSO. Using a combination of HST QSO spectra and ground-based multi-slit spectroscopy, we have shown that many Lyman-Alpha clouds arise in gigantic gaseous envelopes around galaxies. Our analysis so far has been based on HST FOS QSO spectra, where the weakest absorption systems typically detected are ~ 0.3Angstrom, which can arise around galaxies at impact parameters of out to 160 h^-1 kpc. In order to properly understand the nature of gas in and around galaxies we must now explore how far out from the galaxy centre this incredibly tenuous gas extends. To do this, we wish to obtain GHRS spectra of two particularly interesting QSOs, centred on fields where we have already carried out extensive multi-slit redshift surveys, to search for weak Lyman-Alpha absorption associated with the galaxies. Detections or non-detections of absorption associated with galaxies greater than 160 h^-1 kpc will both place fundamental new constraints on the nature of these gigantic gaseous envelopes around galaxies. Questions Observing_Description: The appropriate gratings are the G160M up to 1700A, and the G200M thereafter. Note that there is a group of redshifts very close together towards 0405-12 (1731 to 1736 Angstrom). Also, the z=0.5170 galaxy towards 0405-12 has a reasonably convenient redshift from the point of view of the G200M efficiency. We thus choose 4 spectral ranges to cover, 3 towards 0405-12 and one towards 1001+291. These spectral regions are centred on 1556, 1721 and 1856 Angstrom towards 0405-12 and 1564 towards 1001+291. We have computed the required exposure times using the Case 2 equation on page 34 of the GHRS Handbook version 6.0. Both QSO fluxes are measured to be ~ 2.0 e -14 ergs s^-1 cm^-2 AA^-1. The 1856Angstrom region requires an integration time of 7700s and the other three wavelength regions all approximately 13,600s. Allowing for the relevent overheads, acquisitions etc, we will require a total of 21 orbits to complete the project as described. Real_Time_Justification: We have in hand and are scheduled to obtain a large amount of ground-based supporting observations, which will complement the proposed HST observations. First, we are obtaining more ground-based spectroscopy of galaxies in the fields. Second, we are obtaining ground-based optical (B, V, R, and I) and infrared (K) images of galaxies in the fields, which we will use to measure accurate spectral energy distributions and luminosities of the galaxies. Finally, we are obtaining ground-based high-resolution spectroscopy of the brighter galaxies in the fields, which we will use to measure accurate redshifts and rotational velocities. The proposed HST observations will be used together with these ground-based observations to develop a comprehensive picture of how properties of the absorbers depend on properties of the galaxies. Calibration_Justification: Additional_Comments: Fixed_Targets Target_Number: 01 Target_Name: Q0405-1219 Alternate_Names: PKS 0405-12 Description: GALAXY, QSO Position: RA = 04H 07M 48.420S +/- 0.03S, DEC = -12D 11' 36.00" +/- 0.04", PLATE-ID=0238 Equinox: J2000 RV_or_Z: Z=0.574 Flux: V=15.4 +/- 0.3 B-V=0.18 +/- 0.1 U-B=-0.60 +/- 0.1 F(1600)=2.5 +/- 0.1 E-14 Comments: Target_Number: 02 Target_Name: Q1001+2910 Alternate_Names: TON 28 Description: GALAXY,QSO Position: RA= 10H 04M 02.627S +/- 0.01S, DEC= +28D 55' 35.14" +/- 0.2", PLATE-ID=021H Equinox: J2000 RV_or_Z: Z=0.329 Flux: V=15.5 +/- 0.3 B-V=0.12 +/- 0.1 U-B=-0.90 +/- 0.1 F(1600)=2.5 +/- 0.1E-14 Comments: Visits Visit_Number: 01 Exposure_Number: 10 Target_Name: Q0405-1219 Config: HRS Opmode: ACQ Aperture: 2.0 Sp_Element: MIRROR-N2 Optional_Parameters: BRIGHT=RETURN SEARCH-SIZE=3 Number_of_Iterations: 1 Time_Per_Exposure: 27S Special_Requirements: ONBOARD ACQUISITION FOR 20-70 Exposure_Number: 20 Target_Name: WAVE Config: HRS Opmode: ACCUM Aperture: SC2 Sp_Element: G160M Wavelength: 1556.0 Optional_Parameters: SPYBAL=YES Number_of_Iterations: 1 Time_Per_Exposure: 54.4S Exposure_Number: 30 Target_Name: Q0405-1219 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: G160M Wavelength: 1556.0 Optional_Parameters: STEP-PATT=DEF, FP-SPLIT=NO, COMB=FOUR, SPYBAL=NO Number_of_Iterations: 9 Time_Per_Exposure: 598.4S Special_Requirements: Exposure_Number: 40 Target_Name: Q0405-1219 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: G160M Wavelength: 1556.0 Optional_Parameters: STEP-PATT=DEF, FP-SPLIT=NO, COMB=FOUR, SPYBAL=YES Number_of_Iterations: 8 Time_Per_Exposure: 598.4S Special_Requirements: Exposure_Number: 50 Target_Name: Q0405-1219 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: G160M Wavelength: 1556.0 Optional_Parameters: STEP-PATT=DEF, FP-SPLIT=NO, COMB=FOUR, SPYBAL=YES Number_of_Iterations: 8 Time_Per_Exposure: 598.4S Special_Requirements: Exposure_Number: 60 Target_Name: WAVE Config: HRS Opmode: ACCUM Aperture: SC2 Sp_Element: G200M Wavelength: 1721.0 Optional_Parameters: SPYBAL=YES Number_of_Iterations: 1 Time_Per_Exposure: 27.2S Exposure_Number: 70 Target_Name: Q0405-1219 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: G200M Wavelength: 1721.0 Optional_Parameters: STEP-PATT=DEF, FP-SPLIT=NO, COMB=FOUR, SPYBAL=NO Number_of_Iterations: 9 Time_Per_Exposure: 598.4S Special_Requirements: Visit_Number: 02 Exposure_Number: 10 Target_Name: Q1001+2910 Config: HRS Opmode: ACQ Aperture: 2.0 Sp_Element: MIRROR-N2 Optional_Parameters: BRIGHT=RETURN SEARCH-SIZE=3 Number_of_Iterations: 1 Time_Per_Exposure: 27S Special_Requirements: ONBOARD ACQUISITION FOR 20-50 Exposure_Number: 20 Target_Name: WAVE Config: HRS Opmode: ACCUM Aperture: SC2 Sp_Element: G160M Wavelength: 1564.0 Optional_Parameters: SPYBAL=YES Number_of_Iterations: 1 Time_Per_Exposure: 54.4s Exposure_Number: 30 Target_Name: Q1001+2910 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: G160M Wavelength: 1564.0 Optional_Parameters: STEP-PATT=DEF, FP-SPLIT=NO, COMB=FOUR, SPYBAL=NO Number_of_Iterations: 9 Time_Per_Exposure: 625.6S Special_Requirements: Exposure_Number: 40 Target_Name: Q1001+2910 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: G160M Wavelength: 1564.0 Optional_Parameters: STEP-PATT=DEF, FP-SPLIT=NO, COMB=FOUR, SPYBAL=YES Number_of_Iterations: 8 Time_Per_Exposure: 598.4S Special_Requirements: Exposure_Number: 50 Target_Name: Q1001+2910 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: G160M Wavelength: 1564.0 Optional_Parameters: STEP-PATT=DEF, FP-SPLIT=NO, COMB=FOUR, SPYBAL=YES Number_of_Iterations: 8 Time_Per_Exposure: 598.4S Special_Requirements: Visit_Number: 03 Exposure_Number: 10 Target_Name: Q0405-1219 Config: HRS Opmode: ACQ Aperture: 2.0 Sp_Element: MIRROR-N2 Optional_Parameters: BRIGHT=RETURN SEARCH-SIZE=3 Number_of_Iterations: 1 Time_Per_Exposure: 27S Special_Requirements: ONBOARD ACQUISITION FOR 60-110 Exposure_Number: 60 Target_Name: WAVE Config: HRS Opmode: ACCUM Aperture: SC2 Sp_Element: G200M Wavelength: 1721.0 Optional_Parameters: SPYBAL=YES Number_of_Iterations: 1 Time_Per_Exposure: 27.2S Exposure_Number: 80 Target_Name: Q0405-1219 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: G200M Wavelength: 1721.0 Optional_Parameters: STEP-PATT=DEF, FP-SPLIT=NO, COMB=FOUR, SPYBAL=NO Number_of_Iterations: 8 Time_Per_Exposure: 598.4S Special_Requirements: Exposure_Number: 90 Target_Name: Q0405-1219 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: G200M Wavelength: 1721.0 Optional_Parameters: STEP-PATT=DEF, FP-SPLIT=NO, COMB=FOUR, SPYBAL=YES Number_of_Iterations: 8 Time_Per_Exposure: 598.4S Special_Requirements: Exposure_Number: 95 Target_Name: WAVE Config: HRS Opmode: ACCUM Aperture: SC2 Sp_Element: G200M Wavelength: 1856.0 Optional_Parameters: SPYBAL=YES Number_of_Iterations: 1 Time_Per_Exposure: 27.2S Exposure_Number: 100 Target_Name: Q0405-1219 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: G200M Wavelength: 1856.0 Optional_Parameters: STEP-PATT=DEF, FP-SPLIT=NO, COMB=FOUR, SPYBAL=NO Number_of_Iterations: 7 Time_Per_Exposure: 571.2S Special_Requirements: Exposure_Number: 110 Target_Name: Q0405-1219 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: G200M Wavelength: 1856.0 Optional_Parameters: STEP-PATT=DEF, FP-SPLIT=NO, COMB=FOUR, SPYBAL=YES Number_of_Iterations: 7 Time_Per_Exposure: 571.2S Special_Requirements: Data_Distribution Medium: 8MM Blocking_Factor: 10 Ship_To: PI_Address Ship_Via: UPS Recipient_Email: