5961( 7) - 10/20/95 18:48 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 5961 Version: 7 Check-in Date: ********** 1.Proposal Title: The D/H Ratios in a Double QSO Absorption System towards Q0454-220 ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Quasars GO 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: John Webb University of New South Wales CoI: Jacqueline Bergeron European Southern Observatory N CoI: David Bowen Space Telescope Science Institute N CoI: Bob Carswell Institute of Astronomy, Cambridge N CoI: Roger Ferlet Institut d'Astrophysique N CoI: Ken Lanzetta State University of New York at Stony N Brook CoI: Martin Lemoine Institut d'Astrophysique N CoI: Alfred Vidal--Madjar Institut d'Astrophysique N ------------------------------------------------------------------------------------ 6. Abstract In Cycle 4 we obtained spectra of selected wavelength regions towards the z(em)=0.534, m(u)=15.5 QSO 0454-220. The goal was to derive the deuterium abundance in a known intervening absorption system at z(abs)=0.48. The Cycle 4 data have resulted in the discovery of a double absorption system at z(abs)=0.483137 and z(abs)=0.482279. By a stroke of good fortune, the characteristics of this double system are better than we could have hoped for: (1) the velocity splitting is 174 km/s, sufficiently well separated to estimate D/H in both systems simultaneously, (2) N(HI) and b in both clouds are suitable for measuring D/H, (3), the D absorption is strongest at LyAlpha, which happens to be well placed in efficiency for the G200M grating. Our Cycle 4 data cover the higher order Lyman lines, and existing FOS data covers the Lyman limit, so we already have tight constraints on N(HI) in both clouds. We now need observations of the LyAlpha line to combine with the Cycle 4 data and derive the first D/H estimates at these redshifts. ------------------------------------------------------------------------------------ 5961( 7) - 10/20/95 18:48 - [ 2] Observations Description ------------------------ We will use the GHRS with G200M and LSA to obtain a spectrum of spectral resolution FWHM ~ 14 kms\ and signal-to-noise ratio S/N ~ 8 per diode with a total on--target exposure time of 28,800 s. Note that the S/N in the simulation described in the previous case for support is 4, chosen to provide a worst case scenario. Realistically, we should obtain a signal to noise of 7 per diode. To estimate the required exposure time, we determined the ultraviolet flux from the archive FOS spectrum of 0454-220 and used the sensitivity and dark count values quoted in the Hubble Space Telescope Goddard High Resolution Spectrograph (GHRS) Instrument Handbook, Version 5.0. At the wavelength Lambda = 1802 Angstrom\ of interest, the observed flux is f_Lambda = 6.1 * 10^-15 erg s^-1 cm^-2 AA^-1. Allowing for a dark rate of 0.008 count s^-1, the Case 2 equation on page 29 yields a signal-to-noise ratio of 7 per diode in an exposure time of 28,800 s. Our simulations have shown that this is sufficient to meet our scientific goals. Allowing for acquisition and overhead, we require 13 orbits to reach the required exposure time. Real Time Justification ----------------------- Not applicable. Not applicable. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: STScI Ship Via: UPS Email: bowen@stsci.edu , ------------------------------------------------------------------------------------ 5961( 7) - 10/20/95 18:48 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 0454-220 Galaxy,QSO;ext- RA=04H 56M 08.86S +/- 0.6S, DEC= 2000.0 z=0.534 F(1800)=6e-15 medium,Absorption Line -21D 59' 09.8" +/- 0.6S, PLATE- System ID=029X 5961( 7) - 10/20/95 18:48 - [ 4] 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 ------------------------------------------------------------------------------------------------------------------------------------ 100 0454-220 HRS ACQ 2.0 MIRROR-N2 bright=return,s 1 18S ONBOARD ACQuisition FOR 200-500 earch-size=3 Comments: STEP-TIME=2s. ------------------------------------------------------------------------------------------------------------------------------------ 200 wave HRS accum SC2 G200M 1802.5 spybal=yes 1 def Comments: Wave calib for 300. ------------------------------------------------------------------------------------------------------------------------------------ 300 0454-220 HRS ACCUM 2.0 G200M 1802.5 fp- 46 217.6S split=two,step- patt=5,doppler= def,spybal=no Comments: Observing Lya at 1802.5A. ------------------------------------------------------------------------------------------------------------------------------------ 400 wave HRS accum SC2 G200M 1802.5 spybal=yes 1 def Comments: Wave calib for 500. ------------------------------------------------------------------------------------------------------------------------------------ 500 0454-220 HRS ACCUM 2.0 G200M 1802.5 fp- 46 217.6S split=two,step- patt=5,doppler= def,spybal=no Comments: Observing Lya at 1802.5A. ------------------------------------------------------------------------------------------------------------------------------------ 5961( 7) - 10/20/95 18:48 - [ 5] 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 ------------------------------------------------------------------------------------------------------------------------------------ 100 0454-220 HRS ACQ 2.0 MIRROR-N2 bright=return,s 1 18S ONBOARD ACQuisition FOR 200-500 earch-size=3 Comments: STEP-TIME=2s. ------------------------------------------------------------------------------------------------------------------------------------ 200 wave HRS accum SC2 G200M 1802.5 spybal=yes 1 def Comments: Wave calib for 300. ------------------------------------------------------------------------------------------------------------------------------------ 300 0454-220 HRS ACCUM 2.0 G200M 1802.5 fp- 46 217.6S split=two,step- patt=5,doppler= def,spybal=no Comments: Observing Lya at 1802.5A. ------------------------------------------------------------------------------------------------------------------------------------ 400 wave HRS accum SC2 G200M 1802.5 spybal=yes 1 def Comments: Wave calib for 500. ------------------------------------------------------------------------------------------------------------------------------------ 500 0454-220 HRS ACCUM 2.0 G200M 1802.5 fp- 46 217.6S split=two,step- patt=5,doppler= def,spybal=no Comments: Observing Lya at 1802.5A. ------------------------------------------------------------------------------------------------------------------------------------ 5961( 7) - 10/20/95 18:48 - [ 6] Visit: 03 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 ------------------------------------------------------------------------------------------------------------------------------------ 100 0454-220 HRS ACQ 2.0 MIRROR-N2 bright=return,s 1 18S ONBOARD ACQuisition FOR 200-700 earch-size=3 Comments: STEP-TIME=2s. ------------------------------------------------------------------------------------------------------------------------------------ 200 wave HRS accum SC2 G200M 1802.5 spybal=yes 1 def Comments: Wave calib for 300. ------------------------------------------------------------------------------------------------------------------------------------ 300 0454-220 HRS ACCUM 2.0 G200M 1802.5 fp- 46 217.6S split=two,step- patt=5,doppler= def,spybal=no Comments: Observing Lya at 1802.5A. ------------------------------------------------------------------------------------------------------------------------------------ 400 wave HRS accum SC2 G200M 1802.5 spybal=yes 1 def Comments: Wave calib for 500. ------------------------------------------------------------------------------------------------------------------------------------ 500 0454-220 HRS ACCUM 2.0 G200M 1802.5 fp- 46 217.6S split=two,step- patt=5,doppler= def,spybal=no Comments: Observing Lya at 1802.5A. ------------------------------------------------------------------------------------------------------------------------------------ 600 wave HRS accum SC2 G200M 1802.5 spybal=yes 1 def Comments: Wave calib for 300. ------------------------------------------------------------------------------------------------------------------------------------ 700 0454-220 HRS ACCUM 2.0 G200M 1802.5 fp- 12 217.6S split=two,step- patt=5,doppler= def,spybal=no Comments: Observing Lya at 1802.5A. ------------------------------------------------------------------------------------------------------------------------------------ 5961( 7) - 10/20/95 18:48 - [ 7] Summary Form for Proposal 5961 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ accum ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters bright=return search-size=3 spybal=yes spybal=no doppler=def step-patt=5 fp-split=two ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Quasars ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQuisition FOR 200-500 ONBOARD ACQuisition FOR 200-700 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N2 G200M ------------------------------------------------------------------------------------------------------------------------------------ Target Names 0454-220 wave ------------------------------------------------------------------------------------------------------------------------------------