6819( 6) - 10/14/96 10:00 - [ 0] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6819 Version: 6 Check-in Date: 14-Oct-1996 09:56:20 1.Proposal Title: FOS OBSERVATIONS OF CLOSE QSO PAIRS ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle QSO ABSORPTION LINES GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: PATRICK PETITJEAN INSTITUT D'ASTROPHYSQUE DE PARIS CoI: Jean Surdej Space Telescope Science Institute N CoI: Peter Shaver European Southern Observatory N CoI: Jan Muecket Astrophysikalisches Institut Potsdam N CoI: Marc Remy Institut d'Astrophysique de Liege N CoI: Alain Smette Kapteyn Astronomical Institute N ------------------------------------------------------------------------------------ 6. Abstract We propose to obtain ~ 2 Angstrom resolution FOS ultraviolet spectra of one pair of QSOs with projected linear separation of the order of 400 kpc, in order to probe the extension and structure of the gas giving rise to LyAlpha absorption lines at low redshift (0.8 < z < 1.4). Given the brightness of the QSOs (V = 18.4 and 18.5) to be observed and the spectral range of interest (2200 Angstrom <= Lambda <= 3300 Angstrom), HST + FOS provides us with the unique existing instrumental capability to perform the proposed observations. ------------------------------------------------------------------------------------ Observations Description ------------------------ In order to achieve the scientific goals exposed in the abstract, we intend to obtain FOS spectra of mean resolution 1.5A -- 2.0A FWHM using grating G270H. Note that given the relative faintness of the objects (V=18.5), FOS combined to G270H is a better choice than STIS plus low resolution first-order gratings. We want to be able to detect lines with W > 0.4A at the 4 sigma level. Given the resolution of 2A FWHM, we can achieve this by requesting an exposure time sufficient to get a signal-to-noise ratio of app. 25 per resolution element. We have derived the exposure times for each observation considering a dark count rate of 0.010 count/sec/diode in the FOS/RED mode, the HST + FOS + COSTAR inverse sensitivity (see Tables 1-6 and 1-7 in the HST FOS Instrument Handbook), the throughput of the 1.0" single circular aperture (Table 1-8 in the same reference), a representative wavelength in the ultraviolet (2750A), the V apparent magnitude of the quasars (18.4 and 18.5) and a spectral index alpha = +1 to characterize their spectral energy distribution. We find that our goals should be achieved in 1.6 hour. We have constructed the Ly alpha line equivalent width distribution from published HST data (Bahcall et al. 1993, ApJS 87, 1) and derived that we can expect 8 Ly alpha lines with W > 0.36A and two additional ones with W > 0.25A for a typical redshift path of Delta z = 0.5 in each QSO spectrum. No intermediate resolution spectroscopy of the objects has been done yet. However, even in case a strong Lyman Limit System is present at the redshift of the quasar, it will cut-off the continuum flux below 2300A and thus do not affect our observations. In the following we will use H{0} = 50 km/sec/Mpc and q{0} = 0. The targets: We will restrict the observations to the only pair accepted by the TAC during the Phase I review. Q 1026--0045A&B: The maximum projected linear separation between these two quasars (V(A) = 18.5, z(A) = 1.438 and V(B) = 18.4, z(B) = 1.520) is 411 kpc. We would like to obtain one G270H spectrum of each quasar (2 * 1.6 hr) in order to probe the Ly alpha clouds in the redshift range from z = 0.8 to z = 1.4. Given the integration times calculated above for each individual object and instrumental setting, the time for target acquisition (typically 30 minutes for a pointing accuracy near 0.08''), reacquisition of guide stars and for the instrumental overheads, we find that a total of 6 orbits is necessary in order to achieve the observations of this pair of quasars. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6819( 6) - 10/14/96 10:00 - [ 1] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 Q1026-0045-A GALAXY,QSO,LYMAN ALPHA RA=10H 28M 34.98S +/- 0.10S,DEC= J2000 Z = V = 18.5 CLOUD, -01D 0' 44.42" +/- 1.00",PLATE- 1.438 R = 18.2 ID=023E Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1983.182 0.0 0.0 0.0 2 Q1026-0045-B GALAXY,QSO,LYMAN ALPHA RA=10H 28M 36.98S +/- 0.10S,DEC= J2000 Z = V = 18.3 CLOUD, -01D 0' 27.85" +/- 1.00",PLATE- 1.520 R = 17.9 ID=023E Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1983.182 0.0 0.0 0.0 6819( 6) - 10/14/96 10:00 - [ 2] Visit: 01 Visit Requirements: ON HOLD On Hold Comments: Choose either visit 1 or visit 3. 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 Q1026-0045- FOS/RD ACQ/BIN 4.3 MIRROR 1 60 S ONBOARD ACQ FOR 2 A ARY ------------------------------------------------------------------------------------------------------------------------------------ 2 Q1026-0045- FOS/RD ACQ/PEA 0.3 MIRROR SEARCH-SIZE-X=5,SEARCH-SIZE-Y=5, 1 6 S ONBOARD ACQ FOR 3-4 A K SCAN-STEP-X=0.11,SCAN-STEP-Y=0.11 ------------------------------------------------------------------------------------------------------------------------------------ 3 Q1026-0045- FOS/RD ACCUM 1.0 G270H 2223-32 1 5500 S EXPAND MIN DUR 75% MAX A 78 DUR 125% ------------------------------------------------------------------------------------------------------------------------------------ 4 WAVE FOS/RD ACCUM 1.0 G270H 2223-32 1 DEF END ORBIT 78 ------------------------------------------------------------------------------------------------------------------------------------ 6819( 6) - 10/14/96 10:00 - [ 3] Visit: 02 Visit Requirements: GROUP 1-2 WITHIN 7 D ON HOLD On Hold Comments: Choose either visit 2 or visit 4. 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 Q1026-0045- FOS/RD ACQ/BIN 4.3 MIRROR 1 60 S ONBOARD ACQ FOR 2 B ARY ------------------------------------------------------------------------------------------------------------------------------------ 2 Q1026-0045- FOS/RD ACQ/PEA 0.3 MIRROR SEARCH-SIZE-X=5,SEARCH-SIZE-Y=5, 1 6 S ONBOARD ACQ FOR 3-4 B K SCAN-STEP-X=0.11,SCAN-STEP-Y=0.11 ------------------------------------------------------------------------------------------------------------------------------------ 3 Q1026-0045- FOS/RD ACCUM 1.0 G270H 2223-32 1 5500 S EXPAND MIN DUR 75% MAX B 78 DUR 125% ------------------------------------------------------------------------------------------------------------------------------------ 4 WAVE FOS/RD ACCUM 1.0 G270H 2223-32 1 DEF END ORBIT 78 ------------------------------------------------------------------------------------------------------------------------------------ 6819( 6) - 10/14/96 10:00 - [ 4] Visit: 03 Visit Requirements: ON HOLD On Hold Comments: Visit 03 could replace Visit 01 if the QSO turns out to be variable 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 Q1026-0045- FOS/RD ACQ/PEA 4.3 MIRROR SEARCH-SIZE-X=1,SEARCH-SIZE-Y=3, 1 5 S ONBOARD ACQ FOR 2 SEQ 1-4 A K SCAN-STEP-Y=1.23 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 2 Q1026-0045- FOS/RD ACQ/PEA 1.0 MIRROR SEARCH-SIZE-X=6,SEARCH-SIZE-Y=2, 1 6 S ONBOARD ACQ FOR 3 A K SCAN-STEP-X=0.61,SCAN-STEP-Y=0.61 ------------------------------------------------------------------------------------------------------------------------------------ 3 Q1026-0045- FOS/RD ACQ/PEA 0.5 MIRROR SEARCH-SIZE-X=3,SEARCH-SIZE-Y=3, 1 6 S ONBOARD ACQ FOR 4 A K SCAN-STEP-X=0.29,SCAN-STEP-Y=0.29 ------------------------------------------------------------------------------------------------------------------------------------ 4 Q1026-0045- FOS/RD ACQ/PEA 0.3 MIRROR SEARCH-SIZE-X=4,SEARCH-SIZE-Y=4, 1 6 S ONBOARD ACQ FOR 5-6 A K SCAN-STEP-X=0.11,SCAN-STEP-Y=0.11 ------------------------------------------------------------------------------------------------------------------------------------ 5 Q1026-0045- FOS/RD ACCUM 1.0 G270H 2223-32 1 4600 S EXPAND MIN DUR 75% MAX A 78 DUR 125% ------------------------------------------------------------------------------------------------------------------------------------ 6 WAVE FOS/RD ACCUM 1.0 G270H 2223-32 1 DEF END ORBIT 78 ------------------------------------------------------------------------------------------------------------------------------------ 6819( 6) - 10/14/96 10:00 - [ 5] Visit: 04 Visit Requirements: ON HOLD On Hold Comments: Visit 04 could replace Visit 01 if the QSO turns out to be variable 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 Q1026-0045- FOS/RD ACQ/PEA 4.3 MIRROR SEARCH-SIZE-X=1,SEARCH-SIZE-Y=3, 1 5 S ONBOARD ACQ FOR 2 SEQ 1-4 B K SCAN-STEP-Y=1.23 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 2 Q1026-0045- FOS/RD ACQ/PEA 1.0 MIRROR SEARCH-SIZE-X=6,SEARCH-SIZE-Y=2, 1 6 S ONBOARD ACQ FOR 3 B K SCAN-STEP-X=0.61,SCAN-STEP-Y=0.61 ------------------------------------------------------------------------------------------------------------------------------------ 3 Q1026-0045- FOS/RD ACQ/PEA 0.5 MIRROR SEARCH-SIZE-X=3,SEARCH-SIZE-Y=3, 1 6 S ONBOARD ACQ FOR 4 B K SCAN-STEP-X=0.29,SCAN-STEP-Y=0.29 ------------------------------------------------------------------------------------------------------------------------------------ 4 Q1026-0045- FOS/RD ACQ/PEA 0.3 MIRROR SEARCH-SIZE-X=4,SEARCH-SIZE-Y=4, 1 6 S ONBOARD ACQ FOR 5-6 B K SCAN-STEP-X=0.11,SCAN-STEP-Y=0.11 ------------------------------------------------------------------------------------------------------------------------------------ 5 Q1026-0045- FOS/RD ACCUM 1.0 G270H 2223-32 1 4600 S EXPAND MIN DUR 75% MAX B 78 DUR 125% ------------------------------------------------------------------------------------------------------------------------------------ 6 WAVE FOS/RD ACCUM 1.0 G270H 2223-32 1 DEF END ORBIT 78 ------------------------------------------------------------------------------------------------------------------------------------ 6819( 6) - 10/14/96 10:00 - [ 6] Summary Form for Proposal 6819 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/RD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/BINARY ACQ/PEAK ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SEARCH-SIZE-X=5 SEARCH-SIZE-Y=5 SCAN-STEP-X=0.11 SCAN-STEP-Y=0.11 SCAN-STEP-Y=1.23 SCAN-STEP-Y=0.61 SCAN-STEP-Y=0.29 SEARCH-SIZE-Y=4 SEARCH-SIZE-Y=3 SCAN-STEP-X=0.61 SCAN-STEP-X=0.29 SEARCH-SIZE-X=4 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category QSO ABSORPTION LINES ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ON HOLD ONBOARD ACQ FOR 2 ONBOARD ACQ FOR 3-4 EXPAND MIN DUR 75% MAX DUR 125% END ORBIT GROUP 1-2 WITHIN 7 D ON HOLD ONBOARD ACQ FOR 2 SEQ 1-4 NON-INT ONBOARD ACQ FOR 3 ONBOARD ACQ FOR 4 ONBOARD ACQ FOR 5-6 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G270H ------------------------------------------------------------------------------------------------------------------------------------ Target Names Q1026-0045-A WAVE Q1026-0045-B ------------------------------------------------------------------------------------------------------------------------------------