6237( 6) - 12/13/95 12:06 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6237 Version: 6 Check-in Date: ********** 1.Proposal Title: Evolution of the Molecular Fraction of Damped Lyman-alpha Absorption Systems ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Quasars GTO/HRS 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: EDWARD A. BEAVER UNIVERSITY OF CALIFORNIA, SAN DIEGO CoI: ROSS D. COHEN UNIVERSITY OF CALIFORNIA, SAN DIEGO Y CoI: VESA T. JUNKKARINEN UNIVERSITY OF CALIFORNIA, SAN DIEGO N CoI: ATHANASSIOS DIPLAS UNIVERSITY OF CALIFORNIA, SAN DIEGO N ------------------------------------------------------------------------------------ 6. Abstract Molecular hydrogen measurements are unique diagnostics of the physical conditions in the gas, including temperature, density, and ionizing background. The formation of molecular hydrogen depends as well on dust content. We will use the FOS to measure the column density and excitation of molecular hydrogen in a bright, moderate redshift damped Lyman-alpha absorption system. The very accurate H I column densty determined from the same spectrum will be combined with very high resolution, high signal-to-noise optical spectra to measure metal abundances and dust content. Additional indicators of metallicity, ionization, and dust content will come from metal absorption lines measured in the HST spectrum. The molecular fraction will be compared with the high redshift damped Lyman-alpha systems to study the evolution of these systems. Thus our measurements will provide clues to the nature of the damped Lyman-alpha absorption systems. ------------------------------------------------------------------------------------ 6237( 6) - 12/13/95 12:06 - [ 2] Observations Description ------------------------ This observation is designed to measure the column density and excitation of molecular hydrogen in relatively low resolution FOS data. In order to achieve this we will attain a signal-to-nose of greater than 50 per diode over the entire spectrum and greater than 65 over most of the region of interest. Our simulations show that this is adequate to make these measurements. Another observation of this target which is part of a different program uses less than one quarter of the integration time used for this observation and will not attain high enough signal-to-noise to study molecular hydrogen. That program is designed to study lines of the Lyman-alpha forest. We will use a binary search followed by two stages of peak-up in the 0.3" aperture. This is designed to use the same centering as the flat field observations (accurate to 0.04") in order to achieve highest possible accuracy in flat fielding. Following target acquisition, an 8750s integration will be obtained with the FOS, red detector, G270H grating and 0.3" aperture. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6237( 6) - 12/13/95 12:06 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 PG0935+417 GALAXY,QSO,EXT- RA = 9H 38M 57.03S +/- 0.04S, J2000 Z = V = 16.25 +/- 0.2 MEDIUM,ABSORPTION LINE DEC = 41D 28' 21.5" +/- 0.5", 1.9657 F(2500.0) = 2.0 +/- 0.25 E-15 SYSTEM,IGM PLATE-ID = 01BS Comments: Coordinates are from an inventory GASP measurement by Karla; Absorption redshift z(a)=1.379; Emission redshift from Tytler and Fan 1992 6237( 6) - 12/13/95 12:06 - [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 PG0935+417 FOS/RD ACQ/BIN 4.3 MIRROR BRIGHT=700000 1 10S ONBOARD ACQ FOR 20 ARY Comments: calculated time was 4.53S ------------------------------------------------------------------------------------------------------------------------------------ 20 PG0935+417 FOS/RD ACQ/PEA 0.3 MIRROR SEARCH-SIZE- 1 1S ONBOARD ACQ FOR 30 K Y=5, SCAN-STEP- Y=0.17, SEARCH- SIZE-X=5, SCAN- STEP-X=0.17 ------------------------------------------------------------------------------------------------------------------------------------ 30 PG0935+417 FOS/RD ACQ/PEA 0.3 MIRROR SEARCH-SIZE- 1 10S ONBOARD ACQ FOR 40 K Y=5, SCAN-STEP- Y=0.05, SEARCH- SIZE-X=5, SCAN- STEP-X=0.05 ------------------------------------------------------------------------------------------------------------------------------------ 40 PG0935+417 FOS/RD ACCUM 0.3 G270H 1 8750S ------------------------------------------------------------------------------------------------------------------------------------ 6237( 6) - 12/13/95 12:06 - [ 5] Summary Form for Proposal 6237 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/RD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/BINARY ACQ/PEAK ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BRIGHT=700000 SCAN-STEP-X=0.17 SCAN-STEP-X=0.05 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GTO/HRS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Quasars ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 20 ONBOARD ACQ FOR 30 ONBOARD ACQ FOR 40 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G270H ------------------------------------------------------------------------------------------------------------------------------------ Target Names PG0935+417 ------------------------------------------------------------------------------------------------------------------------------------