Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 5457 Report Date: 18-Jul-95:17:26 Version: ********** Check-in Date: ********** 1.Proposal Title: MEASUREMENT OF ATOMIC DEUTERIUM AND MOLECULAR HYDROGEN 6.7 BILLION YEARS AGO IN GAS OF LOW METALLICITY - CYCLE 4 HIGH ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID QUASARS & AGN GO Sub Category QUASAR ABSORPTION ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Dr. Frank H. Briggs UNIVERSITY OF PITTSBURGH USA (412) 624-9012 PROFESSOR ------------------------------------------------------------------------------------ 7. Abstract GHRS observations of the z=0.692 absorption-line system observed in the spectrum of the quasar 3C286 will provide a determination of the deuterium abundance in relatively un-enriched gas as it was when the Universe was about one half its current age. The observation may produce the second detection of molecular hydrogen in a high redshift absorption system. ------------------------------------------------------------------------------------ 8. Scientific Key Words: ABSORPTION LINES ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 12.20 par: 0 10. Num targs pri: 1 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: HRS ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 5457 PI: Dr. Frank H. Briggs Proposal Title: MEASUREMENT OF ATOMIC DEUTERIUM AND MOLECULAR HYDROGEN 6.7 BILLION YEARS AGO IN GAS OF LOW METALLICITY - CYCLE 4 HIGH ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Pi Frank H. Briggs UNIVERSITY OF PITTSBURGH USA David A. Turnshek UNIVERSITY OF PITTSBURGH USA Valery K. Khersonsky UNIVERSITY OF PITTSBURGH USA ------------------------------------------------------------------------------------ 3. Description of proposed observations. The observational goal is to obtain a single GHRS G160M spectrum of the QSO 3C286 at a resolution R=20,000 with signal-to-noise ratio of about 7 per resolution element. The wavelength interval observed will be 1540-1576 Ang. The SSA will be used and the exposure time will be about 12 hours. NOTE: Please set FLYLIM=2 for this program. This will apparently require the use of special commanding by STScI. On the basis of advice we have gotten from Thanassis Diplas who works with the GHRS team, for a step time of 200 msec ( which we requested and which is realistically the minimum for using FP-SPLIT ), we have requested the use of FLYLIM, thus: FLYLIM=2 ( i.e. OTFA=3) NOTE: OTFA ( on the fly adder) is the REJLIM number, with ( REJLIM = FLYLIM + 1 ), therefore in the 200 msec step time we will want to accept frames with <=2 and reject those with >=3. We also understood from the calibration meeting last fall that we would be better off if the individual exposures were of 4 or 5 minute duration rather than the 10 minute duration in our original Phase II submission. So we are increasing the number of exposures from 70 to 175, and decreasing the time per exposure from 10 minutes to 4 minutes. This should give us more freedom to eliminate small amounts of corrupted data. Based on information from the GHRS Instrument Scientist Dave Soderblom, it is our understanding that the exposure time padding involved in the use of FLYLIM is not charged to the GO nor is it necessary to change any of the exposure times in the program, so this is, in effect, an invisible overhead as far as the GO is concerned. We have also revised our acquisition strategy based on advice from Dave Soderblom, and have corrected some errors ( incorrect mirror, etc. ) which appeared in our original Phase II submission. We had also asked for 100s step time for the acquisitions in our original submission, but Dave Soderblom has informed us that 12.75s is the maximum allowable step time, so we have changed the step time to 12.75s for both the acquisition Exp Log lines, 1 and 2. ( Note that we had originally expected 1200 counts in a 100 sec step time. ) ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. Using the HRS G160M mode and SSA aperture, an exposure time of 12H is required to obtain a spectrum with a signal-to-noise ratio of 7 per resolution element at the expected position of the deuterium lines. With the aperture we propose to use the resolution with be R=20000 which is 4 pixels in 1/4-diode substepping mode (or 0.08 Angstroms resolution). The 1-sigma error in an absorption line equivalent width measurement will be approximately 0.01 Angstrom (observed- frame). ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. Please set FLYLIM=2. We are told that this will require special commanding by STScI. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. Page 3 ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. The data will be reduced and processed on SUN workstations using the software available in IRAF/STSDAS when possible. The deuterium lines will be analyzed both by profile fitting and by computing equivalent widths and performing curve of growth analyses. This will produce a measure of the column density of deuterium in the absorber at z=0.692. If molecular hydrogen is detected, synthetic spectra will be computed and the data will be analyzed to extract values for the column density, Doppler parameter, and excitation temperature. Measurements of the column density of atomic HI are needed for comparison with the DI and H2 column densities; the HI column density can be obtained either from the published finding of the GTO team or by analyzing FOS spectra that will be in the HST archives. ------------------------------------------------------------------------------------ 9. Description of previous HST work. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). Institutional support includes academic year salary for the PI and some administrative help. ------------------------------------------------------------------------------------ 11. Address Information Name: FRANK H. BRIGGS Category: PI Institution: UNIVERSITY OF PITTSBURGH Address: DEPT. OF PHYS. AND ASTRON. City: PITTSBURGH State: PA Zip Code: 15260 Country: USA Telephone: (412) 624-9015/9000 Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 5457 [ 4] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial |Acqui|FLX| Flux data No | Name | Description | Position |Eqnx | Vel. |Prblm|REF| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 1 3C286 E,313,323 RA= 13H 31M 08.29S +/- 1", 2000 Z=0.849 1 V=17.3 +/- 0.2 DEC= 30D 30' 32.9" +/- 1" Comments: Z_ABS=0.6924 POS FROM EARLIER FOS OBS (ROOTNAME: Y0PL0101T) ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5457 [ 5] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 3C286 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN 1 114.75S 35 1 1 CYCLE 4 ONBOARD ACQ FOR 2 Comments: STEP-TIME=12.75S ------------------------------------------------------------------------------------------------------------------------------------ 2 3C286 HRS ACCUM 2.0 G160M 1558 STEP-PATT=DEF 25 4M 7 1 1 CYCLE 4 STEP-TIME=0.2 COMB=FOUR CENSOR=NO DOPPLER=ON FLYLIM=2 ------------------------------------------------------------------------------------------------------------------------------------ 3 3C286 HRS ACCUM 2.0 G160M 1558 STEP-PATT=DEF 25 4M 7 1 1 CYCLE 4 STEP-TIME=0.2 COMB=FOUR CENSOR=NO DOPPLER=ON FLYLIM=2 ------------------------------------------------------------------------------------------------------------------------------------ 4 3C286 HRS ACCUM 2.0 G160M 1558 STEP-PATT=DEF 25 4M 7 1 1 CYCLE 4 STEP-TIME=0.2 COMB=FOUR CENSOR=NO DOPPLER=ON FLYLIM=2 ------------------------------------------------------------------------------------------------------------------------------------ 5 3C286 HRS ACCUM 2.0 G160M 1558 STEP-PATT=DEF 25 4M 7 1 1 CYCLE 4 STEP-TIME=0.2 COMB=FOUR CENSOR=NO DOPPLER=ON FLYLIM=2 ------------------------------------------------------------------------------------------------------------------------------------ 6 3C286 HRS ACCUM 2.0 G160M 1558 STEP-PATT=DEF 25 4M 7 1 1 CYCLE 4 STEP-TIME=0.2 COMB=FOUR CENSOR=NO DOPPLER=ON FLYLIM=2 ------------------------------------------------------------------------------------------------------------------------------------ 7 3C286 HRS ACCUM 2.0 G160M 1558 STEP-PATT=DEF 25 4M 7 1 1 CYCLE 4 STEP-TIME=0.2 COMB=FOUR CENSOR=NO DOPPLER=ON FLYLIM=2 ------------------------------------------------------------------------------------------------------------------------------------ 8 3C286 HRS ACCUM 2.0 G160M 1558 STEP-PATT=DEF 25 4M 7 1 1 CYCLE 4 STEP-TIME=0.2 COMB=FOUR CENSOR=NO DOPPLER=ON FLYLIM=2 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 5457 [ 6] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BRIGHT=RETURN STEP-PATT=DEF STEP-TIME=0.2 COMB=FOUR CENSOR=NO DOPPLER=ON FLYLIM=2 ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 12.20 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category QUASARS & AGN ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category QUASAR ABSORPTION ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CYCLE 4; ONBOARD ACQ FOR 2; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N2 G160M ------------------------------------------------------------------------------------------------------------------------------------ Target Names 3C286 ------------------------------------------------------------------------------------------------------------------------------------