5945( 13) - 11/07/95 22:20 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 5945 Version: 13 Check-in Date: ********** 1.Proposal Title: Diffuse Helium Absorption as a Probe of Quasar History and Intergalactic Gas ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Quasars GO 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Craig Hogan University of Washington CoI: Scott Anderson University of Washington Y ------------------------------------------------------------------------------------ 6. Abstract We propose to reobserve the region of the possible helium Gunn -Peterson edge found by Jakobsen et al., using GHRS G140L (with FLYLIM commanding) to achieve significantly better wavelength calibration, resolution and signal to noise. Together with already extant ground-based data on the quasar and its hydrogen Lyman Alpha absorbers, these proposed GHRS data will be used to confirm that the edge is indeed produced by HeII 304 Angstrom\ absorption, to measure the Stromgren region of ionized helium near the quasar and compare with the corresponding void in the LyAlpha forest, to search for possible emission well beyond the edge corresponding to another void in the LyAlpha forest, and to set combined constraints on quasar luminosity history and IGM density. We will waive all proprietary rights to the data. ------------------------------------------------------------------------------------ 5945( 13) - 11/07/95 22:20 - [ 2] Observations Description ------------------------ Description of the observations. QSO Q0302-003 will be observed with the now available GHRS side 1 and the G140L grating; wavelength coverage of 1235-1520 Angstrom\ is chosen to include the spectral region of interest, while avoiding geocoronal LyAlpha (see discussion below on FLYLIM). The large science aperture (LSA) will be used to maximize throughput, and permit FOS-assisted target acquisition (TA). The spectral region of most interest occurs near 1303 Angstrom\ (He II 304 Angstrom\ redshifted by z=3.286), which is nearly coincident with OI airglow at 1304 Angstrom; thus the observations require ``dark time" when OI 1304 Angstrom\ emission may be neglected. The low flux of Q0302 in this region (~ 10^-16 erg/s/cm^2/Angstrom) necessitates the use of special FLYLIM commanding (page 97 of the GHRS Handbook), in order to reduce the background count rate to an acceptable level. A significant fraction of the average background noise (0.007-0.008 cts/s/diode) arises in short Cerenkov radiation bursts (induced on the digicon faceplate by cosmic rays); such burst events can be rejected using sufficiently short ``STEP-TIME" integrations. With FLYLIM commanding a 0.2s STEP -TIME (the default anyway) integration is performed. At the faint flux of Q0302, this short STEP-TIME will yield <1 count summed over the entire 500 diodes of GHRS. FLYLIM checks each STEP-TIME integration, and if 2 or more counts are detected, that individual STEP-TIME integration is assumed to be dominated by noise and discarded (on-board the spacecraft). Real Time Justification ----------------------- Dark time is required. In order to maximize throughput and make use of FOS- assisted TA, it is necessary to use the LSA. We will choose wavelength coverage with GHRS+G140L to avoid geocoronal LyAlpha (see discussion above). However, the spectral region of most interest occurs at 1303 Angstrom\ (He II 304 Angstrom\ redshifted by z=3.286), which is unfortunately nearly coincident with contaminating airglow OI at 1304 Angstrom. Thus, the most fundamental data will need to be taken during ``dark time" when OI 1304 Angstrom\ emission is negligible. (Also note that OI may conceivably yield a count rate in excess of 1 cts/s spread over ~ 10 diodes in non-dark time with the LSA, and so we are also driven to ``dark time" in order that FLYLIM rejection does not discard all or most of the individual integrations.) The most detailed level of modeling will make use of published ground-based data for the hydrogen LyAlpha forest lines and voids (e.g., Dobrzycki & Bechtold, ApJ, 377, L69, 1991; also, Sargent, Steidel, & Boksenberg, ApJS, 69, 703, 1989), and the systemic redshift of Q0302 has recently been measured by B. Carswell (private communication) from the OIII 5007 emission. Thus, no additional supporting observations are essential. (Although not a part of this proposal, we also point out that extremely deep WFPC2 or FOC parallel imaging data of a field nearby may be acquired simultaneously with the proposed GHRS data on Q0302. Such deep parallel data should prove quite useful, for example, to one or more of the various approved parallel deep survey imaging programs.) Calibration Justification ------------------------- Real_Time_Justification Additional Comments ------------------- This is a rather unusual set of observations, with FLYLIM commanding, FOS- assisted TA into GHRS ------------------------------------------------------------------------------------ 5945( 13) - 11/07/95 22:20 - [ 3] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: OVERNIGHT Email: , ------------------------------------------------------------------------------------ 5945( 13) - 11/07/95 22:20 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 Q0302-0019 GALAXY,QSO RA=03H 04M 49.82S +/- 0.03S, J2000 V=18.4 DEC=-00D 08' 13.6" +/- 0.5", PLATE-ID=03U0 Comments: Coordinates updated from inventory GASP measurement Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1982.940 0.0 0.0 0.0 5945( 13) - 11/07/95 22:20 - [ 5] Visit: 01 Visit Requirements: BETWEEN 29-OCT-1995 AND 5-NOV-1995 On Hold Comments: Additional Comments: The first visit measures UV flux with ACCUM mode, and insures viability of FLYLIM on subsequent visits. 2nd and 3rd visits are ON HOLD, until quick look obtained at 1st visit data. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 101 Q0302-0019 FOS/BL ACQ/PEA 4.3 MIRROR SEARCH-SIZE- 1 24S ONBOARD ACQ FOR 102 K X=1,SCAN-STEP- X=0.0, SEARCH- SIZE-Y=3,SCAN- STEP-Y=1.23 ------------------------------------------------------------------------------------------------------------------------------------ 102 Q0302-0019 FOS/BL ACQ/PEA 1.0 MIRROR SEARCH-SIZE- 1 26S ONBOARD ACQ FOR 103 K X=6,SCAN-STEP- X=0.61, SEARCH- SIZE-Y=2,SCAN- STEP-Y=0.61 ------------------------------------------------------------------------------------------------------------------------------------ 103 Q0302-0019 FOS/BL ACQ/PEA 0.5 MIRROR SEARCH-SIZE- 1 27S ONBOARD ACQ FOR 111-118 K X=3,SCAN-STEP- X=0.29, SEARCH- SIZE-Y=3,SCAN- STEP-Y=0.29 Comments: FOS-assisted TA for GHRS observation. Acquire with FOS then offset to LSA of GHRS before exposure 111. ------------------------------------------------------------------------------------------------------------------------------------ 111 Q0302-0019 HRS ACCUM 2.0 G140L 1240- FLYLIM=2 STEP- 7 244.8S SEQUENCE 111-112 NON-INT 1527 PATT=5 FP- SPLIT=NO Comments: AFTER FOS-ASSISTED TA INTO LSA. ------------------------------------------------------------------------------------------------------------------------------------ 112 Q0302-0019 HRS ACCUM 2.0 G140L 1240- STEP-PATT=5, FP 2 272S 1527 -SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 113 Q0302-0019 HRS ACCUM 2.0 G140L 1240- FLYLIM=2 STEP- 7 244.8S SEQUENCE 113-114 NON-INT 1527 PATT=5 FP- SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 114 Q0302-0019 HRS ACCUM 2.0 G140L 1240- STEP-PATT=5, FP 2 272S 1527 -SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 115 Q0302-0019 HRS ACCUM 2.0 G140L 1240- STEP-PATT=5, FP 7 244.8S SEQUENCE 115-116 NON-INT 1527 -SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 116 Q0302-0019 HRS ACCUM 2.0 G140L 1240- STEP-PATT=5, FP 2 272S 1527 -SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 117 Q0302-0019 HRS ACCUM 2.0 G140L 1240- STEP-PATT=5, FP 7 244.8S SEQUENCE 117-118 NON-INT 1527 -SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 5945( 13) - 11/07/95 22:20 - [ 6] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 118 Q0302-0019 HRS ACCUM 2.0 G140L 1240- STEP-PATT=5, FP 2 272.2S 1527 -SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 5945( 13) - 11/07/95 22:20 - [ 7] Visit: 02 Visit Requirements: BETWEEN 02-DEC-1995 AND 17-DEC-1995 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 ------------------------------------------------------------------------------------------------------------------------------------ 201 Q0302-0019 FOS/BL ACQ/PEA 4.3 MIRROR SEARCH-SIZE- 1 24S ONBOARD ACQ FOR 202 K X=1,SCAN-STEP- X=0.0, SEARCH- SIZE-Y=3,SCAN- STEP-Y=1.23 ------------------------------------------------------------------------------------------------------------------------------------ 202 Q0302-0019 FOS/BL ACQ/PEA 1.0 MIRROR SEARCH-SIZE- 1 26S ONBOARD ACQ FOR 203 K X=6,SCAN-STEP- X=0.61, SEARCH- SIZE-Y=2,SCAN- STEP-Y=0.61 ------------------------------------------------------------------------------------------------------------------------------------ 203 Q0302-0019 FOS/BL ACQ/PEA 0.5 MIRROR SEARCH-SIZE- 1 47S ONBOARD ACQ FOR 211-230 K X=3,SCAN-STEP- X=0.29, SEARCH- SIZE-Y=3,SCAN- STEP-Y=0.29 Comments: FOS-ASSISTED TA FOR GHRS OBSERVATION, THEN OFFSET TO LSA OF GHRS BEFORE EXPOSURE 211 ------------------------------------------------------------------------------------------------------------------------------------ 211 Q0302-0019 HRS ACCUM 2.0 G140L 1240- STEP-PATT=5, FP 2 217.6S SEQUENCE 211-212 NON-INT 1527 -SPLIT=NO Comments: AFTER FOS-ASSISTED TA INTO LSA. ------------------------------------------------------------------------------------------------------------------------------------ 212 Q0302-0019 HRS ACCUM 2.0 G140L 1240- FLYLIM=2, STEP- 8 244.8S 1527 PATT=5, FP- SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 214 Q0302-0019 HRS ACCUM 2.0 G140L 1240- STEP-PATT=5, FP 2 217.6S SEQUENCE 214-215 NON-INT 1527 -SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 215 Q0302-0019 HRS ACCUM 2.0 G140L 1240- FLYLIM=2, STEP- 8 244.8S 1527 PATT=5, FP- SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 217 Q0302-0019 HRS ACCUM 2.0 G140L 1240- STEP-PATT=5, FP 2 217.6S SEQUENCE 217-218 NON-INT 1527 -SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 218 Q0302-0019 HRS ACCUM 2.0 G140L 1240- FLYLIM=2, STEP- 8 244.8S 1527 PATT=5, FP- SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 220 Q0302-0019 HRS ACCUM 2.0 G140L 1240- STEP-PATT=5, FP 2 217.6S SEQUENCE 220-221 NON-INT 1527 -SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 5945( 13) - 11/07/95 22:20 - [ 8] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 221 Q0302-0019 HRS ACCUM 2.0 G140L 1240- FLYLIM=2, STEP- 8 244.8S 1527 PATT=5, FP- SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 223 Q0302-0019 HRS ACCUM 2.0 G140L 1240- STEP-PATT=5, FP 2 217.6S SEQUENCE 223-224 NON-INT 1527 -SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 224 Q0302-0019 HRS ACCUM 2.0 G140L 1240- FLYLIM=2, STEP- 8 244.8S 1527 PATT=5, FP- SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 226 Q0302-0019 HRS ACCUM 2.0 G140L 1240- STEP-PATT=5, FP 2 217.6S SEQUENCE 226-227 NON-INT 1527 -SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 227 Q0302-0019 HRS ACCUM 2.0 G140L 1240- FLYLIM=2, STEP- 8 244.8S 1527 PATT=5, FP- SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 229 Q0302-0019 HRS ACCUM 2.0 G140L 1240- STEP-PATT=5, FP 2 217.6S SEQUENCE 229-230 NON-INT 1527 -SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 230 Q0302-0019 HRS ACCUM 2.0 G140L 1240- FLYLIM=2, STEP- 8 244.8S 1527 PATT=5, FP- SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 5945( 13) - 11/07/95 22:20 - [ 9] Visit: 03 Visit Requirements: SAME ORIENT AS 02 AFTER 02 BY 4D BETWEEN 02-DEC-1995 AND 17-DEC-1995 On Hold Comments: Will use Reuse Target Offset from Visit 2. Use same Guide Stars as Visit 2. 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 ------------------------------------------------------------------------------------------------------------------------------------ 303 Q0302-0019 FOS/BL ACQ/PEA 0.5 MIRROR SEARCH-SIZE- 1 27S ONBOARD ACQ FOR 310-330 SEQ 303-310 NON-INT K X=3,SCAN-STEP- X=0.29, SEARCH- SIZE-Y=3,SCAN- STEP-Y=0.29 Comments: FOS-ASSISTED TA FOR GHRS OBSERVATION, THEN OFFSET TO LSA OF GHRS BEFORE EXPOSURE 310 ------------------------------------------------------------------------------------------------------------------------------------ 310 Q0302-0019 HRS ACCUM 2.0 G140L 1240- FLYLIM=2, STEP- 6 217.6S 1527 PATT=5, FP- SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 311 Q0302-0019 HRS ACCUM 2.0 G140L 1240- STEP-PATT=5, FP 2 217.6S SEQUENCE 311-312 NON-INT 1527 -SPLIT=NO Comments: AFTER FOS-ASSISTED TA INTO LSA. ------------------------------------------------------------------------------------------------------------------------------------ 312 Q0302-0019 HRS ACCUM 2.0 G140L 1240- FLYLIM=2, STEP- 8 244.8S 1527 PATT=5, FP- SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 314 Q0302-0019 HRS ACCUM 2.0 G140L 1240- STEP-PATT=5, FP 2 217.6S SEQUENCE 314-315 NON-INT 1527 -SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 315 Q0302-0019 HRS ACCUM 2.0 G140L 1240- FLYLIM=2, STEP- 8 244.8S 1527 PATT=5, FP- SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 317 Q0302-0019 HRS ACCUM 2.0 G140L 1240- STEP-PATT=5, FP 2 217.6S SEQUENCE 317-318 NON-INT 1527 -SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 318 Q0302-0019 HRS ACCUM 2.0 G140L 1240- FLYLIM=2, STEP- 8 244.8S 1527 PATT=5, FP- SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 320 Q0302-0019 HRS ACCUM 2.0 G140L 1240- STEP-PATT=5, FP 2 217.6S SEQUENCE 320-321 NON-INT 1527 -SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 321 Q0302-0019 HRS ACCUM 2.0 G140L 1240- FLYLIM=2, STEP- 8 244.8S 1527 PATT=5, FP- SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 323 Q0302-0019 HRS ACCUM 2.0 G140L 1240- STEP-PATT=5, FP 2 217.6S SEQUENCE 323-324 NON-INT 1527 -SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 5945( 13) - 11/07/95 22:20 - [ 10] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 324 Q0302-0019 HRS ACCUM 2.0 G140L 1240- FLYLIM=2, STEP- 8 244.8S 1527 PATT=5, FP- SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 326 Q0302-0019 HRS ACCUM 2.0 G140L 1240- STEP-PATT=5, FP 2 217.6S SEQUENCE 326-327 NON-INT 1527 -SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 327 Q0302-0019 HRS ACCUM 2.0 G140L 1240- FLYLIM=2, STEP- 8 244.8S 1527 PATT=5, FP- SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 329 Q0302-0019 HRS ACCUM 2.0 G140L 1240- STEP-PATT=5, FP 2 217.6S SEQUENCE 329-330 NON-INT 1527 -SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 330 Q0302-0019 HRS ACCUM 2.0 G140L 1240- FLYLIM=2, STEP- 8 244.8S 1527 PATT=5, FP- SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ 5945( 13) - 11/07/95 22:20 - [ 11] Summary Form for Proposal 5945 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/BL HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/PEAK ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SEARCH-SIZE-X=1 SCAN-STEP-X=0.0 SEARCH-SIZE-Y=3 SCAN-STEP-Y=1.23 SCAN-STEP-Y=0.61 SCAN-STEP-Y=0.29 FLYLIM=2 STEP-PATT=5 FP-SPLIT=NO STEP-PATT=5 SEARCH-SIZE-Y=2 SCAN-STEP-X=0.29 FLYLIM=2 SEARCH-SIZE-X=3 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Quasars ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 29-OCT-1995 AND 5-NOV-1995 ONBOARD ACQ FOR 102 ONBOARD ACQ FOR 103 ONBOARD ACQ FOR 111-118 SEQUENCE 111-112 NON-INT SEQUENCE 113-114 NON-INT SEQUENCE 115-116 NON-INT SEQUENCE 117-118 NON-INT BETWEEN 02-DEC-1995 AND 17-DEC-1995 ONBOARD ACQ FOR 202 ONBOARD ACQ FOR 203 ONBOARD ACQ FOR 211-230 SEQUENCE 211-212 NON-INT SEQUENCE 214-215 NON-INT SEQUENCE 217-218 NON-INT SEQUENCE 220-221 NON-INT SEQUENCE 223-224 NON-INT SEQUENCE 226-227 NON-INT SEQUENCE 229-230 NON-INT SAME ORIENT AS 02 AFTER 02 BY 4D BETWEEN 02-DEC-1995 AND 17-DEC-1995 ONBOARD ACQ FOR 310-330 SEQ 303-310 NON-INT SEQUENCE 311-312 NON-INT SEQUENCE 314-315 NON-INT SEQUENCE 317-318 NON-INT SEQUENCE 320-321 NON-INT SEQUENCE 323-324 NON-INT SEQUENCE 326-327 NON-INT SEQUENCE 329-330 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G140L ------------------------------------------------------------------------------------------------------------------------------------ Target Names Q0302-0019 ------------------------------------------------------------------------------------------------------------------------------------