Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 5715 Report Date: 18-Jul-95:17:53 Version: ********** Check-in Date: ********** 1.Proposal Title: PROBING THE VOIDS - II - CARRYOVER ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID QUASARS & AGN GO/CAR 3584 Sub Category QUASAR ABSORPTION ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone John T. Stocke UNIVERSITY OF COLORADO USA 303-492-2695 ------------------------------------------------------------------------------------ 7. Abstract We propose to obtain medium-resolution GHRS (G160M) exposures of 4 AGNs behind two well-studied galaxy voids (Coma and Perseus) to search for H I (Lyman-alpha) absorption systems with equivalent width greater than 50 mA. A detection of HI absorbers within galaxy voids will help resolve a basic question of whether the 3C- 273 H I absorbers are survivors from the high redshift population or are recently formed (ejected\?) due to starburst activity in nearby galaxies. These observations will also increase our knowledge of the clustering properties of the surprising low- z H I systems. Based on the line density seen by GHRS toward 3C-273 (one Ly-alpha system per 4000 km/s of pathlength) we expect to observe at least 4 absorbers (EW greater than 50 mA) within 16,000 km/s of pathlength through the two galaxy voids. We may actually see more absorbers if the H I clouds are more frequent within voids. Theoretical scenarios for the production and confinement of intergalactic Ly-alpha clouds predict that this might be the case. Only HST, with its UV sensitivity, can find out. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 15.10 par: 0 10. Num targs pri: 2 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: HRS ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 5715 PI: John T. Stocke Proposal Title: PROBING THE VOIDS - II - CARRYOVER ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Pi John T. Stocke UNIVERSITY OF COLORADO, CASA USA John M. Shull UNIVERSITY OF COLORADO, CASA USA ------------------------------------------------------------------------------------ 3. Description of proposed observations. GHRS/G160M spectra of 4 UV bright AGN behind nearby galaxy voids will be obtained. We intend to obtain S/N = 30 spectra at a reso- lution of about 50 km/s in order to obtain a limiting equivalent width of about 30-50mA. The exposures are timed in about 30min blocks and uses FP-SPLIT to obtain 4 separate spectra of about 8 min. duration. Seven or 16 of these spectra are then accumulated for the final total exposure times of 3.8 or 8.7 hours. The smaller numbers refer to Mark 421 and 335, the longer exposure times to Mark 501 and I Zw I. CENSOR is invoked to reduce noise for these low count rate sources. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. The HST and GHRS are required to search for low-z, low column density Ly-alphas towards AGN background to voids. Only HST/GHRS has the required sensitivity and resolution to detect 50 mA equivalent width Ly-alphas. The redshift range of nearby voids ( z < 0.03) places these lines in the UV. ------------------------------------------------------------------------------------ 9. Description of previous HST work. P2717 ("Probing the Voids I")--Stocke and Shull (6.7 hrs with FOS) is related to this project but considers different, fainter targets, was to detect stronger metal absorption systems and uses the FOS. The FOS spectra for two objects are in -hand. No voids absorptions have been discovered but we have discovered multiple, intrinsic systems in PG 1351+64. Analysis is progressing and a paper is in preparation, which will be submitted this Spring. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). CASA here at the University of CO operates workstations for spectral and imaging data reduction running under UNIX. For this HST project we will employ a SUN/SPARC2station connected and serviced by a SUN4/470. This SUN 4 node supplies disk space and reduction packages including IRAF and STDAS. While these facilities are currently being used for ground-based data reduction, funds are requested in this proposal for a new hard disk which will allow HST data to be reduced without severely interfering with this on-going effort. ------------------------------------------------------------------------------------ 11. Address Information Name: JOHN T. STOCKE Category: PI Institution: UNIVERSITY OF COLORADO Address: CENTER FOR ASTROPHYSICS AND SPACE ASTRONOMY (CASA) CAMPUS BOX 389 City: BOULDER State: CO Zip Code: 80309 Country: USA Telephone: 303-492-1521 Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 5715 [ 3] ------------------------------------------------------------------------------------------------------------------------------------ 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 MARK421 E, 316 PLATE-ID=01PU, 2000 Z=0.031 1 V=13.51 RA=11H 04M 27.407S +/- 2 B-V=0.56 0.03S, DEC=+38D 12' 30.76" +/-0.3" ------------------------------------------------------------------------------------------------------------------------------------ 4 IZwI E, 313 PLATE-ID=028Y, 2000 Z=0.061 1 V=14.03 RA=00H 53M 34.938S +/- 2 B-V=0.38 0.03S, DEC=+12D 41' 36.30" +/-0.3" ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5715 [ 4] ------------------------------------------------------------------------------------------------------------------------------------ 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 MARK421 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN 1 9.0S 1 1 ONBOARD ACQ FOR 2 CYCLE 4 ------------------------------------------------------------------------------------------------------------------------------------ 2 MARK421 HRS ACCUM 2.0 G160M 1240 FP-SPLIT=STD 8 2000S 1 1 CYCLE 4 CENSOR=YES ------------------------------------------------------------------------------------------------------------------------------------ 3 IZwI HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN 1 9.0S 1 2 ONBOARD ACQ FOR 4 CYCLE 4 ------------------------------------------------------------------------------------------------------------------------------------ 4 IZwI HRS ACCUM 2.0 G160M 1241 FP-SPLIT=STD 12 1960S 1 2 CYCLE 4 CENSOR=YES ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 5715 [ 5] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BRIGHT=RETURN FP-SPLIT=STD CENSOR=YES ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO/CAR ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 15.10 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category QUASARS & AGN ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category QUASAR ABSORPTION ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 2; CYCLE 4; ONBOARD ACQ FOR 4; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N2 G160M ------------------------------------------------------------------------------------------------------------------------------------ Target Names MARK421 IZwI ------------------------------------------------------------------------------------------------------------------------------------