6410( 9) - 05/25/96 19:10 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6410 Version: 9 Check-in Date: 25-May-1996 19:07:25 1.Proposal Title: Low Redshift Lyman Alpha Forest Clouds: Their Kinematics and Their Relation to Galaxies ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle QSO ABSORPTION LINES GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Michael Rauch California Institute of Technology CoI: Ray Weymann Carnegie Observatories N CoI: Simon Morris Dominion Astrophysical Observatory N CoI: Guenther Hasinger Astrophys. Institut Potsdam N CoI: Lance Miller Royal Observatory Edinburgh N CoI: Mike Read Royal Observatory Edinburgh N ------------------------------------------------------------------------------------ 6. Abstract We wish to study the physical nature of low redshift Lyman Alpha absorption systems and their relation to galaxies. The recent ROSAT discovery of the optically-bright x -ray selected QSO RX J1230.8+0115 (z_em = 0.117, m_v = 14.7) has fortuitiously provided us with a bright quasar only 0.9 degrees away from 3C273 (the brightest QSO in the sky). We propose to obtain high dispersion spectroscopy of RX J1230.8+0115 with the GHRS/G160M,G140L gratings in order to investigate the presence and the kinematics of common absorption features in both QSO spectra, on scales between 211 h_75^-1 kpc and 4.9 h_75^-1 Mpc, probing down to column densities of 10^12 cm^-2. Recent Cy4 results suggest Ly Alpha length scales of ~ 1 h_75^-1 Mpc for the higher column density systems. Measurements of velocity and column density in both lines-of -sight, along with redshifts of nearby galaxies will help to discriminate between models of galactic absorption and to map the distribution of Hydrogen gas in the local universe. This project is unique in two aspects: we are observing two of the brightest QSOs on the sky, along lines-of-sight running through the outskirts of the Virgo cluster, and, the line-of- sight to and the galaxy field around 3C273 has been studied in great detail during the past few years. Information available on the low redshift absorbers towards 3C273 includes unique echelle UV spectroscopy, a deep 21 cm map, a redshift survey of nearby galaxies, and a 54'*54' deep mosaic of the field. Combining this information with a new line-of-sight which can also be probed to very low column density, we will be able to shed light on the question of whether the low redshift Lyman Alpha forest is related to galaxies or represents a truly intergalactic phenomenon. ------------------------------------------------------------------------------------ 6410( 9) - 05/25/96 19:10 - [ 2] Observations Description ------------------------ We propose to observe the x-ray selected QSO RX J1230.8+0115 (z_em = 0.117, m_v = 14.7), a companion to 3C273 only 0.9degreespoint away, to study absorption features common to both lines-of-sight, and their relation to galaxies. Our proposal has two objectives: o (A) study the three lowest redshift clouds (for which we have obtained detailed information along the 3C273 line-of-sight) towards QSO RX J1230.8+0115 at high resolution with the GHRS and the G160M grating. As a result we will obtain very accurate (a few km/s) velocities, column densities, and line profiles. The grating will be set such as to cover about 1217-1253 A. medskip o (B) study the whole line of sight towards QSO RX J1230.8+0115 at intermediate resolution with GHRS and the G140L grating. This will provide us with statistical estimates of the coherence length/spatial correlation function of the low redshift LyAlpha clouds on scales up to several Mpc. medskip RX J1230.8+0115 has optical colors which are very similar to 3C273 and a V magnitude two magnitudes fainter than 3C273. The flux at 1220 Angstrom in 3C273 is 2.1 * 10^-13, from which we estimate the corresponding flux in its companion to be ~ 3.3* 10^-14. From the GHRS handbook we estimate, taking into account the dark count rate, that 9.8 hours or 15 orbits will be required to obtain the same S/N as for the 3C273 observations. (We prefer G160M (side 2) to G140M (side 1) because of its larger spectral coverage, cleaner flat field, and because the 3C273 observations were obtained with G160M.) Similarly, for the G140L observations, we estimate that 2.2 hours, or 4 orbits will be required. Since the G160M data involve side 2 and G140L involves side 1, an overhead of about 40 minutes is required to switch between the two. We are advised that this operational warmup period may be shortened, and that in any case a large fraction of this warmup can occur during earth occultation; we have therefore allowed 10 additional minutes to allow for the side 1/side 2 switch. medskip Both observations aim at reaching the same signal-to-noise as obtained earlier for 3C273, to make the data directly comparable. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6410( 9) - 05/25/96 19:10 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 QSO- GALAXY,QSO,LYMAN ALPHA RA=12H 30M 50.04S +/- J2000 Z = V = 14.7+/-0.4 123050+01152 CLOUD, 0.3",DEC=01D 15' 21.7" +/- 0.117 F(1220)=3.3e-14 2 0.3",PLATE-ID=00BB Comments: Could not retrieve the GSC plate to check with finding chart (not available at STScI ?). Assume, however, that our object is identical to GSC 289-430, which is within 2.4 arcsecs of our nominal position. 6410( 9) - 05/25/96 19:10 - [ 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 QSO-123050+ HRS ACQ 2.0 MIRROR-N2 1 54. S ONBOARD ACQ FOR 20-100 011522 ------------------------------------------------------------------------------------------------------------------------------------ 20 WAVE HRS ACCUM SC2 G160M 1217.5- 1 54.4 S 1253.5 ------------------------------------------------------------------------------------------------------------------------------------ 30 QSO-123050+ HRS ACCUM 2.0 G160M 1217.5- FP-SPLIT=STD 3 1958.4 011522 1253.5 ------------------------------------------------------------------------------------------------------------------------------------ 50 WAVE HRS ACCUM SC2 G160M 1217.5- 1 54.4 S 1253.5 ------------------------------------------------------------------------------------------------------------------------------------ 60 QSO-123050+ HRS ACCUM 2.0 G160M 1217.5- FP-SPLIT=STD 3 1958.4 011522 1253.5 ------------------------------------------------------------------------------------------------------------------------------------ 70 WAVE HRS ACCUM SC2 G140L 1175.-1 1 54.4 S 452. ------------------------------------------------------------------------------------------------------------------------------------ 80 QSO-123050+ HRS ACCUM 2.0 G140L 1175.-1 FP-SPLIT=STD 3 1740.8 011522 452. ------------------------------------------------------------------------------------------------------------------------------------ 90 WAVE HRS ACCUM SC2 G140L 1175.-1 1 54.4 S 452. ------------------------------------------------------------------------------------------------------------------------------------ 100 QSO-123050+ HRS ACCUM 2.0 G140L 1175.-1 FP-SPLIT=STD 3 1740.8 011522 452. ------------------------------------------------------------------------------------------------------------------------------------ 6410( 9) - 05/25/96 19:10 - [ 5] Visit: 02 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 QSO-123050+ HRS ACQ 2.0 MIRROR-N2 1 54. S ONBOARD ACQ FOR 20-120 011522 ------------------------------------------------------------------------------------------------------------------------------------ 20 WAVE HRS ACCUM SC2 G160M 1217.5- 1 54.4 S 1253.5 ------------------------------------------------------------------------------------------------------------------------------------ 30 QSO-123050+ HRS ACCUM 2.0 G160M 1217.5- FP-SPLIT=STD 3 1849.6 011522 1253.5 ------------------------------------------------------------------------------------------------------------------------------------ 50 WAVE HRS ACCUM SC2 G160M 1217.5- 1 54.4 S 1253.5 ------------------------------------------------------------------------------------------------------------------------------------ 60 QSO-123050+ HRS ACCUM 2.0 G160M 1217.5- FP-SPLIT=STD 3 1849.6 011522 1253.5 ------------------------------------------------------------------------------------------------------------------------------------ 70 WAVE HRS ACCUM SC2 G160M 1217.5- 1 54.4 S 1253.5 ------------------------------------------------------------------------------------------------------------------------------------ 80 QSO-123050+ HRS ACCUM 2.0 G160M 1217.5- FP-SPLIT=STD 3 1849.6 011522 1253.5 ------------------------------------------------------------------------------------------------------------------------------------ 90 WAVE HRS ACCUM SC2 G160M 1217.5- 1 54.4 S 1253.5 ------------------------------------------------------------------------------------------------------------------------------------ 100 QSO-123050+ HRS ACCUM 2.0 G160M 1217.5- FP-SPLIT=STD 3 1849.6 011522 1253.5 ------------------------------------------------------------------------------------------------------------------------------------ 110 WAVE HRS ACCUM SC2 G160M 1217.5- 1 54.4 S 1253.5 ------------------------------------------------------------------------------------------------------------------------------------ 120 QSO-123050+ HRS ACCUM 2.0 G160M 1217.5- FP-SPLIT=STD 1 2502.4 011522 1253.5 ------------------------------------------------------------------------------------------------------------------------------------ 6410( 9) - 05/25/96 19:10 - [ 6] Summary Form for Proposal 6410 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters FP-SPLIT=STD ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category QSO ABSORPTION LINES ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 20-100 ONBOARD ACQ FOR 20-120 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N2 G160M G140L ------------------------------------------------------------------------------------------------------------------------------------ Target Names QSO-123050+011522 WAVE ------------------------------------------------------------------------------------------------------------------------------------