8127( 6) - 02/24/00 16:24 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 8127 Version: 6 Check-in Date: 24-Feb-2000 16:23:43 1.Proposal Title: The Homogeneity of Damped LyAlpha Systems (and Variability in BAL Systems) ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 8 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Eric Monier Ohio State University CoI: Prof. David Turnshek University of Pittsburgh N CoI: Dr. Sandhya Rao University of Pittsburgh N CoI: Dr. Brian Espey Space Telescope Science Institute N ------------------------------------------------------------------------------------ 5. Abstract We propose an investigation of the damped LyAlpha line at z_abs = 1.6595 in the gravitationally lensed Cloverleaf QSO, seen in the composite FOS-G270H spectrum of the Cloverleaf. The metal lines of the system have been previously studied along the individual lines of sight using FOS G400H and G570H spectra, which indicate that there are variations in the columns of gas observed among the four sight-lines over scales of ~ 4h^-1 kpc (H_0 = 100h km s^-1 Mpc ^-1, q_0 = 0.5). We propose STIS observations that will enable us to measure the individual ionH1 column densities in the LyAlpha line along all four sight-lines, the values of which will provide an indication of the size-scale and homogeneity of the structures that give rise to damped LyAlpha systems, important constraints on models for these systems. On these scales, does a damped system resemble a large homogeneous structure, or are there significant column density variations due to inhomogeneities or individual giant hydrogen clouds? The results of the proposed observations will allow us to consider this question. As an added benefit, the STIS observations will at the same time allow us to reobserve the individual Broad Absorption Line spectra of the Cloverleaf components. This information can be compared with earlier HST- FOS G400H and G570H spectra to search for and analyze changes in strength which are known to occur in some BAL systems. Such measurements provide important constraints on BAL outflows. ------------------------------------------------------------------------------------ 8127( 6) - 02/24/00 16:24 - [ 2] Observations Description ------------------------ We will obtain 6 orbits of data using the STIS CCD mode and the G430L grating with the 52*0.2 arcsecond slit positioned across Components A and C, which are separated by 0.73 arcseconds and can be placed in the slit simultaneously with an ORIENT constraint on the roll angle. In addition, we will obtain 10 orbits of data with the same instrument and grating but with the slit positioned this time across Components B and D, which are separated by 0.89 arcseconds. This also requires a roll angle constraint. The A/C visit will include all 6 orbits, but the B/C observation will be split into two visits of 5 orbits each. Acquisition of the targets will be achieved by first acquiring a faint (V=18.5 or so) star 18.5" away from the Cloverleaf, and the offsetting with a Small Angle Maneuver (SAM) to either Component A or B. The astrometry for this offset has been obtained from WFPC2 observations in which both the Cloverleaf and the star are present on the PC. The ORIENTs to position A and C (or B and D) in the slit simultaneously have also been calculated using WFPC2 observations of the Cloverleaf (see Turnshek et al. 1997, ApJ 485, 100). A peak-up will be performed to center the lensed component in the slit. In the region of the DLA line (3250 Ang) the spectra obtained will be read-noise-limited. It is therefore desirable to perform integrations that are as long as possible, but there is also the need to account for cosmic ray removal in the final spectra. The orbits are split in half, using CR-SPLIT=2. Dithering is performed along the slit for successive orbits to remove hot pixels in the final spectra. The A/C visit will have an integration time of 238 minutes after the various acquisition, reacquistion, and overhead times have been accounted for. The second (B/D) observation will be split into two visits of 5 orbits each, for a total integration time of 390 minutes. Estimating a value for the flux of Components A and C of F_Lambda = 2.7 * 10^-17 ergs s^-1 cm^-2 A^-1 at 3240Angstrom\ (determined from the composite G270H spectrum scaled by a factor determined from the individual G400H spectra), we used the STIS Spectroscopic Exposure Time simulator to calculate that a S/N ratio of 13.3 per resolution element can be obtained in 286 minutes. Components B and D are slightly fainter (F_Lambda = 2.0 * 10^-17 and 2.5 * 10^-17 ergs s^-1 cm^-2 AA^-1 at 3240Angstrom, respectively). With the additional integration time we can obtain a S/N ratio per resolution element of 12.5 for Component B and 14.9 for Component D. The S/N achieved in the vicinity of the damped LyAlpha line will allow us to discern column density differences down to at least a factor of 3 (see Figure 6, which shows a simulation of what is expected for various ionH1 column densities at S/N ~ 10). In the optical part of the spectrum, where the major BALs exist, extremely high signal-to-noise will be achieved. The analysis of the damped LyAlpha line will require evaluation of the influence of the BALs in the region, which will be performed with the aid of careful divisions of the component spectra. The LyAlpha line will then be fit with a Voigt profile to estimate the column density in each of the components. Variations among the BALs along the four lines of sight will be evaluated through divisions of the spectra. Real Time Justification ----------------------- None. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 8127( 6) - 02/24/00 16:24 - [ 3] Data Distribution Paper Products: NO Media: ELECTRONIC Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 8127( 6) - 02/24/00 16:24 - [ 4] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 H1413-OFFSET STAR RA= 14H 15M 47.42S +/- 0.1S, 2000 V = 19.0 DEC= 11D 29' 51.03" +/- 1.5", PLATE-ID = 01US Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1982.30 0 0 0 2 H1413+1143-A GALAXY, QSO, RA-OFF= -1.1779S +/- 0.0004S, 2000 Z=2.54 V = 18.2 Gravitational Lens, DEC-OFF= -7.600" +/- 0.014", Lyman Alpha Cloud FROM 1 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1995.12 0 0 0 3 H1413+1143-B GALAXY, QSO, RA-OFF = -1.1274S +/- 0.0004S, 2000 Z=2.54 V = 18.4 Gravitational Lens, DEC-OFF = -7.433" +/- 0.016", B-V = 0.5 Lyman Alpha Cloud FROM 1 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1995.12 0 0 0 8127( 6) - 02/24/00 16:24 - [ 5] Visit: 01 Visit Priority: Visit Requirements: ORIENT 7.57946D TO 13.57946D ORIENT 187.57946D TO 193.57946D SCHEDulability 100% GROUP 1-3 WITHIN 7D 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 H1413-OFFSE STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 20 S T CD P ------------------------------------------------------------------------------------------------------------------------------------ 11 H1413-OFFSE STIS/C ACQ/PEA 52X0.1 MIRROR 1 15 S T CD K ------------------------------------------------------------------------------------------------------------------------------------ 12 H1413+1143- STIS/C ACCUM 52X0.2 G430L 4300 CR-SPLIT=NO ,BINAXIS2=2 1 1400 S EXPAND A CD ------------------------------------------------------------------------------------------------------------------------------------ 13 H1413+1143- STIS/C ACCUM 52X0.2 G430L 4300 CR-SPLIT=2 ,PATTERN=ALONG-SLIT , 1 2564 S EXPAND A CD NUM-POS=5 ,STEP-SIZE=0.5 , BINAXIS2=2 ------------------------------------------------------------------------------------------------------------------------------------ 8127( 6) - 02/24/00 16:24 - [ 6] Visit: 02 Visit Priority: Visit Requirements: ORIENT 17.83078D TO 23.83078D ORIENT 197.83078D TO 203.83078D SCHEDulability 100% 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 ------------------------------------------------------------------------------------------------------------------------------------ 20 H1413-OFFSE STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 20 S T CD P ------------------------------------------------------------------------------------------------------------------------------------ 21 H1413-OFFSE STIS/C ACQ/PEA 52X0.1 MIRROR 1 15 S T CD K ------------------------------------------------------------------------------------------------------------------------------------ 22 H1413+1143- STIS/C ACCUM 52X0.2 G430L 4300 CR-SPLIT=NO ,BINAXIS2=2 1 1400 S EXPAND B CD ------------------------------------------------------------------------------------------------------------------------------------ 23 H1413+1143- STIS/C ACCUM 52X0.2 G430L 4300 CR-SPLIT=2 ,PATTERN=ALONG-SLIT , 1 2564 S EXPAND B CD NUM-POS=4 ,STEP-SIZE=0.5 , BINAXIS2=2 ------------------------------------------------------------------------------------------------------------------------------------ 8127( 6) - 02/24/00 16:24 - [ 7] Visit: 03 Visit Priority: Visit Requirements: ORIENT 17.83078D TO 23.83078D ORIENT 197.83078D TO 203.83078D SCHEDulability 100% 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 ------------------------------------------------------------------------------------------------------------------------------------ 30 H1413-OFFSE STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 20 S T CD P ------------------------------------------------------------------------------------------------------------------------------------ 31 H1413-OFFSE STIS/C ACQ/PEA 52X0.1 MIRROR 1 15 S T CD K ------------------------------------------------------------------------------------------------------------------------------------ 32 H1413+1143- STIS/C ACCUM 52X0.2 G430L 4300 CR-SPLIT=NO ,BINAXIS2=2 1 1400 S EXPAND B CD ------------------------------------------------------------------------------------------------------------------------------------ 33 H1413+1143- STIS/C ACCUM 52X0.2 G430L 4300 CR-SPLIT=2 ,PATTERN=ALONG-SLIT , 1 2564 S EXPAND B CD NUM-POS=4 ,STEP-SIZE=0.5 , BINAXIS2=2 ------------------------------------------------------------------------------------------------------------------------------------ 8127( 6) - 02/24/00 16:24 - [ 8] Summary Form for Proposal 8127 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F28X50LP 52X0.1 52X0.2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAK ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=POINT BINAXIS2=2 STEP-SIZE=0.5 CR-SPLIT=NO NUM-POS=4 PATTERN=ALONG-SLIT ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 7.57946D TO 13.57946D ORIENT 187.57946D TO 193.57946D SCHEDulability 100% GROUP 1-3 WITHIN 7D EXPAND ORIENT 17.83078D TO 23.83078D ORIENT 197.83078D TO 203.83078D SCHEDulability 100% ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G430L ------------------------------------------------------------------------------------------------------------------------------------ Target Names H1413-OFFSET H1413+1143-A H1413+1143-B ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 4300 ------------------------------------------------------------------------------------------------------------------------------------