8182( 3) - 05/24/99 10:50 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 8182 Version: 3 Check-in Date: 18-Feb-1999 17:30:24 1.Proposal Title: The Extent of Metal Transport in the Low Redshift Intergalactic Medium ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 8 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: John Stocke University of Colorado CoI: Dr. J. Michael Shull University of Colorado, Boulder N CoI: Dr. Mark Giroux University of Colorado, Boulder N ------------------------------------------------------------------------------------ 5. Abstract We propose to detect or at least place strong upper limits on the abundance of C IV in 7 strong (280-740 mAngstrom\ equivalent width) low-redshift LyAlpha absorption systems along the line of sight to the bright quasar H1821+643. This quasar lies in an extensively surveyed field, so that all LyAlpha absorbers are known to be within 10^2-10^3 kpc of a neighboring luminous galaxy. We will be sensitive to C IV absorption at the 15-30 mAngstrom\ level, well below the average C IV equivalent width associated with low-redshift LyAlpha absorbers of this strength, as inferred by line- stacking techniques using FOS data. The C IV measurements will begin to map the extent of the metals associated with galaxies or with the large-scale environment in which they form. Measurements of higher Lyman series lines scheduled for FUSE or already available will constrain the H I column density and hence the metallicity. As a result, initial studies of the metallicity gradient of the intergalactic medium (IGM) at large distances from luminous galaxies will be possible. Such studies are possible only at the lowest redshifts, where we know the locations of the LyAlpha clouds from HST spectroscopy and the galaxies from ground- based redshift surveys. ------------------------------------------------------------------------------------ 8182( 3) - 05/24/99 10:50 - [ 2] Observations Description ------------------------ We plan four exposures totalling 457 minutes with STIS: a 58 minute exposure using the G140M grating at prime center 1586 Angstrom, and three exposures of 175, 114, and 110 minutes using three settings of the G230M grating (prime centers 1769 Angstrom , 1851 Angstrom , and secondary center 1884 Angstrom ). Using the STIS Exposure Time Estimator, we estimate this will provide a S/N >= 20 for all of the absorption lines in Table 1, and thus rest equivalent widths of 15-30 mAngstrom\ with the 0.06 and 0.09 Angstrom\ resolutions of the G140M and G230M respectively. The total request including instrument overhead and single step target acquisition is 5 orbits. A single exposure with the E230M would require ~ 10 orbits to reach similar equivalent width limits and would still not cover all systems in Table 1. The proposed observations will cover the expected wavelengths of both lines in the C IV doublet. The LyAlpha emission and associated LyAlpha absorption (z = 0.297) in H1821+643 will also be observed at the G140M setting. Real Time Justification ----------------------- None, aside from CVZ to minimize number of orbits required. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Paper Products: YES Media: ELECTRONIC Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 8182( 3) - 05/24/99 10:50 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 H1821+643 GALAXY, QSO RA=18H 21M 57.12S +/- 0.01S, J2000.0 Z=0.297 V = 13.61+/-0.4 DEC=64D 20' 36.7" +/- 0.2", F(1500)=6.5+/-0.5e-14 PLATE-ID=00T0 8182( 3) - 05/24/99 10:50 - [ 4] Visit: 01 Visit Priority: Visit Requirements: CVZ 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 H1821+643 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 0.6 S ONBOARD ACQuisition FOR CD P 2-5 ------------------------------------------------------------------------------------------------------------------------------------ 2 H1821+643 STIS/F ACCUM 52X0.2 G140M 1567 1 54 M NO SPLIT UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 3 H1821+643 STIS/N ACCUM 52X0.2 G230M 1769 2 81 M NO SPLIT UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 4 H1821+643 STIS/N ACCUM 52X0.2 G230M 1851 1 107.49 NO SPLIT UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 5 H1821+643 STIS/N ACCUM 52X0.2 G230M 1884 1 103.581 NO SPLIT UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8182( 3) - 05/24/99 10:50 - [ 5] Summary Form for Proposal 8182 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F28X50LP 52X0.2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD STIS/FUV-MAMA STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=POINT ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CVZ ONBOARD ACQuisition FOR 2-5 NO SPLIT ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G140M G230M ------------------------------------------------------------------------------------------------------------------------------------ Target Names H1821+643 ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 1567 1769 1851 1884 ------------------------------------------------------------------------------------------------------------------------------------