8097( 4) - 11/03/99 07:16 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 8097 Version: 4 Check-in Date: 03-Nov-1999 07:15:47 1.Proposal Title: C IV High Velocity Clouds: Remnants of the Local Group? ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 8 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Ken Sembach The Johns Hopkins University CoI: Dr. Blair Savage University of Wisconsin-Madison N CoI: Dr. Todd Tripp Princeton University N ------------------------------------------------------------------------------------ 5. Abstract We have recently studied two high velocity (V_LSR <-100 km/sec) clouds (HVCs) in the direction of Mrk 509 that have unusual ionization properties. The clouds exhibit strong C IV absorption with little or no detectable low ion (C II, Si II) absorption or H I 21cm emission. Our Cycle 6 program to study the properties of the HVCs toward Mrk 509 in detail revealed that they are likely very low density, low pressure gas clouds in the Local Group (or distant Galactic halo) subject to the extragalactic ionizing background. Their ionization properties resemble those of the outer diffuse halos of damped LyAlpha absorbers and the low N(H I) metal line absorption systems seen in the spectra of high redshift quasars. These C IV-HVCs present important opportunities for relating the properties of nearby intergalactic gas (or an extended Galactic halo) to the properties of gas in higher-z systems. Here, we will obtain STIS spectra to study the ionization properties of C IV-HVCs along the PG 1116+215 sight line. We will compare their properties with those of the C IV-HVCs toward Mrk 509 to test the hypothesis that these clouds are remnants from the formation of the Local Group. The results have implications for the origin of HVCs, the processes that distribute and ionize diffuse gas in the Local Group, the extent of the Galactic halo, and the interpretation of high-z quasar absorption line systems. PKS 2155-304 was originally in this program but was taken away by the super -TAC, so no PKS 2155-304 observations will be specified in this Phase 2 submission. ------------------------------------------------------------------------------------ 8097( 4) - 11/03/99 07:16 - [ 2] Observations Description ------------------------ Our proposed STIS observations are designed to study the ionization and elemental abundances of the high velocity gas toward PG 1116+215. We will use the intermediate resolution STIS echelle gratings (E140M and E230M) to observe neutral and ionized gas species in the 1150-1735A and 2011-2819A wavelength ranges. We will obtain the observations through the 0.2"x0.06" aperture. We determined continuum fluxes using low resolution FOS/GHRS spectra. Exposure time estimates are based on these fluxes and the STIS exposure time tool output. PG1116+215 requires two visits since STIS/MAMA observations are generally no more than 5 orbits in duration. Real Time Justification ----------------------- None Calibration Justification ------------------------- None Additional Comments ------------------- None ------------------------------------------------------------------------------------ Data Distribution Paper Products: YES Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 8097( 4) - 11/03/99 07:16 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 PG1116+215 GALAXY, QSO, QUASAR RA=11H 19M 08.7S +/-0.3", J2000 Z=0.1765 V = 15.17 DEC=+21D 19' 18.2" +/-0.3" 0 F-CONT(1300)=3.0+/-0.5e-14 F-CONT(1500)=2.6+/-0.5e-14 F-CONT(2600)=1.7+/-0.5e-14 Comments: Continuum fluxes from previous GHRS G140L and FOS G230H spectra in the HST archive. Fluxes are variable. 8097( 4) - 11/03/99 07:16 - [ 4] Visit: 01 Visit Priority: Visit Requirements: On Hold Comments: Additional Comments: Visit 1 to start E140M observation. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 PG1116+215 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 3.0 S CD P Comments: Expect approx 8, 000 counts in 3x3 checkbox (S/N=88). Brightest pixel has only 4800 e-, so well below detector saturation. Target acquisition ETC used with 1x1 binning, GAIN=4 e-/ADU, CR-SPLIT=1, and QSO spectral energy distribution with V=15.2 and z=0.1765. ------------------------------------------------------------------------------------------------------------------------------------ 2 PG1116+215 STIS/C ACQ/PEA 0.2X0.0 MIRROR 1 3.0 S CD K 6 Comments: Expect approx 33, 000 counts in 3x3 checkbox for clear filter, so about 50% of that for the 0.2x0.06 slit. Need 5, 000 for a good peak-up, so this ought to work just fine. Other input parameters same as above. ------------------------------------------------------------------------------------------------------------------------------------ 3 PG1116+215 STIS/F ACCUM 0.2X0.0 E140M 1425 1 1980 S UV-MAM 6 A Comments: Far-UV MAMA exposure covers 1150-1700 A at ~10 km/s resolution. ------------------------------------------------------------------------------------------------------------------------------------ 4 PG1116+215 STIS/F ACCUM 0.2X0.0 E140M 1425 8 1330 S UV-MAM 6 A Comments: Far-UV MAMA exposure covers 1150-1700 A at ~10 km/s resolution. ------------------------------------------------------------------------------------------------------------------------------------ 8097( 4) - 11/03/99 07:16 - [ 5] Visit: 02 Visit Priority: Visit Requirements: On Hold Comments: Additional Comments: Visit 2 to finish E140M and do E230M observation. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 PG1116+215 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 3.0 S CD P Comments: Same as Visit 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 PG1116+215 STIS/C ACQ/PEA 0.2X0.0 MIRROR 1 3.0 S CD K 6 Comments: Same as Visit 1 ------------------------------------------------------------------------------------------------------------------------------------ 3 PG1116+215 STIS/F ACCUM 0.2X0.0 E140M 1425 1 1980 S UV-MAM 6 A Comments: Far-UV MAMA exposure covers 1150-1700 A at ~10 km/s resolution. ------------------------------------------------------------------------------------------------------------------------------------ 4 PG1116+215 STIS/F ACCUM 0.2X0.0 E140M 1425 4 1330 S UV-MAM 6 A Comments: Far-UV MAMA exposure covers 1150-1700 A at ~10 km/s resolution. ------------------------------------------------------------------------------------------------------------------------------------ 5 PG1116+215 STIS/N ACCUM 0.2X0.0 E230M 2415 1 1215 S UV-MAM 6 A Comments: Near-UV MAMA exposure covers 2011-2819 A at ~10 km/s resolution. Secondary tilt position covers NUV better than primary tilt positions. ------------------------------------------------------------------------------------------------------------------------------------ 6 PG1116+215 STIS/N ACCUM 0.2X0.0 E230M 2415 2 1330 S UV-MAM 6 A Comments: Near-UV MAMA exposure covers 2011-2819 A at ~10 km/s resolution. Secondary tilt position covers NUV better than primary tilt positions. ------------------------------------------------------------------------------------------------------------------------------------ 7 PG1116+215 STIS/N ACCUM 0.2X0.0 E230M 2415 1 1550 S UV-MAM 6 A Comments: Near-UV MAMA exposure covers 2011-2819 A at ~10 km/s resolution. Secondary tilt position covers NUV better than primary tilt positions. ------------------------------------------------------------------------------------------------------------------------------------ 8097( 4) - 11/03/99 07:16 - [ 6] Summary Form for Proposal 8097 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F28X50LP 0.2X0.06 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD STIS/FUV-MAMA STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAK ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=POINT ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR E140M E230M ------------------------------------------------------------------------------------------------------------------------------------ Target Names PG1116+215 ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 1425 2415 ------------------------------------------------------------------------------------------------------------------------------------