Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 5299 Report Date: 18-Jul-95:17:07 Version: ********** Check-in Date: ********** 1.Proposal Title: HIGHLY IONIZED GAS IN THE WARPED OUTER GALAXY: CYCLE 4 MEDIUM ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID INTERSTELLAR MEDIUM GO Sub Category ABSORPTION LINES ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Limin Lu UNIVERSITY OF WISCSONSIN-MAD USA ------------------------------------------------------------------------------------ 7. Abstract We propose to obtain GHRS G160M observations (FWHM=15 km/s) of the C IV 1548,1550 doublet and the N V 1238,1242 doublet absorption produced by the Milky Way disk and halo gas toward the bright quasar H1821+643. Existing GHRS observations of the N V doublet toward H1821+643 reveal the presence of a large amount of N V gas at large negative velocity (-140 km/s). This gas is probably associated with the outer warp of the Galaxy. The gas is estimated to have a Galactocentric distance of ~25 kpc, and to be ~11 kpc above the disk. The existence of a large amount of highly ionized gas in the outer halo of the Galaxy is difficult to understand. The proposed observations will allow us to supplement the existing N V data to accurately measure the N V column density, and to examine the detailed velocity structure. The N V absorption will be compared with the C IV absorption in order to understand the ionization mechanism of the outer halo gas. The comparison will also allow us to examine how the ionization level of the gas depends Galactocentric distance by using Galactic rotation as a tool to locate the gas. The study will be aided by low ion lines. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 10.00 par: 0 10. Num targs pri: 1 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: HRS ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 5299 PI: Limin Lu Proposal Title: HIGHLY IONIZED GAS IN THE WARPED OUTER GALAXY: CYCLE 4 MEDIUM ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Pi Limin Lu UNIVERSITY OF WISCSONSIN-MADISON USA Blair D. Savage UNIVERSITY OF WISCSONSIN-MADISON USA Kenneth R. Sembach MASSACHUSETTS INSTITUTE OF USA TECHNOLOGY ------------------------------------------------------------------------------------ 3. Description of proposed observations. We will make GHRS observations of the quasar H 1821+643. The G160M grating and the Large Science Aperture will be used for two setups, one centered at 1540 angstroms, and the other centered at 1250 angstroms. The former will cover the C IV 1548, 1550 and Si II 1526 resonance lines, and the latter will cover the N V 1238, 1242, S II 1250, 1253, 1259, and Si II 1260 resonance lines. All measurements will be made with two samples per diode substepping, and with standard FP-SPLIT. All S/N and exposure time estimates are based on FOS spectrum of the target. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. The proposed study requires UV capabilities. The IUE is incapable of carrying out the proposed study because of its limited spectral resolution and S/N characteristics. The FOS observations (already exist) are of too low resolution for the proposed scientific analysis. The GHRS on board the HST is the only instrument that can achieve the required high resolution, high S/N observations. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. No request for special scheduling or real-time observations. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. We request a Pt lamp exposure be obtained immediately prior to each of the two science observations. This is necessary because the proposed scientific analysis requires comparison of absorption velocities between different ion species. Thus accurate wavelength calibration is crucial. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. No additional comments or requests ------------------------------------------------------------------------------------ 9. Description of previous HST work. The proposers are involved in the following HST programs: GTO1162-Interstellar Abundances Toward Extreme Depletion Sight Lines (Savage and Cardelli) GTO1165,3960,4094-Spectroscopy of Milky Way Halo Gas (Savage, Sembach, and Cardelli) GO2257-Physical Conditions in the Gaseous Galactic Halo (Savage, Sembach, and Cardelli) GO2424-Quasar Absorption Line Survey (Bahcall et al, including Savage) GO3463-Highly Ionized Nitrogen in the Galactic Halo (Savage, Sembach, and Lu) Most of the data have been received and analized. There have been 16 publications so far based on these data. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). The University of Wisconsin will provide data handling and analysis facilities available through the Midwest Astronomical Data Reduction and Analysis Facility. ------------------------------------------------------------------------------------ 11. Address Information Page 3 Name: LIMIN LU Category: PI Institution: UNIVERSITY OF WISCONSIN-MADISON Address: DEPARTMENT OF ASTRONOMY 475 N. CHARTER STREET City: MADISON State: WI Zip Code: 53706 Country: USA Telephone: 608-265-2626 Telex (or e-mail): 26542 UOFWISC MDS ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 5299 [ 4] ------------------------------------------------------------------------------------------------------------------------------------ 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 H1821+643 E,313,314 RA=18H 21M 57.11S+/-.01S, 2000 Z=0.297 1 V=14.1 DEC=+64D 20' 36.7"+/-0.1" 2 F-CONT(1240)=3.5E-14 3 F-CONT(1550)=4.5E-14 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5299 [ 5] ------------------------------------------------------------------------------------------------------------------------------------ 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 ------------------------------------------------------------------------------------------------------------------------------------ 100 H1821+643 HRS ACQ 2.0 MIRROR-N2 SEARCH-SIZE=5 1 100S 1 1 ONBOARD ACQ FOR BRIGHT=RETURN 101 CYCLE 4 / 100-106 Comments: STEP-TIME=4S EXPECTED COUNT RATE WITH N2: 2230 C/S ------------------------------------------------------------------------------------------------------------------------------------ 101 H1821+643 HRS ACQ/ 2.0 MIRROR-N2 1 204S 1 1 ONBOARD ACQ FOR PEAKUP 102-106 Comments: STEP-TIME=2S ------------------------------------------------------------------------------------------------------------------------------------ 102 H1821+643 HRS IMAGE 2.0 MIRROR-N2 NX=16 1 5.12M 1 1 NY=16 Comments: TAKE MAP AFTER CENTERING STEP- TIME=1.2S ------------------------------------------------------------------------------------------------------------------------------------ 103 H1821+643 HRS ACCUM 2.0 G160M 1250 STEP-PATT=4 9 19.2M 10 2 1 FP-SPLIT=STD 172.8M ------------------------------------------------------------------------------------------------------------------------------------ 104 WAVE HRS ACCUM SC2 G160M 1250 1 1M 1 CALIB FOR 103 NO SLEW GROUP 103-104 NO GAP ------------------------------------------------------------------------------------------------------------------------------------ 105 H1821+643 HRS ACCUM 2.0 G160M 1540 STEP-PATT=4 14 19.2M 15 3 1 FP-SPLIT=STD 268.8M ------------------------------------------------------------------------------------------------------------------------------------ 106 WAVE HRS ACCUM SC2 G160M 1540 1 1M 1 CALIB FOR 105 NO SLEW GROUP 105-106 NO GAP ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 5299 [ 6] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAKUP IMAGE ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SEARCH-SIZE=5 BRIGHT=RETURN NX=16 NY=16 STEP-PATT=4 FP-SPLIT=STD ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 10.00 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category INTERSTELLAR MEDIUM ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category ABSORPTION LINES ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 101; CYCLE 4 / 100-106; ONBOARD ACQ FOR 102-106; CALIB FOR 103 NO SLEW; GROUP 103-104 NO GAP CALIB FOR 105 NO SLEW; GROUP 105-106 NO GAP ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N2 G160M ------------------------------------------------------------------------------------------------------------------------------------ Target Names H1821+643 ------------------------------------------------------------------------------------------------------------------------------------