5882( 9) - 08/02/96 11:57 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 5882 Version: 9 Check-in Date: 02-Aug-1996 12:52:50 1.Proposal Title: ECH-A Studies of Single Interstellar Clouds ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Interstellar Medium GO 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: LEWIS HOBBS UNIVERSITY OF CHICAGO CoI: Donald Morton Herzberg Institute of Astrophysics N CoI: Lyman Spitzer Princeton University N CoI: Daniel Welty University of Chicago N CoI: Donald York University of Chicago N ------------------------------------------------------------------------------------ 6. Abstract We propose to use the high spectral resolution of the ECH-A mode of the GHRS to record the resolved components of a number of interstellar absorption lines in the UV spectra of each of two stars, Rho Leo and 1 Sco, for which we have acquired G160M and ECH-B spectra in Cycles 1 and 2. The lines to be observed are the following: (1) C I, C I*, and C I** in the multiplet near 1329 Angstrom; (2) N I 1159, 1160 Angstrom; (3) N I 1199, 1200, 1201 Angstrom; (4) O I 1355 Angstrom; (5) Mg II 1239, 1240 Angstrom; (6) Si III 1206 Angstrom; (7) P II 1301 Angstrom; (8) S II 1250, 1253 Angstrom; and (9) S III 1190 Angstrom. The primary purpose of the observations is to determine accurately the temperatures, total densities, fractional ionizations, and linear sizes of many individual clouds, as well as the relative abundances of up to 20 elements in the clouds. The total spacecraft time required to carry out the proposed observations is about 25 per cent of the time previously allocated to our program in Cycles 1 and 2, when the ECH-A mode was not available. Approval of this request for an incrementally small amount of observing time would provide a disproportionately large scientific return from our program and would enable us to achieve nearly all of our original scientific goals., ------------------------------------------------------------------------------------ 5882( 9) - 08/02/96 11:57 - [ 2] Observations Description ------------------------ Measured fluxes extending down to about 1380 Angstrom\\ have been published for Rho Leo and 1 Sco. The absolute sensitivity of the ECH-A mode of the GHRS is given in Table 8-3 of version 5.0 of the GHRS Instrument Handbook. These two kinds of data can be combined to predict instrumental counting rates and, for a specified S/N ratio, exposure times. The steps in calculating the corresponding number of orbits required are explained in the Proposal Instructions for Cycle 5., The case of 1 Sco will be used as an illustration. At 1355 Angstrom, the star's flux is F= 9.4* 10^-10 erg/s/cm^2/Angstrom, and the sensitivity of the GHRS through the SSA is S= 1.28* 10^11* 0.676* 0.667 = 5.8* 10^10 (count/s) per (erg/s/cm^2/Angstrom), where the latter two factors account for the blaze function and the ratio of the throughputs of the SSA and LSA. The product F*S = 55 count/s, so that an exposure time of 3.0 min should yield S/N = 100, which is our goal. Two such exposures, offset by a half diode to provide proper sampling of the data, require a total exposure time at 1355 Angstrom\\ of 6.0 min. When the exposure times at all eight wavelength settings are similarly calculated, the total exposure time required for 1 Sco is about 83 min, of which 27 min are utilized at the 1159 Angstrom\\ setting alone. The times required for instrumental overhead, target acquisition in the SSA, and one acquisition plus two reacquisitions of a guide star are 32, 19, and 24 min, respectively. The resulting grand total of 158 min requires almost exactly 3 orbits., Analogous calculations show that the observations of the brighter star Rho Leo requires only 2 orbits, if the relatively long 1159 Angstrom\\ exposure is omitted; this weak line actually is unlikely to be reliably detected toward Rho Leo, owing to the relatively low total interstellar column density along that light path. Real Time Justification ----------------------- None Calibration Justification ------------------------- None Additional Comments ------------------- We are conducting coordinated ground-based observing programs at the Kitt Peak, McDonald, and Anglo-Australian observatories. The goal of these programs is to obtain interstellar line observations of unprecedented quality for the twelve stars which we observed with HST/GHRS in Cycles 1 and 2. We plan to measure the Na I, Ca II, K I, and Ti II lines at instrumental resolutions between 0.3 and 1.2 kms, at a typical S/N ratio of 100. The first two papers which have been published in this series are the following:, - Hobbs and Welty 1991, ``The Interstellar D1 Line at High Resolution'', ApJ, 368, 426, - Welty, Hobbs, and Kulkarni 1994, ``A High-Resolution Survey of Interstellar Na I D1 Lines'', ApJ, 436, 152. ------------------------------------------------------------------------------------ 5882( 9) - 08/02/96 11:57 - [ 3] Data Distribution Media: 6250BPI Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 5882( 9) - 08/02/96 11:57 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HD91316 STAR, B0-B2 III-I RA = 10H 32M 48.67S +/- 0.01S, J2000 V = +42 V = 3.90+/-0.02 DEC = 09D 18' 23.6" +/- 0.1" B-V = -0.14+/-0.02 TYPE=B1IB E(B-V) = 0.05 F(1480)=1.51+/-0.2e-09 Comments: Coordinates are from Hipparcos INCA Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000.000 -0.0006 -0.0060 0.0013 2 HD141637 STAR, B0-B2 V-IV RA = 15H 50M 58.70S +/- 0.01S, J2000 V = +03 V = 4.59+/-0.02 DEC = -25D 45' 4.7" +/- 0.1" B-V = -0.05+/-0.02 TYPE=B2.5V E(B-V) = 0.16 F(1480)=7.3+/-1.0e-10 Comments: Coordinates are from Hipparcos INCA Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000.000 -0.001478 -0.0270 0.0050 5882( 9) - 08/02/96 11:57 - [ 5] 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 HD91316 HRS ACQ 2.0 MIRROR-N1 SEARCH-SIZE=3,BRIGHT=RETURN, 1 1.8 S ONBOARD ACQ FOR 2 LOCATE=YES Comments: STEP-TIME=0.2S ------------------------------------------------------------------------------------------------------------------------------------ 2 HD91316 HRS ACQ/PEA 0.25 MIRROR-N1 SEARCH-SIZE=5 1 5 S ONBOARD ACQ FOR 4-9 KUP Comments: STEP-TIME=0.2S ------------------------------------------------------------------------------------------------------------------------------------ 4 HD91316 HRS ACCUM 0.25 ECH-A 1205.0 FP-SPLIT=DSFOUR,STEP-PATT=7 1 652.9 S Comments: SiIII ------------------------------------------------------------------------------------------------------------------------------------ 5 HD91316 HRS ACCUM 0.25 ECH-A 1239.9 FP-SPLIT=DSFOUR,STEP-PATT=7 1 544.1 S Comments: MgII(2) ------------------------------------------------------------------------------------------------------------------------------------ 6 HD91316 HRS ACCUM 0.25 ECH-A 1252.2 FP-SPLIT=DSFOUR,STEP-PATT=7 1 326.5 S Comments: SII(2) ------------------------------------------------------------------------------------------------------------------------------------ 7 HD91316 HRS ACCUM 0.25 ECH-A 1303.9 FP-SPLIT=DSFOUR,STEP-PATT=7 1 217.7 S Comments: PII ------------------------------------------------------------------------------------------------------------------------------------ 8 HD91316 HRS ACCUM 0.25 ECH-A 1331.0 FP-SPLIT=DSFOUR,STEP-PATT=7 1 326.5 S Comments: CI, CI*, CI** ------------------------------------------------------------------------------------------------------------------------------------ 9 HD91316 HRS ACCUM 0.25 ECH-A 1192.3 FP-SPLIT=DSFOUR,STEP-PATT=7 1 870.5 S Comments: SIII, SiII* ------------------------------------------------------------------------------------------------------------------------------------ 5882( 9) - 08/02/96 11:57 - [ 6] 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 ------------------------------------------------------------------------------------------------------------------------------------ 11 HD141637 HRS ACQ 2.0 MIRROR-N1 SEARCH-SIZE=3,BRIGHT=RETURN, 1 1.8 S ONBOARD ACQ FOR 12 LOCATE=YES Comments: STEP-TIME=0.2S ------------------------------------------------------------------------------------------------------------------------------------ 12 HD141637 HRS ACQ/PEA 0.25 MIRROR-N1 SEARCH-SIZE=5 1 5 S ONBOARD ACQ FOR 15-21 KUP Comments: STEP-TIME=0.2S ------------------------------------------------------------------------------------------------------------------------------------ 15 HD141637 HRS ACCUM 0.25 ECH-A 1205.0 FP-SPLIT=DSFOUR,STEP-PATT=7 1 1088.1 Comments: SiIII ------------------------------------------------------------------------------------------------------------------------------------ 16 HD141637 HRS ACCUM 0.25 ECH-A 1239.9 FP-SPLIT=DSFOUR,STEP-PATT=7 1 652.9 S Comments: MgII(2) ------------------------------------------------------------------------------------------------------------------------------------ 17 HD141637 HRS ACCUM 0.25 ECH-A 1252.2 FP-SPLIT=DSFOUR,STEP-PATT=7 1 435.3 S Comments: SII(2) ------------------------------------------------------------------------------------------------------------------------------------ 18 HD141637 HRS ACCUM 0.25 ECH-A 1303.9 FP-SPLIT=DSFOUR,STEP-PATT=7 1 435.3 S Comments: PII ------------------------------------------------------------------------------------------------------------------------------------ 19 HD141637 HRS ACCUM 0.25 ECH-A 1331.0 FP-SPLIT=DSFOUR,STEP-PATT=7 1 435.3 S Comments: CI, CI*, CI** ------------------------------------------------------------------------------------------------------------------------------------ 20 HD141637 HRS ACCUM 0.25 ECH-A 1357.2 FP-SPLIT=DSFOUR,STEP-PATT=7 1 652.9 S Comments: OI ------------------------------------------------------------------------------------------------------------------------------------ 21 HD141637 HRS ACCUM 0.25 ECH-A 1192.3 FP-SPLIT=DSFOUR,STEP-PATT=7 1 1196.9 Comments: SIII, SiII* ------------------------------------------------------------------------------------------------------------------------------------ 5882( 9) - 08/02/96 11:57 - [ 7] Visit: 51 Visit Requirements: On Hold Comments: Additional Comments: HOPR repeat of exp. 7 of Visit 1 Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 HD91316 HRS ACQ 2.0 MIRROR-N1 SEARCH-SIZE=3,BRIGHT=RETURN, 1 1.8 S ONBOARD ACQ FOR 2 LOCATE=YES Comments: STEP-TIME=0.2S ------------------------------------------------------------------------------------------------------------------------------------ 2 HD91316 HRS ACQ/PEA 0.25 MIRROR-N1 SEARCH-SIZE=5 1 5 S ONBOARD ACQ FOR 7 KUP Comments: STEP-TIME=0.2S ------------------------------------------------------------------------------------------------------------------------------------ 7 HD91316 HRS ACCUM 0.25 ECH-A 1303.9 FP-SPLIT=DSFOUR,STEP-PATT=7 1 217.7 S Comments: PII ------------------------------------------------------------------------------------------------------------------------------------ 5882( 9) - 08/02/96 11:57 - [ 8] Visit: 52 Visit Requirements: On Hold Comments: Additional Comments: HOPR repeat of exp. 15-17 of Visit 2 Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 11 HD141637 HRS ACQ 2.0 MIRROR-N1 SEARCH-SIZE=3,BRIGHT=RETURN, 1 1.8 S ONBOARD ACQ FOR 12 LOCATE=YES Comments: STEP-TIME=0.2S ------------------------------------------------------------------------------------------------------------------------------------ 12 HD141637 HRS ACQ/PEA 0.25 MIRROR-N1 SEARCH-SIZE=5 1 5 S ONBOARD ACQ FOR 15-17 KUP Comments: STEP-TIME=0.2S ------------------------------------------------------------------------------------------------------------------------------------ 15 HD141637 HRS ACCUM 0.25 ECH-A 1205.0 FP-SPLIT=DSFOUR,STEP-PATT=7 1 1088.1 Comments: SiIII ------------------------------------------------------------------------------------------------------------------------------------ 16 HD141637 HRS ACCUM 0.25 ECH-A 1239.9 FP-SPLIT=DSFOUR,STEP-PATT=7 1 652.9 S Comments: MgII(2) ------------------------------------------------------------------------------------------------------------------------------------ 17 HD141637 HRS ACCUM 0.25 ECH-A 1252.2 FP-SPLIT=DSFOUR,STEP-PATT=7 1 435.3 S Comments: SII(2) ------------------------------------------------------------------------------------------------------------------------------------ 5882( 9) - 08/02/96 11:57 - [ 9] Summary Form for Proposal 5882 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAKUP ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SEARCH-SIZE=3 BRIGHT=RETURN LOCATE=YES SEARCH-SIZE=5 STEP-PATT=7 FP-SPLIT=DSFOUR ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Interstellar Medium ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 2 ONBOARD ACQ FOR 4-9 ONBOARD ACQ FOR 12 ONBOARD ACQ FOR 15-21 ONBOARD ACQ FOR 7 ONBOARD ACQ FOR 15-17 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N1 ECH-A ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD91316 HD141637 ------------------------------------------------------------------------------------------------------------------------------------