6739( 6) - 07/11/96 10:01 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6739 Version: 6 Check-in Date: 11-Jul-1996 09:57:35 1.Proposal Title: Search for Interstellar Water in Translucent Molecular Clouds ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle INTERSTELLAR MEDIUM GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: DAVID NEUFELD NEUFELD THE JOHNS HOPKINS UNIVERSITY CoI: John Stauffer Smithsonian Astrophysical Obs. N CoI: Gary Melnick Smithsonian Astrophysical Obs. N CoI: Steven Lepp University of Nevada, Las Vegas N ------------------------------------------------------------------------------------ 6. Abstract We propose to search for ultraviolet line absorption due to interstellar water in the translucent molecular clouds which lie in front of the stars HD169454 and HD154368, using Echelle -A of the Goddard High Resolution Spectrograph. The proposed observations will provide a crucial test of astrochemical models for the formation and destruction of interstellar water; such models predict that the proposed observations will lead to the first detection of water (and the first detection of any polyatomic molecule) in the diffuse interstellar medium. ------------------------------------------------------------------------------------ 6739( 6) - 07/11/96 10:01 - [ 2] Observations Description ------------------------ The goal of the observations is to measure the equivalent widths of two water absorption lines in the 6.6 magnitude B1Ia supergiant star HD169454 and in the 6.1 magnitude O9.5 star HD154368. The water absorption lines are the rm~ C ^1B_1 - ~ X ^1A_1 1_11-1_01 transition at 1240.153 Angstrom and the rm~ C ^1B_1 - ~ X ^1A_1 2_11-1_01 transition at 1239.382 Angstrom. The required integration times of 4.0 hours on each source are chosen to yield spectra of S/N = 20 and 80 (per resolution element) for HD169454 and HD154368 respectively, corresponding to 3Sigma uncertainties in the absorption line equivalent widths of 2.0 mAngstrom and 0.5 mAngstrom. Including guide star acquisition, target acquisition, and instrument overheads, we will require 6 orbits for each source. So as to observe both spectral lines simultaneously, we will adopt a central wavelength setting of 1240Angstrom. In order to obtain the most sensitive measurements of weak absorption features, we will use the small science aperture (SSA) with the Echelle-A spectrograph for both observations. Real Time Justification ----------------------- None. Calibration Justification ------------------------- None. Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: OVERNIGHT Email: , ------------------------------------------------------------------------------------ 6739( 6) - 07/11/96 10:01 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HD169454 STAR, B0-B2 III-I RA=18H 25M 15.20S +/- 0.01S, J2000 V = 6.610+/-0.015 DEC=-13D 58' 42.3" +/- 0.1" TYPE=B1IA B-V = 0.95+/-0.09 E(B-V) = 1.14+/-0.1 F-CONT(1240)=4.5e-13 F-LINE(1240)=-4.5e-13 W-LINE(1240)=0.007 Comments: F-CONT estimate is based upon IUE spectra of similar stars and dust extinction curves from manual. F-LINE and W-LINE are theoretical predictions. It is not possible to assign meaningful error bars to these quantities. 2 HD154368 STAR, SUPERGIANT O RA=17H 06M 28.39S +/- 0.01S, J2000 V = 6.116+/-0.008 DEC=-35D 27' 04.0" +/- 0.1" TYPE=O9.5IAB B-V = 0.54+/-0.09 E(B-V) = 0.82+/-0.1 F-CONT(1240)=8.4e-12 F-LINE(1240)=-2.0e-12 W-LINE(1240)=0.004 Comments: F-CONT estimate is based upon IUE spectra of similar stars and dust extinction curves from manual. F-LINE and W-LINE are theoretical predictions. It is not possible to assign meaningful error bars to these quantities. 6739( 6) - 07/11/96 10:01 - [ 4] 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 HD169454 HRS ACQ 2.0 MIRROR-N1 BRIGHT=RETURN,SEARCH-SIZE=3 1 3.6 S ONBOARD ACQ FOR 2 Comments: STEP-TIME=0.4S. ------------------------------------------------------------------------------------------------------------------------------------ 2 HD169454 HRS ACQ/PEA 0.25 MIRROR-N1 SEARCH-SIZE=5 1 20.0 S ONBOARD ACQ FOR 3-7 KUP Comments: STEP-TIME=0.8S ------------------------------------------------------------------------------------------------------------------------------------ 3 WAVE HRS ACCUM SC2 ECH-A 1238 SPYBAL=YES 1 DEF ------------------------------------------------------------------------------------------------------------------------------------ 4 HD169454 HRS ACCUM 0.25 ECH-A 1238 FP-SPLIT=NO,STEP-PATT=DEF 11 326.4 S Comments: USE FP-SPLIT=NO, BECAUSE EXPECTED S/N(CONT) IS ONLY 20 FOR SUM OF EXPOSURES 4-7 ------------------------------------------------------------------------------------------------------------------------------------ 5 HD169454 HRS ACCUM 0.25 ECH-A 1238 FP-SPLIT=NO,STEP-PATT=DEF 11 326.4 S ------------------------------------------------------------------------------------------------------------------------------------ 6 HD169454 HRS ACCUM 0.25 ECH-A 1238 FP-SPLIT=NO,STEP-PATT=DEF 11 326.4 S ------------------------------------------------------------------------------------------------------------------------------------ 7 HD169454 HRS ACCUM 0.25 ECH-A 1238 FP-SPLIT=NO,STEP-PATT=DEF 11 326.4 S ------------------------------------------------------------------------------------------------------------------------------------ 6739( 6) - 07/11/96 10:01 - [ 5] 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 ------------------------------------------------------------------------------------------------------------------------------------ 8 HD154368 HRS ACQ 2.0 MIRROR-N1 BRIGHT=RETURN,SEARCH-SIZE=3 1 1.8 S ONBOARD ACQ FOR 9 Comments: STEP-TIME=0.2S ------------------------------------------------------------------------------------------------------------------------------------ 9 HD154368 HRS ACQ/PEA 0.25 MIRROR-N1 SEARCH-SIZE=5 1 5.0 S ONBOARD ACQ FOR 10-14 KUP Comments: STEP-TIME=0.2S ------------------------------------------------------------------------------------------------------------------------------------ 10 WAVE HRS ACCUM SC2 ECH-A 1238 SPYBAL=YES 1 DEF ------------------------------------------------------------------------------------------------------------------------------------ 11 HD154368 HRS ACCUM 0.25 ECH-A 1238 FP-SPLIT=STD,STEP-PATT=DEF 2 1849.6 Comments: USE FP-SPLIT=STD, BECAUSE EXPECTED S/N(CONT) IS 80 FOR SUM OF EXPOSURES 11-14 ------------------------------------------------------------------------------------------------------------------------------------ 12 HD154368 HRS ACCUM 0.25 ECH-A 1238 FP-SPLIT=STD,STEP-PATT=DEF 2 1849.6 ------------------------------------------------------------------------------------------------------------------------------------ 13 HD154368 HRS ACCUM 0.25 ECH-A 1238 FP-SPLIT=STD,STEP-PATT=DEF 2 1849.6 ------------------------------------------------------------------------------------------------------------------------------------ 14 HD154368 HRS ACCUM 0.25 ECH-A 1238 FP-SPLIT=STD,STEP-PATT=DEF 2 1740.8 ------------------------------------------------------------------------------------------------------------------------------------ 6739( 6) - 07/11/96 10:01 - [ 6] Summary Form for Proposal 6739 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAKUP ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BRIGHT=RETURN SEARCH-SIZE=3 SEARCH-SIZE=5 SPYBAL=YES STEP-PATT=DEF FP-SPLIT=NO FP-SPLIT=STD ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category INTERSTELLAR MEDIUM ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 2 ONBOARD ACQ FOR 3-7 ONBOARD ACQ FOR 9 ONBOARD ACQ FOR 10-14 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N1 ECH-A ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD169454 WAVE HD154368 ------------------------------------------------------------------------------------------------------------------------------------