! Proposal 6739, submission 2 ! PI: David Neufeld ! Received Thu Feb 22 23:39:13 EST 1996 ! From: neufeld@skysrv.Pha.Jhu.EDU Proposal_Information Title: Search for Interstellar Water in Translucent Molecular Clouds Proposal_Category: GO Scientific_Category: INTERSTELLAR MEDIUM Cycle: 6 Investigators PI_name: David Neufeld PI_Institution: Johns Hopkins University CoI_Name: John Stauffer CoI_Institution: Smithsonian Astrophysical Obs. Contact: CoI_Name: Gary Melnick CoI_Institution: Smithsonian Astrophysical Obs. Contact: CoI_Name: Steven Lepp CoI_Institution: University of Nevada, Las Vegas Contact: 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. Questions Observing_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: Fixed_Targets Target_Number: 1 Target_Name: HD169454 Alternate_Names: GSC5702-282 Description: STAR, B0-B2 III-I Position: RA=18H 25M 15.20S +/- 0.01S, DEC=-13D 58' 42.3" +/- 0.1" Equinox: J2000 RV_or_Z: RA_PM: ! Units are seconds of time per year Dec_PM: ! Units are seconds of arc per year Epoch: Annual_Parallax: Flux: V=6.610 +/- 0.015, 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. Target_Number: 2 Target_Name: HD154368 Alternate_Names: GSC7369-106 Description: STAR, SUPERGIANT O Position: RA=17H 06M 28.39S +/- 0.01S, DEC=-35D 27' 04.0" +/- 0.1" Equinox: J2000 RV_or_Z: RA_PM: ! Units are seconds of time per year Dec_PM: ! Units are seconds of arc per year Epoch: Annual_Parallax: Flux: V=6.116 +/- 0.008, 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. Visits ! Section 6 Visit_Number: 1 Visit_Requirements: ! Section 7.1 On_Hold_Comments: Visit_Comments: Exposure_Number: 1 Target_Name: HD169454 Config: HRS Opmode: ACQ Aperture: 2.0 Sp_Element: MIRROR-N1 Wavelength: Optional_Parameters: BRIGHT=RETURN, SEARCH-SIZE=3 Number_of_Iterations: 1 Time_Per_Exposure: 3.6S Special_Requirements: ONBOARD ACQ FOR 2 Comments: STEP-TIME=0.4S. Exposure_Number: 2 Target_Name: HD169454 Config: HRS Opmode: ACQ/PEAKUP Aperture: 0.25 Sp_Element: MIRROR-N1 Wavelength: Optional_Parameters: SEARCH-SIZE=5 Number_of_Iterations: 1 Time_Per_Exposure: 20.0S Special_Requirements: ONBOARD ACQ FOR 3-7 Comments: STEP-TIME=0.8S Exposure_Number: 3 Target_Name: WAVE Config: HRS Opmode: ACCUM Aperture: SC2 Sp_Element: ECH-A Wavelength: 1238 Optional_Parameters: SPYBAL=YES Number_of_Iterations: 1 Time_Per_Exposure: DEF Special_Requirements: Comments: Exposure_Number: 4 Target_Name: HD169454 Config: HRS Opmode: ACCUM Aperture: 0.25 Sp_Element: ECH-A Wavelength: 1238 Optional_Parameters: FP-SPLIT=NO, STEP-PATT=DEF Number_of_Iterations: 11 Time_Per_Exposure: 326.4S Special_Requirements: Comments: USE FP-SPLIT=NO, BECAUSE EXPECTED S/N(CONT) IS ONLY 20 FOR SUM OF EXPOSURES 4-7 Exposure_Number: 5 Target_Name: HD169454 Config: HRS Opmode: ACCUM Aperture: 0.25 Sp_Element: ECH-A Wavelength: 1238 Optional_Parameters: FP-SPLIT=NO, STEP-PATT=DEF Number_of_Iterations: 11 Time_Per_Exposure: 326.4S Special_Requirements: Comments: Exposure_Number: 6 Target_Name: HD169454 Config: HRS Opmode: ACCUM Aperture: 0.25 Sp_Element: ECH-A Wavelength: 1238 Optional_Parameters: FP-SPLIT=NO, STEP-PATT=DEF Number_of_Iterations: 11 Time_Per_Exposure: 326.4S Special_Requirements: Comments: Exposure_Number: 7 Target_Name: HD169454 Config: HRS Opmode: ACCUM Aperture: 0.25 Sp_Element: ECH-A Wavelength: 1238 Optional_Parameters: FP-SPLIT=NO, STEP-PATT=DEF Number_of_Iterations: 11 Time_Per_Exposure: 326.4S Special_Requirements: Comments: Visit_Number: 2 Visit_Requirements: ! Section 7.1 On_Hold_Comments: Visit_Comments: Exposure_Number: 8 Target_Name: HD154368 Config: HRS Opmode: ACQ Aperture: 2.0 Sp_Element: MIRROR-N1 Wavelength: Optional_Parameters: BRIGHT=RETURN, SEARCH-SIZE=3 Number_of_Iterations: 1 Time_Per_Exposure: 1.8S Special_Requirements: ONBOARD ACQ FOR 9 Comments: STEP-TIME=0.2S Exposure_Number: 9 Target_Name: HD154368 Config: HRS Opmode: ACQ/PEAKUP Aperture: 0.25 Sp_Element: MIRROR-N1 Wavelength: Optional_Parameters: SEARCH-SIZE=5 Number_of_Iterations: 1 Time_Per_Exposure: 5.0S Special_Requirements: ONBOARD ACQ FOR 10-14 Comments: STEP-TIME=0.2S Exposure_Number: 10 Target_Name: WAVE Config: HRS Opmode: ACCUM Aperture: SC2 Sp_Element: ECH-A Wavelength: 1238 Optional_Parameters: SPYBAL=YES Number_of_Iterations: 1 Time_Per_Exposure: DEF Special_Requirements: Comments: Exposure_Number: 11 Target_Name: HD154368 Config: HRS Opmode: ACCUM Aperture: 0.25 Sp_Element: ECH-A Wavelength: 1238 Optional_Parameters: FP-SPLIT=STD, STEP-PATT=DEF Number_of_Iterations: 2 Time_Per_Exposure: 1849.6S Special_Requirements: Comments: USE FP-SPLIT=STD, BECAUSE EXPECTED S/N(CONT) IS 80 FOR SUM OF EXPOSURES 11-14 Exposure_Number: 12 Target_Name: HD154368 Config: HRS Opmode: ACCUM Aperture: 0.25 Sp_Element: ECH-A Wavelength: 1238 Optional_Parameters: FP-SPLIT=STD, STEP-PATT=DEF Number_of_Iterations: 2 Time_Per_Exposure: 1849.6S Special_Requirements: Comments: Exposure_Number: 13 Target_Name: HD154368 Config: HRS Opmode: ACCUM Aperture: 0.25 Sp_Element: ECH-A Wavelength: 1238 Optional_Parameters: FP-SPLIT=STD, STEP-PATT=DEF Number_of_Iterations: 2 Time_Per_Exposure: 1849.6S Special_Requirements: Comments: Exposure_Number: 14 Target_Name: HD154368 Config: HRS Opmode: ACCUM Aperture: 0.25 Sp_Element: ECH-A Wavelength: 1238 Optional_Parameters: FP-SPLIT=STD, STEP-PATT=DEF Number_of_Iterations: 2 Time_Per_Exposure: 1740.8S Special_Requirements: Comments: Data_Distribution Medium: 8MM ! 8MM or 6250BPI or 1600BPI Blocking_Factor: 10 ! 10 or 1 ! Only astronomers with very old 9- ! track tape drives should consider ! a blocking factor of 1 Ship_To: PI_Address Ship_Via: OVERNIGHT Recipient_Email: