! Proposal 5893, submission 2 ! PI: Alfred Vidal-Madjar ! Received Fri Apr 21 08:45:18 EDT 1995 ! From: alfred@iap.fr ! Hubble Space Telescope Cycle 5 (1995) Phase II Proposal Template ! $Id: 5893,v 6.1 1995/05/15 21:24:25 pepsa Exp $ ! ! Refer to the HST Phase II Proposal Instructions to fill this out ! ! Anything after a "!" is ignored, and may be deleted ! ! All keywords with multiple entries are comma delimited except the ! Visit_Requirements and Special_Requirements keywords which can be ! delimited with carriage returns or semi-colons, but not commas ! ! For help call your Program Coordinator: Alice Berman ! Phone: 410 338-4462 , E-mail: aberman@stsci.edu ! ! This partially completed template was generated from a Phase I proposal. ! Name of Phase I Proposal: vidal-madjar-500.prop ! Date generated: Fri Dec 16 16:46:25 EST 1994 ! Proposal_Information ! Section 4 Title: Deuterium in the local interstellar medium toward hot stars Proposal_Category: GO Scientific_Category: Interstellar Medium Cycle: 5 Investigators PI_name: Alfred Vidal-Madjar PI_Institution: Institut d'Astrophysique de Paris CoI_Name: J. Audouze CoI_Institution: Institut d'Astrophysique de Paris Contact: ! Y or N (designate at most one contact) CoI_Name: M. Casse CoI_Institution: Service d'Astrophysique DAPNIA, Saclay Contact: ! Y or N (designate at most one contact) CoI_Name: R. Ferlet CoI_Institution: Institut d'Astrophysique de Paris Contact: ! Y or N (designate at most one contact) CoI_Name: C. Gry CoI_Institution: Laboratoire d'Astrophysique de Marseille Contact: ! Y or N (designate at most one contact) CoI_Name: D. Koester CoI_Institution: Universitaet Kiel Contact: ! Y or N (designate at most one contact) CoI_Name: M. Lemoine CoI_Institution: Institut d'Astrophysique de Paris Contact: ! Y or N (designate at most one contact) CoI_Name: E. Vangioni-Flam CoI_Institution: Institut d'Astrophysique de Paris Contact: ! Y or N (designate at most one contact) CoI_Name: J. Webb CoI_Institution: University of New South Wales Contact: ! Y or N (designate at most one contact) Abstract: ! Free format text (please update) The proposed observations are the necessary continuation of an approved Cycle 1 proposal aiming at deriving the deuterium abundance in the local interstellar medium toward nearby hot stars. The present D/H ratio within the galaxy is one of the key-parameters of galactic evolution models. Although a very accurate measurement of the interstellar D/H ratio was made recently toward Alpha Aur using HST-GHRS (Linsky et al., 1993), it seems to us that the value of the present D/H ratio is not settled as yet. Many data set, as well as our recent Cycle 1 data toward G191-B2B, have suggested the possible existence of variations of this ratio, which might have some consequence on the galactic evolution of deuterium. These same Cycle 1 data seem to indicate also that a refined estimate of the Linsky et al. value should lie closer to 1.4 times 10^-5 than to 1.7 times 10^-5. We propose to carry out new and highly accurate measurements of the D/H ratio in the local medium by complementing our Cycle 1 observations toward G191-B2B ! Epsilon and Beta CMa, and Sirius-A with observations of two extremely important spectral regions using the Ech-A grating, namely the N I triplet (1200Angstrom) and the Lyman-alpha line where our previous G160M grating prevented us from constraining more tightly the D/H ratios. The efficiency and the availability of the Ech-A grating, as well as the quality of our already acquired data provides exceptional opportunities for carrying out precise measurements of D/H ratios in a relatively short integration time. Questions ! Free format text (please update) Observing_Description: We plan to perform the following observations using the Small Science Aperture (SSA): Object Wavelength Grating count/s/d G191-B2B N I 1200A Ech-A47 0.3 H I 1216A Ech-A46 0.07 O I 1302A Ech-A43 0.42 ! Epsilon CMa: & ! \n 1200Angstrom & Ech-A order 47 & 490 , & \hi 1216Angstrom & ! Ech-A order 46 & 110, & O I 1302Angstrom & Ech-A order 43 & ! 1500, Beta CMa: & \n 1200Angstrom & Ech-A order 47 & 530, & ! \hi 1216Angstrom & Ech-A order 46 & 137, & O I 1302Angstrom & ! Ech-A order 43 & 1500, Sirius A: & \n 1200Angstrom & Ech-A ! order 47 & 2.7, & \hi 1216Angstrom & Ech-A order 46 & 0.43, & ! O I 1302Angstrom & Ech-A order 43 & 520, Sirius B: & \n ! 1200Angstrom & Ech-A order 47 & 1.21, & \hi 1216Angstrom & ! Ech-A order 46 & 0.36, & O I 1302Angstrom & Ech-A order 43 & ! 11.9, & Mg II 2800Angstrom & Ech-B order 24 & 47, & Fe II ! 2344Angstrom & Ech-B order 20 & 47, & 1200Angstrom & G160M & ! 8 , endtabular The fluxes of G191-B2B ! , Epsilon CMa, Beta CMa and Sirius-A at 1200Angstrom, 1215Angstrom, 1302Angstrom were taken from our previous HST-GHRS observations and from Snow & Jenkins (1977). ! The fluxes of Sirius-B were taken from Wegner & Swanson (1991). These fluxes were converted into counts/s/diode using the Post-Costar GHRS Instrument Handbook data (table 8.3 for Ech-A, table 8.4 for Ech-B and table 8.2 for G160M) taking into account the blaze function of the Echelle gratings and a throughput of 50\ Epsilon CMa flux at 1200Angstrom is 2.2times10^-8 erg.s^-1.cm^-2.AA^-1, the sensitivity of Ech-A in the 47th order is 0.46times10^11 counts/s/diode/(erg.s^-1.cm^-2.AA^-1), with a factor 0.96 arising from the blaze function and a factor 0.5 to convert to the use of the SSA, gives 486 counts/s/diode., We then convert these counts into integration time by requiring a signal-to-noise ratio at least S/N=20 per pixel, i.e. S/N=40 per diode. The photon noise is dominating in all considered settings. The orbits are calculated following the instructions of the Phase I Proposal Handbook:, - G191-B2B ! Sirius-A and Sirius-B will be acquired with the N1-N2 mirrors, which asks for 31 minutes during the first orbit for each, i.e. 12 mn for acquiring the guide star, 11 mn for acquiring the target and another 8 mn for peak-up. Each exposure will be preceded by a WAVE exposure (3 mn) in order to have accurate radial velocities for each interstellar component in each setting, and 4 mn overhead are taken into account in the ACCUM mode. Three additional minutes are considered for each change in wavelength, and 6 mn per additional orbit for re-acquisition. ! For Sirius-B, 45 mn are ! taken into account to change sides., -Epsilon CMa and Beta ! CMa have to be acquired with the attenuated mirrors, which ! requires 20 mn to acquire the target and another 17 mn for ! peakup. One orbit is thus devoted for each of these stars to ! acquisition, and the other to science exposures., Note: we ! consider the total integration time to be relatively short in ! view of the number of targets proposed. ! Although the proposed ! observations of G191-B2B represent half the total time ! requested, G191-B2B is also the target toward which an ! extremely precise estimate of the D/H ratio may be made ! because of the high quality of our Cycle 1 data. Still, if ! the grand total orbit time is found too large, the present ! observational programme may be spread over different HST ! cycles. We ask the TAC to bear these comments in mind., Real_Time_Justification: There are optimum times in the year (typically a three month window) for obtaining Lyman-alpha observations toward white dwarfs. These times are when the velocity of the Earth is such that the geocoronal Lyman alpha emission (arising in the Earth atmosphere) is centered in the core of the \hi\ absorption profile, so that it may be easily isolated and removed. This strategy has been used for our Cycle 1 observations of G191-B2B (see fig.1) where the geocoronal emission is correctly centered but however almost affected the \la\ blue wing. For Cycle 5 observations we will locate the geocoronal emission further away from both \la\ wings to better avoid any contamination. ! We will need an accurate acquisition of ! Sirius-B, due to the presence of its companion star Sirius-A, ! whose flux can be as high as 100 times the flux of Sirius-B ! at the wavelengths we consider (the maximum ratio of 100 is ! obtained at 2800Angstrom ). We estimated this contamination ! during the observations to be negligible if Sirius-B is well ! centered on the entrance slit. Calibration_Justification: ! Move appropriate text from Real_Time_Justification None. Additional_Comments: Fixed_Targets ! Section 5.1 ! Updated target information 5/15/95 - AFB Target_Number: 1 Target_Name: G191-B2B Alternate_Names: GSC3734-00506, WD 0501+527,EG247 Description: STAR, DA Position: RA = 05H 05M 30.62S +/- 0.02S, DEC = 52D 49' 54.0" +/- 0.2", PLATE-ID = 0005 Equinox: J2000 RV_or_Z: RA_PM: 0.000 ! Units are seconds of time per year Dec_PM: 0.000 ! Units are seconds of arc per year Annual_Parallax: 0.0210 +/- 0.002 Flux: V=11.88 +/- 0.40, B-V=-0.32, F(1199) = 13. +/- 3. E-12, F(1215) = 4. +/- 2. E-13, F(1304) = 10. +/- 2. E-12 ! Include at least V and B-V Comments: Coordinates are from GSC ! Orig. values: ! Position: RA = 05H 05M 30.62S +/- 0.03", ! DEC = +52D 49' 54.0" +/- 0.03" ! Epoch: 2000 ! Flux: V=11.73 +/- 0.2 ! This is a template for a single visit containing a single exposure ! Repeat exposure and visit blocks as needed Visits Visit_Number: 1 Visit_Requirements: BETWEEN 18-JUL-95 AND 7-SEP-95 ! Section 7.1 ! Uncomment or copy visit level special requirements needed ! Most of these requirements (including ORIENT) will limit scheduling ! PCS MODE [Fine | Gyro] ! GUIDing TOLerance ! ORIENTation TO ! ORIENTation TO FROM ! ORIENTation TO FROM NOMINAL ! SAME ORIENTation AS ! CVZ ! PARallel ! AFTER [BY [TO ]] ! AFTER ! BEFORE ! BETWEEN AND ! GROUP WITHIN