! $Id: 6476,v 7.1 1996/06/19 14:28:14 pepsa Exp $ Proposal_Information ! Section 4 Title: A study of circumstellar material formed in a hydrogen-deficient environment Proposal_Category: GO Scientific_Category: HOT STARS Cycle: 6 Investigators PI_name: John Drilling PI_Institution: Louisiana State University CoI_Name: James Hecht CoI_Institution: Aerospace Corporation Contact: ! Y or N (designate at most one contact) CoI_Name: Simon Jeffery CoI_Institution: University of St Andrews Contact: ! Y or N (designate at most one contact) CoI_Name: Geoffrey Clayton CoI_Institution: University of Colorado Contact: ! Y or N (designate at most one contact) Abstract: ! Free format text (please update) Observing time is requested to obtain low-resolution UV spectra of the hot R CrB star V348 Sgr at maximum light and deep into the ascending portion of its light curve. These spectra will be used along with simultaneous optical spectrophotometry to determine the nature of newly-formed circumstellar material around this star. V348 Sgr is the only object for which an accurate extinction curve for freshly ejected dust can be determined entirely from observation to wavelengths shorter than 2500 Angstrom. An intriguing possibility is the that signature of fullerenes may be identifiable in the extinction curve obtained from these observations. Questions ! Free format text (please update) Observing_Description: Strategy has been change to observe the target three times for one orbit each. The reason for this is that, although the observation we just got of V348 Sgr is a good one, we did not get it at maximum light as planned, but one magnitude below maximum. Since the scientific goal of the proposal is to obtain the extinction curve of V348 Sgr, failure to obtain a spectrum at maximum light will be disasterous. Executing Visit 1 at maximum light would be a waste, since the maximum practical signal-to-noise is obtainable in one orbit, whereas executing Visit 2 two more times would give us twice the chance of obtaining the spectrum at maximum light and hopefully an additional spectrum during a minimum, which will improve the accuracy of the extinction curve. Original description: We require low resolution spectra of V348 Sgr covering the entire space ultraviolet accessible to HST, including well- exposed images covering the region of the 2500Angstrom\ absorption bump, and as close to Ly-Alpha as possible. These must be obtained when the star reaches V=13.5 following an absorption event, and following its subsequent return to maximum (V=12.2). Since 2500Angstrom\ lies at the upper and lower limits of gratings G160L and G270H respectively, the most efficient way to obtain the desired observations when V348 Sgr reaches V=13.5 is to obtain an exposure with the G270H grating during the first of two adjacent orbits. We can fulfill the conditions for fast target acquisition with the 1 arcsec aperture, and so will be able to expose for 30 minutes, giving a minimum S:N (7 Angstrom) ~20:1. During the second orbit we shall expose for 41 minutes with the G160L grating to obtain similar S:N. A third orbit will be required to obtain the spectrum after V348 Sgr has returned to maximum light. Shorter exposures with both gratings (G270H and G160L) will be made which will provide S:N>~100:1. Visit & Grating & Lambda(Angstrom) & Flux(10^-16) & ct s^-1diode^-1 &Expo. (m)& S/N (7Angstrom) & Orbits Visit 1 & G270H & 2500 & 4 & 0.07 & 30 & 20 & 1 & G160L & 2500 & 4 & 0.09 & 41 & 20 & 1 Visit 2 & G270H & 2500 & 300 & 23 & 10 & 100 & & G160L & 2500 & 300 & 18 & 14 & 100 & 1 Total Orbits = 3 Real_Time_Justification: The first observations must be made as a target of opportunity since they require V348 Sgr to be obscured by 1.3 magnitudes of dust. The lead time cannot be longer than four weeks. The second observations should be scheduled between four and six weeks later, after the star has returned to maximum light. A network of groundbased observers will be established to monitor V348 Sgr for light declines. The average time between minima for V348 Sgr is about 200 days, so the probability of obtaining the observations is high (>50\%). Ground-based observations will be coordinated with the HST observations. Calibration_Justification: ! Move appropriate text from Additional_Comments: Fixed_Targets ! Section 5.1 Target_Number: 1 Target_Name: V348-SGR Alternate_Names: Description: STAR Position: RA=18H 40M 19.93S +/- 0.05", DEC=-22D 54' 28.63" +/- 0.5", PLATE-ID = 067T Equinox: 2000 RV_or_Z: V=+174 RA_PM: ! Units are seconds of time per year Dec_PM: ! Units are seconds of arc per year Epoch: Annual_Parallax: Flux: ! Include at least V and B-V V=13.5 +/- 1.0 ! 12.2 +/- 0.1 for Visit 2 B=13.8 +/- 1.0 ! 12.5 +/- 0.1 for Visit 2 F(2500)=4 +/- 2 E-16 ! 3 +/- 1 E-14 for Visit 2 Comments: Target measured in GSC by Ron Downes Target_Number: 2 Target_Name: V348-SGR-OFFSET Alternate_Names: Description: STAR Position: RA=18H 40M 21.01S +/- 0.05", DEC=-22D 54' 23.6" +/- 0.5", PLATE-ID = 067T Equinox: 2000 RV_or_Z: V=+174 RA_PM: ! Units are seconds of time per year Dec_PM: ! Units are seconds of arc per year Epoch: Annual_Parallax: Flux: V=15.4 +/- 1.0 B=1.4 +/- 1.0 Comments: Target position measured in GSC by Ron Downes. Target magnitude measured from Sky Survey by Ron Downes. Visits ! Section 6 Visit_Number: 1 Visit_Requirements: ON HOLD SCHED 100% ! Section 7.1 On_Hold_Comments: Target of Opportunity Visit_Comments: Exposure_Number: 10 ! Section 6.5 Target_Name: V348-SGR-OFFSET Config: FOS/BL Opmode: ACQ/BINARY Aperture: 4.3 Sp_Element: MIRROR Wavelength: Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 7.5S Special_Requirements: ONBOARD ACQ FOR 20-30 Exposure_Number: 20 ! Section 6.5 Target_Name: V348-SGR Config: FOS/BL Opmode: ACCUM Aperture: 1.0-PAIR-A Sp_Element: G270H Wavelength: 2500 Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 8M Special_Requirements: ! Section 7.2 Exposure_Number: 30 ! Section 6.5 Target_Name: V348-SGR Config: FOS/BL Opmode: ACCUM Aperture: 1.0-PAIR-A Sp_Element: G160L Wavelength: 2500 Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 10.33M Special_Requirements: Visit_Number: 2 Visit_Requirements: ON HOLD SCHED 100% ! Section 7.1 On_Hold_Comments: TARGET OF OPPORTUNITY Visit_Comments: Exposure_Number: 10 ! Section 6.5 Target_Name: V348-SGR-OFFSET Config: FOS/BL Opmode: ACQ/BINARY Aperture: 4.3 Sp_Element: MIRROR Wavelength: Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 7.5S Special_Requirements: ONBOARD ACQ FOR 20-30 Exposure_Number: 20 ! Section 6.5 Target_Name: V348-SGR Config: FOS/BL Opmode: ACCUM Aperture: 1.0-PAIR-A Sp_Element: G270H Wavelength: 2500 Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 8M Special_Requirements: ! Section 7.2 Exposure_Number: 30 ! Section 6.5 Target_Name: V348-SGR Config: FOS/BL Opmode: ACCUM Aperture: 1.0-PAIR-A Sp_Element: G160L Wavelength: 2500 Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 10.33M Special_Requirements: Comments: Visit_Number: 3 Visit_Requirements: SCHED 100% ! Section 7.1 On_Hold_Comments: Visit_Comments: Exposure_Number: 10 ! Section 6.5 Target_Name: V348-SGR-OFFSET Config: FOS/BL Opmode: ACQ/BINARY Aperture: 4.3 Sp_Element: MIRROR Wavelength: Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 7.5S Special_Requirements: ONBOARD ACQ FOR 20-30 Exposure_Number: 20 ! Section 6.5 Target_Name: V348-SGR Config: FOS/BL Opmode: ACCUM Aperture: 1.0-PAIR-A Sp_Element: G270H Wavelength: 2500 Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 8M Special_Requirements: ! Section 7.2 Exposure_Number: 30 ! Section 6.5 Target_Name: V348-SGR Config: FOS/BL Opmode: ACCUM Aperture: 1.0-PAIR-A Sp_Element: G160L Wavelength: 2500 Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 10.33M Special_Requirements: Comments: Data_Distribution ! Defaults indicated; change if desired 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 ! STSCI or PI_Address or ! PI Address from Phase I is: ! ! Dept. of Physics and Astronomy ! Louisiana State University ! Baton Rouge, Louisiana 70803 Ship_Via: UPS ! UPS (2-day) or OVERNIGHT ! Overnight shipping done at PI expense Recipient_Email: ! Needed if Ship_To: is not PI_Address ! ! Let us know what you think of this template and software! ! Please send a list of your likes and dislikes to your Program Coordinator