6470( 8) - 06/04/96 18:11 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6470 Version: 8 Check-in Date: 04-Jun-1996 18:04:42 1.Proposal Title: Decoding the Inner Disk about Beta- Pictoris ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle BINARIES AND STAR FOR GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Alfred Schultz Computer Sciences Corporation CoI: Fred Bruhweiler Catholic University of America N CoI: Kwang-Ping Cheng California State University Fullerton N CoI: Michael DiSanti Catholic University of America N CoI: Forrest Hamilton Computer Sciences Corporation N CoI: Dorothy Fraquelli Computer Sciences Corporation N CoI: Helen Hart Computer Sciences Corporation N CoI: Charles ``Tony'' Keyes Space Telescope Science Institute N CoI: Kent Reinhard Doane College, Crete N CoI: Daryl Swade Computer Sciences Corporation N ------------------------------------------------------------------------------------ 6. Abstract The FOS will be used to study the UV emission line characteristics of the inner disk about Beta Pictoris at a distance of 1.3" from the star. Our goal is to investigate the proposed infall and subsequent sublimation of comet-like bodies into beta Pictoris and to study the composition of inner disk material. Due to the favorable edge-on orientation of the disk, the gaseous component of the disk has been detected in absorption. The inner disk gases are excited, dissociated, and ionized by stellar photons. The detection of emissions from the gaseous disk in the vicinity of the star, possibly cometary in nature (eg., CS 2576 Angstrom, OH 3064 Angstrom), would unequivocally establish the sublimation of comet-like bodies or possibly volatiles from grains within the circumstellar disk. Our ultimate goal is to ascertain the composition of the inner disk. The GHRS will be employed to acquire the bright targets (alpha and beta Pictoris) followed by slewing the telescope to position the targets into the FOS aperture. The core of the PSF will be positioned behind the space separating the FOS 0.5-PAIR apertures. Spectra using the G190H and G270H gratings, spectral interval 1573 - 3301 Angstrom, will be obtained of both sides of the disk. Cycle 6 is the last opportunity to assess the spectral characteristics of the inner disk material in this wavelength region. ------------------------------------------------------------------------------------ 6470( 8) - 06/04/96 18:11 - [ 2] Observations Description ------------------------ FOS spectra with the the 0.4'' paired apertures (0.5-PAIR) using the G190H and G270H gratings will be obtained of alpha and beta Pictoris. Each aperture will be at a distance of ~1.3'' from the bright stars. The bright stars will be acquired with the GHRS and the telescope slewed to position alpha and beta Pic into the FOS blue aperture. The FOS shutter will be closed during the slew. The stellar PSF for each target star will be positioned between the paired apertures, isolating the core of the PSF from the FOS detector. A total of two FOS ``RAPID'' mode observations (one for each grating) of each star will be obtained. The paired aperture will allow separate spectra for each side of the disk to be obtained. The observations need to be repeated for alpha Pic. The alpha Pic observations will be scaled and subtracted from the Beta Pic observations. We expect the alpha Pic observations to contain mostly slight scatter and light from the diffraction spikes. The remaining time during the first orbit after the acquisition will be used to obtain spectra. We estimate a total of ~3600 seconds of integration time will be available for each grating. This observing strategy will generate quite a few spectra. Depending upon the RAPID mode READ-TIME, a minimum of ~96 spectra (READ-TIME=74 seconds), or up to ~1100 spectra (READ-TIME=6.4 seconds) will be obtained for each bright star. The READ-TIME exposure is split between the two apertures. A read time of 74 seconds will yield a 37 second exposure in each aperture. We model the FOS disk exposures by first, assuming the surface brightness of the circumstellar disk is ~16.0 mag/sq. arcsecond as reported by Paresce and Burrows (1987), and second, the disk flux is mostly reflected light from beta Pic, a A5-type star. Using a 16 magnitude A5-star, a 1000 second exposure will yield 100 counts (S/N ~10) for each side of the disk with the G190H grating, and 300 counts (S/N ~17) with the G270H grating. In practice, the exposure lengths will be increased to fill the orbit. Light scatter within the telescope will be a problem. We are unsure at this time the magnitude of the scatter, and will employ FOS ``RAPID'' mode to decrease the effects of overexposure and wrap around in the spectra. Each visit to a target star will follow a 3-orbit sequence. First Orbit: 7.5 minutes for guide star acquisition GHRS LSA acquisition slewing to the FOS blue aperture start FOS ``RAPID'' mode observation (G190H) 0.5-PAIR aperture Second Orbit: 6 minutes for guide star reacquisition complete G190H ``RAPID'' observation start FOS ``RAPID'' mode observation (G270H) 0.5-PAIR aperture Third Orbit: 6 minutes for guide star reacquisition complete G270H ``RAPID'' observation Real Time Justification ----------------------- Two requirements are necessary to spectroscopically observe the inner disk: 1) GHRS acquisition of the targets and positioning of the bright stars at the center of the FOS large science aperture, and 2) the orientation (ORIENT) to be used should be +30 degrees, or +210 degrees. A GHRS acquisition is required to acquire the targets and correctly position the core of the stellar PSFs in the FOS blue aperture. The FOS aperture wheel will be prepositioned to the 0.4" paired aperture position. Positioning in the FOS aperture is critical so as not to cause overexposure effects in the FOS diodes. The orientation (ORIENT) should be such that the dust disk appears in opposing FOS 0.4" apertures with the central star behind the space between the two apertures. From discussions with two STScI scientists, using the GHRS to acquire a bright star and slewing to the FOS aperture has been tested and was successful. It should be possible to position Alpha & Beta Pic in the center of the FOS aperture. We want to position the bright targets in the center of the large aperture and NOT in one of the small 0.4" paired apertures. The accuracy of the pointing after slewing from the HRS to the center of the 4.3 aperture of the FOS/Blue is ~0.2". There should not be a problem with centering a star between the 0.5-PAIR apertures with the star occulted. FOS spectra (G190H & G270GH) will be obtained of stars SS2-213 (A5) & SS2-201 (A7), to be used as calibration targets. Spectral features of the disk need to be identified from those of beta Pic (type-A5). In addition, we expect during the reduction of the disk spectra to subtract the spectra obtained of alpha Pic (type-A7). This step may introduce false absorption features. We estmate a 1000 second exposure with the G190H & G270H gratings will yield ~400 cts. at 2300 Angstrom\\ and ~1500 cts. at 3100 Angstrom\\ for SS2-213 (A5), and ~400 cts. at 2300 Angstrom\\ and ~2000 cts at 3100 Angstrom\\ for SS2-201 (A7). These count rates are for quarter-step pixel. The S/N will range from ~20 to ~40. Each visit to a Calibration star will follow a 2-orbit sequence. First Orbit: 7.5 minutes for guide star acquisition FOS ACQ/BINARY acquisition 4.3" aperture (2.1 sec) FOS ACQ/PEAK 5x5 search upper 0.25-PAIR aperture (2.0 sec/dwell point) FOS ACQ/PEAK 5x5 search upper 0.25-PAIR aperture (2.0 sec/dwell point) total overhead 43 minutes Second Orbit: 6 minutes for guide star reacquisition 1000 second ACCUM G190H upper 0.5 -PAIR aperture 1000 second ACCUM G270H upper 0.5-PAIR aperture 10 minutes of overhead Cycle 6 Calibration Orbits: 4 Exposures: 4 Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 6470( 8) - 06/04/96 18:11 - [ 3] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6470( 8) - 06/04/96 18:11 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HD39060 STAR,A4-A9 III- RA=5H 47M 17.1S +/- 0.01S, DEC=- J2000.0 V=+20 SURF(V) = 16.3 I,PROTOPLANETARY DISK 51D 03' 59.4" +/- 0.1" SURF(B) = 16.6 SURF(R) = 15.9 SURF(I) = 15.9 Comments: Beta Pic proper motion, parallax, V-magnitude=3.85, color index B-V=0.171, spectral type=A5III, and radial velocity obtained from The Hipparcos Input catalogue, EAS SP-1136, 1992. Surface brightness/sq. arcsecond for the circumstellar disk obtained from Paresce and Burrows 1989, Ap.J., 319, L23-L25. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) J2000.0 0.001273 0.079 0.055 2 HD50241 STAR,A4-A9 V-IV RA=6H 48M 11.437S +/- 0.01S, J2000.0 V=+20.6 V = 3.266+/-0.05 DEC=-61D 56' 28.95" +/- 0.1" TYPE=A7IV B-V = 0.225+/-0.19 Comments: Alpha Pic proper motion, parallax, V-magnitude=3.266, color index B-V=0.225, spectral type=A7IV, and radial velocity obtained from The Hipparcos Input catalogue, EAS SP-1136, 1992. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) J2000.0 -0.007319 0.269 0.046 3 SS2-201 STAR RA=12H 44M 20.45S +/- 0.01S, J2000.0 B = 12.5+/-0.05 DEC=33D 36' 12.59" +/- 0.1", TYPE=A7IV PLATE-ID=01PQ Comments: SS2-201 blue magnitude and spectral type obtained from Sanduleak, N. 1988, Ap.J.Suppl.Ser., 66, 309. Blue magnitude is an eye estimate of the image density combined with image diameters on POSS O-prints. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1983.13305 0.0 0.0 0.0 4 SS2-213 STAR RA=12H 48M 55.81S +/- 0.01S, J2000.0 B = 13.0+/-0.05 DEC=33D 19' 34.72" +/- 0.1", TYPE=A5IV PLATE-ID=01PQ Comments: SS2-213 blue magnitude and spectral type obtained from Sanduleak, N. 1988, Ap.J.Suppl.Ser., 66, 309. Blue magnitude is an eye estimate of the image density combined with image diameters on POSS O-prints. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1983.13305 0.0 0.0 0.0 6470( 8) - 06/04/96 18:11 - [ 5] Visit: 01 Visit Requirements: PCS MODE Fine ORIENT 208D TO 228D GROUP 1-2 WITHIN 30D On Hold Comments: Additional Comments: Offset angle used for the ORIENT calculation was 8.2 degreees as defined for the FOS/BL paired apertures. The disk is aligned NNE to SSW (30 deg. and 210 deg.). An of 208D to 228D is also an exceptable range for ORIENT. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 HD39060 FOS/BL ACQ/PEA 4.3 G130H SCAN-STEP-Y=1.23,SEARCH-SIZE-Y=3, 1 3 S ONBOARD ACQ FOR 2 K SEARCH-SIZE-X=1 Comments: Stage 1 of 4 stage peakup ------------------------------------------------------------------------------------------------------------------------------------ 2 HD39060 FOS/BL ACQ/PEA 1.0-PAI G130H SCAN-STEP-Y=0.602, 1 3 S ONBOARD ACQ FOR 3 K R-A SCAN-STEP-X=0.602,SEARCH-SIZE-Y=2 ,SEARCH-SIZE-X=6 Comments: Stage 2 of 4 stage peakup. ------------------------------------------------------------------------------------------------------------------------------------ 3 HD39060 FOS/BL ACQ/PEA 0.5-PAI G190H SCAN-STEP-Y=0.3,SCAN-STEP-X=0.3, 1 1 S ONBOARD ACQ FOR 4 K R-A SEARCH-SIZE-Y=3,SEARCH-SIZE-X=3 Comments: Stage 3 of 4 stage peakup. ------------------------------------------------------------------------------------------------------------------------------------ 4 HD39060 FOS/BL ACQ/PEA 0.25-PA G190H SCAN-STEP-Y=0.172, 1 1 S ONBOARD ACQ FOR 5-6 K IR-A SCAN-STEP-X=0.172,SEARCH-SIZE-Y=3 ,SEARCH-SIZE-X=3 Comments: Stage 4 of 4 stage peakup. ------------------------------------------------------------------------------------------------------------------------------------ 5 HD39060 FOS/BL RAPID 0.5-PAI G190H READ-TIME=60.0,SUB-STEP=4, 1 2880 S POS TARG 0.0078,-1.3075 R-A STEP-PATT=OBJ-OBJ Comments: Spectra will be read from each aperture. The exposure will be split into 30sec of integration time in each aperture. POS TARG to position star between apertures. ------------------------------------------------------------------------------------------------------------------------------------ 6 HD39060 FOS/BL RAPID 0.5-PAI G270H READ-TIME=60.0,SUB-STEP=4, 1 2880 S SAME POS AS 5 R-A STEP-PATT=OBJ-OBJ Comments: Spectra will be read from each aperture. The exposure will be split into 30sec of integration time in each aperture. ------------------------------------------------------------------------------------------------------------------------------------ 6470( 8) - 06/04/96 18:11 - [ 6] Visit: 02 Visit Requirements: PCS MODE Fine On Hold Comments: Additional Comments: We wish to have this visit scheduled close in time to visit one since we plan to subtact the Alpha-Pic spectra from the Beta-Pic one. In doing so we would like to keep the light path through HST to be as identical as possible for visits 1 & 2. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 HD50241 FOS/BL ACQ/PEA 4.3 G130H SCAN-STEP-Y=1.23,SEARCH-SIZE-Y=3, 1 3 S ONBOARD ACQ FOR 2 K SEARCH-SIZE-X=1 Comments: Stage 1 of 4 stage peakup ------------------------------------------------------------------------------------------------------------------------------------ 2 HD50241 FOS/BL ACQ/PEA 1.0-PAI G130H SCAN-STEP-Y=0.602, 1 3 S ONBOARD ACQ FOR 3 K R-A SCAN-STEP-X=0.602,SEARCH-SIZE-Y=2 ,SEARCH-SIZE-X=6 Comments: Stage 2 of 4 stage peakup. ------------------------------------------------------------------------------------------------------------------------------------ 3 HD50241 FOS/BL ACQ/PEA 0.5-PAI G190H SCAN-STEP-Y=0.3,SCAN-STEP-X=0.3, 1 1 S ONBOARD ACQ FOR 4 K R-A SEARCH-SIZE-Y=3,SEARCH-SIZE-X=3 Comments: Stage 3 of 4 stage peakup. ------------------------------------------------------------------------------------------------------------------------------------ 4 HD50241 FOS/BL ACQ/PEA 0.25-PA G190H SCAN-STEP-Y=0.172, 1 1 S ONBOARD ACQ FOR 5-6 K IR-A SCAN-STEP-X=0.172,SEARCH-SIZE-Y=3 ,SEARCH-SIZE-X=3 Comments: Stage 4 of 4 stage peakup. ------------------------------------------------------------------------------------------------------------------------------------ 5 HD50241 FOS/BL RAPID 0.5-PAI G190H READ-TIME=60.0,SUB-STEP=4, 1 2880 S POS TARG 0.0078,-1.3075 R-A STEP-PATT=OBJ-OBJ Comments: Spectra will be read from each aperture. The exposure will be split into 30sec of integration time in each aperture. POS TARG to position star between apertures. ------------------------------------------------------------------------------------------------------------------------------------ 6 HD50241 FOS/BL RAPID 0.5-PAI G270H READ-TIME=60.0,SUB-STEP=4, 1 2880 S SAME POS AS 5 R-A STEP-PATT=OBJ-OBJ Comments: Spectra will be read from each aperture. The exposure will be split into 30sec of integration time in each aperture. ------------------------------------------------------------------------------------------------------------------------------------ 6470( 8) - 06/04/96 18:11 - [ 7] Visit: 03 Visit Requirements: PCS MODE Fine 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 SS2-201 FOS/BL ACQ/BIN 4.3 MIRROR 1 1.75 S ONBOARD ACQ FOR 2 ARY Comments: A normal BINARY. ------------------------------------------------------------------------------------------------------------------------------------ 2 SS2-201 FOS/BL ACQ/PEA 0.25-PA MIRROR SCAN-STEP-X=0.17,SCAN-STEP-Y=0.17 1 2.0 S ONBOARD ACQ FOR 3 K IR-A ,SEARCH-SIZE-X=5,SEARCH-SIZE-Y=5, TYPE=UP ------------------------------------------------------------------------------------------------------------------------------------ 3 SS2-201 FOS/BL ACQ/PEA 0.25-PA MIRROR SCAN-STEP-X=0.052, 1 2.0 S ONBOARD ACQ FOR 4-5 K IR-A SCAN-STEP-Y=0.052,SEARCH-SIZE-X=5 ,SEARCH-SIZE-Y=5,TYPE=UP ------------------------------------------------------------------------------------------------------------------------------------ 4 SS2-201 FOS/BL ACCUM 0.5-PAI G190H 1 900 S R-A Comments: Spectra will be read from the upper aperture. ------------------------------------------------------------------------------------------------------------------------------------ 5 SS2-201 FOS/BL ACCUM 0.5-PAI G270H 1 900 S R-A Comments: Spectra will be read from the upper aperture. ------------------------------------------------------------------------------------------------------------------------------------ 6470( 8) - 06/04/96 18:11 - [ 8] Visit: 04 Visit Requirements: PCS MODE Fine 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 SS2-213 FOS/BL ACQ/BIN 4.3 MIRROR 1 2.54 S ONBOARD ACQ FOR 2 ARY Comments: A normal BINARY. ------------------------------------------------------------------------------------------------------------------------------------ 2 SS2-213 FOS/BL ACQ/PEA 0.25-PA MIRROR SCAN-STEP-X=0.17,SCAN-STEP-Y=0.17 1 2.0 S ONBOARD ACQ FOR 3-4 K IR-A ,SEARCH-SIZE-X=5,SEARCH-SIZE-Y=5, TYPE=UP ------------------------------------------------------------------------------------------------------------------------------------ 3 SS2-213 FOS/BL ACQ/PEA 0.25-PA MIRROR SCAN-STEP-X=0.052, 1 2.0 S ONBOARD ACQ FOR 4-5 K IR-A SCAN-STEP-Y=0.052,SEARCH-SIZE-X=5 ,SEARCH-SIZE-Y=5,TYPE=UP ------------------------------------------------------------------------------------------------------------------------------------ 4 SS2-213 FOS/BL ACCUM 0.5-PAI G190H 1 900 S R-A Comments: Spectra will be read from the upper aperture. ------------------------------------------------------------------------------------------------------------------------------------ 5 SS2-213 FOS/BL ACCUM 0.5-PAI G270H 1 900 S R-A Comments: Spectra will be read from the upper aperture. ------------------------------------------------------------------------------------------------------------------------------------ 6470( 8) - 06/04/96 18:11 - [ 9] Summary Form for Proposal 6470 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/BL ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/PEAK RAPID ACQ/BINARY ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SCAN-STEP-Y=1.23 SEARCH-SIZE-Y=3 SEARCH-SIZE-X=1 SEARCH-SIZE-X=6 SEARCH-SIZE-X=3 SCAN-STEP-X=0.172 STEP-PATT=OBJ-OBJ SUB-STEP=4 SEARCH-SIZE-Y=2 SCAN-STEP-X=0.3 SCAN-STEP-Y=0.172 READ-TIME=60.0 TYPE=UP SEARCH-SIZE-Y=5 SEARCH-SIZE-X=5 SCAN-STEP-Y=0.052 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category BINARIES AND STAR FORMATION ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PCS MODE Fine ORIENT 208D TO 228D GROUP 1-2 WITHIN 30D ONBOARD ACQ FOR 2 ONBOARD ACQ FOR 3 ONBOARD ACQ FOR 4 ONBOARD ACQ FOR 5-6 POS TARG 0.0078,-1.3075 SAME POS AS 5 PCS MODE Fine ONBOARD ACQ FOR 4-5 ONBOARD ACQ FOR 3-4 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G130H G190H G270H MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD39060 HD50241 SS2-201 SS2-213 ------------------------------------------------------------------------------------------------------------------------------------