9062( 5) - 08/17/01 11:56 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 9062 Version: 5 Check-in Date: 17-Aug-2001 11:55:49 1.Proposal Title: Observations of Comet Borrelly to Support the New Millennium/DS1 Flyby Occurring 23 September 2001 ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 10 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: S. Stern Southwest Research Institute CoI: Dr. Roland Meier Xerox Corp. N CoI: Dr. Robert M. Nelson Jet Propulsion Laboratory N CoI: Dr. Juergen Oberst DLR N CoI: Dr. Joel Wm. Parker Southwest Research Institute N CoI: Dr. Bill R. Sandel University of AZ N CoI: Dr. Larry Soderblom USGS N CoI: Dr. Nicholas Thomas Max Planck Institute fuer Aeronomie N CoI: Dr. Joseph J. Wang JPL N CoI: Dr. Harold Weaver Johns-Hopkins University N CoI: Dr. David T. Young University of Michigan N CoI: Dr. Roger V. Yelle Northern Arizona University N CoI: Dr. Mike A'Hearn University of Maryland N CoI: Dr. Frances Bagenal University of Colorado N CoI: Dr. Daniel C. Boice Southwest Research Institute N CoI: Dr. Daniel T. Britt University of Tennessee N CoI: Dr. Robert H. Brown University of Arizona N CoI: Dr. Bonnie J. Buratti Jet Propulsion Laboratory N CoI: Dr. Frank Crary University of Michigan N CoI: Dr. Paul Feldman Johns-Hopkins University N CoI: Dr. Michel Festou Obs Midi-Pyrenees N CoI: Dr. Wing-Huen Ip MPAe N ------------------------------------------------------------------------------------ 5. Abstract The New Millenium Program (NMP) Deep Space 1 asteroid-comet flyby mission is now en route to comet 19P/Borrelly for a late September 2001 flyby. DS1 carries particle and field instruments, a monochrome imager, and an IR imaging spectrometer; its UV spectrometer is inoperable. On behalf of the DS1 Science Team, we request STIS imagery and spectroscopy of comet Borrelly at the time of the DS1 encounter in order to provide both support science and context for the flyby datasets; the proposed Borrelly observations will also reveal important new information relating to the intriguing carbon- depletion in this bright, well-known comet with an origin in the Kuiper Belt. ------------------------------------------------------------------------------------ 9062( 5) - 08/17/01 11:56 - [ 2] Observations Description ------------------------ The DS1 encounter with 19P/Borrelly will occur on 2001 Sep 22 UTC 22:30 (22:42 UTC light travel time corrected). On 23 Sep 2001, Borrelly will be 1.36 AU from the Sun, 1.48 AU from Earth, and the Sun-Earth-Borrelly angle will be 63 deg. The comet will be within 0.01 AU of perihelion, and fully within HST's observing constraints. Borrelly's RA and Dec rates on the sky (120 and 33 arcsec/hr, respectively, i.e., a combined rate of <1 arcsec/sec) are small, and well within our experience base using HST/STIS. \medskip As described above, we wish to obtain STIS/MAMA spectra using G140L and G230L, as well as continuum STIS/CCD imagery to document coma dust's morphology before and after the spectra are obtained. \medskip The G140L exposure time requirement is defined to achieve an SNR=5 on the strongest (i.e., (1, 0)) CO band, which occurs at 1510 Angstrom. Based on our experience with HST observations of comets, we adopt the 0.2" slit for the STIS spectroscopy; this slit provides the resolution needed to pull out the CO Fourth Positive bands above scattered H LyAlpha. Assuming a typical water production rate of 5times10^28 sec for Borrelly at perihelion (A'Hearn et al. 1995), and a (conservatively low) CO/H_2O ratio of 2 (averaged over a 0.2x0.5" extraction, centered on the coma). The STIS ETC reveals that this signal will require some 100 min of exposure time to achieve SNR=5.footnoteBy the way, we note that ground-based, IR observations of CO in 19P/Borrelly near the time of the DS1 encounter will be severely limited by the poor geocentric radial velocity (dotDelta~-7.8 km s^- 1) at that time, which is not a problem for the HST observations. Now consider the G230L observations. For the OH itself, we expect a 3 KiloRayleigh (0-0) band signal in the 25x0.2" STIS slit. Because the time required to obtain a nice (SNR=10) measurement of this signal is just seconds, we opt to invest the time to detect the weaker CS, as a guide to the C-depletion problem described in the Scientific Justification; we estimate that for a typical 1000:1 H_2O:CS abundance ratio (e.g., Mumma et al. 1993), a CS (0-0, 2575 Angstrom) signal of ~150 will be generated; this signal can be measured in 30 min of integration time at SNR=7. \medskip Summarizing, we thus wish to obtain: (i) 100 min of G140L STIS/FUV integration using the 0.2" slit to cover the 1150-- 1700 Angstrom\ region, (ii) 60 min G230L STIS/NUV integration using the same slit to cover the 1600--3100 Angstrom\ region, and short bracketing (<1 min) STIS/IMAGE exposures using the F28x50LP filter (over a 28x50" FOV; pixel scale of 110 km/pixel) to document the real time inner coma morphology as seen from HST's position orbiting Earth at the start and the end of our observing sequence.footnoteCoI Weaver's observations of Hale-Bopp with STIS have shown that this is an excellent filter for cometary broadband imagery. As described below, a 4 orbit observation sequence is required (including overheads) to obtain this dataset. \medskip Based on HST's orbit, one estimates there will be a minimum of 48 minutes of observing time per orbit for Borrelly (see Table 6.1, HST Cycle 10 Primer). We pessimistically estimate that 6 minutes will be taken up by Guide Star Acq each observing orbit. The bracketing STIS/CCD images will require a total of 6 min each, including overheads. The G140L observation can thus, after Guide Star Acq, the CCD image, and an 8 min overhead for STIS/MAMA startup, obtain some 48-6-6-8=28 min of integration time on orbit 1. On each of orbits 2 and 3, the STIS/MAMA G140L can obtain another 34 min of G140L integration, after accountin for GS Acq and STIS overheads, giving a total of 96 min using G140L. On orbit 4 we will again acquire Borrelly (6 min), take 1 min to cover STIS overheads for continuing the G230L integration, and 6 min (at the end) to obtain the second and last CCD image of the 4- orbit sequence. This leaves 48-6-1-6=35 min for G230L integration, slightly exceeding our 30 min requirement. \medskip We are requesting a total of 8 orbits, in two 4- orbit blocks some 12+/-6 hours on either side of the DS1 encounter, in order to obtain information on the first-order time variation in H_2O and CO production rates around the time of the flyby. Although we hope that both 4- orbit sequences can be awarded by the TAC, we recognize that oversubscription is high on HST. Therefore, we point out that a minimum program, consisting of a single 4-orbit sequence on encounter day would be sufficient to meet the primary objectives in support of DS1. Real Time Justification ----------------------- In order to obtain our observations in conjunction with the DS1 flyby of Borrelly, this is necessarily a time-critical proposal. We stress, however, our requirement is not to observe during the actual orbit of HST when DS1 makes its closest approach. Instead, we desire to observe 36+/-11 hours before the DS1 closest approach and 11+/-11 hours after DS1 closest approach. We suppose that the DS1 encounter itself is also a coordinated observation. More seriously, a campaign to observe Borrelly during the period leading up to and then following the DS1 encounter is being designed. DS1 Science team members D. Boice, D. Britt, B. Buratti, R. Meier, and J. Oberst are coordinating that campaign. Proposals to Chandra and a mm-wave bolometer facility have already been submitted (FUSE, we note, cannot observe Borrelly owing to its near 80 deg sun avoidance angle constraint); a groundbased imaging and spectroscopy campaign will be organized early in 2001. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 9062( 5) - 08/17/01 11:56 - [ 3] TARGET LIST Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 | TARGET NAME: BORRELLY ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: COMET 19P/Borrelly ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | TYPE=COMET,Q=1.358202453,E=0.623896623,I | =30.324665,O=75.4248303,W=353.3758642,T | = 14-Sep- | 2001:17:33:20.2,EQUINOX=J2000,EPOCH=08- | Sep-2001,A1=3.84E-10,A2=-3.86E-10 | | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 9.2 | Orbit elements are from Horizons, | based on JPL#K013/44 values. | Ephemeris Uncertainty: 10000 KM | Acquisition Uncertainty: 10 " | ------------------------------------------------------------------------------------------------------------------------------------ 9062( 5) - 08/17/01 11:56 - [ 4] Visit: 01 Visit Priority: Visit Requirements: BETWEEN 20-Sep-2001:23:42:00.0 AND 21-Sep-2001:21:43:00.0 SEQ 01, 02, 03, 04 WITHIN 4 Orbits On Hold Comments: Additional Comments: The Special Requirement for the timing of this visit is imposed by the need to have the HST observations occur 36+/-11 hours BEFORE the DS1 encounter with Borrelly, which is expected to occur at 2001 Sep 22 UTC 22:30 (UTC 22:42 light travel time corrected) with a current uncertainty of about 17 minutes. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 11 BORRELLY STIS/C ACQ F28X50L MIRROR 1 30 S REQ EPHEM CORR OFF1 CD P ------------------------------------------------------------------------------------------------------------------------------------ 12 BORRELLY STIS/F TIME-TA 52X0.2 G140L 1425 BUFFER-TIME=500 1 35 M REQ EPHEM CORR OFF1 UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 9062( 5) - 08/17/01 11:56 - [ 5] Visit: 02 Visit Priority: Visit Requirements: BETWEEN 20-Sep-2001:23:42:00.0 AND 21-Sep-2001:21:43:00.0 SEQ 01, 02, 03, 04 WITHIN 4 Orbits On Hold Comments: Additional Comments: The Special Requirement for the timing of this visit is imposed by the need to have the HST observations occur 36+/-11 hours BEFORE the DS1 encounter with Borrelly, which is expected to occur at 2001 Sep 22 UTC 22:30 (UTC 22:42 light travel time corrected) with a current uncertainty of about 17 minutes. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 21 BORRELLY STIS/C ACQ F28X50L MIRROR 1 30 S REQ EPHEM CORR OFF2 CD P ------------------------------------------------------------------------------------------------------------------------------------ 22 BORRELLY STIS/N TIME-TA 52X0.5 G230L 2376 BUFFER-TIME=500 1 27 M REQ EPHEM CORR OFF2 UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 23 BORRELLY STIS/C ACCUM F28X50L MIRROR GAIN=4,CR-SPLIT=NO 1 30 S REQ EPHEM CORR OFF2 CD P Comments: We are stting the GAIN=4 to increase dynamic range, and also so these images will have the same gain as the ACQ images. ------------------------------------------------------------------------------------------------------------------------------------ 9062( 5) - 08/17/01 11:56 - [ 6] Visit: 03 Visit Priority: Visit Requirements: BETWEEN 20-Sep-2001:23:42:00.0 AND 21-Sep-2001:21:43:00.0 SEQ 01, 02, 03, 04 WITHIN 4 Orbits On Hold Comments: Additional Comments: The Special Requirement for the timing of this visit is imposed by the need to have the HST observations occur 36+/-11 hours BEFORE the DS1 encounter with Borrelly, which is expected to occur at 2001 Sep 22 UTC 22:30 (UTC 22:42 light travel time corrected) with a current uncertainty of about 17 minutes. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 31 BORRELLY STIS/C ACQ F28X50L MIRROR 1 30 S REQ EPHEM CORR OFF3 CD P ------------------------------------------------------------------------------------------------------------------------------------ 32 BORRELLY STIS/F TIME-TA 52X0.2 G140L 1425 BUFFER-TIME=500 1 35 M REQ EPHEM CORR OFF3 UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 9062( 5) - 08/17/01 11:56 - [ 7] Visit: 04 Visit Priority: Visit Requirements: BETWEEN 20-Sep-2001:23:42:00.0 AND 21-Sep-2001:21:43:00.0 SEQ 01, 02, 03, 04 WITHIN 4 Orbits On Hold Comments: Additional Comments: The Special Requirement for the timing of this visit is imposed by the need to have the HST observations occur 36+/-11 hours BEFORE the DS1 encounter with Borrelly, which is expected to occur at 2001 Sep 22 UTC 22:30 (UTC 22:42 light travel time corrected) with a current uncertainty of about 17 minutes. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 41 BORRELLY STIS/C ACQ F28X50L MIRROR 1 30 S REQ EPHEM CORR OFF4 CD P ------------------------------------------------------------------------------------------------------------------------------------ 42 BORRELLY STIS/N TIME-TA 52X0.5 G230L 2376 BUFFER-TIME=500 1 27 M REQ EPHEM CORR OFF4 UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 43 BORRELLY STIS/C ACCUM F28X50L MIRROR GAIN=4,CR-SPLIT=NO 1 30 S REQ EPHEM CORR OFF4 CD P Comments: We are setting the GAIN=4 to increase dynamic range, and also so these images will have the same gain as the ACQ images. ------------------------------------------------------------------------------------------------------------------------------------ 9062( 5) - 08/17/01 11:56 - [ 8] Visit: 05 Visit Priority: Visit Requirements: BETWEEN 22-Sep-2001:22:42:00.0 AND 23-Sep-2001:20:42:00.0 SEQ 05, 06, 07, 08 WITHIN 7 Orbits On Hold Comments: Additional Comments: The Special Requirement for the timing of this visit is imposed by the need to have the HST observations occur 11+/-11 hours AFTER the DS1 encounter with Borrelly, which is expected to occur at 2001 Sep 22 UTC 22:30 (UTC 22:42 light travel time corrected) with a current uncertainty of about 17 minutes. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 51 BORRELLY STIS/C ACQ F28X50L MIRROR 1 30 S REQ EPHEM CORR OFF5 CD P ------------------------------------------------------------------------------------------------------------------------------------ 52 BORRELLY STIS/F TIME-TA 52X0.2 G140L 1425 BUFFER-TIME=500 1 35 M REQ EPHEM CORR OFF5 UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 9062( 5) - 08/17/01 11:56 - [ 9] Visit: 06 Visit Priority: Visit Requirements: BETWEEN 22-Sep-2001:22:42:00.0 AND 23-Sep-2001:20:42:00.0 SEQ 05, 06, 07, 08 WITHIN 7 Orbits On Hold Comments: Additional Comments: The Special Requirement for the timing of this visit is imposed by the need to have the HST observations occur 11+/-11 hours AFTER the DS1 encounter with Borrelly, which is expected to occur at 2001 Sep 22 UTC 22:30 (UTC 22:42 light travel time corrected) with a current uncertainty of about 17 minutes. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 61 BORRELLY STIS/C ACQ F28X50L MIRROR 1 30 S REQ EPHEM CORR OFF6 CD P ------------------------------------------------------------------------------------------------------------------------------------ 62 BORRELLY STIS/N TIME-TA 52X0.5 G230L 2376 BUFFER-TIME=500 1 27 M REQ EPHEM CORR OFF6 UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 63 BORRELLY STIS/C ACCUM F28X50L MIRROR GAIN=4,CR-SPLIT=NO 1 30 S REQ EPHEM CORR OFF6 CD P Comments: We are stting the GAIN=4 to increase dynamic range, and also so these images will have the same gain as the ACQ images. ------------------------------------------------------------------------------------------------------------------------------------ 9062( 5) - 08/17/01 11:56 - [ 10] Visit: 07 Visit Priority: Visit Requirements: BETWEEN 22-Sep-2001:22:42:00.0 AND 23-Sep-2001:20:42:00.0 SEQ 05, 06, 07, 08 WITHIN 7 Orbits On Hold Comments: Additional Comments: The Special Requirement for the timing of this visit is imposed by the need to have the HST observations occur 11+/-11 hours AFTER the DS1 encounter with Borrelly, which is expected to occur at 2001 Sep 22 UTC 22:30 (UTC 22:42 light travel time corrected) with a current uncertainty of about 17 minutes. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 71 BORRELLY STIS/C ACQ F28X50L MIRROR 1 30 S REQ EPHEM CORR OFF7 CD P ------------------------------------------------------------------------------------------------------------------------------------ 72 BORRELLY STIS/F TIME-TA 52X0.2 G140L 1425 BUFFER-TIME=500 1 35 M REQ EPHEM CORR OFF7 UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 9062( 5) - 08/17/01 11:56 - [ 11] Visit: 08 Visit Priority: Visit Requirements: BETWEEN 22-Sep-2001:22:42:00.0 AND 23-Sep-2001:20:42:00.0 SEQ 05, 06, 07, 08 WITHIN 7 Orbits On Hold Comments: Additional Comments: The Special Requirement for the timing of this visit is imposed by the need to have the HST observations occur 11+/-11 hours AFTER the DS1 encounter with Borrelly, which is expected to occur at 2001 Sep 22 UTC 22:30 (UTC 22:42 light travel time corrected) with a current uncertainty of about 17 minutes. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 81 BORRELLY STIS/C ACQ F28X50L MIRROR 1 30 S REQ EPHEM CORR OFF8 CD P ------------------------------------------------------------------------------------------------------------------------------------ 82 BORRELLY STIS/N TIME-TA 52X0.5 G230L 2376 BUFFER-TIME=500 1 27 M REQ EPHEM CORR OFF8 UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 83 BORRELLY STIS/C ACCUM F28X50L MIRROR GAIN=4,CR-SPLIT=NO 1 30 S REQ EPHEM CORR OFF8 CD P Comments: We are setting the GAIN=4 to increase dynamic range, and also so these images will have the same gain as the ACQ images. ------------------------------------------------------------------------------------------------------------------------------------ 9062( 5) - 08/17/01 11:56 - [ 12] Summary Form for Proposal 9062 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F28X50LP 52X0.2 52X0.5 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD STIS/FUV-MAMA STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ TIME-TAG ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=500 CR-SPLIT=NO GAIN=4 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 20-Sep-2001 23 42 00.0 AND 21-Sep-2001 21 43 00.0 SEQ 01, 02, 03, 04 WITHIN 4 Orbits REQ EPHEM CORR OFF1 BETWEEN 20-Sep-2001 23 42 00.0 AND 21-Sep-2001 21 43 00.0 SEQ 01, 02, 03, 04 WITHIN 4 Orbits REQ EPHEM CORR OFF2 BETWEEN 20-Sep-2001 23 42 00.0 AND 21-Sep-2001 21 43 00.0 SEQ 01, 02, 03, 04 WITHIN 4 Orbits REQ EPHEM CORR OFF3 BETWEEN 20-Sep-2001 23 42 00.0 AND 21-Sep-2001 21 43 00.0 SEQ 01, 02, 03, 04 WITHIN 4 Orbits REQ EPHEM CORR OFF4 BETWEEN 22-Sep-2001 22 42 00.0 AND 23-Sep-2001 20 42 00.0 SEQ 05, 06, 07, 08 WITHIN 7 Orbits REQ EPHEM CORR OFF5 BETWEEN 22-Sep-2001 22 42 00.0 AND 23-Sep-2001 20 42 00.0 SEQ 05, 06, 07, 08 WITHIN 7 Orbits REQ EPHEM CORR OFF6 BETWEEN 22-Sep-2001 22 42 00.0 AND 23-Sep-2001 20 42 00.0 SEQ 05, 06, 07, 08 WITHIN 7 Orbits REQ EPHEM CORR OFF7 BETWEEN 22-Sep-2001 22 42 00.0 AND 23-Sep-2001 20 42 00.0 SEQ 05, 06, 07, 08 WITHIN 7 Orbits REQ EPHEM CORR OFF8 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G140L G230L ------------------------------------------------------------------------------------------------------------------------------------ Target Names BORRELLY ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 1425 2376 ------------------------------------------------------------------------------------------------------------------------------------