9302( 5) - 09/11/02 06:44 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 9302 Version: 5 Check-in Date: 11-Sep-2002 06:43:13 1.Proposal Title: Comet Hale-Bopp at large heliocentric distance ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GTO/ACS 11 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Holland Ford The Johns Hopkins University CoI: Paul Feldman Johns Hopkins University Y ------------------------------------------------------------------------------------ 5. Abstract The objective is to determine the size, shape, and possible presence of a small, possibly bound, companion. The latter has been reported by Marchis et al. using the ADONIS adaptive optics system on the ESO 3.6 meter telescope. They claim separations of the two components of 0.23'' (November 1997) and 0.36'' (January 1998) when the comet was 3.3 and 4.1 AU from the Sun. Such a companion is not evident in any STIS images recorded by Weaver et al., but these were single snapshots in time and the companion may have been occulted. The discovery of a bound companion, and the subsequent determination of its orbital period, would provide the first determination of a cometary mass and the density of a cometary nucleus. At large heliocentric distances there will still be residual dust coma so the highest possible spatial resolution (HRC near 300 nm) is needed to model the coma and photometrically isolate the nucleus. The near infrared is best suited for evaluation of the spatial distribution of the dust coma. With proper choice of filter it is also possible to search for a gas coma (CN at 388 nm). Ideally the comet should be imaged over a complete 11.3 hour rotation period, but a half period would be sufficient to obtain an idea of the shape of the reflecting body. Hale-Bopp is visible throughout 2002. During the period 1 March 2002 to 28 February 2003 the heliocentric distance increases from 15.2 to 17.3 AU. The expected nucleus magnitude (visible) is 16.5-17.0 ------------------------------------------------------------------------------------ 9302( 5) - 09/11/02 06:44 - [ 2] Observations Description ------------------------ The sequence of observations is as follows: In each of two visits, the comet is imaged in the HRC in both the near-ultraviolet and the red. Increased dynamic range is obtained with F330W by taking two images differing in exposure time by a factor of 10. In addition, a red image is also obtained with the WFC to serve as a continuum background for a WFC exposure centered on the CN band at 3883 A using a ramp filter. The CN image is taken during the first visit. An off-band exposure (at 3720 A) is also taken during the second visit. Real Time Justification ----------------------- None Calibration Justification ------------------------- None Additional Comments ------------------- None ------------------------------------------------------------------------------------ 9302( 5) - 09/11/02 06:44 - [ 3] TARGET LIST Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 | TARGET NAME: HALE-BOPP ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: COMET Hale-Bopp ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | TYPE=COMET,Q=0.923833746,E=0.994978756,I | =89.4451741,O=282.228075,W=130.737792,T | = 31-Mar- | 1997:01:37:13.0,EQUINOX=J2000,EPOCH=01- | Oct-2002 | | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 17+/-2 | V-mag is for the nucleus. These B-V = 0.8 | elements are from JPL-192 updated 10 V-R = 0.4 | Sept 2002 with geometric osculating | elements for the current epoch. | Ephemeris Uncertainty: 25000 KM | Acquisition Uncertainty: 10 " | ------------------------------------------------------------------------------------------------------------------------------------ 9302( 5) - 09/11/02 06:44 - [ 4] Visit: 01 Visit Priority: Visit Requirements: SCHED 100% SEQ 1-2 WITHIN 2ORBITS 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 ------------------------------------------------------------------------------------------------------------------------------------ 11 HALE-BOPP ACS/HR ACCUM HRC F330W CR-SPLIT=2 1 20.0 S C ------------------------------------------------------------------------------------------------------------------------------------ 12 HALE-BOPP ACS/HR ACCUM HRC F330W CR-SPLIT=2 1 200.0 S C ------------------------------------------------------------------------------------------------------------------------------------ 13 HALE-BOPP ACS/HR ACCUM HRC F814W CR-SPLIT=NO 1 3.0 S C ------------------------------------------------------------------------------------------------------------------------------------ 14 HALE-BOPP ACS/HR ACCUM HRC F814W CR-SPLIT=2 1 30.0 S C ------------------------------------------------------------------------------------------------------------------------------------ 21 HALE-BOPP ACS/WF ACCUM WFC F814W CR-SPLIT=NO 1 5.0 S SAME POS AS 22 C ------------------------------------------------------------------------------------------------------------------------------------ 22 HALE-BOPP ACS/WF ACCUM WFC FR388N 3883.0 CR-SPLIT=2 1 700.0 S C ------------------------------------------------------------------------------------------------------------------------------------ 9302( 5) - 09/11/02 06:44 - [ 5] Visit: 02 Visit Priority: Visit Requirements: 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 ------------------------------------------------------------------------------------------------------------------------------------ 31 HALE-BOPP ACS/HR ACCUM HRC F330W CR-SPLIT=2 1 20.0 S C ------------------------------------------------------------------------------------------------------------------------------------ 32 HALE-BOPP ACS/HR ACCUM HRC F330W CR-SPLIT=2 1 200.0 S C ------------------------------------------------------------------------------------------------------------------------------------ 33 HALE-BOPP ACS/HR ACCUM HRC F814W CR-SPLIT=NO 1 3.0 S C ------------------------------------------------------------------------------------------------------------------------------------ 34 HALE-BOPP ACS/HR ACCUM HRC F814W CR-SPLIT=2 1 30.0 S C ------------------------------------------------------------------------------------------------------------------------------------ 41 HALE-BOPP ACS/WF ACCUM WFC F814W CR-SPLIT=NO 1 5.0 S SAME POS AS 42 C ------------------------------------------------------------------------------------------------------------------------------------ 42 HALE-BOPP ACS/WF ACCUM WFC FR388N 3720.0 CR-SPLIT=2 1 900.0 S C ------------------------------------------------------------------------------------------------------------------------------------ 9302( 5) - 09/11/02 06:44 - [ 6] Summary Form for Proposal 9302 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures HRC WFC ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/HRC ACS/WFC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=2 CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GTO/ACS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements SCHED 100% SEQ 1-2 WITHIN 2ORBITS SAME POS AS 22 SAME POS AS 42 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F330W F814W FR388N ------------------------------------------------------------------------------------------------------------------------------------ Target Names HALE-BOPP ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 3883.0 3720.0 ------------------------------------------------------------------------------------------------------------------------------------