7428( 12) - 12/31/97 14:43 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 7428 Version: 12 Check-in Date: 31-Dec-1997 14:41:40 1.Proposal Title: The nucleus of comet 55P/Tempel-Tuttle, the parent of the Leonid Meteors ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 7 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: PHILIPPE LAMY LABORATOIRE D'ASTRONOMIE SPATIALE CoI: Michael A'HEARN University of Maryland N CoI: Martin BEECH University of Western Ontario N CoI: Peter BROWN University of Western Ontario N CoI: Laurent JORDA Max-Planck-Institut fur Aeronomie N CoI: Uwe KELLER Max-Planck-Institut fur Aeronomie N CoI: Imre TOTH Konkoly Observatory N CoI: Harold WEAVER The John Hopkins IUniversity N CoI: Donald YEOMANS Jet Propulsion Laboratory N ------------------------------------------------------------------------------------ 5. Abstract This is the continuation of GO 6621 (PI: M. A'Hearn) which received long-term (2- year) status in cycle 6 to observe the periodic comet 55P/Tempel-Tuttle, the parent of the Leonid meteor stream, whose forthcoming return provides a very rare opportunity to study the nucleus of a P/Halley class comet (P = 33 yr, aphelion = 20 AU) and the relationship of cometary ejection processes to a major meteor stream. The comet comes to perihelion in cycle 7 with an unusually close approach to Earth 40 days before, on 17 January 1998. At the geocentric distance of 0.45 AU, the Planetary Camera will achieve a spatial resolution (2 pixels) of 30 km allowing light from the nucleus to be clearly distinguished from light due to the surrounding coma. Understanding the expected meteor storm in the Leonid shower requires knowledge of the comet's nuclear properties. We plan to measure the B, V, R, I magnitudes of the nucleus in order to derive its color, and we plan to study its rotational properties by measuring its projected cross sections as a function of time. Concurent thermal infrared observations (ISOCAM, ground-based infrared camera) will allow to derive its albedo and in turn its size with very minimal asumptions. The HST images will also enable us to study the circum-nuclear region, in particular, the relationship of the nuclear outgassing and the physical properties of the dust (e.g., its color) to the nuclear rotation. We expect to image possible dust structures and to possibly map the sources of dust on the nucleus. ------------------------------------------------------------------------------------ 7428( 12) - 12/31/97 14:43 - [ 2] Observations Description ------------------------ This program was allocated 4 orbits and each orbit corresponds to a new visit. Labeling the consecutive orbits as 1, 2, 3,..... we want to observe in orbits 1, 3, 5, and 7 which covers a total clock time of about 10.5 hrs (going to the end of the final orbit) with sampling every 1.5 hrs. The comet passes fairly close to the earth, which means that it will have a fast apparent motion. This, of course, severely limits GS selection. The planners should simply try to find a window that allows for the maximum possible observing time to be executed under GS tracking control. As a last resort, we may have to perform some of the observations under GYRO control. Please contact Hal Weaver (weaver@pha.jhu.edu) if you have any questions about the observing plan. Real Time Justification ----------------------- Comet 55P/Tempel-Tuttle must be observed on 10 January 1998 - 8/+2 days, a time interval resulting from a compromise between spatial resolution, phase angle and apparent motion as explained above. We shall propose for ground-based observing time contemporaneous (preferably simultaneous) with the HST observations to obtain thermal infrared images of 55P/Tempel- Tuttle. Although premature at this time, this will most likely be a proposal to use the MIRAC2 camera at the IRTF. We hope to detect the nucleus allowing us to cleanly separate the size from the albedo. We shall also use part of our unusued time on ISOCAM (because of cancelled programs) to perform similar observations. Because of different constraints imposed by the operation of ISO, the observations will be scheduled in the second half of December 1997 and possibly, in early February 1998. Finally, high resolution ground-based CCD images will be obtained over a period overlapping the HST observations in order to complement them and to put them in a broader interval of cometary activity. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: ELECTRONIC Blocking Factor: 10 Ship To: Dr. Harold A. Weaver, 48 Bellchase Court, Baltimore, MD 21208 Ship Via: Email: weaver@pha.jhu.edu ------------------------------------------------------------------------------------ 7428( 12) - 12/31/97 14:43 - [ 3] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 | TARGET NAME: TEMPEL-TUTTLE ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: COMET Tempel-Tuttle ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | TYPE=COMET,Q=0.9766084,E=0.9055097,I=162 | .48590,O=235.25626,W=172.49335,T = 28- | Feb- | 1998:02:21:59.4,EQUINOX=J2000,EPOCH=08- | Jan-1998 | | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 17.3+/-1 | V-mag is for the nucleus. The coma B-V = 0.8 | might contribute some extra flux to V-R = 0.4 | the peak pixel but should be well | below the nucleus contribution. | These elements are from JPL 47. | Ephemeris Uncertainty: 1630 KM | Acquisition Uncertainty: 5 " | ------------------------------------------------------------------------------------------------------------------------------------ 7428( 12) - 12/31/97 14:43 - [ 4] Visit: 01 Visit Priority: Visit Requirements: BETWEEN 07-Jan-1998 AND 12-Jan-1998 SCHED 100% DROP TO GYRO IF NECESSARY GUID TOL 2" 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 TEMPEL-TUTT WFPC2 IMAGE PC1-FIX F675W CR-SPLIT=NO 2 60 S REQ EPHEM CORR TT1 SEQ LE 11-16 NON-INT Comments: Nominal exp time for this filter ------------------------------------------------------------------------------------------------------------------------------------ 12 TEMPEL-TUTT WFPC2 IMAGE PC1-FIX F675W CR-SPLIT=NO 1 30 S REQ EPHEM CORR TT1 LE Comments: In case the nucleus is brighter than expected ------------------------------------------------------------------------------------------------------------------------------------ 13 TEMPEL-TUTT WFPC2 IMAGE PC1-FIX F439W CR-SPLIT=NO 1 300 S REQ EPHEM CORR TT1 LE Comments: Nominal exp time for this filter ------------------------------------------------------------------------------------------------------------------------------------ 14 TEMPEL-TUTT WFPC2 IMAGE PC1-FIX F439W CR-SPLIT=NO 1 200 S REQ EPHEM CORR TT1 LE Comments: Nominal exp time for this filter ------------------------------------------------------------------------------------------------------------------------------------ 15 TEMPEL-TUTT WFPC2 IMAGE PC1-FIX F555W CR-SPLIT=NO 2 60 S REQ EPHEM CORR TT1 LE Comments: Nominal exp time for this filter ------------------------------------------------------------------------------------------------------------------------------------ 16 TEMPEL-TUTT WFPC2 IMAGE PC1-FIX F814W CR-SPLIT=NO 2 60 S REQ EPHEM CORR TT1 LE Comments: Nominal exp time for this filter ------------------------------------------------------------------------------------------------------------------------------------ 7428( 12) - 12/31/97 14:43 - [ 5] Visit: 02 Visit Priority: Visit Requirements: AFTER 01 BY 1.75 Orbits TO 2.25 Orbits SCHED 100% DROP TO GYRO IF NECESSARY GUID TOL 2" 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 ------------------------------------------------------------------------------------------------------------------------------------ 21 TEMPEL-TUTT WFPC2 IMAGE PC1-FIX F675W CR-SPLIT=NO 2 60 S REQ EPHEM CORR TT2 SEQ LE 21-26 NON-INT Comments: Nominal exp time for this filter ------------------------------------------------------------------------------------------------------------------------------------ 22 TEMPEL-TUTT WFPC2 IMAGE PC1-FIX F675W CR-SPLIT=NO 1 30 S REQ EPHEM CORR TT2 LE Comments: In case the nucleus is brighter than expected ------------------------------------------------------------------------------------------------------------------------------------ 23 TEMPEL-TUTT WFPC2 IMAGE PC1-FIX F439W CR-SPLIT=NO 1 300 S REQ EPHEM CORR TT2 LE Comments: Nominal exp time for this filter ------------------------------------------------------------------------------------------------------------------------------------ 24 TEMPEL-TUTT WFPC2 IMAGE PC1-FIX F439W CR-SPLIT=NO 1 200 S REQ EPHEM CORR TT2 LE Comments: Nominal exp time for this filter ------------------------------------------------------------------------------------------------------------------------------------ 25 TEMPEL-TUTT WFPC2 IMAGE PC1-FIX F555W CR-SPLIT=NO 2 60 S REQ EPHEM CORR TT2 LE Comments: Nominal exp time for this filter ------------------------------------------------------------------------------------------------------------------------------------ 26 TEMPEL-TUTT WFPC2 IMAGE PC1-FIX F814W CR-SPLIT=NO 2 60 S REQ EPHEM CORR TT2 LE Comments: Nominal exp time for this filter ------------------------------------------------------------------------------------------------------------------------------------ 7428( 12) - 12/31/97 14:43 - [ 6] Visit: 03 Visit Priority: Visit Requirements: AFTER 01 BY 3.75 Orbits TO 4.25 Orbits SCHED 100% DROP TO GYRO IF NECESSARY GUID TOL 2" 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 TEMPEL-TUTT WFPC2 IMAGE PC1-FIX F675W CR-SPLIT=NO 2 60 S REQ EPHEM CORR TT3 SEQ LE 31-36 NON-INT Comments: Nominal exp time for this filter ------------------------------------------------------------------------------------------------------------------------------------ 32 TEMPEL-TUTT WFPC2 IMAGE PC1-FIX F675W CR-SPLIT=NO 1 30 S REQ EPHEM CORR TT3 LE Comments: In case the nucleus is brighter than expected ------------------------------------------------------------------------------------------------------------------------------------ 33 TEMPEL-TUTT WFPC2 IMAGE PC1-FIX F439W CR-SPLIT=NO 1 300 S REQ EPHEM CORR TT3 LE Comments: Nominal exp time for this filter ------------------------------------------------------------------------------------------------------------------------------------ 34 TEMPEL-TUTT WFPC2 IMAGE PC1-FIX F439W CR-SPLIT=NO 1 200 S REQ EPHEM CORR TT3 LE Comments: Nominal exp time for this filter ------------------------------------------------------------------------------------------------------------------------------------ 35 TEMPEL-TUTT WFPC2 IMAGE PC1-FIX F555W CR-SPLIT=NO 2 60 S REQ EPHEM CORR TT3 LE Comments: Nominal exp time for this filter ------------------------------------------------------------------------------------------------------------------------------------ 36 TEMPEL-TUTT WFPC2 IMAGE PC1-FIX F814W CR-SPLIT=NO 2 60 S REQ EPHEM CORR TT3 LE Comments: Nominal exp time for this filter ------------------------------------------------------------------------------------------------------------------------------------ 7428( 12) - 12/31/97 14:43 - [ 7] Visit: 04 Visit Priority: Visit Requirements: AFTER 01 BY 5.75 Orbits TO 6.25 Orbits SCHED 100% DROP TO GYRO IF NECESSARY GUID TOL 2" 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 ------------------------------------------------------------------------------------------------------------------------------------ 41 TEMPEL-TUTT WFPC2 IMAGE PC1-FIX F675W CR-SPLIT=NO 2 60 S REQ EPHEM CORR TT4 SEQ LE 41-46 NON-INT Comments: Nominal exp time for this filter ------------------------------------------------------------------------------------------------------------------------------------ 42 TEMPEL-TUTT WFPC2 IMAGE PC1-FIX F675W CR-SPLIT=NO 1 30 S REQ EPHEM CORR TT4 LE Comments: In case the nucleus is brighter than expected ------------------------------------------------------------------------------------------------------------------------------------ 43 TEMPEL-TUTT WFPC2 IMAGE PC1-FIX F439W CR-SPLIT=NO 1 300 S REQ EPHEM CORR TT4 LE Comments: Nominal exp time for this filter ------------------------------------------------------------------------------------------------------------------------------------ 44 TEMPEL-TUTT WFPC2 IMAGE PC1-FIX F439W CR-SPLIT=NO 1 200 S REQ EPHEM CORR TT4 LE Comments: Nominal exp time for this filter ------------------------------------------------------------------------------------------------------------------------------------ 45 TEMPEL-TUTT WFPC2 IMAGE PC1-FIX F555W CR-SPLIT=NO 2 60 S REQ EPHEM CORR TT4 LE Comments: Nominal exp time for this filter ------------------------------------------------------------------------------------------------------------------------------------ 46 TEMPEL-TUTT WFPC2 IMAGE PC1-FIX F814W CR-SPLIT=NO 2 60 S REQ EPHEM CORR TT4 LE Comments: Nominal exp time for this filter ------------------------------------------------------------------------------------------------------------------------------------ 7428( 12) - 12/31/97 14:43 - [ 8] Summary Form for Proposal 7428 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 07-Jan-1998 AND 12-Jan-1998 SCHED 100% DROP TO GYRO IF NECESSARY GUID TOL 2" REQ EPHEM CORR TT1 SEQ 11-16 NON-INT REQ EPHEM CORR TT1 AFTER 01 BY 1.75 Orbits TO 2.25 Orbits SCHED 100% DROP TO GYRO IF NECESSARY GUID TOL 2" REQ EPHEM CORR TT2 SEQ 21-26 NON-INT REQ EPHEM CORR TT2 AFTER 01 BY 3.75 Orbits TO 4.25 Orbits SCHED 100% DROP TO GYRO IF NECESSARY GUID TOL 2" REQ EPHEM CORR TT3 SEQ 31-36 NON-INT REQ EPHEM CORR TT3 AFTER 01 BY 5.75 Orbits TO 6.25 Orbits SCHED 100% DROP TO GYRO IF NECESSARY GUID TOL 2" REQ EPHEM CORR TT4 SEQ 41-46 NON-INT REQ EPHEM CORR TT4 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F675W F439W F555W F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names TEMPEL-TUTTLE ------------------------------------------------------------------------------------------------------------------------------------