! This is version "b" of this proposal and was generated and submitted ! by Hal Weaver on 2/16/96. Here I have changed the ELs so that we ! read all four chips. (In the Kopff program we read only 1 chip ! in order to avoid possible tape volume problems due to the many ! images taken in that program.) Proposal_Information ! Section 4 Title: The nucleus of comet 46P/Wirtanen Proposal_Category: GO Scientific_Category: SOLAR SYSTEM Cycle: 6 Investigators PI_name: Philippe LAMY PI_Institution: Laboratoire d'Astronomie Spatiale CoI_Name: Michael F. A'HEARN CoI_Institution: University of Maryland Contact: ! Y or N (designate at most one contact) CoI_Name: Eberhard GR"U N CoI_Institution: Max-Planck-Institut fur Kernphysik Contact: ! Y or N (designate at most one contact) CoI_Name: Laurent JORDA CoI_Institution: Observatoire de Meudon Contact: ! Y or N (designate at most one contact) CoI_Name: Uwe KELLER CoI_Institution: Max-Planck-Institut fur Aeronomie Contact: ! Y or N (designate at most one contact) CoI_Name: Zdenek SEKANINA CoI_Institution: Jet Propulsion Laboratory Contact: ! Y or N (designate at most one contact) CoI_Name: Imre T'O TH CoI_Institution: Konkoly Observatory Contact: ! Y or N (designate at most one contact) CoI_Name: Harold A. WEAVER CoI_Institution: Applied Research Corporation Contact: ! Y or N (designate at most one contact) Abstract: ! Free format text (please update) We propose Planetary Camera observations of comet 46P/Wirtanen, which is the target of the approved ROSETTA rendezvous mission, the third cornerstone of the ESA Horizon 2000 program. Except for a few photographic "nuclear" magnitudes which suggest a radius of 1.6 km (assuming an albedo of 0.04), little is known about the properties of its nucleus and it is of utmost importance to attempt to characterize it to the fullest possible extent. Unfortunately, comet 46P/Wirtanen will not come close to the Earth during the next decade so that the only possible approach to studying the nucleus consists in observing it at large heliocentric distances when the activity is very low. The high spatial resolution offered by the Planetary Camera ( 100 km for 2 pixels) and its high sensitivity will allow us to detect any faint coma and substract it with minimal assumptions. We propose to measure the V and R 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. We have an approved program to observe the nucleus of comet 46P/Wirtanen with ISOCAM in the thermal infrared so that we shall derive its albedo and in turn its size with very minimal asumptions by combining HST and ISO observations. Should structures be detected in the faint coma, we shall map the sources of dust on the nucleus. The determination of these basic properties is essential for the preparation of the ROSETTA mission. Questions ! Free format text (please update) Observing_Description: The proposed sequence of observations results from a compromise between the scientific requirements of an adequate temporal coverage, and the necessarily limited time available on the HST. We request 8 near-contiguous orbits for comet 46P/Wirtanen (the exact scheduling will be worked out and optimized with the STScI staff as done for our observations of comet Borrelly). This will give a time coverage of approximately 12 to 18 hours (depending upon whether orbits are contiguous or nearly contiguous), well adapted to the presently observed mean value of 10 hours for the rotation period of short-period comets. Each orbit includes three F675W images and two F555W images. We have treated each orbit as a separate visit, even though it may be possible to support several orbits with the same pair of guide stars. Each visit consists of one orbit with the following exposure sequence in each orbit: F675W, two 300 sec images F555W, two 300 sec images F675W, one 200 sec image The above sequence will be used a total of 8 times = 8 orbits. We want all of the orbits to be completed within ~10 HST orbits, which means that a 1 or 2 orbit gap within the sequence is acceptable. We enforce this timing by using the visit special requirement: SEQ WITHIN 960M. This program should be executed sometime between 31-JUL-96 and 20-AUG-96. We have used the REQ EPHEM CORR on all exps in order to leave open the possibility of uplinking an ephemeris correction in case it's needed. Please note that we intend to update the comet's orbital elements during the last available opportunity (i.e., prior to final SMS generation). Real_Time_Justification: As it is entirely excluded to perform simultaneous observations with HST and ISO because of very different operational constraints, the best approach consists in optimizing the two programs separately. Subsequent matching of the visible and infrared light curves during the analysis should not introduce any major uncertainty in the determination of the properties of the nucleus (our proposed plans call for just a few weeks between the two campaigns). For the HST observations, the optimization led to choosing a window of 20 days centered on 10 August 1996. In addition, the 8 requested orbits must be taken over a period of about 10 HST orbits (i.e., there can be a couple orbit gap). We have an approved program to observe cometary nuclei with ISOCAM and comet 46P/Wirtanen is number 1 on our target list (the referees recommended that this comet "must be done"). Thanks to the high sensitivity and good spatial resolution of ISOCAM, it will be possible to detect the thermal emission (8 -15 microns) of the nuclei above the contribution of the coma. Due to different constraints, it is entirely excluded to consider simultaneous HST-ISO observations. However, with only a few weeks between the ISOCAM observations and the HST observations, it will be possible to determine the relative phases of the two datasets and thus to compare the visible (HST) and the infrared (ISO) light curves so as to derive the albedo of the nucleus following a method extensively used on asteroids and on a few cometary nuclei ( e.g., P/Arend- Rigaux). Ground-based CCD images will be secured before the HST observations in order to refine the ephemerides of the comet. Calibration_Justification: ! Move appropriate text from Real_Time_Justification Additional_Comments: Solar_System_Targets ! Section 5.2 Target_Number: 1 Target_Name: WIRTANEN Description: COMET 46P/WIRTANEN Level_1: TYPE = COMET, ! Satellite of Sun Q=1.06397530, E=0.65677159, I=11.722697, O=82.208922, W=356.321837, T=14-MAR-1997:03:22:18.336, EQUINOX=J2000, EPOCH=18-AUG-1996, A1=3.20814603395E-09, A2=-1.75045585208E-09 Ephem_Uncert: 6000KM ! Needed for REQ EPHEM CORR sp req Acq_Uncert: 5" ! Needed for SAVE and USE OFFSET sp reqs Window: Flux: V = 20.1 +/- 0.5 ! Include at least V and B-V B-V = 0.65 Comments: New elements from Hal Weaver; 7/23/96. Visits ! Section 6 Visit_Number: 1 Visit_Requirements: SEQ 1-8 WITHIN 10 ORBITS ! Section 7.1 BETWEEN 10-AUG-96 AND 02-SEP-96 Visit_Comments: Each visit should take 1 orbit. We want to complete the entire program within 10 orbits, if possible. Exposure_Number: 11 ! Section 6.5 Target_Name: WIRTANEN Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F675W Wavelength: Optional_Parameters: CR-SPLIT = NO Number_of_Iterations: 2 Time_Per_Exposure: 600S Special_Requirements: REQ EPHEM CORR WIRT1 SEQ 11-12 NON-INT Comments: Exposure_Number: 12 ! Section 6.5 Target_Name: WIRTANEN Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F555W Wavelength: Optional_Parameters: CR-SPLIT = NO Number_of_Iterations: 1 Time_Per_Exposure: 500S Special_Requirements: REQ EPHEM CORR WIRT1 Comments: ! Exposure_Number: 13 ! Section 6.5 ! Target_Name: WIRTANEN ! Config: WFPC2 ! Opmode: IMAGE ! Aperture: PC1 ! Sp_Element: F675W ! Wavelength: ! Optional_Parameters: CR-SPLIT = NO !Number_of_Iterations: 1 ! Time_Per_Exposure: 200S !Special_Requirements: REQ EPHEM CORR WIRT1 ! Comments: Visit_Number: 2 Visit_Requirements: ! Section 7.1 Exposure_Number: 21 ! Section 6.5 Target_Name: WIRTANEN Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F675W Wavelength: Optional_Parameters: CR-SPLIT = NO Number_of_Iterations: 2 Time_Per_Exposure: 600S Special_Requirements: REQ EPHEM CORR WIRT1 SEQ 21-22 NON-INT Comments: Exposure_Number: 22 ! Section 6.5 Target_Name: WIRTANEN Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F555W Wavelength: Optional_Parameters: CR-SPLIT = NO Number_of_Iterations: 1 Time_Per_Exposure: 500S Special_Requirements: REQ EPHEM CORR WIRT1 Comments: ! Exposure_Number: 23 ! Section 6.5 ! Target_Name: WIRTANEN ! Config: WFPC2 ! Opmode: IMAGE ! Aperture: PC1 ! Sp_Element: F675W ! Wavelength: ! Optional_Parameters: CR-SPLIT = NO !Number_of_Iterations: 1 ! Time_Per_Exposure: 200S !Special_Requirements: REQ EPHEM CORR WIRT1 ! Comments: Visit_Number: 3 Visit_Requirements: ! Section 7.1 Exposure_Number: 31 ! Section 6.5 Target_Name: WIRTANEN Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F675W Wavelength: Optional_Parameters: CR-SPLIT = NO Number_of_Iterations: 2 Time_Per_Exposure: 600S Special_Requirements: REQ EPHEM CORR WIRT1 SEQ 31-32 NON-INT Comments: Exposure_Number: 32 ! Section 6.5 Target_Name: WIRTANEN Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F555W Wavelength: Optional_Parameters: CR-SPLIT = NO Number_of_Iterations: 1 Time_Per_Exposure: 500S Special_Requirements: REQ EPHEM CORR WIRT1 Comments: ! Exposure_Number: 33 ! Section 6.5 ! Target_Name: WIRTANEN ! Config: WFPC2 ! Opmode: IMAGE ! Aperture: PC1 ! Sp_Element: F675W ! Wavelength: ! Optional_Parameters: CR-SPLIT = NO !Number_of_Iterations: 1 ! Time_Per_Exposure: 200S !Special_Requirements: REQ EPHEM CORR WIRT1 ! Comments: Visit_Number: 4 Visit_Requirements: ! Section 7.1 Exposure_Number: 41 ! Section 6.5 Target_Name: WIRTANEN Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F675W Wavelength: Optional_Parameters: CR-SPLIT = NO Number_of_Iterations: 2 Time_Per_Exposure: 600S Special_Requirements: REQ EPHEM CORR WIRT1 SEQ 41-42 NON-INT Comments: Exposure_Number: 42 ! Section 6.5 Target_Name: WIRTANEN Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F555W Wavelength: Optional_Parameters: CR-SPLIT = NO Number_of_Iterations: 1 Time_Per_Exposure: 500S Special_Requirements: REQ EPHEM CORR WIRT1 Comments: ! Exposure_Number: 43 ! Section 6.5 ! Target_Name: WIRTANEN ! Config: WFPC2 ! Opmode: IMAGE ! Aperture: PC1 ! Sp_Element: F675W ! Wavelength: ! Optional_Parameters: CR-SPLIT = NO !Number_of_Iterations: 1 ! Time_Per_Exposure: 200S !Special_Requirements: REQ EPHEM CORR WIRT1 ! Comments: Visit_Number: 5 Visit_Requirements: ! Section 7.1 Exposure_Number: 51 ! Section 6.5 Target_Name: WIRTANEN Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F675W Wavelength: Optional_Parameters: CR-SPLIT = NO Number_of_Iterations: 2 Time_Per_Exposure: 600S Special_Requirements: REQ EPHEM CORR WIRT1 SEQ 51-52 NON-INT Comments: Exposure_Number: 52 ! Section 6.5 Target_Name: WIRTANEN Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F555W Wavelength: Optional_Parameters: CR-SPLIT = NO Number_of_Iterations: 1 Time_Per_Exposure: 500S Special_Requirements: REQ EPHEM CORR WIRT1 Comments: ! Exposure_Number: 53 ! Section 6.5 ! Target_Name: WIRTANEN ! Config: WFPC2 ! Opmode: IMAGE ! Aperture: PC1 ! Sp_Element: F675W ! Wavelength: ! Optional_Parameters: CR-SPLIT = NO !Number_of_Iterations: 1 ! Time_Per_Exposure: 200S !Special_Requirements: REQ EPHEM CORR WIRT1 ! Comments: Visit_Number: 6 Visit_Requirements: ! Section 7.1 Exposure_Number: 61 ! Section 6.5 Target_Name: WIRTANEN Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F675W Wavelength: Optional_Parameters: CR-SPLIT = NO Number_of_Iterations: 2 Time_Per_Exposure: 600S Special_Requirements: REQ EPHEM CORR WIRT1 SEQ 61-62 NON-INT Comments: Exposure_Number: 62 ! Section 6.5 Target_Name: WIRTANEN Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F555W Wavelength: Optional_Parameters: CR-SPLIT = NO Number_of_Iterations: 1 Time_Per_Exposure: 500S Special_Requirements: REQ EPHEM CORR WIRT1 Comments: ! Exposure_Number: 63 ! Section 6.5 ! Target_Name: WIRTANEN ! Config: WFPC2 ! Opmode: IMAGE ! Aperture: PC1 ! Sp_Element: F675W ! Wavelength: ! Optional_Parameters: CR-SPLIT = NO !Number_of_Iterations: 1 ! Time_Per_Exposure: 200S !Special_Requirements: REQ EPHEM CORR WIRT1 ! Comments: Visit_Number: 7 Visit_Requirements: ! Section 7.1 Exposure_Number: 71 ! Section 6.5 Target_Name: WIRTANEN Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F675W Wavelength: Optional_Parameters: CR-SPLIT = NO Number_of_Iterations: 2 Time_Per_Exposure: 600S Special_Requirements: REQ EPHEM CORR WIRT1 SEQ 71-72 NON-INT Comments: Exposure_Number: 72 ! Section 6.5 Target_Name: WIRTANEN Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F555W Wavelength: Optional_Parameters: CR-SPLIT = NO Number_of_Iterations: 1 Time_Per_Exposure: 500S Special_Requirements: REQ EPHEM CORR WIRT1 Comments: ! Exposure_Number: 73 ! Section 6.5 ! Target_Name: WIRTANEN ! Config: WFPC2 ! Opmode: IMAGE ! Aperture: PC1 ! Sp_Element: F675W ! Wavelength: ! Optional_Parameters: CR-SPLIT = NO !Number_of_Iterations: 1 ! Time_Per_Exposure: 200S !Special_Requirements: REQ EPHEM CORR WIRT1 ! Comments: Visit_Number: 8 Visit_Requirements: ! Section 7.1 Exposure_Number: 81 ! Section 6.5 Target_Name: WIRTANEN Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F675W Wavelength: Optional_Parameters: CR-SPLIT = NO Number_of_Iterations: 2 Time_Per_Exposure: 600S Special_Requirements: REQ EPHEM CORR WIRT1 SEQ 81-82 NON-INT Comments: Exposure_Number: 82 ! Section 6.5 Target_Name: WIRTANEN Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F555W Wavelength: Optional_Parameters: CR-SPLIT = NO Number_of_Iterations: 1 Time_Per_Exposure: 500S Special_Requirements: REQ EPHEM CORR WIRT1 Comments: ! Exposure_Number: 83 ! Section 6.5 ! Target_Name: WIRTANEN ! Config: WFPC2 ! Opmode: IMAGE ! Aperture: PC1 ! Sp_Element: F675W ! Wavelength: ! Optional_Parameters: CR-SPLIT = NO !Number_of_Iterations: 1 ! Time_Per_Exposure: 200S !Special_Requirements: REQ EPHEM CORR WIRT1 ! 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: Dr. Harold Weaver 48 Bellchase Court Pikesville, MD 21208 ! STSCI or PI_Address or ! PI Address from Phase I is: ! ! BP 8 ! Marseille cedex 12 ! 13376 ! ! Ship_Via: UPS ! UPS (2-day) or OVERNIGHT ! Overnight shipping done at PI expense Recipient_Email: weaver@ari.net ! 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