! File: 5020C.PROP ! Database: PEPDB ! Date: 23-FEB-1994:15:46:00 coverpage: title_1: SEPARATE LIGHTCURVES OF PLUTO AND CHARON-SPLIT OF 3848 sci_cat: SOLAR SYSTEM sci_subcat: MINOR PLANETS proposal_for: GO longterm: 1 pi_title: DR. pi_fname: MARC pi_mi: W. pi_lname: BUIE pi_inst: LOWELL OBSERVATORY pi_country: USA pi_phone: 602-774-3358 hours_pri: 12.14 num_pri: 1 wf_pc: Y time_crit: Y funds_amount: 306000 funds_length: 24 funds_date: JUN-92 off_fname: ROBERT off_mi: L. off_lname: MILLIS off_title: DIRECTOR off_inst: LOWELL OBSERVATORY off_addr_1: MARS HILL RD., 1400 WEST off_city: FLAGSTAFF off_state: AZ off_zip: 86001 off_country: USA off_phone: (602)774-3358 ! end of coverpage abstract: line_1: With this program we will begin a systematic effort to collect separate line_2: lightcurve data on the Pluto and Charon system. Such observations will line_3: continue to improve the albedo mapping of their surfaces by splitting the line_4: present ground-based ambiguity in the combined lightcurve. The 3848 obs. line_5: must be done at the such times when it is within 25 arcseconds of a star of line_6: similar brightness. Such data will provide both the lightcurves and the line_7: phase angle behavior of each object. In addition to the photometry, line_8: astrometric measurements of Pluto and Charon relative to each of the background line_9: field stars can be made from the imaging data. In sufficient quantity, these line_10: data will further refine our knowledge of the sizes and relative masses of line_11: Pluto and Charon. Continued work on the photometry will allow us to watch the line_12: lightcurve evolution as Pluto moves away from the sun and as the Sun progresses line_13: to higher and higher latitudes. 5020 is a continuation of 3848, replacing obs. line_14: lost in the safing event of Mar. 1993., and due to subsequent pointing line_15: restrictions. 5020 measures the Pluto-Charon system and the stars separately. ! ! end of abstract general_form_proposers: lname: BUIE fname: MARC title: PI mi: W. inst: LOWELL OBSERVATORY country: USA ! lname: THOLEN fname: DAVID mi: J. inst: UNIVERSITY OF HAWAII country: USA ! lname: WASSERMAN fname: LARRY mi: H. inst: LOWELL OBSERVATORY country: USA ! ! end of general_form_proposers block general_form_text: question: 3 section: 1 line_1: All observations are blind-pointed PC exposures of the Pluto-Charon line_2: system while in the same PC6 field of view with a star similar in line_3: brightness to Pluto. For each appulse, we take two sets of exposures line_4: separated by at least 6 hours to get distinct lightcurve points. line_5: During 10 of the 12 appulses, we will take exposures only in F555W. line_6: During the other 2 appulses we will take exposures in F439W and F555W. line_7: The target pointing is constructed so that the telescope is pointed to line_8: and tracks the mid-point between the Pluto-Charon barycenter and the line_9: appulse star. The window on the target specification is defined to line_10: include only the time the star and Pluto can appear on PC6 for nominal line_11: roll. The window is conservative at a level of 3" on each side to line_12: allow for pointing errors from the guide stars and for slight line_13: off-nominal roll conditions. If off-nominal roll is required to line_14: schedule the observations, the PI can provide verification on whether line_15: the pointing will work or not. The only hard and fast rule for line_16: checking this is to see if Pluto and the star are on PC6 for the given line_17: time and roll angle. The PI is willing to provide additional line_18: information if off-nominal roll is required to schedule the line_19: observations. line_21: Tracking the mid-point between Pluto and the appulse star will cause line_22: some slight trailing for the F555W exposures and more noticeable line_23: trailing for the F439W exposures. Both Pluto and the star will be ! question: 3 section: 2 line_1: trailed by nearly equal amounts. To allow us to remove the effects of line_2: the trailing, we require full pointing (V1 and V3 on the line_3: plane-of-the-sky) reconstructions with each observation. We would also line_4: appreciate a FHST update immediately before each visit to provide the line_5: best possible information on roll angle. The default tracking mode of line_6: fine-lock is preferred for all observations but coarse-track is line_7: acceptable if there aren't enough stars to support fine-lock. line_9: We have chosen 12 appulses from the full set of 24. This set of 12 line_10: maximizes the scientific return for the allotted spacecraft time. line_11: However, some of these appulses may be unobservable due to SAA passages line_12: or lunar avoidance. The other 12 appulses are provided as backup line_13: observations if any of the original 12 cannot be scheduled. The PI line_14: must be contacted for the replacement observation since it depends on line_15: the coverage lost by the unschedulable observation. line_17: The primary set of observations from the SELECT SET are EXP LOG LINEs line_18: 10, 30, 50, 70, 90, 100, 130, 150, 170, 190, 210, and 220. ! question: 4 section: 1 line_1: Separating the individual lightcurves of Pluto and Charon is a very difficult line_2: task from ground-based observatories. At best, their separation is 1 line_3: arc-sec. Under the best conditions from the best site at the best telescope line_4: (often considered to be CFHT on Mauna Kea), it is possible to get separate line_5: magnitudes for Pluto and Charon, near elongation, under conditions of line_6: excellent seeing. However, collecting a complete lightcurve becomes line_7: extremely difficult when conditions of telescope scheduling and weather are line_8: confronted. In this case, weather includes losing a night to bad seeing, not line_9: just poor photometric conditions. The telescope scheduling difficulties are line_10: not to be understated. Due to the slow rotation period of Pluto, photometric line_11: measurements are spread out over a large number of nights. These line_12: observations do not take very much time but at present scheduling practices line_13: at most telescopes preclude using a large number of partial nights. Also, line_14: resolved images near minimum separation cannot be obtained from the ground. line_16: The Hubble Space Telescope counters both of these difficulties. The enhanced line_17: spatial resolution of HST can easily separate the two bodies, even fairly line_18: close to minimum separation (about 0.2 arcsec). The image degradation caused line_19: by the spherical aberration may actually be beneficial to this project because line_20: more source photons can be collected per image. Given the low efficiency of line_21: this program, the photometric signal-to-noise ratio of the observations as a line_22: function of spacecraft time is greatly increased by the aberration. Also, line_23: the larger image size to pixel size ratio will permit a more accurate ! question: 4 section: 2 line_1: determination of the image centroid, thereby improving the relative line_2: astrometry of the two bodies. line_4: An additional advantage of HST is the way it is scheduled and run. An line_5: observation of this nature requiring periodic, short obseravations can line_6: be accomodated much more easily than with most ground-based observatories. ! question: 5 section: 1 line_1: This proposal will require special scheduling to ensure that Pluto is line_2: always seen in a field with another similarly bright star. All the line_3: special scheduling is provided as time windows on the target list. line_4: The initial set of observations chosen from the candiate SELECT set line_5: provides optimum lightcurve and solar phase angle coverage. line_7: ADDENDUM: This proposal (5020) replaces the portion of 3848 that could line_8: not be scheduled due to the SADE failure in Mar-Apr 1993. The strategy line_9: is changed to cover specific longitudes even when a field does not contain line_10: a field star. To make up for the loss in photometric accuracy with not line_11: having the field star, each Pluto observation is followed by a photometric line_12: reference star measurement. The conditional requirements are intended to line_13: ensure that a photometric reference is measured close in time to the line_14: Pluto observations. ! question: 6 section: 1 line_1: For accurate image deconvolutions and positional measurements we require line_2: full pointing reconstructions (RA and DEC vs. time) during each exposure. line_3: This will allow us to create numerical PSFs that match the actual jitter line_4: and tracking that occurs during each exposure. We also need the best line_5: possible knowledge of the roll angle of the spacecraft. If possible, line_6: please schedule an FHST update immediately prior to each observation. ! question: 7 section: 1 line_1: The data reduction and analysis will be carried out by the proposers on their line_2: currently available computers. We expect additional work to be carried out line_3: by a post-doc for whom we wish to procure a new workstation. line_5: The data reductions will require PSF fitting to establish the magnitudes and line_6: relative positions of Pluto, Charon, and the field star. These data must be line_7: cross referenced with the nearly simultaneous ground-based observations of the line_8: combined magnitudes to complete the photometric reductions prior to modeling. line_9: Ground-based astrometry must also be collected so that the astrometric net line_10: provided by the appulse star can be calibrated. We plan to try conventional line_11: Schmidt astrometry on this field but if this proved inadequate we will do line_12: the astrometry using wide-field plates to be taken at CFHT on Mauna Kea. line_13: Our goal is to obtain astrometry at the 0.001" level. This may prove infeasible line_14: but is required to advance our knowledge of the individual densities of line_15: Pluto and Charon. line_17: Once the astrometric and lightcurve reductions are complete, the observations line_18: will be added to existing orbit and albedo models. ! question: 8 section: 1 line_1: Ground-based observations will be required to establish a high-precision line_2: astrometric net which will tie together all the individual HST line_3: observations. This net of stars will cover all of the appulse stars in line_4: our candiate list. Without these supporting observations, we will be unable line_5: to provide any information about the barycentric motion of Pluto and Charon. line_7: We also must continue to provide ground-based combined lightcurve line_8: measurements. The photometric accuracy of HST and the PC are insufficient line_9: for our models. By combining extremely accurate low spatial resolution line_10: ground-based observations with lower accuracy high spatial resolution data, line_11: we can achieve significant improvements in our model of the surface of Pluto line_12: and Charon. The ground-based observations are essential for maximizing the line_13: return from the HST data. ! question: 10 section: 1 line_1: The PI and Co-I's already have most of the computer facilities and line_2: the necessary access to ground-based telescopes to support this project. line_3: The PI will also work to secure computing time from supercomputer centers line_4: such as NCSA or SDSC to support the albedo modeling efforts. ! !end of general form text general_form_address: lname: BUIE fname: MARC mi: W. category: PI inst: LOWELL OBSERVATORY addr_1: MARS HILL ROAD, 1400 WEST city: FLAGSTAFF state: AZ zip: 86001 country: USA phone: (602)774-3358 ! ! end of general_form_address records fixed_targets: targnum: 107 name_1: GSC-5011-0069 descr_1: A 125; pos_1: RA = 15H 29M 00.089S +/- 0.001S, pos_2: DEC = -04D 07' 46.51" +/- 0.01" equinox: J2000 pm_or_par: N comment_1: PHOTOMETRIC REFERENCE STAR. fluxnum_1: 1 fluxval_1: V=14.96+/-0.5 ! ! end of fixed targets solar_system_targets: targnum: 1 name_1: PL-CH-A descr_1: PLANET PLUTO lev1_1: STD=PLUTO wind_1: CML OF PLUTO FROM EARTH BETWEEN 347 353 fluxnum_1: 1 fluxval_1: V=14.164+/-0.042 fluxnum_2: 2 fluxval_2: B-V=0.842+/-0.001 ! targnum: 2 name_1: PL-CH-B descr_1: PLANET PLUTO lev1_1: STD=PLUTO wind_1: CML OF PLUTO FROM EARTH BETWEEN 212 218 fluxnum_1: 1 fluxval_1: V=14.164+/-0.042 fluxnum_2: 2 fluxval_2: B-V=0.842+/-0.001 ! targnum: 3 name_1: PL-CH-C descr_1: PLANET PLUTO lev1_1: STD=PLUTO wind_1: CML OF PLUTO FROM EARTH BETWEEN 187 193 fluxnum_1: 1 fluxval_1: V=14.164+/-0.042 fluxnum_2: 2 fluxval_2: B-V=0.842+/-0.001 ! targnum: 4 name_1: PL-CH-D descr_1: PLANET PLUTO lev1_1: STD=PLUTO wind_1: CML OF PLUTO FROM EARTH BETWEEN 119 125 fluxnum_1: 1 fluxval_1: V=14.164+/-0.042 fluxnum_2: 2 fluxval_2: B-V=0.842+/-0.001 ! targnum: 5 name_1: PL-CH-E descr_1: PLANET PLUTO lev1_1: STD=PLUTO wind_1: CML OF PLUTO FROM EARTH BETWEEN 37 43 fluxnum_1: 1 fluxval_1: V=14.164+/-0.042 fluxnum_2: 2 fluxval_2: B-V=0.842+/-0.001 ! targnum: 6 name_1: PL-CH-F descr_1: PLANET PLUTO lev1_1: STD=PLUTO wind_1: CML OF PLUTO FROM EARTH BETWEEN 7 13 fluxnum_1: 1 fluxval_1: V=14.164+/-0.042 fluxnum_2: 2 fluxval_2: B-V=0.842+/-0.001 ! ! end of solar system targets ! No generic target records found exposure_logsheet: linenum: 5.000 sequence_1: DEFINE sequence_2: PLV targname: # config: PC opmode: IMAGE aperture: PC6 sp_element: F555W num_exp: 2 time_per_exp: 30S s_to_n: 100 fluxnum_1: 1 priority: 1 req_1: CYCLE 2; ! linenum: 10.000 sequence_1: USE PLV targname: PL-CH-A comment_1: GROUP 10-61 WITHIN 6.4D; ! linenum: 11.000 sequence_1: USE PLV targname: GSC-5011-0069 ! linenum: 20.000 sequence_1: USE PLV targname: PL-CH-B ! linenum: 21.000 sequence_1: USE PLV targname: GSC-5011-0069 req_1: COND IF 11,20 GT 6 DAYS APART ! linenum: 30.000 sequence_1: USE PLV targname: PL-CH-C ! linenum: 31.000 sequence_1: USE PLV targname: GSC-5011-0069 req_1: COND IF 11,30 GT 6 DAYS APART ! linenum: 40.000 sequence_1: USE PLV targname: PL-CH-D ! linenum: 41.000 sequence_1: USE PLV targname: GSC-5011-0069 req_1: COND IF 11,40 GT 6 DAYS APART ! linenum: 50.000 sequence_1: USE PLV targname: PL-CH-E ! linenum: 51.000 sequence_1: USE PLV targname: GSC-5011-0069 req_1: COND IF 11,50 GT 6 DAYS APART ! linenum: 60.000 sequence_1: USE PLV targname: PL-CH-F ! linenum: 61.000 sequence_1: USE PLV targname: GSC-5011-0069 req_1: COND IF 11,60 GT 6 DAYS APART ! ! end of exposure logsheet ! No scan data records found