9508( 4) - 06/18/02 08:17 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 9508 Version: 4 Check-in Date: 18-Jun-2002 08:17:02 1.Proposal Title: A binary system in the Kuiper Belt: 1998\_WW31 ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 11 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Christian Veillet Canada-France-Hawaii Telescope Corporation CoI: Dr. Joel Parker SWRI-Boulder N CoI: Dr. Ian Griffin STSCI N ------------------------------------------------------------------------------------ 5. Abstract 1998\_WW31 is the first Kuiper Belt Object, outside the pair Pluto/Charon, to be discovered as a binary object. Though only preliminary results are available from two orbits of HST DDT observation when this proposal is submitted, the pair exhibits a very high eccentricity (larger than 0.5) and a period of 570 days. The purpose of this proposal is to complete the monitoring of the pair on a full orbit, up to February 2003. Monitoring will then have to cease (Sun too close). The binarity of an asteroid allows the determination of the total mass of the system and provides important information on the past Kuiper Belt environment (formation/collisions/capture processes). If size can be obtained from albedo determination, the mass will give the density, a key parameter for any study of the origin and evolution of the Kuiper Belt. Hubble's unparalleled resolution provides the unique way to acquire observations of the pair good enough to access the physical characteristics of this system with a high degree of confidence, as the high eccentricity of the orbit keeps the two components less than 1 arc-second apart for most of the orbit. The observations would be made public immediately to allow the continuation of the education program offering to follow the pair on a regular basis to illustrate the prediction/verification iterative process of science and the direct use of simple laws for the determination of key parameters. ------------------------------------------------------------------------------------ 9508( 4) - 06/18/02 08:17 - [ 2] Observations Description ------------------------ This is a continuation of an ongoing program that has produced results we are happy with so far. To get a continuous series of observations without changing the instrumental parameters is important. We didn't find compelling reasons to change and move to a different instrument or to a different mode of observing. , Here are the current observing conditions we wish to keep: beginitemize em One HST orbit per month em Observations in three filters (F555W F675W F814W) on each HST orbit em 2 exposures per filter. Exposure times are 230s, 230s, and 300s respectively for F555W, F675W, and F814W. enditemize The S/N ratio is good enough for a very precise relative astrometry (by combining all exposures), and relative photometry allows a reasonably good color comparison of the two components. Real Time Justification ----------------------- beginitemize em Time-critical observations, As the main goal of the proposal is to complete a dense coverage of the orbit over a full period, the observations are obviously time- critical. enditemize We would like to release the observations immediately to allow the continuation of an education program based on the monitoring of the pair, which we hope to have in place by the end of 2001. Calibration Justification ------------------------- Real_Time_Justification Additional Comments ------------------- Note comment in Exposure 10 of Visits 03 and 06 for trying to optimize the exposure time. ------------------------------------------------------------------------------------ 9508( 4) - 06/18/02 08:17 - [ 3] TARGET LIST Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 | TARGET NAME: 1998WW31 ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: ASTEROID Binary Transneptunian Object ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | TYPE=ASTEROID,A=44.8945523,E=0.0815092,I | =6.77827,O=237.09776,W=54.21451,M=117.57 | 661,EPOCH=06-May-2002,EQUINOX=J2000 | | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 23.5 | Osculating elements are from the | Minor Planet Center (MPEC 2002-C17) | as available on 2002 Feb 8. From 24 | observations at 4 oppositions, 1998- | 2001, mean residual 0.30 arcsec. | Last observed on 2001 Oct. 12. | Please contact us before | observations are put into the | schedule so we can provide you with | the most recent elements. Updated | 6/18/02: I figure these revised MPC | elements for 1998 WW31 will be | sufficient, since I don't think | there will be any additional | observations before you need the | update. | ------------------------------------------------------------------------------------------------------------------------------------ 9508( 4) - 06/18/02 08:17 - [ 4] Visit: 01 Visit Priority: Visit Requirements: BETWEEN 13-Jul-2002 AND 17-Jul-2002 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 1998WW31 WFPC2 IMAGE PC1 F675W 1 1000 S ------------------------------------------------------------------------------------------------------------------------------------ 20 1998WW31 WFPC2 IMAGE PC1 F555W 1 1200 S EXPAND ------------------------------------------------------------------------------------------------------------------------------------ 9508( 4) - 06/18/02 08:17 - [ 5] Visit: 02 Visit Priority: Visit Requirements: BETWEEN 13-Aug-2002 AND 17-Aug-2002 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 1998WW31 WFPC2 IMAGE PC1 F675W 1 1000 S ------------------------------------------------------------------------------------------------------------------------------------ 20 1998WW31 WFPC2 IMAGE PC1 F814W 1 1200 S EXPAND ------------------------------------------------------------------------------------------------------------------------------------ 9508( 4) - 06/18/02 08:17 - [ 6] Visit: 03 Visit Priority: Visit Requirements: BETWEEN 13-Sep-2002 AND 17-Sep-2002 On Hold Comments: Additional Comments: Note comment in Exposure 10 for trying to optimize the exposure time. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 1998WW31 WFPC2 IMAGE PC1 F675W 4 500 S EXPAND Comments: Our goal for this observation is to get the maximum possible total exposure time AND breaking up the observation into 4 (ideally equal length) exposures. With RPS2, this visit gets divided into 3x500s and 1x700s exposures. No matter how we try to divide it, we cannot get a more even division, e.g., 2x500s and 2x600s. If, when you schedule this observation with the actual visibility you CAN get more exposure time and/or more evenly divided exposures, that would be wonderful. ------------------------------------------------------------------------------------------------------------------------------------ 9508( 4) - 06/18/02 08:17 - [ 7] Visit: 04 Visit Priority: Visit Requirements: BETWEEN 13-Oct-2002 AND 17-Oct-2002 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 1998WW31 WFPC2 IMAGE PC1 F675W 1 1000 S ------------------------------------------------------------------------------------------------------------------------------------ 20 1998WW31 WFPC2 IMAGE PC1 F555W 1 1200 S EXPAND ------------------------------------------------------------------------------------------------------------------------------------ 9508( 4) - 06/18/02 08:17 - [ 8] Visit: 05 Visit Priority: Visit Requirements: BETWEEN 13-Nov-2002 AND 17-Nov-2002 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 1998WW31 WFPC2 IMAGE PC1 F675W 1 1000 S ------------------------------------------------------------------------------------------------------------------------------------ 20 1998WW31 WFPC2 IMAGE PC1 F814W 1 1100 S ------------------------------------------------------------------------------------------------------------------------------------ 9508( 4) - 06/18/02 08:17 - [ 9] Visit: 06 Visit Priority: Visit Requirements: BETWEEN 13-Dec-2002 AND 17-Dec-2002 On Hold Comments: Additional Comments: Note comment in Exposure 10 for trying to optimize the exposure time. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 1998WW31 WFPC2 IMAGE PC1 F675W 4 500 S EXPAND Comments: Our goal for this observation is to get the maximum possible total exposure time AND breaking up the observation into 4 (ideally equal length) exposures. With RPS2, this visit gets divided into 3x500s and 1x700s exposures. No matter how we try to divide it, we cannot get a more even division, e.g., 2x500s and 2x600s. If, when you schedule this observation with the actual visibility you CAN get more exposure time and/or more evenly divided exposures, that would be wonderful. ------------------------------------------------------------------------------------------------------------------------------------ 9508( 4) - 06/18/02 08:17 - [ 10] Visit: 07 Visit Priority: Visit Requirements: BETWEEN 13-Jan-2003 AND 17-Jan-2003 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 1998WW31 WFPC2 IMAGE PC1 F675W 1 1000 S ------------------------------------------------------------------------------------------------------------------------------------ 20 1998WW31 WFPC2 IMAGE PC1 F555W 1 1200 S EXPAND ------------------------------------------------------------------------------------------------------------------------------------ 9508( 4) - 06/18/02 08:17 - [ 11] Visit: 08 Visit Priority: Visit Requirements: BETWEEN 13-Feb-2003 AND 17-Feb-2003 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 1998WW31 WFPC2 IMAGE PC1 F675W 1 1000 S ------------------------------------------------------------------------------------------------------------------------------------ 20 1998WW31 WFPC2 IMAGE PC1 F814W 1 1200 S EXPAND ------------------------------------------------------------------------------------------------------------------------------------ 9508( 4) - 06/18/02 08:17 - [ 12] Summary Form for Proposal 9508 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PC1 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 13-Jul-2002 AND 17-Jul-2002 EXPAND BETWEEN 13-Aug-2002 AND 17-Aug-2002 BETWEEN 13-Sep-2002 AND 17-Sep-2002 BETWEEN 13-Oct-2002 AND 17-Oct-2002 BETWEEN 13-Nov-2002 AND 17-Nov-2002 BETWEEN 13-Dec-2002 AND 17-Dec-2002 BETWEEN 13-Jan-2003 AND 17-Jan-2003 BETWEEN 13-Feb-2003 AND 17-Feb-2003 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F675W F555W F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names 1998WW31 ------------------------------------------------------------------------------------------------------------------------------------