6521( 3) - 03/04/96 10:48 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6521 Version: 3 Check-in Date: 04-Mar-1996 10:42:00 1.Proposal Title: A search for outgassing from Kuiper Belt Objects ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle SOLAR SYSTEM GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Alan Fitzsimmons Queen's University of Belfast CoI: D'o nal 'O Ceallaigh Queen's University of Belfast N CoI: Iwan Williams Queen Mary & Westfield College N CoI: Mike Irwin APM Unit, Royal Greenwich Observatory N CoI: Wing Ip Max Planck Institut fuer aeronomie N CoI: Nicolas Thomas Max Planck Institut fuer aeronomie N ------------------------------------------------------------------------------------ 6. Abstract In the past 3 years almost 30 small bodies lying on the inner edge of the proposed Kuiper-Belt have been discovered using ground-based facilities. Their observed magnitudes of V >~ 22.4 imply diameters of <~ 400 km. From observations of comae around distant objects (Chiron, P/Halley, P/Bowell) it is now known that comets may continue outgassing to at least 13-19 AU, probably driven by CO sublimation. Therefore it is possible and indeed likely that Kuiper-Belt Objects also possess active surfaces. The Planetary Camera will be used to image 4 bright Kuiper-Belt Objects in order to search for comae around these bodies, thereby providing constraints on the present rate of mass-loss from their surfaces. The observations proposed here would be able to detect a mass-loss rate of 100 g s^-1 from the surface. Due to their large distance, the HST is the only telescope with the required sensitivity and spatial resolution to carry out this investigation. ------------------------------------------------------------------------------------ 6521( 3) - 03/04/96 10:48 - [ 2] Observations Description ------------------------ We will image each of the 4 target KBO's (1992 QB1, 1993 SB, 1993 SC, 1994 TB) using the Planetary Camera plus F555W filter. The decision to obtain imaging though one filter alone was made as it is not known a-priori which objects exhibit outgassing, and thus multi-wavelength imaging could not be considered an efficient use of spacecraft time. The F555W was chosen for two reasons. First, it is not possible to predict the size distribution of dust particles surrounding a KBO, but given that it may be dominated by particles of size <~ a few microns, then observations at V should ensure the best chance of detection of reflected solar flux. Secondly, the on-going calibration of the WFPC2 will regularly measure the psf through this filter throughout cycle 6 (S. Casertano, STScI, priv. comm.). These calibration exposures will ensure accurate knowledge of the WFPC2+F555W psf near the time of observation. Use of the RPS2 scheduling software has revealed that the most efficient use of time would involve two exposures per orbit, of length 1100 seconds and 1000 seconds. We calculate that a total integration time of 8400 seconds will allow a 3-sigma detection of the coma at 0.2 arcseconds radius when azimuthaly averaged. We require a 1-orbit visit to a star, with repeated imaging to allow us to observe the effect of OTA breathing on the psf (see below). For the Kuiper-belt objects we are requesting one visit to each of the four primary targets. 1992 QB1 will be observed for 3 orbits (2 images obtained per orbit), while 4 orbits will be used for 1993 SB, 1993 SC, and 1994 TB. Real Time Justification ----------------------- As stated above, the primary contraints in the SNR for detection of comae will arise from both the wings of the psf from the KBO and the zodiacal light. As nothing can be done to minimise the former, we therefore request LOW-SKY for these observations. Calibration Justification ------------------------- The technical review of our phase I proposal suggested that some of the allocated time might be used for measurement of the psfs during our observations. Given that our severest constraint will be the breathing of the OTA, we have therefore decided to spend 1 orbit repeatedly observing the photometric standard F823-76 in order to study this effect. This observation will take place shortly after the observations of 1993 SC, for which it will be directly applicable. By comparing these observations with the on-going WFPC2 calibration observations taken routinely, we should be able to account for the effect of breathing in all of our other observations. Additional Comments ------------------- ------------------------------------------------------------------------------------ 6521( 3) - 03/04/96 10:48 - [ 3] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6521( 3) - 03/04/96 10:48 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 F823-76- CALIBRATION,POINT RA=00H 06M 23.80S +/- 0.1S,DEC=- J2000 V = 17.39+/-0.01 CALIB SPREAD FUNCTION 00D 27' 06.0" +/- 0.3", PLATE- B-V = 0.56+/-0.01 ID=012J Comments: Photometric standard, coords obtained from GASP Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1982.569 0.0 0.0 0.0 6521( 3) - 03/04/96 10:48 - [ 5] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 2 | TARGET NAME: 1994TB ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: ASTEROID ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | TYPE=ASTEROID,A=39.2481967,E=0.3042266,I | =12.11788,O=317.32134,W=97.13693,M=327.2 | 4746,EPOCH=27-Apr-1996,EQUINOX=J2000 | | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 22.1+/-0.2 | Kuiper-belt object. Latest elements | are provided (3-Feb-96). | ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 3 | TARGET NAME: 1993SC ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: ASTEROID ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | TYPE=ASTEROID,A=39.7302529,E=0.1906946,I | =5.15053,O=354.63040,W=317.10923,M=36.28 | 235,EPOCH=27-Apr-1996,EQUINOX=J2000 | | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 22.5+/-0.2 | Kuiper-belt object. Latest elements | are provided (3-Feb-96). | ------------------------------------------------------------------------------------------------------------------------------------ 6521( 3) - 03/04/96 10:48 - [ 6] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 4 | TARGET NAME: 1993SB ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: ASTEROID ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | TYPE=ASTEROID,A=39.3203433,E=0.3162029,I | =1.93207,O=354.81337,W=78.40501,M=321.35 | 135,EPOCH=27-Apr-1996,EQUINOX=J2000 | | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 23.3+/-0.2 | Kuiper-belt object. Latest elements | are provided (3-Feb-96). | ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 5 | TARGET NAME: 1992QB1 ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: ASTEROID ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | TYPE=ASTEROID,A=44.0765083,E=0.0725545,I | =2.18167,O=359.39220,W=1.01946,M=3.95094 | ,EPOCH=27-APR-96,EQUINOX=J2000, | | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 23.3+/-0.2 | Kuiper-belt object. Latest elements | are provided (3-Feb-96). | ------------------------------------------------------------------------------------------------------------------------------------ 6521( 3) - 03/04/96 10:48 - [ 7] Visit: 01 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 1994TB WFPC2 IMAGE PC1 F555W 4 2100S LOW-SKY ------------------------------------------------------------------------------------------------------------------------------------ 6521( 3) - 03/04/96 10:48 - [ 8] Visit: 02 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 1993SC WFPC2 IMAGE PC1 F555W 4 2100S LOW-SKY ------------------------------------------------------------------------------------------------------------------------------------ 6521( 3) - 03/04/96 10:48 - [ 9] Visit: 03 Visit Requirements: SEQ 2-3 WITHIN 24H 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 F823-76- WFPC2 IMAGE PC1 F555W 11 140S CALIB ------------------------------------------------------------------------------------------------------------------------------------ 6521( 3) - 03/04/96 10:48 - [ 10] Visit: 04 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 1993SB WFPC2 IMAGE PC1 F555W 4 2100S LOW-SKY ------------------------------------------------------------------------------------------------------------------------------------ 6521( 3) - 03/04/96 10:48 - [ 11] Visit: 05 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 1992QB1 WFPC2 IMAGE PC1 F555W 3 2100S LOW-SKY ------------------------------------------------------------------------------------------------------------------------------------ 6521( 3) - 03/04/96 10:48 - [ 12] Summary Form for Proposal 6521 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category SOLAR SYSTEM ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements LOW-SKY SEQ 2-3 WITHIN 24H ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F555W ------------------------------------------------------------------------------------------------------------------------------------ Target Names 1994TB 1993SC F823-76-CALIB 1993SB 1992QB1 ------------------------------------------------------------------------------------------------------------------------------------