7884( 2) - 11/21/97 08:31 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 7884 Version: 2 Check-in Date: 21-Nov-1997 08:30:21 1.Proposal Title: Observation of Two Comet-Asteroid Transition Objects ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 7 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: HUMBERTO CAMPINS UNIVERSITY OF FLORIDA CoI: Donald McCarthy University of Arizona N CoI: Harold Weaver Johns Hopkins University N ------------------------------------------------------------------------------------ 5. Abstract The two Earth-crossing asteroids most likely to be extinct or dormant comets are 4015 Wilson-Harrington and 3200 Phaethon. We propose to obtain near infrared observations of these two objects in order to characterize their surfaces. These observations will be combined with results from our ground based study of cometary nuclei in an effort to determine the origin of these two objects. ------------------------------------------------------------------------------------ 7884( 2) - 11/21/97 08:31 - [ 2] Observations Description ------------------------ We request one orbit for each of our two objects. The proposed observations are time-constrained, however, they are not restricted to a particular date. The ideal periods requested are when the objects are brightest and closest to opposition. However, there is considerable flexibility, at least three weeks in either direction for 4015 W-H and starting on July 16 for 3200 Phaethon (when it reaches 50 degrees solar elongation, but it will be about 1 magnitude fainter at that time). The ideal dates are late February 1998 for 4015 W-H, and as close to mid November 1998 as possible for 3200 Phaethon. The RA, Dec. solar elongation and predicted V and K magnitudes for the ideal periods are: 4015 W-H on Feb. 25 1998. RA 10h 24m 18sec Dec. +06 15 51 Elong. 177 degrees, Vmag = 21.1, K mag= 19.7 3200 Phaethon on Oct.1 1998 RA 03h 44m 41sec Dec. +40 26 10 Elong. 148 degrees, Vmag = 18.9, K mag= 17.5 Both objects move at a rate of less than 0.1 arcsec/sec, well within the tracking capability of HST. Having used the Exposure Time Calculator on the www, we come up with the following integration times: 4015 W-H. 1500 seconds to obtain a 1.1-1.9 micron GRISM B spectrum wit a S/N 12 per point and a spectral resolution of 10. Plus 700 seconds to obtain a S/N 10 on filter F196N, and about 120 seconds to obtain S/N 30 on filter F150W. F150W observations are for calibration of the spectrum. The F196N will provide coverage just longward of the G141 range, where telluric absorption is significant, and where we expect absoptions from H_2O ice and hydrated minerals. 3200 Phaethon. 500 seconds to obtain a 1.1-1.9 micron GRISM B spectrum with a S/N 14 per point and a spectral resolution of 200. 250 seconds to obtain a 0.8-1.2 micron GRISM A spectrum with a S/N 10 per point and a spectral resolution of 200. 1700 seconds to obtain a 1.4-2.5 micron GRISM C spectrum with a S/N 10 per point and a spectral resolution of about 10. 15 seconds to obtain S/N 30 on filter F150W. The observations will use the MULTIACCUM mode to provide lower read noise and to assist in the removal of cosmic ray events. We also plan to combine 2 or 3 GRISM observations adding up to the total integration times given above. This will help remove the effects of "grot" and bad pixels. Real Time Justification ----------------------- As discussed in the scientific justification, we will complement our HST results with existing, as well as future, ground based observations at shorter and longer wavelengths. More specifically, we plan to obtain 0.3 to 1 micron spectra from University of Arizona telescopes, and we will apply for time on the Keck telescope to obtain spectra longward of 2 microns. We have already obtained and published broad band photometry from 1 to 10 microns of 4015 W-H (Campins et al. 1995). Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 7884( 2) - 11/21/97 08:31 - [ 3] Data Distribution Media: DAT Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 7884( 2) - 11/21/97 08:31 - [ 4] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 | TARGET NAME: WILSON-HARRINGTON ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: Comet, asteroid ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | TYPE=ASTEROID,A=2.6443591,E=0.6217198,I= | 2.78294,O=270.9290,W=90.94756,M=132.1492 | 4,EPOCH=06-Jul-1998,EQUINOX=J2000 | | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | PHASE OF WILSON-HARRINGTON FROM EARTH | BETWEEN 0. 8.5 | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 21.5+/-0.3 | | ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 2 | TARGET NAME: PHAETHON ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: ASTEROID ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | TYPE=ASTEROID,A=1.2713187,E=0.8900418,I= | 22.10430,O=265.57319,W=321.83105,M=128.1 | 9651,EPOCH=06-Jul-1998,EQUINOX=J2000 | | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | PHASE OF PHAETHON FROM EARTH BETWEEN 0. | 20 | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 18.0+/-0.4 | | ------------------------------------------------------------------------------------------------------------------------------------ 7884( 2) - 11/21/97 08:31 - [ 5] Visit: 01 Visit Priority: 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 WILSON-HARR NIC3 MULTIAC NIC3-FI F150W SAMP-SEQ=STEP8,NSAMP=16, 1 DEF INGTON CUM X PATTERN=SPIRAL-DITH,NUM-POS=3, DITH-SIZE=1.5 ------------------------------------------------------------------------------------------------------------------------------------ 20 WILSON-HARR NIC3 MULTIAC NIC3-FI F196N SAMP-SEQ=STEP16,NSAMP=20, 1 DEF INGTON CUM X PATTERN=SPIRAL-DITH,NUM-POS=3, DITH-SIZE=1.5 ------------------------------------------------------------------------------------------------------------------------------------ 21 WILSON-HARR NIC3 MULTIAC NIC3-FI G141 SAMP-SEQ=STEP32,NSAMP=23, 1 DEF INGTON CUM X PATTERN=SPIRAL-DITH,NUM-POS=3, DITH-SIZE=1.5 ------------------------------------------------------------------------------------------------------------------------------------ 7884( 2) - 11/21/97 08:31 - [ 6] Visit: 02 Visit Priority: 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 PHAETHON NIC3 MULTIAC NIC3-FI F150W SAMP-SEQ=STEP8,NSAMP=7, 1 DEF CUM X PATTERN=SPIRAL-DITH,NUM-POS=3, DITH-SIZE=1.5 ------------------------------------------------------------------------------------------------------------------------------------ 20 PHAETHON NIC3 MULTIAC NIC3-FI G096 SAMP-SEQ=STEP8,NSAMP=15, 1 DEF CUM X PATTERN=SPIRAL-DITH,NUM-POS=3, DITH-SIZE=1.5 ------------------------------------------------------------------------------------------------------------------------------------ 21 PHAETHON NIC3 MULTIAC NIC3-FI G141 SAMP-SEQ=STEP8,NSAMP=25, 1 DEF CUM X PATTERN=SPIRAL-DITH,NUM-POS=3, DITH-SIZE=1.5 ------------------------------------------------------------------------------------------------------------------------------------ 22 PHAETHON NIC3 MULTIAC NIC3-FI G206 SAMP-SEQ=STEP64,NSAMP=16, 1 DEF CUM X PATTERN=SPIRAL-DITH,NUM-POS=3, DITH-SIZE=1.5 ------------------------------------------------------------------------------------------------------------------------------------ 7884( 2) - 11/21/97 08:31 - [ 7] Summary Form for Proposal 7884 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations NIC3 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SAMP-SEQ=STEP8 NSAMP=16 PATTERN=SPIRAL-DITH NUM-POS=3 DITH-SIZE=1.5 NSAMP=20 NSAMP=23 NSAMP=7 NSAMP=15 NSAMP=25 SAMP-SEQ=STEP64 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F150W F196N G141 G096 G206 ------------------------------------------------------------------------------------------------------------------------------------ Target Names WILSON-HARRINGTON PHAETHON ------------------------------------------------------------------------------------------------------------------------------------