12042( 7) - 17-Aug-2010 12:24:30 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 12042 Version: 7 Check-in Time: 17-Aug-2010 12:24:30 STScI Edit Number: 4 Title COS-GTO: Pluto ------------------------------------------------------------------------------------ Type Cycle GTO/COS 18 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. James C. Green University of Colorado at Boulder CoI: Dr. Cynthia Froning University of Colorado at Boulder N CoI: Dr. John R. Spencer Southwest Research Institute Y CoI: Dr. S. Alan Stern Southwest Research Institute N CoI: Dr. Nathaniel J. Cunningham University of Nebraska - Lincoln N ------------------------------------------------------------------------------------ Abstract We seek to measure Pluto's albedo below 2100, to better constrain surface composition. COS observations will provide a substantial improvement in the S/N of Pluto spectra from <1800 to 2100. Accumulation of past HST/FOS spectra yields extremely low S/N below 2000 (S/N of only 1-3 in 100 bins; Krasnopolsky 2001). We expect to achieve S/N=5 at 1950 with 10 binning. In addition to spectrally broad albedo measurements, these observations could reveal line or molecular band emission, such as C I 1931 or CO 1993. ------------------------------------------------------------------------------------ Observations Description ------------------------ COS NUV spectra of Pluto from 1700 to 2100 using G230L at 3000 central wavelength, for a total of 5 orbits. Only one grating position (central wavelength) is required to cover the specified wavelength band. Observations will be divided into two visits: 2 orbits at one central meridional longitude, and 3 orbits at another; in this way, the spectra can be coadded for the greatest signal-to-noise, and compared to look for longitude-specific differences in absorption spectrum. The chosen longitudes (90 and 270 degrees) correspond to greatest angular separation of Charon from Pluto, reaching 0.85"; the position angle (CCW from north) of Charon from Pluto is about 150 and 330 degrees for these cases. ORIENT is specified in order to minimize spectral confusion, by aligning Charon in the cross-dispersion direction. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- 12042( 7) - 17-Aug-2010 12:24:30 - [ 2] ORIENT calculation: U3 axis is at 135 degrees from COS +Y (spatial) direction, and at 135+180 = 315 degrees from -Y With Pluto viewed at CML = 90, Charon is near position angle 153 degrees; Pluto-Charon vector can extend along either +Y or -Y. So we have ORIENT near 135+153 = 288 degrees or near 315 + 153 = 468 ==> 108 degrees. With Pluto viewed at CML = 270, Charon is near position angle 333 degrees (180 degrees from above). Same calculation as above -- 135 + 333 ==> 108 degrees orient, 315 + 333 ==> 288 degrees. We've specified the desired CML +/- 15 degrees, which provides ~12 hr obs windows; ORIENT window of +/- 5 degrees keeps 4+ months available. ------------------------------------------------------------------------------------ 12042( 7) - 17-Aug-2010 12:24:30 - [ 3] TARGET LIST Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 TARGET NAME: PLUTO-90LONG ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: PLANET PLANET PLUTO ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 TARGET POSITION LEVEL 2 STD=PLUTO ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 WINDOWS CML OF PLUTO FROM EARTH BETWEEN 80 100 ------------------------------------------------------------------------------------------------------------------------------------ DATA COMMENTS V = 14.0 +/- 0.5 about 1 magnitude dimmer in mid-UV relative to visible, F(2400)=1E-16 based on albedo measurements -- 0.2 - 0.25 in mid UV, instead of 0.5 - 0.66 in visible Ephemeris Center: EARTH (used mV = 15 solar-type spectrum for ETC) Specified window -- CML of 90+/-10 degrees -- puts Charon near largest separation from Pluto, and at position angle near 150 degrees. ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 2 TARGET NAME: PLUTO-270LONG ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: PLANET PLANET PLUTO ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 TARGET POSITION LEVEL 2 STD=PLUTO ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 WINDOWS CML OF PLUTO FROM EARTH BETWEEN 260 280 ------------------------------------------------------------------------------------------------------------------------------------ DATA COMMENTS V = 14.0 +/- 0.5 Specified window -- CML of 270+/-10 degrees -- puts F(2400)=1E-16 Charon near largest separation from Pluto, and at position angle near 330 degrees. Ephemeris Center: EARTH ------------------------------------------------------------------------------------------------------------------------------------ 12042( 7) - 17-Aug-2010 12:24:30 - [ 4] Visit: 01 Visit Requirements: ORIENT 260D TO 290 D; ORIENT 90D TO 120 D; BETWEEN 20-AUG-2010:00:00:00 AND 30-SEP-2010:23:59:59 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 PLUTO-90LON COS/NUV ACQ/SEA PSA MIRRORA SCAN-SIZE=2 1 25 S G RCH ------------------------------------------------------------------------------------------------------------------------------------ 2 PLUTO-90LON COS/NUV ACQ/IMA PSA MIRRORA 1 25 S G GE Comments: COS ETC: COS.A204186 for estimation of acquisition time. Assumed solar-type Kurucz spectrum with effective m_V=15.0, normal airglow. S/N = 40 in 23.5s ------------------------------------------------------------------------------------------------------------------------------------ 3 PLUTO-90LON COS/NUV TIME-TA PSA G230L 3000 BUFFER-TIME=1970, FP-POS=2 1 1970 S G G Comments: ETC: COS.A204190 gives buffer-time of 2/3 * 26913s ------------------------------------------------------------------------------------------------------------------------------------ 4 PLUTO-90LON COS/NUV TIME-TA PSA G230L 3000 BUFFER-TIME=2971, FP-POS=3 1 2971 S G G ------------------------------------------------------------------------------------------------------------------------------------ 5 PLUTO-90LON COS/NUV TIME-TA PSA G230L 3000 BUFFER-TIME=2971, FP-POS=4 1 2971 S G G ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ PLUTO-90LONG 1 COS/NUV ACQ/SEA PSA MIRRORA none none none none 1 N/A RCH PLUTO-90LONG 2 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE PLUTO-90LONG 3 COS/NUV TIME-TA PSA G230L 3000 none none none none 1 N/A G PLUTO-90LONG 4 COS/NUV TIME-TA PSA G230L 3000 none none none none 2 N/A G PLUTO-90LONG 5 COS/NUV TIME-TA PSA G230L 3000 none none none none 3 N/A G 12042( 7) - 17-Aug-2010 12:24:30 - [ 5] Visit: 02 Visit Requirements: ORIENT 280D TO 290 D; ORIENT 100D TO 110 D; BETWEEN 20-AUG-2010:00:00:00 AND 30-SEP-2010:23:59:59 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 PLUTO-270LO COS/NUV ACQ/SEA PSA MIRRORA SCAN-SIZE=2 1 25 S NG RCH ------------------------------------------------------------------------------------------------------------------------------------ 2 PLUTO-270LO COS/NUV ACQ/IMA PSA MIRRORA 1 25 S NG GE ------------------------------------------------------------------------------------------------------------------------------------ 3 PLUTO-270LO COS/NUV TIME-TA PSA G230L 3000 BUFFER-TIME=1970, FP-POS=2 1 1970 S NG G ------------------------------------------------------------------------------------------------------------------------------------ 4 PLUTO-270LO COS/NUV TIME-TA PSA G230L 3000 BUFFER-TIME=1335, FP-POS=3 1 1445 S NG G ------------------------------------------------------------------------------------------------------------------------------------ 5 PLUTO-270LO COS/NUV TIME-TA PSA G230L 3000 BUFFER-TIME=1445, FP-POS=4 1 1445 S NG G ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ PLUTO-270LONG 1 COS/NUV ACQ/SEA PSA MIRRORA none none none none 1 N/A RCH PLUTO-270LONG 2 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE PLUTO-270LONG 3 COS/NUV TIME-TA PSA G230L 3000 none none none none 1 N/A G PLUTO-270LONG 4 COS/NUV TIME-TA PSA G230L 3000 none none none none 2 N/A G PLUTO-270LONG 5 COS/NUV TIME-TA PSA G230L 3000 none none none none 2 N/A G 12042( 7) - 17-Aug-2010 12:24:30 - [ 6] Summary Form for Proposal 12042 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/NUV ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/IMAGE, ACQ/SEARCH, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=1335, BUFFER-TIME=1445, BUFFER-TIME=1970, BUFFER-TIME=2971, FP-POS=2, FP-POS=3, FP-POS=4, SCAN-SIZE=2 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 20-AUG-2010:00:00:00 AND 30-SEP-2010:23:59:59, ORIENT 100D TO 110 D, ORIENT 260D TO 290 D, ORIENT 280D TO 290 D, ORIENT 90D TO 120 D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G230L, MIRRORA ------------------------------------------------------------------------------------------------------------------------------------ Target Names PLUTO-270LONG, PLUTO-90LONG ------------------------------------------------------------------------------------------------------------------------------------