7183( 3) - 02/23/98 10:53 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 7183 Version: 3 Check-in Date: 23-Feb-1998 10:52:42 1.Proposal Title: NEAR-INFRARED SPECTRAL REFLECTIVITY OF PUCK ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GTO/NIC 7 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: BRADFORD A. SMITH INSTITUTE FOR ASTRONOMY CoI: ROLAND MEIER UNIVERSTIY OF HAWAII N ------------------------------------------------------------------------------------ 5. Abstract Voyager provided no information on the spectral reflectivities of the small, dark, inner satellites that it discovered around Uranus and Neptune. These objects are too faint and too close to their respective planets to be well measured from the ground. Observations should be made when Puck is near maximum elongation and with Uranus just outside the field of view. Multispectral filter photometry of Puck, the brightest of the small dark Uranus satellites, will be done in filters identical to those used on Neptune's Proteus. Puck has an albedo of 0.07, similar to that of Proteus, suggesting common origin. Intercomparisons will be made among the dark bodies of the outer solar system and the small, dark satellites of Mars. ------------------------------------------------------------------------------------ 7183( 3) - 02/23/98 10:53 - [ 2] Observations Description ------------------------ Program 7183 is devoted to broad and medium band photometry of Puck. With the current exposure times we will reach the following S/N: Filter F110W, flux = 4.13E-5 Jy, t = 2 x 64 sec, total S/N = 58 ; Filter F160W, flux = 2.79E-5 Jy, t = 2 x 128 sec, total S/N = 45 ; Filter F204M, flux = 2.26E-5 Jy, t = 4 x 192 sec, total S/N = 24 ; Filter F237M, flux = 1.86E-5 Jy, t = 7 x 128 sec, total S/N = 8.5; None of the MULTIACCUM sequences is read-noise limited, and a background flux from Uranus up to two orders of magnitude larger than the flux of Puck should not saturate the detector. Uranus north pole is tipped over by about 90 degrees to the west compared to all other planets. In a sky-projected view Puck moves on an elliptical orbit around Uranus with the major axis tilted by about 6 degrees relative to the celestial South-North direction. Maximal elongation of Puck is only ~7 arcsec which has to be compared with the 19.2 x 19.2 arcsec^2 FOV of camera NIC2. Since we don't want any part of Uranus in the FOV, a proper orientation of the FOV is crucial. We also require that Puck is imaged near maximal elongation to keep the glare from the central planet as low as possible. This sets another tight geometrical constraint. We offset the FOV from Uranus so that camera NIC2 covers the area near Puck's "Eastern", i.e. Northern in a celestial coordinate system, (or "Western", i.e. Southern in a celestial coordinate system) elongation but leaves a minimal distance of 1.7 arcsec between the limb of Uranus and camera 2. We require that Puck is closer than 8.2 arcsec to the center of NIC2. That way, Puck is for at least 2 hours inside the FOV, which should provide plenty of time for scheduling purposes. On the other hand Puck is at least 1.7 arcsec away from the edge of camera NIC2. The safety margin of 1.7 arcsec accounts for possible absolute pointing errors. We are using a ONE-CHOP pattern with a chop-through of 0.9527 arcsec (~12.5 pixels) along the x-axis of the NIC2 detector, i.e. we are choping roughly East -West, to reduce the risk of hitting bad pixels, to improve the accuracy of the photometry, and to minimize the risk of putting the object on top of a reflection. For longer exposures we also do a small dither step in y direction of 3.5 pixels or 0.2643". At any time Puck can be observed near the eastern OR western elongation. In RPS2 only one of the two possibilities can be implemented. To change the side, modify keyword ANG to ANG+180 degrees (see also comments under target 1). Around August 4 the nominal orientation of the U3 axis flips over by 180 degrees. Owing to RPS2 limitations and our tight ORIENT angles we are forced to introduce two artificial time periods during which we use different ORIENTs to account for the change in the position angle of the U3 axis. Currently the "Spring" version is implemented. To switch to the "Fall" version, special requirement "ORIENT ..." *AND* "BETWEEN ..." have to be modified. See also corresponding comments under visit 1. Parameters used for this template are summarized below: Distance Puck-Uranus: 13.11 arcsec ; Separation center NIC2 - Proteus: 8.2 arcsec ; Pattern: chop in x direction, POS TARGs in y direction (long exposures only) ; Spring: Position angle: 5 degrees (or 185 degrees) ; Orientation: 230 TO 236 degrees ; Period: May 20 to Aug 4, 1998 ; U3 nominal: ~253 degrees ; Fall: Position angle: 185 degrees (or 5 degrees) ; Orientation: 44 TO 50 degrees ; Period: Aug 4 to Oct 15, 1998 ; U3 nominal: ~73 degrees ; Real Time Justification ----------------------- None Calibration Justification ------------------------- None Additional Comments ------------------- None ------------------------------------------------------------------------------------ 7183( 3) - 02/23/98 10:53 - [ 3] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: Rodger I. Thompson*University of Arizona*Steward Obs./NICMOS*933 N. Cherry Ave*Tucson, AZ 85721-0065 Ship Via: Email: thompson@as.arizona.edu ------------------------------------------------------------------------------------ 7183( 3) - 02/23/98 10:53 - [ 4] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 | TARGET NAME: URANUS-PUCK ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE PUCK ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=URANUS | TYPE=POS_ANGLE,RAD=13.11,ANG=5,REF=NORTH | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | SEP OF PUCK URANUS-PUCK FROM EARTH LT | 8.2" | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 20.2+/-0.5 | ANG=5 can be replaced by ANG=185 if J = 19.1+/-0.5 | other ansa is prefered for H = 18.8+/-0.5 | scheduling purposes. Position URANUS K = 18.7+/-0.5 | -PUCK defines the center of camera | NIC2 so that: (a) No part of Uranus | is in the FOV if used with ORIENT | 230D TO 236D or ORIENT 44D TO 50D. | (b) Near maximal elongation PUCK is | for at least two hours within the | FOV. | ------------------------------------------------------------------------------------------------------------------------------------ 7183( 3) - 02/23/98 10:53 - [ 5] Visit: 01 Visit Priority: Visit Requirements: SCHED 90% ORIENT 230D TO 236D BETWEEN 20-MAY-1998 AND 4-AUG-1998 On Hold Comments: Additional Comments: *IMPORTANT* : Visit can also be scheduled for fall 1998 using the following modifications: ORIENT ... -> ORIENT 44D TO 50D ; BETWEEN ... -> BETWEEN 5- AUG-1998 AND 15-OCT-1998 Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 URANUS-PUCK NIC2 MULTIAC NIC2-FI F110W 1.10000 PATTERN = ONE-CHOP,NUM-POS = 2 , 1 DEF CUM X CHOP-SIZE = 0.9527,SAMP-SEQ = STEP64,NSAMP = 9 ------------------------------------------------------------------------------------------------------------------------------------ 2 URANUS-PUCK NIC2 MULTIAC NIC2-FI F160W 1.60000 PATTERN = ONE-CHOP,NUM-POS = 2 , 1 DEF CUM X CHOP-SIZE = 0.9527,SAMP-SEQ = STEP64,NSAMP = 10 ------------------------------------------------------------------------------------------------------------------------------------ 3 URANUS-PUCK NIC2 MULTIAC NIC2-FI F204M 2.04000 PATTERN = ONE-CHOP,NUM-POS = 2 , 1 DEF CUM X CHOP-SIZE = 0.9527,SAMP-SEQ = STEP64,NSAMP = 11 ------------------------------------------------------------------------------------------------------------------------------------ 4 URANUS-PUCK NIC2 MULTIAC NIC2-FI F204M 2.04000 PATTERN = ONE-CHOP,NUM-POS = 2 , 1 DEF POS TARG 0, -0.2643 CUM X CHOP-SIZE = 0.9527,SAMP-SEQ = STEP64,NSAMP = 11 ------------------------------------------------------------------------------------------------------------------------------------ 5 URANUS-PUCK NIC2 MULTIAC NIC2-FI F237M 2.37500 PATTERN = ONE-CHOP,NUM-POS = 2 , 1 DEF POS TARG 0, -0.2643 CUM X CHOP-SIZE = 0.9527,SAMP-SEQ = STEP64,NSAMP = 10 ------------------------------------------------------------------------------------------------------------------------------------ 6 URANUS-PUCK NIC2 MULTIAC NIC2-FI F237M 2.37500 PATTERN = ONE-CHOP,NUM-POS = 2 , 2 DEF CUM X CHOP-SIZE = 0.9527,SAMP-SEQ = STEP64,NSAMP = 10 ------------------------------------------------------------------------------------------------------------------------------------ 7 URANUS-PUCK NIC2 MULTIAC NIC2-FI F237M 2.37500 SAMP-SEQ = STEP64,NSAMP = 10 1 DEF CUM X ------------------------------------------------------------------------------------------------------------------------------------ 7183( 3) - 02/23/98 10:53 - [ 6] Summary Form for Proposal 7183 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations NIC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters PATTERN = ONE-CHOP NUM-POS = 2 CHOP-SIZE = 0.9527 SAMP-SEQ = STEP64 NSAMP = 9 NSAMP = 10 NSAMP = 11 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GTO/NIC ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements SCHED 90% ORIENT 230D TO 236D BETWEEN 20-MAY-1998 AND 4-AUG-1998 POS TARG 0, -0.2643 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F110W F160W F204M F237M ------------------------------------------------------------------------------------------------------------------------------------ Target Names URANUS-PUCK ------------------------------------------------------------------------------------------------------------------------------------