7182( 3) - 03/04/98 09:37 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 7182 Version: 3 Check-in Date: 04-Mar-1998 09:36:38 1.Proposal Title: NEAR-INFRARED SPECTRAL REFLECTIVITY OF PROTEUS ------------------------------------------------------------------------------------ 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 Proteus is near maximum elongation and with Neptune just outside the field of view. Multispectral filter photometry of Proteus, the brightest of the small dark Neptune satellites, will be done in filters identical to those used on Uranus's Puck. Proteus has an albedo of 0.07, similar to that of Puck, suggesting common origin. Intercomparisons will be made among the dark bodies of the outer solar system and the small, dark satellites of Mars. ------------------------------------------------------------------------------------ 7182( 3) - 03/04/98 09:37 - [ 2] Observations Description ------------------------ Program 7182 is devoted to broad and medium band photometry of Proteus. With the current exposure times we will reach the following S/N: Filter F110W, flux = 3.77E-5 Jy, t = 2 x 64 sec, total S/N = 56 ; Filter F160W, flux = 2.54E-5 Jy, t = 2 x 128 sec, total S/N = 42 ; Filter F204M, flux = 2.07E-5 Jy, t = 4 x 192 sec, total S/N = 22 ; Filter F237M, flux = 1.69E-5 Jy, t = 7 x 128 sec, total S/N = 7.5; None of the MULTIACCUM sequences is read-noise limited, and a background flux from Neptune up to two orders of magnitude larger than the flux of Proteus should not saturate the detector. In a sky-projected view Proteus moves on an elliptical orbit around Neptune with the major axis tilted by about 5.5 degrees relative to the celestial East-West direction. Maximal elongation of Proteus is only ~6 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 Neptune in the FOV, a proper orientation of the FOV is crucial. We also require that Proteus 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 Neptune so that camera NIC2 covers the area near Proteus' Eastern (or Western) elongation but leaves a minimal distance of 1.7 arcsec between the limb of Neptune and camera 2. We require that Proteus is closer than 8.2 arcsec to the center of NIC2. That way, Proteus is for at least 2 hours inside the FOV, which should provide plenty of time for scheduling purposes. On the other hand Proteus 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 0.9438 arcsec (~ 12.5 pixels) along the y-axis of the NIC2 detector, i.e. we are choping roughly North-South, 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 x direction of 3.5 pixels or 0.2668". At any time Proteus 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 Proteus-Neptune: 12.58 arcsec ; Separation center NIC2 - Proteus: 8.2 arcsec ; Pattern: chop in y direction, POS TARGs in x direction (long exposures only) ; Spring: Position angle: 95 degrees (or 275 degrees) ; Orientation: 230 TO 236 degrees ; Period: May 15 to Aug 4, 1998 ; U3 nominal: ~253 degrees ; Fall: Position angle: 275 degrees (or 95 degrees) ; Orientation: 44 TO 50 degrees ; Period: Aug 4 to Oct 10, 1998 ; U3 nominal: ~73 degrees ; Real Time Justification ----------------------- None Calibration Justification ------------------------- None Additional Comments ------------------- None ------------------------------------------------------------------------------------ 7182( 3) - 03/04/98 09:37 - [ 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 ------------------------------------------------------------------------------------ 7182( 3) - 03/04/98 09:37 - [ 4] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 | TARGET NAME: NEPTUNE-PROTEUS ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE PROTEUS ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=NEPTUNE | TYPE=POS_ANGLE,RAD=12.58,ANG=95,REF=NORT | H | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | SEP OF PROTEUS NEPTUNE-PROTEUS FROM | EARTH LT 8.2" | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 20.3+/-0.5 | ANG=95 can be replaced by ANG=275 if J = 19.2+/-0.5 | other ansa is prefered for H = 18.9+/-0.5 | scheduling purposes. Position K = 18.8+/-0.5 | NEPTUNE-PROTEUS defines the center | of camera NIC2 so that: (a) No part | of Neptune is in the FOV if used | with ORIENT 230D TO 236D or ORIENT | 44D TO 50D. (b) Near maximal | elongation PROTEUS is for at least | two hours within the FOV. | ------------------------------------------------------------------------------------------------------------------------------------ 7182( 3) - 03/04/98 09:37 - [ 5] Visit: 01 Visit Priority: Visit Requirements: SCHED 90% ORIENT 230D TO 236D BETWEEN 15-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 10-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 NEPTUNE-PRO NIC2 MULTIAC NIC2-FI F110W 1.10000 PATTERN = ONE-CHOP,NUM-POS = 2 , 1 DEF TEUS CUM X CHOP-SIZE = 0.9438,PATTERN-ORIENT = 95,SAMP-SEQ = STEP64,NSAMP = 9 ------------------------------------------------------------------------------------------------------------------------------------ 2 NEPTUNE-PRO NIC2 MULTIAC NIC2-FI F160W 1.60000 PATTERN = ONE-CHOP,NUM-POS = 2 , 1 DEF TEUS CUM X CHOP-SIZE = 0.9438,PATTERN-ORIENT = 95,SAMP-SEQ = STEP64,NSAMP = 10 ------------------------------------------------------------------------------------------------------------------------------------ 3 NEPTUNE-PRO NIC2 MULTIAC NIC2-FI F204M 2.04000 PATTERN = ONE-CHOP,NUM-POS = 2 , 1 DEF TEUS CUM X CHOP-SIZE = 0.9438,PATTERN-ORIENT = 95,SAMP-SEQ = STEP64,NSAMP = 11 ------------------------------------------------------------------------------------------------------------------------------------ 4 NEPTUNE-PRO NIC2 MULTIAC NIC2-FI F204M 2.04000 PATTERN = ONE-CHOP,NUM-POS = 2 , 1 DEF POS TARG -0.2668, 0 TEUS CUM X CHOP-SIZE = 0.9438,PATTERN-ORIENT = 95,SAMP-SEQ = STEP64,NSAMP = 11 ------------------------------------------------------------------------------------------------------------------------------------ 5 NEPTUNE-PRO NIC2 MULTIAC NIC2-FI F237M 2.37500 PATTERN = ONE-CHOP,NUM-POS = 2 , 1 DEF POS TARG -0.2668, 0 TEUS CUM X CHOP-SIZE = 0.9438,PATTERN-ORIENT = 95,SAMP-SEQ = STEP64,NSAMP = 10 ------------------------------------------------------------------------------------------------------------------------------------ 6 NEPTUNE-PRO NIC2 MULTIAC NIC2-FI F237M 2.37500 PATTERN = ONE-CHOP,NUM-POS = 2 , 2 DEF TEUS CUM X CHOP-SIZE = 0.9438,PATTERN-ORIENT = 95,SAMP-SEQ = STEP64,NSAMP = 10 ------------------------------------------------------------------------------------------------------------------------------------ 7 NEPTUNE-PRO NIC2 MULTIAC NIC2-FI F237M 2.37500 SAMP-SEQ = STEP64,NSAMP = 10 1 DEF TEUS CUM X ------------------------------------------------------------------------------------------------------------------------------------ 7182( 3) - 03/04/98 09:37 - [ 6] Summary Form for Proposal 7182 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations NIC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters PATTERN = ONE-CHOP NUM-POS = 2 CHOP-SIZE = 0.9438 PATTERN-ORIENT = 95 SAMP-SEQ = STEP64 NSAMP = 9 NSAMP = 10 NSAMP = 11 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GTO/NIC ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements SCHED 90% ORIENT 230D TO 236D BETWEEN 15-MAY-1998 AND 4-AUG-1998 POS TARG -0.2668, 0 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F110W F160W F204M F237M ------------------------------------------------------------------------------------------------------------------------------------ Target Names NEPTUNE-PROTEUS ------------------------------------------------------------------------------------------------------------------------------------