7244( 17) - 09/22/98 11:50 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 7244 Version: 17 Check-in Date: 22-Sep-1998 11:48:50 1.Proposal Title: Imaging of the Neptune Ring ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GTO/NIC 7 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Rich Terrile Jet Propulsion Laboratory CoI: C. Dumas Jet Propulsion Laboratory N CoI: D. W. Koerner Jet Propulsion Laboratory N CoI: B. A. Smith University of Hawaii N CoI: R. Meier University of Hawaii N CoI: E. Becklin University of California Los Angeles N CoI: P. Nicholson Cornell University N CoI: R. H. Brown University of Arizona N CoI: T. Owen University of Hawaii N ------------------------------------------------------------------------------------ 5. Abstract The arcs in the Neptune ring have not been seen since Voyager 2 imaged them in 1989. NICMOS images made within a methane band, which suppress the scattered light from Neptune, may reveal the ring arcs, the brightest components of the Neptune ring system. Modern observations, when tied to the Voyager results, would constrain models for the dynamics and stablity of these ring arcs. These observations would also provide the means of monitoring their behavior over longer periods of time. The F187W filter in camera NIC2 was selected because it covers a strong Neptune methane absorption band, even though this observation could also be done in several others filters and in other NICMOS cameras. ------------------------------------------------------------------------------------ 7244( 17) - 09/22/98 11:50 - [ 2] Observations Description ------------------------ These observations make use of NICMOS Camera 2 to image the ring arcs of Neptune. The aperture should be positioned immediately adjacent to that edge of the planet which is closest to the ring arcs (with the planet outside the field of view). To accomplish this, Neptune is chosen as the primary target, an orient is specified, and the target is simply offset the proper distance from the true center of the array (aperture given as NIC2-FIX). We note here that, since Neptune is designated as the target but moved out of the field of view, RPS2 yields a feasibility error message which we have ignored. The F187W filter is designated, since it covers a methane band in which light from Neptune is greatly diminished. Observations should be scheduled when the center of the ring arcs is at Western Elongation. This is achieved by specifying an orbital period as determined from the Voyager observations and a phase range equal to the angular width of the arcs and centered on the timing of Western Elongation of the arc center. We have updated the period of rotation of the Arcs and the Julian date of Eastern elongation (zero phase) accordingly to the measurements made on the first set of data collected during the visit # 3 (June 03, 1998). The motion adopted for the arc is now 820.1118 deg/day. We note here that a secular correction of up to 8 minutes may be warranted, depending on the timing of the observations. This correction is small compared to the ephemeris uncertainty or the transit time of the arcs, so it is not of paramount importance. Diffraction patterns caused by light from Neptune that is diffracted by the spiders into the NICMOS light path should be tilted by about 45 degrees in respect to the ring plane. This is automatically done by orient requirements which line up the rotational axis (PA ~ -3 deg from North) of the Neptune-ring system with the Y-axis of the array. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: Rodger Thompson, Steward Observatory, University of Arizona, Tucson, AZ 85721 Ship Via: Email: thompson@as.arizona.edu ------------------------------------------------------------------------------------ 7244( 17) - 09/22/98 11:50 - [ 3] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 | TARGET NAME: NEPTUNE ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: PLANET ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=NEPTUNE | | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 18.0+/-0.5 | The real target here is Neptune's SIZE=2 | RING ARCS, but since their | rotational axis is coincident with | Neptune's, we just position Neptune | off the chip (to diminish scattered | light) at the time of Eastern | Elongation. This is easier, since an | ephemeris already exists at STSci | for Neptune. The timing of Eastern | Elongation can be easily specified | by using a period and phase derived | from the Voyager data. Since the | rings have not been observed | subsequently, no update to this | timing will be attempted. | ------------------------------------------------------------------------------------------------------------------------------------ 7244( 17) - 09/22/98 11:50 - [ 4] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 2 | TARGET NAME: NEPTUNE1 ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: PLANET ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=NEPTUNE | STD=LARISSA | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | OLG OF LARISSA BETWEEN 230 310 | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 18.0+/-0.5 | The real target here is Neptune's SIZE=2 | RING ARCS, but since their | rotational axis is coincident with | Neptune's, we just position Neptune | off the chip (to diminish scattered | light) at the time of Western | Elongation. This is easier, since an | ephemeris already exists at STSci | for Neptune. We specify an | additional target (Larissa) to be in | the range of 230 to 310 in orbital | longitude (Western elongation) in | order to use this satellite as an | additional calibration (astrometric | and photometric) for the Arcs. | ------------------------------------------------------------------------------------------------------------------------------------ 7244( 17) - 09/22/98 11:50 - [ 5] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 3 | TARGET NAME: NEPTUNE2 ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: PLANET ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=NEPTUNE | STD=LARISSA | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | OLG OF LARISSA BETWEEN 50 130 | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | V = 18.0+/-0.5 | The real target here is Neptune's SIZE=2 | RING ARCS, but since their | rotational axis is coincident with | Neptune's, we just position Neptune | along the Y axis of the chip to get | the arcs either at Eastern or | Western elongation. We specify an | additional target (Larissa) to be in | the range of 230 to 310 in orbital | longitude (Western elongation) or 50 | to 130 (Eastern elongation) in order | to use this satellite as an | additional calibration (astrometric | and photometric) for the Arcs. | ------------------------------------------------------------------------------------------------------------------------------------ 7244( 17) - 09/22/98 11:50 - [ 6] Visit: 01 Visit Priority: Visit Requirements: SCHED 30% ORIENT 32D TO 52D PERIOD 10.5351487775 H AND ZERO-PHASE JD2450995.965280 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 NEPTUNE1 NIC2 MULTIAC NIC2-FI F187W 1.87500 SAMP-SEQ=STEP16,NSAMP=19, 1 DEF POS TARG -10.50,-6.23 CUM X PATTERN=YSTRIP-DITH,NUM-POS=11, PHASE 0.43 TO 0.57 SEQ 1 DITH-SIZE=1.2458, NON-INT PATTERN-ORIENT=177 ------------------------------------------------------------------------------------------------------------------------------------ 7244( 17) - 09/22/98 11:50 - [ 7] Visit: 02 Visit Priority: Visit Requirements: SCHED 30% ORIENT 32D TO 52D PERIOD 10.5351487775 H AND ZERO-PHASE JD2450995.965280 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 NEPTUNE1 NIC2 MULTIAC NIC2-FI F187W 1.87500 SAMP-SEQ=STEP16,NSAMP=19, 1 DEF POS TARG -10.50,-6.23 CUM X PATTERN=YSTRIP-DITH,NUM-POS=11, PHASE 0.43 TO 0.57 SEQ 1 DITH-SIZE=1.2458, NON-INT PATTERN-ORIENT=177 ------------------------------------------------------------------------------------------------------------------------------------ 7244( 17) - 09/22/98 11:50 - [ 8] Visit: 03 Visit Priority: Visit Requirements: SCHED 30% ORIENT 213D TO 235D PERIOD 10.5350638888H AND ZERO-PHASE JD2450630.723 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 NEPTUNE NIC2 MULTIAC NIC2-FI F187W 1.87500 SAMP-SEQ=STEP64,NSAMP=21 ,PATTERN 1 DEF POS TARG 11.1, 0 PHASE CUM X = YSTRIP-DITH,NUM-POS = 3, 0.93 TO 0.07 DITH-SIZE = 3.0375 , PATTERN-ORIENT = 358 ------------------------------------------------------------------------------------------------------------------------------------ 7244( 17) - 09/22/98 11:50 - [ 9] Visit: 51 Visit Priority: Visit Requirements: SCHED 30% ORIENT 59D TO 79D PERIOD 10.5351487775H AND ZERO-PHASE JD2450995.96528 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 NEPTUNE2 NIC2 MULTIAC NIC2-FI F187W 1.87500 SAMP-SEQ=STEP16,NSAMP=19 ,PATTERN 1 DEF POS TARG 0, 3.58 PHASE CUM X = YSTRIP-DITH,NUM-POS = 11, 0.93 TO 0.07 SEQ 1 DITH-SIZE = 0.7172 , NON-INT PATTERN-ORIENT = DETECTOR ------------------------------------------------------------------------------------------------------------------------------------ 7244( 17) - 09/22/98 11:50 - [ 10] Visit: 52 Visit Priority: Visit Requirements: SCHED 30% ORIENT 59D TO 79D PERIOD 10.5351487775H AND ZERO-PHASE JD2450995.96528 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 NEPTUNE2 NIC2 MULTIAC NIC2-FI F187W 1.87500 SAMP-SEQ=STEP16,NSAMP=19 ,PATTERN 1 DEF POS TARG 0, 3.58 PHASE CUM X = YSTRIP-DITH,NUM-POS = 11, 0.93 TO 0.07 SEQ 1 DITH-SIZE = 0.7172 , NON-INT PATTERN-ORIENT = DETECTOR ------------------------------------------------------------------------------------------------------------------------------------ 7244( 17) - 09/22/98 11:50 - [ 11] Summary Form for Proposal 7244 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures NIC2-FIX ------------------------------------------------------------------------------------------------------------------------------------ Configurations NIC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SAMP-SEQ=STEP16 NSAMP=19 PATTERN=YSTRIP-DITH NUM-POS=11 DITH-SIZE=1.2458 PATTERN-ORIENT=177 PATTERN-ORIENT = 358 PATTERN-ORIENT = DETECTOR DITH-SIZE = 0.7172 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GTO/NIC ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements SCHED 30% ORIENT 32D TO 52D PERIOD 10.5351487775 H AND ZERO-PHASE JD2450995.965280 POS TARG -10.50,-6.23 PHASE 0.43 TO 0.57 SEQ 1 NON-INT SCHED 30% ORIENT 213D TO 235D PERIOD 10.5350638888H AND ZERO-PHASE JD2450630.723 POS TARG 11.1, 0 PHASE 0.93 TO 0.07 SCHED 30% ORIENT 59D TO 79D PERIOD 10.5351487775H AND ZERO-PHASE JD2450995.96528 POS TARG 0, 3.58 PHASE 0.93 TO 0.07 SEQ 1 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F187W ------------------------------------------------------------------------------------------------------------------------------------ Target Names NEPTUNE1 NEPTUNE NEPTUNE2 ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 1.87500 ------------------------------------------------------------------------------------------------------------------------------------