5782( 0) - 07/18/95 17:58 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 5782 Version: ********** Check-in Date: ********** 1.Proposal Title: SATURN RING-PLANE CROSSING, MAY 1995 ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Solar System GTO/HSP 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Bosh, Amanda Lowell Obs. ------------------------------------------------------------------------------------ 6. Abstract In 1995-1996, the Earth and the Sun will pass through Saturn's ring plane. The Earth will pass through 3 times (22 May 1995, 10 August 1995, 11 Feb 1996), and the Sun will pass through once (19 November 1995). All but the 11 Feb 1996 event will be visible from HST. During the crossings of the Earth through Saturn's ring plane, the rings will become very thin and dark. By monitoring the brightness of the rings as they become very thin, we will be able to determine the time of ring-plane crossing and the residual brightness of the rings at this time. The time of the ring- plane crossing will place additional constraints on the precession rate of Saturn's pole. The recent occultations by Saturn's rings have produced a measurement of this value, but it is not known very well (French et al., 1993; Bosh, 1994; Elliot et al., 1993). A measure of the brightness of the rings in their edge- on configuration, combined with photometric properties of the rings derived from early calibration observations will allow us to determine the thickness of the rings. ------------------------------------------------------------------------------------ 5782( 0) - 07/18/95 17:58 - [ 2] Observations Description ------------------------ We will monitor the brightness of Saturn's rings as the Earth passes through Saturn's ring plane. This set of observations covers the first of the crossings of the Earth through Saturn's ring-plane for the 1995-1996 events. We will obtain a series of WFPC2 images at 8900 A (in methane band, to reduce scattered light from Saturn) of Saturn and its rings for 7 orbits centered on the predicted time of ring-plane crossing. Imaging for 7 orbits allows for uncertainty in the precession of Saturn's ring-plane pole. Each orbit will consist of a set of 2 short exposures (for satellite photometric calibration) and as many 400-sec exposures as will fit in the rest of the orbit (to detect residual flux from vertical face of rings). An additional orbit before or after the event (preferably after) will obtain additional calibration data. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- Time critical long observation. Will be near Moon. Will need to ignore SAA to greatest extent possible (including dropping to gyro control if necessary). May have to use guidestar handoff. Edited 4/21 to replace POS TARGs with SSTL offsets, and use CH4 filter "apertures". (ADS) ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 5782( 0) - 07/18/95 17:58 - [ 3] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 | TARGET NAME: SATURN ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: PLANET SATURN ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=SATURN | TYPE=POS_ANGLE, RAD=16.3, ANG=49, | REF=SUN | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | WND1= 20-MAY-1995 TO 25-MAY-1995 | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | SURF(V) = 7.0 +/- 0.1 B-V = 1.0 +/- 0.1 | Planet center, for WF obs. | ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 2 | TARGET NAME: SATURN-PC ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: RING SATURN ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=SATURN | TYPE=POS_ANGLE, RAD=14.1, ANG=38, | REF=SUN | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | WND1= 20-MAY-1995 TO 25-MAY-1995 | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | SURF(V) = 15.0 +/- 0.5 | West ansa of outer main ring. | ------------------------------------------------------------------------------------------------------------------------------------ 5782( 0) - 07/18/95 17:58 - [ 4] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 3 | TARGET NAME: SATURN-WEST-ERING ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: RING SATURN ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD = SATURN | TYPE = TORUS, LONG = 90, LAT = 0, RAD = | 3.25E05, POLE_LAT = +90, POLE_LONG = 0 | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | SURF(V) = 18.6 | Western ansa of Saturn E ring | centered 50 arcsec from center of | Saturn. | ------------------------------------------------------------------------------------------------------------------------------------ 5782( 0) - 07/18/95 17:58 - [ 5] Visit: 01 Visit Requirements: BETWEEN 21-MAY-95:23:40 AND 22-MAY-95:01:16 ORIENT -24D TO 24D FROM NOMINAL 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 SATURN WFPC2 IMAGE FQCH4W3 FQCH4N 8922 CR-SPLIT=NO, 2 7S SEQ 10-20 NON-INT NO SPLIT CLOCKS=YES, ATD -GAIN=7 Comments: IGNORE SAA, short exposure for satellite photometry ------------------------------------------------------------------------------------------------------------------------------------ 20 SATURN WFPC2 IMAGE FQCH4W3 FQCH4N 8922 CR-SPLIT=NO, 3 400S SAME POS AS 10 CLOCKS=YES, ATD -GAIN=7 Comments: CH4 EXPOSURES FULL ACQ, IGNORE SAA ------------------------------------------------------------------------------------------------------------------------------------ 40 SATURN WFPC2 IMAGE FQCH4W3 FQCH4N 8922 CR-SPLIT=NO, 2 7S SEQ 40-50 NON-INT NO SPLIT CLOCKS=YES, ATD -GAIN=7 Comments: IGNORE SAA, short exposures for satellite photometry ------------------------------------------------------------------------------------------------------------------------------------ 50 SATURN WFPC2 IMAGE FQCH4W3 FQCH4N 8922 CR-SPLIT=NO, 4 400S SAME POS AS 40 CLOCKS=YES, ATD -GAIN=7 Comments: CH4 EXPOSURES REACQ, IGNORE SAA ------------------------------------------------------------------------------------------------------------------------------------ 70 SATURN WFPC2 IMAGE FQCH4W3 FQCH4N 8922 CR-SPLIT=NO, 2 7S SEQ 70-80 NON-INT NO SPLIT CLOCKS=YES, ATD -GAIN=7 Comments: IGNORE SAA, short exposures for satellite photometry ------------------------------------------------------------------------------------------------------------------------------------ 80 SATURN WFPC2 IMAGE FQCH4W3 FQCH4N 8922 CR-SPLIT=NO, 4 400S SAME POS AS 70 CLOCKS=YES, ATD -GAIN=7 Comments: CH4 EXPOSURES REACQ, IGNORE SAA ------------------------------------------------------------------------------------------------------------------------------------ 100 SATURN WFPC2 IMAGE FQCH4W3 FQCH4N 8922 CR-SPLIT=NO, 2 7S SEQ 100-110 NON-INT NO SPLIT CLOCKS=YES, ATD -GAIN=7 Comments: IGNORE SAA, short exposures for satellite photometry ------------------------------------------------------------------------------------------------------------------------------------ 110 SATURN WFPC2 IMAGE FQCH4W3 FQCH4N 8922 CR-SPLIT=NO, 4 400S SAME POS AS 100 CLOCKS=YES, ATD -GAIN=7 Comments: CH4 EXPOSURES REACQ, IGNORE SAA ------------------------------------------------------------------------------------------------------------------------------------ 5782( 0) - 07/18/95 17:58 - [ 6] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 130 SATURN WFPC2 IMAGE FQCH4W3 FQCH4N 8922 CR-SPLIT=NO, 2 7S SEQ 130-140 NON-INT NO SPLIT CLOCKS=YES, ATD -GAIN=7 Comments: IGNORE SAA, short exposures for satellite photometry ------------------------------------------------------------------------------------------------------------------------------------ 140 SATURN WFPC2 IMAGE FQCH4W3 FQCH4N 8922 CR-SPLIT=NO, 4 400S SAME POS AS 130 CLOCKS=YES, ATD -GAIN=7 Comments: CH4 EXPOSURES REACQ, IGNORE SAA ------------------------------------------------------------------------------------------------------------------------------------ 160 SATURN WFPC2 IMAGE FQCH4W3 FQCH4N 8922 CR-SPLIT=NO, 2 7S SEQ 160-170 NON-INT NO SPLIT CLOCKS=YES, ATD -GAIN=7 Comments: IGNORE SAA, short exposures for satellite photometry ------------------------------------------------------------------------------------------------------------------------------------ 170 SATURN WFPC2 IMAGE FQCH4W3 FQCH4N 8922 CR-SPLIT=NO, 4 400S SAME POS AS 160 CLOCKS=YES, ATD -GAIN=7 Comments: CH4 EXPOSURES REACQ, IGNORE SAA ------------------------------------------------------------------------------------------------------------------------------------ 190 SATURN WFPC2 IMAGE FQCH4W3 FQCH4N 8922 CR-SPLIT=NO, 2 7S SEQ 190-200 NON-INT NO SPLIT CLOCKS=YES, ATD -GAIN=7 Comments: IGNORE SAA, short exposures for satellite photometry ------------------------------------------------------------------------------------------------------------------------------------ 200 SATURN WFPC2 IMAGE FQCH4W3 FQCH4N 8922 CR-SPLIT=NO, 4 400S SAME POS AS 190 CLOCKS=YES, ATD -GAIN=7 Comments: CH4 EXPOSURES REACQ, IGNORE SAA ------------------------------------------------------------------------------------------------------------------------------------ 5782( 0) - 07/18/95 17:58 - [ 7] Visit: 02 Visit Requirements: SEQ 1-2 WITHIN 24H ORIENT -24D TO 24D FROM NOMINAL 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 ------------------------------------------------------------------------------------------------------------------------------------ 220 SATURN-PC WFPC2 IMAGE PC1-FIX FQCH4P15 8922 CR-SPLIT=NO 3 100S Comments: test exposure for Nicholson ------------------------------------------------------------------------------------------------------------------------------------ 230 SATURN WFPC2 IMAGE FQCH4W3 FQCH4N 8922 CR-SPLIT=NO, 3 60S CLOCKS=YES, ATD -GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ 240 SATURN-WEST WFPC2 IMAGE WF2-FIX F675W 6714 CR- 1 400S POS TARG 16.8, -9.0 NO SPLIT -ERING SPLIT=NO,SUM=2X 2 Comments: Test exposure for Nicholson ------------------------------------------------------------------------------------------------------------------------------------ 5782( 0) - 07/18/95 17:58 - [ 8] Summary Form for Proposal 5782 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO CLOCKS=YES ATD-GAIN=7 SUM=2X2 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GTO/HSP ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Solar System ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 21-MAY-95 23 40 AND 22-MAY-95 01 16 ORIENT -24D TO 24D FROM NOMINAL SEQ 10-20 NON-INT NO SPLIT SAME POS AS 10 SEQ 40-50 NON-INT NO SPLIT SAME POS AS 40 SEQ 70-80 NON-INT NO SPLIT SAME POS AS 70 SEQ 100-110 NON-INT NO SPLIT SAME POS AS 100 SEQ 130-140 NON-INT NO SPLIT SAME POS AS 130 SEQ 160-170 NON-INT NO SPLIT SAME POS AS 160 SEQ 190-200 NON-INT NO SPLIT SAME POS AS 190 SEQ 1-2 WITHIN 24H ORIENT -24D TO 24D FROM NOMINAL POS TARG 16.8, -9.0 NO SPLIT ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements FQCH4N FQCH4P15 F675W ------------------------------------------------------------------------------------------------------------------------------------ Target Names SATURN SATURN-PC SATURN-WEST-ERING ------------------------------------------------------------------------------------------------------------------------------------