6842( 2) - 01/25/96 16:07 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6842 Version: 2 Check-in Date: 25-Jan-1996 16:00:40 1.Proposal Title: EVOLUTION OF THE NEW BRIGHT SPOT ON IO ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Solar System GO 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: John Spencer Lowell Observatory CoI: Melissa McGrath Space Telescope Science Institute Y CoI: Alfred McEwen USGS Flagstaff N ------------------------------------------------------------------------------------ 6. Abstract We would like to re-observe the new bright spot that we discovered in HST images of Io taken in July 1995, in order to determine the evolution of its spectral reflectivity with time. Observations with WFPC2 on a single orbit in late Februray or March 1996 would fill a large time gap between the July 1995 discovery images and the first Galileo images (and possible Cycle 6 HST images) in July 1996. ------------------------------------------------------------------------------------ Observations Description ------------------------ We use one HST orbit to obtain multicolor WFPC2 images of Io, centered in the PC chip. The filters to be used are F343N (500s), F375N (500s), F410M (10s), F467M (3s), F502N (16s), F588N (3s), F658N (6s), and F791W (2.3s). For maximum time separation from the planned July 1996 Galileo images of Io, HST observations should be made as soon as possible after February 20th 1996, when Jupiter becomes far enough from the Sun for HST to observe. Io central longitudes between 300 and 340 degrees are needed in order to get a good view of the new spot, which is at longitude 325 degrees (central longitudes must be less than about 340 to avoid eclipses and occultations by Jupiter). Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 6842( 2) - 01/25/96 16:07 - [ 2] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6842( 2) - 01/25/96 16:07 - [ 3] TARGET LIST b)Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 | TARGET NAME: IO-LON320 ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE IO ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD=JUPITER | STD=IO | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | OLG OF IO BETWEEN 300 340 | ------------------------------------------------------------------------------------------------------------------------------------ DATA | COMMENTS | SURF(V) = 5.14 | Io should be in full sunlight (not B-V = 1.2 | in Jupiter's shadow umbra or | penumbra) for all exposures. | Execution as soon as feasible after | 20 Febr is highly desired. | ------------------------------------------------------------------------------------------------------------------------------------ 6842( 2) - 01/25/96 16:07 - [ 4] Visit: 01 Visit Requirements: BETWEEN 20-FEB-96 AND 10-MAR-96 On Hold Comments: Additional Comments: Execution as soon as feasible after 20 Febr is highly desired. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 IO-LON320 WFPC2 IMAGE PC1 F343N CR-SPLIT=NO,ATD 1 500S -GAIN=15 ------------------------------------------------------------------------------------------------------------------------------------ 2 IO-LON320 WFPC2 IMAGE PC1 F375N ATD-GAIN=15 1 500S ------------------------------------------------------------------------------------------------------------------------------------ 3 IO-LON320 WFPC2 IMAGE PC1 F410M ATD-GAIN=15 1 10S ------------------------------------------------------------------------------------------------------------------------------------ 4 IO-LON320 WFPC2 IMAGE PC1 F467M ATD-GAIN=15 1 3.0S ------------------------------------------------------------------------------------------------------------------------------------ 5 IO-LON320 WFPC2 IMAGE PC1 F502N ATD-GAIN=15 1 16S ------------------------------------------------------------------------------------------------------------------------------------ 6 IO-LON320 WFPC2 IMAGE PC1 F588N ATD-GAIN=15 1 3.0S ------------------------------------------------------------------------------------------------------------------------------------ 7 IO-LON320 WFPC2 IMAGE PC1 F658N ATD-GAIN=15 1 6.0S ------------------------------------------------------------------------------------------------------------------------------------ 8 IO-LON320 WFPC2 IMAGE PC1 F791W ATD-GAIN=15 1 0.23S ------------------------------------------------------------------------------------------------------------------------------------ 6842( 2) - 01/25/96 16:07 - [ 5] Summary Form for Proposal 6842 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO ATD-GAIN=15 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Solar System ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 20-FEB-96 AND 10-MAR-96 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F343N F375N F410M F467M F502N F588N F658N F791W ------------------------------------------------------------------------------------------------------------------------------------ Target Names IO-LON320 ------------------------------------------------------------------------------------------------------------------------------------