13328( 8) - 11-Feb-2014 12:03:11 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 13328 Version: 8 Check-in Time: 11-Feb-2014 12:03:11 STScI Edit Number: 6 Title Observing Ganymede's atmosphere and auroras with COS and STIS ------------------------------------------------------------------------------------ Type Cycle GO 21 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Jonathan D. Nichols University of Leicester Y CoI: Prof. John T. Clarke Boston University N CoI: Dr. Nigel Bannister University of Leicester N CoI: Dr. Emma J. Bunce University of Leicester N CoI: Prof. Stanley W. Cowley University of Leicester N CoI: Prof. Stephen Milan University of Leicester N CoI: Ms. Pippa Molyneux University of Leicester N CoI: Prof. Denis Grodent Universite de Liege N CoI: Prof. Carol Paty Georgia Institute of Technology N ------------------------------------------------------------------------------------ Abstract Jupiter's satellite Ganymede is one of the solar system's most intriguing moons, and the importance of studying Ganymede is vividly highlighted by the recent selection of the ESA L-class mission JUICE. Ganymede possesses an oxygen atmosphere and the only known 'magnetosphere within a magnetosphere', and the continuous impingement of Jupiter's magnetospheric plasma on Ganymede thus makes the satellite an ideal control case for studying the interaction of any cosmic body with an external wind. Auroral emissions are crucial diagnostics of this interaction, but spectra of Ganymede's FUV auroras have only been obtained with GHRS and STIS. Fundamental outstanding questions thus remain as to the nature of this unique satellites's atmosphere and its magnetosphere, and we will use the significantly improved sensitivity of COS, combined with the imaging capabilities of STIS, to examine Ganymede's FUV atmospheric emissions in order to answer the following questions: * How does Ganymede's magnetosphere interact with Jupiter's? * What is the nature of Ganymede's oxygen atmosphere? Ganymede has never been observed with COS, and STIS observations of both hemispheres have not been obtained in the same epoch, such that this program will provide the most significant advancements in our understanding of the atmosphere and magnetosphere of this enigmatic satellite for over a decade. HST is the only observatory capable of obtaining these observations and execution of this program during Cycle 21 is extremely highly desirable, since the unprecedented new information these observations will return are urgently required by those who are now designing instruments for the JUICE mission. ------------------------------------------------------------------------------------ Observations Description ------------------------ The proposed observations will consist of COS and STIS exposures of Ganymede near eastern and western elongation, with two visits scheduled 1/2 Ganymede orbit apart. Each visit will consist of 4 orbits, 2 COS and 2 STIS, for a total of 8 orbits in the program. In orbits 1, 2, and 4 in each visit, Ganymede will first be acquired. The first and last orbit in each visit will consist of 13328( 8) - 11-Feb-2014 12:03:11 - [ 2] STIS/FUV-MAMA G140L 52X2 TIME-TAG spectroscopy, while the middle two orbits will consist of COS/FUV G140L TIME-TAG spectroscopy of the reflected solar continuum from the surface of Ganymede, plus the atmospheric absorption and airglow/auroral emissions. Ideally, the STIS and COS orbits would be contiguous, such that the first and last STIS image in each visit will be obtained roughly half a jovian rotation apart in order to capture variability. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 13328( 8) - 11-Feb-2014 12:03:11 - [ 3] TARGET LIST Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 TARGET NAME: GANYMEDE-EAST ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE SATELLITE GANYMEDE ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 TARGET POSITION LEVEL 2 STD=JUPITER STD=GANYMEDE ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 WINDOWS SEP OF GANYMEDE-EAST JUPITER FROM EARTH GT 30", SEP OF GANYMEDE-EAST CALLISTO FROM EARTH GT 10", SEP OF GANYMEDE-EAST IO FROM EARTH GT 10", SEP OF GANYMEDE-EAST EUROPA FROM EARTH GT 10", OLG OF GANYMEDE-EAST BETWEEN 70 110, SEP OF GANYMEDE-EAST SUN FROM EARTH GT 150D ------------------------------------------------------------------------------------------------------------------------------------ DATA COMMENTS V = 5.5 +/- 0.1 Ganymede within +/-20 degrees of eastern elongation and within +/- 30 degrees of opposition. These constraints could be relaxed somewhat to ease scheduling if Ephemeris Center: EARTH necessary. ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 4 TARGET NAME: GANYMEDE-WEST ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE SATELLITE GANYMEDE ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 TARGET POSITION LEVEL 2 STD=JUPITER STD=GANYMEDE ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 WINDOWS SEP OF GANYMEDE-WEST JUPITER FROM EARTH GT 30", SEP OF GANYMEDE-WEST CALLISTO FROM EARTH GT 10", SEP OF GANYMEDE-WEST IO FROM EARTH GT 10", SEP OF GANYMEDE-WEST EUROPA FROM EARTH GT 10", OLG OF GANYMEDE-WEST BETWEEN 250 290, SEP OF GANYMEDE-WEST SUN FROM EARTH GT 150D ------------------------------------------------------------------------------------------------------------------------------------ DATA COMMENTS V = 5.5 +/- 0.1 Ganymede within +/-20 degrees of western elongation and within +/- 30 degrees of opposition. These constraints could be relaxed somewhat to ease scheduling if Ephemeris Center: EARTH necessary. ------------------------------------------------------------------------------------------------------------------------------------ 13328( 8) - 11-Feb-2014 12:03:11 - [ 4] TARGET LIST Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 5 TARGET NAME: GANYMEDE-WEST-EXTENDED ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE SATELLITE GANYMEDE ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 TARGET POSITION LEVEL 2 STD=JUPITER STD=GANYMEDE ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 WINDOWS SEP OF GANYMEDE-WEST-EXTENDED JUPITER FROM EARTH GT 30", SEP OF GANYMEDE-WEST-EXTENDED CALLISTO FROM EARTH GT 10", SEP OF GANYMEDE-WEST-EXTENDED IO FROM EARTH GT 10", SEP OF GANYMEDE-WEST-EXTENDED EUROPA FROM EARTH GT 10", OLG OF GANYMEDE-WEST-EXTENDED BETWEEN 250 290, SEP OF GANYMEDE-WEST-EXTENDED SUN FROM EARTH GT 120D ------------------------------------------------------------------------------------------------------------------------------------ DATA COMMENTS V = 5.5 +/- 0.1 Ganymede within +/-20 degrees of western elongation and within +/- 30 degrees of opposition. These constraints could be relaxed somewhat to ease scheduling if Ephemeris Center: EARTH necessary. ------------------------------------------------------------------------------------------------------------------------------------ 13328( 8) - 11-Feb-2014 12:03:11 - [ 5] Visit: G1 Visit Requirements: On Hold Comments: Additional Comments: Eastern elongation - defined by target. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 GANYMEDE-EA STIS/CCD ACQ F28X50LP MIRROR ACQTYPE=DIFFUSE, CHECKBOX=37, 1 0.1 S (0.1 ST DIFFUSE-CENTER=GEOMETRIC-CENTE S) R Comments: Ganymede V mag near to opposition is ~4.6. Surface brightness for disc of diameter 1.7" is then ~5.5. In ETC run STIS.ta.510225, I used a Castelli-Kurucz G2V spectrum normalised to V = 5.5 / arcsec squared and diameter = 1.7. The minimum exposure time is less than the CCD saturation time of ~0.5 s. ------------------------------------------------------------------------------------------------------------------------------------ 2 GANYMEDE-EA STIS/FUV TIME-TA 52X2 G140L 1425 BUFFER-TIME=443 1 885 S (885 POS TARG null, -4 ST -MAMA G S) Comments: In STIS.sp.517958 I used an archive spectrum of the same target and instrument set-up. Buffer Time = Texp / 2. POS-TARG of y=-4" moves the target out of the blotch region (slightly less than does the 52X2D1 aperture, but the target is >1") ------------------------------------------------------------------------------------------------------------------------------------ 3 GANYMEDE-EA STIS/FUV TIME-TA 52X2 G140L 1425 BUFFER-TIME=443 1 885 S (885 POS TARG null, -4 ST -MAMA G S) Comments: In STIS.sp.517958 I used an archive spectrum of the same target and instrument set-up. Buffer Time = Texp / 2. POS-TARG of y=-4" moves the target out of the blotch region (slightly less than does the 52X2D1 aperture, but the target is >1") ------------------------------------------------------------------------------------------------------------------------------------ 13328( 8) - 11-Feb-2014 12:03:11 - [ 6] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 4 GANYMEDE-EA COS/NUV ACQ/SEA BOA MIRRORA SCAN-SIZE=2 1 3 S (3 S) ST RCH Comments: Ganymede V mag near to opposition is ~4.6, and the surface brightness for a disc of diameter 1.7" is then ~5.5. Ganymede's albedo over 2400-3000 A ranges from ~7% on the trailing side to ~20% on the leading side (Nelson et al., 1987), vs. ~43% in the visible, and is thus ~0.8-2.0 mags dimmer in this waveband than in the visible. ACQ/SEARCH ETC runs using an extended source (a normalised Castelli-Kurucz G2V spectrum), yield for the BOA/MIRRORA: mV_eff = 7.5 (COS.ta.517264) Texp(SNR = 60) = 2.4873 s mV_eff = 6.3 (COS.ta.517265 ) Texp(SNR = 60) = 0.7901 s Using a 3 s exposure then gives a good SNR for all cases: mV_eff = 7.5 (COS.ta.517267) SNR(Texp = 3 s) = 65.8941, total count rate = 2, 554.089 counts/s mV_eff = 6.3 (COS.ta.517268 ) SNR(Texp = 3 s) = 116.915, total count rate = 5, 667.150 counts/s ------------------------------------------------------------------------------------------------------------------------------------ 5 GANYMEDE-EA COS/NUV ACCUM BOA MIRRORA 1 3 S (3 S) ST Comments: This exposure is to verify Ganymede's position in the aperture. We have the same Texp and count rates as for Exposure 5, but imaging ETC runs give SNRs of: mV_eff = 7.5 (COS.im.517270) SNR(Texp = 3 s) = 46.1111, total count rate = 2, 554.089 counts/s mV_eff = 6.3 (COS.im.517273) SNR(Texp = 3 s) = 80.2784, total count rate = 5, 667.150 counts/s ------------------------------------------------------------------------------------------------------------------------------------ 13328( 8) - 11-Feb-2014 12:03:11 - [ 7] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 6 GANYMEDE-EA COS/FUV TIME-TA PSA G140L 1280 BUFFER-TIME=878, FLASH=YES, 1 988 S (988 ST G FP-POS=1 S) Comments: Ganymede V mag near to opposition is ~4.6, and the surface brightness for a disc of diameter 1.7" is then ~5.5. Ganymede's albedo in near 1400 A is ~2.3% (Feldman et al., 2000), vs. ~43% in the visible, and is thus ~3.2 mags dimmer in this waveband than in the visible. In ETC run COS.sp.517981 I used a Castelli-Kurucz G2V spectrum normalised to mV_eff = 8.7 / arcsec squared and diameter = 1.7", plus two emission lines representative of the fluxes observed by Feldman et al. (2000): Center 1304.0 A FWHM 30.0 A Flux 2.3e-15 erg/cm^2/s Center 1356.0 A FWHM 30.0 A Flux 4.4e-15 erg/cm^2/s The Buffer Time is 19, 639 s, thus well over an orbit. Here, I've used Texp - 110 to minimise the time between the two exposures. ------------------------------------------------------------------------------------------------------------------------------------ 7 GANYMEDE-EA COS/FUV TIME-TA PSA G140L 1280 BUFFER-TIME=1.3E4, FLASH=YES, 1 989 S (989 ST G FP-POS=2 S) Comments: ETC Buffer Time is, as for Exposure 6, ~20k s. Multiplied by 2/3 = 13092, rounded down to 13, 000 s as this is the second exposure in the orbit. ------------------------------------------------------------------------------------------------------------------------------------ 8 GANYMEDE-EA COS/FUV TIME-TA PSA G140L 1280 BUFFER-TIME=1298, FLASH=YES, 1 1408 S ST G FP-POS=3 (1408 S) Comments: ETC Buffer Time is, as for Exposure 6, ~20k s. Here, I've used Texp - 110 to minimise the time between the two exposures. ------------------------------------------------------------------------------------------------------------------------------------ 9 GANYMEDE-EA COS/FUV TIME-TA PSA G140L 1280 BUFFER-TIME=1.3E4, FLASH=YES, 1 1409 S ST G FP-POS=4 (1409 S) Comments: ETC Buffer Time is, as for Exposure 6, ~20k s. Multiplied by 2/3 = 13092, rounded down to 13, 000 s as this is the second exposure in the orbit. ------------------------------------------------------------------------------------------------------------------------------------ 13328( 8) - 11-Feb-2014 12:03:11 - [ 8] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 GANYMEDE-EA STIS/CCD ACQ F28X50LP MIRROR ACQTYPE=DIFFUSE, CHECKBOX=37, 1 0.1 S (0.1 ST DIFFUSE-CENTER=GEOMETRIC-CENTE S) R Comments: Ganymede V mag near to opposition is ~4.6. Surface brightness for disc of diameter 1.7" is then 5.6. In ETC run STIS.ta.510225, I used a Castelli-Kurucz G2V spectrum normalised to V = 5.6 / arcsec squared and diameter = 1.7. ------------------------------------------------------------------------------------------------------------------------------------ 11 GANYMEDE-EA STIS/FUV TIME-TA 52X2 G140L 1425 BUFFER-TIME=443 1 885 S (885 POS TARG null, -4 ST -MAMA G S) Comments: In STIS.sp.517958 I used an archive spectrum of the same target and instrument set-up. Buffer Time = Texp / 2. POS-TARG of y=-4" moves the target out of the blotch region (slightly less than does the 52X2D1 aperture, but the target is >1") ------------------------------------------------------------------------------------------------------------------------------------ 12 GANYMEDE-EA STIS/FUV TIME-TA 52X2 G140L 1425 BUFFER-TIME=443 1 885 S (885 POS TARG null, -4 ST -MAMA G S) Comments: In STIS.sp.517958 I used an archive spectrum of the same target and instrument set-up. Buffer Time = Texp / 2. POS-TARG of y=-4" moves the target out of the blotch region (slightly less than does the 52X2D1 aperture, but the target is >1") ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ GANYMEDE-EAST 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A GANYMEDE-EAST 2 STIS/FUV TIME-TA 52X2 G140L 1425 none none none none 1 N/A -MAMA G GANYMEDE-EAST 3 STIS/FUV TIME-TA 52X2 G140L 1425 none none none none 1 N/A -MAMA G GANYMEDE-EAST 4 COS/NUV ACQ/SEA BOA MIRRORA none none none none 2 N/A RCH GANYMEDE-EAST 5 COS/NUV ACCUM BOA MIRRORA none none none none 2 N/A GANYMEDE-EAST 6 COS/FUV TIME-TA PSA G140L 1280 none none none none 2 N/A G 13328( 8) - 11-Feb-2014 12:03:11 - [ 9] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ GANYMEDE-EAST 7 COS/FUV TIME-TA PSA G140L 1280 none none none none 2 N/A G GANYMEDE-EAST 8 COS/FUV TIME-TA PSA G140L 1280 none none none none 3 N/A G GANYMEDE-EAST 9 COS/FUV TIME-TA PSA G140L 1280 none none none none 3 N/A G GANYMEDE-EAST 10 STIS/CCD ACQ F28X50LP MIRROR none none none none 4 N/A GANYMEDE-EAST 11 STIS/FUV TIME-TA 52X2 G140L 1425 none none none none 4 N/A -MAMA G GANYMEDE-EAST 12 STIS/FUV TIME-TA 52X2 G140L 1425 none none none none 4 N/A -MAMA G 13328( 8) - 11-Feb-2014 12:03:11 - [ 10] Visit: G2 Visit Requirements: AFTER G1 BY 2.5 D TO 4.5 D On Hold Comments: Additional Comments: Western elongation - defined by target. The AFTER timing requirement ensures that the two visits occur in the same orbit of the satellite, a key aspect of this proposal. If scheduling is difficult, this could be interpreted as BEFORE by the same amount of time. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 GANYMEDE-WE STIS/CCD ACQ F28X50LP MIRROR ACQTYPE=DIFFUSE, CHECKBOX=37, 1 0.1 S (0.1 ST DIFFUSE-CENTER=GEOMETRIC-CENTE S) R Comments: Ganymede V mag near to opposition is ~4.6. Surface brightness for disc of diameter 1.7" is then ~5.5. In ETC run STIS.ta.510225, I used a Castelli-Kurucz G2V spectrum normalised to V = 5.5 / arcsec squared and diameter = 1.7. The minimum exposure time is less than the CCD saturation time of ~0.5 s. ------------------------------------------------------------------------------------------------------------------------------------ 2 GANYMEDE-WE STIS/FUV TIME-TA 52X2 G140L 1425 BUFFER-TIME=443 1 885 S (885 POS TARG null, -4 ST -MAMA G S) Comments: In STIS.sp.517958 I used an archive spectrum of the same target and instrument set-up. Buffer Time = Texp / 2. POS-TARG of y=-4" moves the target out of the blotch region (slightly less than does the 52X2D1 aperture, but the target is >1") ------------------------------------------------------------------------------------------------------------------------------------ 3 GANYMEDE-WE STIS/FUV TIME-TA 52X2 G140L 1425 BUFFER-TIME=443 1 885 S (885 POS TARG null, -4 ST -MAMA G S) Comments: In STIS.sp.517958 I used an archive spectrum of the same target and instrument set-up. Buffer Time = Texp / 2. POS-TARG of y=-4" moves the target out of the blotch region (slightly less than does the 52X2D1 aperture, but the target is >1") ------------------------------------------------------------------------------------------------------------------------------------ 13328( 8) - 11-Feb-2014 12:03:11 - [ 11] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 4 GANYMEDE-WE COS/NUV ACQ/SEA BOA MIRRORA SCAN-SIZE=2 1 3 S (3 S) ST RCH Comments: Ganymede V mag near to opposition is ~4.6, and the surface brightness for a disc of diameter 1.7" is then ~5.5. Ganymede's albedo over 2400-3000 A ranges from ~7% on the trailing side to ~20% on the leading side (Nelson et al., 1987), vs. ~43% in the visible, and is thus ~0.8-2.0 mags dimmer in this waveband than in the visible. ACQ/SEARCH ETC runs using an extended source (a normalised Castelli-Kurucz G2V spectrum), yield for the BOA/MIRRORA: mV_eff = 7.5 (COS.ta.517264) Texp(SNR = 60) = 2.4873 s mV_eff = 6.3 (COS.ta.517265 ) Texp(SNR = 60) = 0.7901 s Using a 3 s exposure then gives a good SNR for all cases: mV_eff = 7.5 (COS.ta.517267) SNR(Texp = 3 s) = 65.8941, total count rate = 2, 554.089 counts/s mV_eff = 6.3 (COS.ta.517268 ) SNR(Texp = 3 s) = 116.915, total count rate = 5, 667.150 counts/s ------------------------------------------------------------------------------------------------------------------------------------ 5 GANYMEDE-WE COS/NUV ACCUM BOA MIRRORA 1 3 S (3 S) ST Comments: This exposure is to verify Ganymede's position in the aperture. We have the same Texp and count rates as for Exposure 5, but imaging ETC runs give SNRs of: mV_eff = 7.5 (COS.im.517270) SNR(Texp = 3 s) = 46.1111, total count rate = 2, 554.089 counts/s mV_eff = 6.3 (COS.im.517273) SNR(Texp = 3 s) = 80.2784, total count rate = 5, 667.150 counts/s ------------------------------------------------------------------------------------------------------------------------------------ 13328( 8) - 11-Feb-2014 12:03:11 - [ 12] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 6 GANYMEDE-WE COS/FUV TIME-TA PSA G140L 1280 BUFFER-TIME=878, FLASH=YES, 1 988 S (988 ST G FP-POS=1 S) Comments: Ganymede V mag near to opposition is ~4.6, and the surface brightness for a disc of diameter 1.7" is then ~5.5. Ganymede's albedo in near 1400 A is ~2.3% (Feldman et al., 2000), vs. ~43% in the visible, and is thus ~3.2 mags dimmer in this waveband than in the visible. In ETC run COS.sp.517981 I used a Castelli-Kurucz G2V spectrum normalised to mV_eff = 8.7 / arcsec squared and diameter = 1.7", plus two emission lines representative of the fluxes observed by Feldman et al. (2000): Center 1304.0 A FWHM 30.0 A Flux 2.3e-15 erg/cm^2/s Center 1356.0 A FWHM 30.0 A Flux 4.4e-15 erg/cm^2/s The Buffer Time is 19, 639 s, thus well over an orbit. Here, I've used Texp - 110 to minimise the time between the two exposures. ------------------------------------------------------------------------------------------------------------------------------------ 7 GANYMEDE-WE COS/FUV TIME-TA PSA G140L 1280 BUFFER-TIME=1.3E4, FLASH=YES, 1 989 S (989 ST G FP-POS=2 S) Comments: ETC Buffer Time is, as for Exposure 6, ~20k s. Multiplied by 2/3 = 13092, rounded down to 13, 000 s as this is the second exposure in the orbit. ------------------------------------------------------------------------------------------------------------------------------------ 8 GANYMEDE-WE COS/FUV TIME-TA PSA G140L 1280 BUFFER-TIME=1298, FLASH=YES, 1 1408 S ST G FP-POS=3 (1408 S) Comments: ETC Buffer Time is, as for Exposure 6, ~20k s. Here, I've used Texp - 110 to minimise the time between the two exposures. ------------------------------------------------------------------------------------------------------------------------------------ 9 GANYMEDE-WE COS/FUV TIME-TA PSA G140L 1280 BUFFER-TIME=1.3E4, FLASH=YES, 1 1409 S ST G FP-POS=4 (1409 S) Comments: ETC Buffer Time is, as for Exposure 6, ~20k s. Multiplied by 2/3 = 13092, rounded down to 13, 000 s as this is the second exposure in the orbit. ------------------------------------------------------------------------------------------------------------------------------------ 13328( 8) - 11-Feb-2014 12:03:11 - [ 13] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 GANYMEDE-WE STIS/CCD ACQ F28X50LP MIRROR ACQTYPE=DIFFUSE, CHECKBOX=37, 1 0.1 S (0.1 ST DIFFUSE-CENTER=GEOMETRIC-CENTE S) R Comments: Ganymede V mag near to opposition is ~4.6. Surface brightness for disc of diameter 1.7" is then 5.6. In ETC run STIS.ta.510225, I used a Castelli-Kurucz G2V spectrum normalised to V = 5.6 / arcsec squared and diameter = 1.7. ------------------------------------------------------------------------------------------------------------------------------------ 11 GANYMEDE-WE STIS/FUV TIME-TA 52X2 G140L 1425 BUFFER-TIME=443 1 885 S (885 POS TARG null, -4 ST -MAMA G S) Comments: In STIS.sp.517958 I used an archive spectrum of the same target and instrument set-up. Buffer Time = Texp / 2. POS-TARG of y=-4" moves the target out of the blotch region (slightly less than does the 52X2D1 aperture, but the target is >1") ------------------------------------------------------------------------------------------------------------------------------------ 12 GANYMEDE-WE STIS/FUV TIME-TA 52X2 G140L 1425 BUFFER-TIME=443 1 885 S (885 POS TARG null, -4 ST -MAMA G S) Comments: In STIS.sp.517958 I used an archive spectrum of the same target and instrument set-up. Buffer Time = Texp / 2. POS-TARG of y=-4" moves the target out of the blotch region (slightly less than does the 52X2D1 aperture, but the target is >1") ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ GANYMEDE-WEST 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A GANYMEDE-WEST 2 STIS/FUV TIME-TA 52X2 G140L 1425 none none none none 1 N/A -MAMA G GANYMEDE-WEST 3 STIS/FUV TIME-TA 52X2 G140L 1425 none none none none 1 N/A -MAMA G GANYMEDE-WEST 4 COS/NUV ACQ/SEA BOA MIRRORA none none none none 2 N/A RCH GANYMEDE-WEST 5 COS/NUV ACCUM BOA MIRRORA none none none none 2 N/A GANYMEDE-WEST 6 COS/FUV TIME-TA PSA G140L 1280 none none none none 2 N/A G 13328( 8) - 11-Feb-2014 12:03:11 - [ 14] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ GANYMEDE-WEST 7 COS/FUV TIME-TA PSA G140L 1280 none none none none 2 N/A G GANYMEDE-WEST 8 COS/FUV TIME-TA PSA G140L 1280 none none none none 3 N/A G GANYMEDE-WEST 9 COS/FUV TIME-TA PSA G140L 1280 none none none none 3 N/A G GANYMEDE-WEST 10 STIS/CCD ACQ F28X50LP MIRROR none none none none 4 N/A GANYMEDE-WEST 11 STIS/FUV TIME-TA 52X2 G140L 1425 none none none none 4 N/A -MAMA G GANYMEDE-WEST 12 STIS/FUV TIME-TA 52X2 G140L 1425 none none none none 4 N/A -MAMA G 13328( 8) - 11-Feb-2014 12:03:11 - [ 15] Visit: G3 Visit Requirements: On Hold Comments: Additional Comments: Western elongation - defined by target. The AFTER timing requirement ensures that the two visits occur in the same orbit of the satellite, a key aspect of this proposal. If scheduling is difficult, this could be interpreted as BEFORE by the same amount of time. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 GANYMEDE-WE COS/NUV ACQ/SEA BOA MIRRORA SCAN-SIZE=2 1 3 S (3 S) GS ACQ SCENARIO BASE1B3 ST-EXTENDED RCH Comments: Ganymede V mag near to opposition is ~4.6, and the surface brightness for a disc of diameter 1.7" is then ~5.5. Ganymede's albedo over 2400-3000 A ranges from ~7% on the trailing side to ~20% on the leading side (Nelson et al., 1987), vs. ~43% in the visible, and is thus ~0.8-2.0 mags dimmer in this waveband than in the visible. ACQ/SEARCH ETC runs using an extended source (a normalised Castelli-Kurucz G2V spectrum), yield for the BOA/MIRRORA: mV_eff = 7.5 (COS.ta.517264) Texp(SNR = 60) = 2.4873 s mV_eff = 6.3 (COS.ta.517265 ) Texp(SNR = 60) = 0.7901 s Using a 3 s exposure then gives a good SNR for all cases: mV_eff = 7.5 (COS.ta.517267) SNR(Texp = 3 s) = 65.8941, total count rate = 2, 554.089 counts/s mV_eff = 6.3 (COS.ta.517268 ) SNR(Texp = 3 s) = 116.915, total count rate = 5, 667.150 counts/s ------------------------------------------------------------------------------------------------------------------------------------ 13328( 8) - 11-Feb-2014 12:03:11 - [ 16] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 2 GANYMEDE-WE COS/NUV ACCUM BOA MIRRORA 1 3 S (3 S) ST-EXTENDED Comments: This exposure is to verify Ganymede's position in the aperture. We have the same Texp and count rates as for Exposure 5, but imaging ETC runs give SNRs of: mV_eff = 7.5 (COS.im.517270) SNR(Texp = 3 s) = 46.1111, total count rate = 2, 554.089 counts/s mV_eff = 6.3 (COS.im.517273) SNR(Texp = 3 s) = 80.2784, total count rate = 5, 667.150 counts/s ------------------------------------------------------------------------------------------------------------------------------------ 3 GANYMEDE-WE COS/FUV TIME-TA PSA G140L 1280 BUFFER-TIME=878, FLASH=YES, 1 988 S (988 ST-EXTENDED G FP-POS=3 S) Comments: Ganymede V mag near to opposition is ~4.6, and the surface brightness for a disc of diameter 1.7" is then ~5.5. Ganymede's albedo in near 1400 A is ~2.3% (Feldman et al., 2000), vs. ~43% in the visible, and is thus ~3.2 mags dimmer in this waveband than in the visible. In ETC run COS.sp.517981 I used a Castelli-Kurucz G2V spectrum normalised to mV_eff = 8.7 / arcsec squared and diameter = 1.7", plus two emission lines representative of the fluxes observed by Feldman et al. (2000): Center 1304.0 A FWHM 30.0 A Flux 2.3e-15 erg/cm^2/s Center 1356.0 A FWHM 30.0 A Flux 4.4e-15 erg/cm^2/s The Buffer Time is 19, 639 s, thus well over an orbit. Here, I've used Texp - 110 to minimise the time between the two exposures. ------------------------------------------------------------------------------------------------------------------------------------ 4 GANYMEDE-WE COS/FUV TIME-TA PSA G140L 1280 BUFFER-TIME=1.3E4, FLASH=YES, 1 989 S (989 ST-EXTENDED G FP-POS=3 S) Comments: ETC Buffer Time is, as for Exposure 6, ~20k s. Multiplied by 2/3 = 13092, rounded down to 13, 000 s as this is the second exposure in the orbit. ------------------------------------------------------------------------------------------------------------------------------------ 13328( 8) - 11-Feb-2014 12:03:11 - [ 17] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 5 GANYMEDE-WE COS/FUV TIME-TA PSA G140L 1280 BUFFER-TIME=1298, FLASH=YES, 1 1408 S ST-EXTENDED G FP-POS=4 (1408 S) Comments: ETC Buffer Time is, as for Exposure 6, ~20k s. Here, I've used Texp - 110 to minimise the time between the two exposures. ------------------------------------------------------------------------------------------------------------------------------------ 6 GANYMEDE-WE COS/FUV TIME-TA PSA G140L 1280 BUFFER-TIME=1.3E4, FLASH=YES, 1 1409 S ST-EXTENDED G FP-POS=4 (1409 S) Comments: ETC Buffer Time is, as for Exposure 6, ~20k s. Multiplied by 2/3 = 13092, rounded down to 13, 000 s as this is the second exposure in the orbit. ------------------------------------------------------------------------------------------------------------------------------------ 7 GANYMEDE-WE STIS/CCD ACQ F28X50LP MIRROR ACQTYPE=DIFFUSE, CHECKBOX=37, 1 0.1 S (0.1 GS ACQ SCENARIO BASE1B3 ST-EXTENDED DIFFUSE-CENTER=GEOMETRIC-CENTE S) R Comments: Ganymede V mag near to opposition is ~4.6. Surface brightness for disc of diameter 1.7" is then 5.6. In ETC run STIS.ta.510225, I used a Castelli-Kurucz G2V spectrum normalised to V = 5.6 / arcsec squared and diameter = 1.7. ------------------------------------------------------------------------------------------------------------------------------------ 8 GANYMEDE-WE STIS/FUV TIME-TA 52X2 G140L 1425 BUFFER-TIME=443 1 885 S (885 POS TARG null, -4 ST-EXTENDED -MAMA G S) Comments: In STIS.sp.517958 I used an archive spectrum of the same target and instrument set-up. Buffer Time = Texp / 2. POS-TARG of y=-4" moves the target out of the blotch region (slightly less than does the 52X2D1 aperture, but the target is >1") ------------------------------------------------------------------------------------------------------------------------------------ 9 GANYMEDE-WE STIS/FUV TIME-TA 52X2 G140L 1425 BUFFER-TIME=443 1 885 S (885 POS TARG null, -4 ST-EXTENDED -MAMA G S) Comments: In STIS.sp.517958 I used an archive spectrum of the same target and instrument set-up. Buffer Time = Texp / 2. POS-TARG of y=-4" moves the target out of the blotch region (slightly less than does the 52X2D1 aperture, but the target is >1") ------------------------------------------------------------------------------------------------------------------------------------ 13328( 8) - 11-Feb-2014 12:03:11 - [ 18] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ GANYMEDE-WEST-EXTEN 1 COS/NUV ACQ/SEA BOA MIRRORA none none none none 1 N/A DED RCH GANYMEDE-WEST-EXTEN 2 COS/NUV ACCUM BOA MIRRORA none none none none 1 N/A DED GANYMEDE-WEST-EXTEN 3 COS/FUV TIME-TA PSA G140L 1280 none none none none 1 N/A DED G GANYMEDE-WEST-EXTEN 4 COS/FUV TIME-TA PSA G140L 1280 none none none none 1 N/A DED G GANYMEDE-WEST-EXTEN 5 COS/FUV TIME-TA PSA G140L 1280 none none none none 2 N/A DED G GANYMEDE-WEST-EXTEN 6 COS/FUV TIME-TA PSA G140L 1280 none none none none 2 N/A DED G GANYMEDE-WEST-EXTEN 7 STIS/CCD ACQ F28X50LP MIRROR none none none none 3 N/A DED GANYMEDE-WEST-EXTEN 8 STIS/FUV TIME-TA 52X2 G140L 1425 none none none none 3 N/A DED -MAMA G GANYMEDE-WEST-EXTEN 9 STIS/FUV TIME-TA 52X2 G140L 1425 none none none none 3 N/A DED -MAMA G 13328( 8) - 11-Feb-2014 12:03:11 - [ 19] Summary Form for Proposal 13328 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures 52X2, BOA, F28X50LP, PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV, COS/NUV, STIS/CCD, STIS/FUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, ACQ, ACQ/SEARCH, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=DIFFUSE, BUFFER-TIME=1.3E4, BUFFER-TIME=1298, BUFFER-TIME=443, BUFFER-TIME=878, CHECKBOX=37, DIFFUSE-CENTER=GEOMETRIC-CENTER, FLASH=YES, FP-POS=1, FP-POS=2, FP-POS=3, FP-POS=4, SCAN-SIZE=2 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements AFTER G1 BY 2.5 D TO 4.5 D, GS ACQ SCENARIO BASE1B3, POS TARG null, -4 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G140L, MIRROR, MIRRORA ------------------------------------------------------------------------------------------------------------------------------------ Target Names GANYMEDE-EAST, GANYMEDE-WEST, GANYMEDE-WEST-EXTENDED ------------------------------------------------------------------------------------------------------------------------------------