11162( 3) - 08/29/07 06:51 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 11162 Version: 3 Check-in Time: 29-Aug-2007 10:51:23 STScI Edit Number: 1 Title Understanding the Long Term Impacts of Low Magnetic Accretion ------------------------------------------------------------------------------------ Type Cycle Parallel Pointing Tolerance GO 16 ------------------------------------------------------------------------------------ Investigators Contact? PI: Prof. Paula Szkody University of Washington CoI: Dr. Thomas Harrison New Mexico State University N CoI: Dr. Steve B. Howell National Optical Astronomy Observatories, N AURA CoI: Dr. Boris T. Gaensicke The University of Warwick N ------------------------------------------------------------------------------------ Abstract The low accretion rate Polar EF Eri has been in a low state for more than 9 years. Our recent GALEX photometry revealed a source of UV light that is producing more flux than the white dwarf and which is highly modulated on the 81 min orbital period of the system. We request UV spectra with the SBC on the ACS to resolve whether limb darkening or cyclotron emission can explain the observed phenomena and provide insight on the long term heating effects under low accretion scenarios. ------------------------------------------------------------------------------------ 11162( 3) - 08/29/07 06:51 - [ 2] Observations Description ------------------------ Our scientific goals require UV observations that cover all orbital phases of EF Eri. To do this, we request 4 contiguous HST orbits using the ACS with the SBC and Prism PR110L. This will give us UV coverage from about 1170-1800\AA. We have prior experience with the SBC observations with PR110L from our Cycle 13 observations of three pulsating white dwarfs. Given the 81 min orbital period of EF Eri and the 96 min HST orbit cycle, the first orbit on EF Eri (with about 4 min for setup) will cover phases 0-0.53 (arbitrary zero), the second HST orbit phases 0.12-0.70, the 3rd phases 0.31-0.89 and the 4th 0.50-0.08. Thus, 4 orbits will ensure total phase coverage, with some phases having multiple overlaps so they can be added to increase the S/N. We will be able to create light curves throughout the wavelength range as well as analyze spectra at both the high and low fluxes of the UV modulation in order to resolve the source of FUV light. Our analysis of the pulsating white dwarf in the system SDSS0131-09 (Szkody et al. 2007, ApJ, 658, 1188) showed that we can determine temperatures to an accuracy of 1000K using the SBC low resolution prism. SDSSJ0131 had a comparable V mag of 18 and a slightly lower 1500A flux (1.1X10^{-15} ergs/cm^2/s/A) compared to EF Eri where GALEX measured a 1500A flux of 1.3X10^{-15}ergs/cm^2$/s/A. Our access to the SMARTS consortium guarantees several observations per week to monitor the state of EF Eri. We can supplement this with AAVSO observers, APO observers and other worldwide monitors to ensure that EF Eri would be in a low state throughout the HST observations. Due to the inactivity during the last 9 yrs, it is very unlikely that EF Eri would suddenly enter a high state with no warning. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 11162( 3) - 08/29/07 06:51 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 V-EF-ERI STAR, POLAR RA=03H14M13.0300S +/- 0.1", J2000 V = 18.0+/-2.0 DEC=-22D35'41.40" +/- 0.1" only observe in low state near 18 Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. 11162( 3) - 08/29/07 06:51 - [ 4] Visit: 01 Visit Priority: Visit Requirements: AFTER A1 BY 2 Orbits TO 5.5 Orbits On Hold Comments: Additional Comments: Ground observations will be used to ensure EF Eri at low state of 18th mag. AFTER BY requirement needed to verify the brightness of the target using ground observations. Also, uplink opportunities are needed in the ~2 orbit interval to clear the NSSC-I Event Flag 2 and allow high-voltage turn-on, if the target is determined to be safe. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 V-EF-ERI ACS/SBC ACCUM SBC F140LP 1 15 S ------------------------------------------------------------------------------------------------------------------------------------ 2 V-EF-ERI ACS/SBC ACCUM SBC PR110L 9 239 S ------------------------------------------------------------------------------------------------------------------------------------ 3 V-EF-ERI ACS/SBC ACCUM SBC PR110L 1 85 S ------------------------------------------------------------------------------------------------------------------------------------ 4 V-EF-ERI ACS/SBC ACCUM SBC PR110L 10 239 S ------------------------------------------------------------------------------------------------------------------------------------ 5 V-EF-ERI ACS/SBC ACCUM SBC PR110L 10 239 S ------------------------------------------------------------------------------------------------------------------------------------ 6 V-EF-ERI ACS/SBC ACCUM SBC PR110L 10 239 S ------------------------------------------------------------------------------------------------------------------------------------ 7 DARK S/C DATA NONE 1 10 S SPEC COM INSTR EJFLAG2CLR Comments: Set NSSC-I Event Flag 2 to allow high-voltage turn-on. Insert SQL for qasi_states ACS start/end = WFHROPER, DOOR start/end = OPEN, HCOR start/end = HOLD, LAMP start/end = HOLD, and WCOR start/end = HOLD. ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ V-EF-ERI 1 ACS/SBC ACCUM SBC F140LP none none none none 1 N/A V-EF-ERI 2 ACS/SBC ACCUM SBC PR110L none none 1 none 1 N/A V-EF-ERI 2 ACS/SBC ACCUM SBC PR110L none none 2 none 1 N/A V-EF-ERI 2 ACS/SBC ACCUM SBC PR110L none none 3 none 1 N/A V-EF-ERI 2 ACS/SBC ACCUM SBC PR110L none none 4 none 1 N/A V-EF-ERI 2 ACS/SBC ACCUM SBC PR110L none none 5 none 1 N/A V-EF-ERI 2 ACS/SBC ACCUM SBC PR110L none none 6 none 1 N/A V-EF-ERI 2 ACS/SBC ACCUM SBC PR110L none none 7 none 1 N/A V-EF-ERI 2 ACS/SBC ACCUM SBC PR110L none none 8 none 1 N/A V-EF-ERI 2 ACS/SBC ACCUM SBC PR110L none none 9 none 1 N/A V-EF-ERI 3 ACS/SBC ACCUM SBC PR110L none none none none 1 N/A V-EF-ERI 4 ACS/SBC ACCUM SBC PR110L none none 1 none 2 N/A 11162( 3) - 08/29/07 06:51 - [ 5] 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 | ------------------------------------------------------------------------------------------------------------------------------------ V-EF-ERI 4 ACS/SBC ACCUM SBC PR110L none none 2 none 2 N/A V-EF-ERI 4 ACS/SBC ACCUM SBC PR110L none none 3 none 2 N/A V-EF-ERI 4 ACS/SBC ACCUM SBC PR110L none none 4 none 2 N/A V-EF-ERI 4 ACS/SBC ACCUM SBC PR110L none none 5 none 2 N/A V-EF-ERI 4 ACS/SBC ACCUM SBC PR110L none none 6 none 2 N/A V-EF-ERI 4 ACS/SBC ACCUM SBC PR110L none none 7 none 2 N/A V-EF-ERI 4 ACS/SBC ACCUM SBC PR110L none none 8 none 2 N/A V-EF-ERI 4 ACS/SBC ACCUM SBC PR110L none none 9 none 2 N/A V-EF-ERI 4 ACS/SBC ACCUM SBC PR110L none none 10 none 2 N/A V-EF-ERI 5 ACS/SBC ACCUM SBC PR110L none none 1 none 3 N/A V-EF-ERI 5 ACS/SBC ACCUM SBC PR110L none none 2 none 3 N/A V-EF-ERI 5 ACS/SBC ACCUM SBC PR110L none none 3 none 3 N/A V-EF-ERI 5 ACS/SBC ACCUM SBC PR110L none none 4 none 3 N/A V-EF-ERI 5 ACS/SBC ACCUM SBC PR110L none none 5 none 3 N/A V-EF-ERI 5 ACS/SBC ACCUM SBC PR110L none none 6 none 3 N/A V-EF-ERI 5 ACS/SBC ACCUM SBC PR110L none none 7 none 3 N/A V-EF-ERI 5 ACS/SBC ACCUM SBC PR110L none none 8 none 3 N/A V-EF-ERI 5 ACS/SBC ACCUM SBC PR110L none none 9 none 3 N/A V-EF-ERI 5 ACS/SBC ACCUM SBC PR110L none none 10 none 3 N/A V-EF-ERI 6 ACS/SBC ACCUM SBC PR110L none none 1 none 4 N/A V-EF-ERI 6 ACS/SBC ACCUM SBC PR110L none none 2 none 4 N/A V-EF-ERI 6 ACS/SBC ACCUM SBC PR110L none none 3 none 4 N/A V-EF-ERI 6 ACS/SBC ACCUM SBC PR110L none none 4 none 4 N/A V-EF-ERI 6 ACS/SBC ACCUM SBC PR110L none none 5 none 4 N/A V-EF-ERI 6 ACS/SBC ACCUM SBC PR110L none none 6 none 4 N/A V-EF-ERI 6 ACS/SBC ACCUM SBC PR110L none none 7 none 4 N/A V-EF-ERI 6 ACS/SBC ACCUM SBC PR110L none none 8 none 4 N/A V-EF-ERI 6 ACS/SBC ACCUM SBC PR110L none none 9 none 4 N/A V-EF-ERI 6 ACS/SBC ACCUM SBC PR110L none none 10 none 4 N/A 11162( 3) - 08/29/07 06:51 - [ 6] Visit: A1 Visit Priority: Visit Requirements: On Hold Comments: Additional Comments: This Visit sets the NSSC-I Event Flag 2 that disables the high-voltage turn-on. The high-voltage will be enabled, to allow SBC observations in the corresponding Visit, using real-time commanding if the target is determined to be safe. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 DARK S/C DATA NONE 1 25 S SPEC COM INSTR EJFLAG2 Comments: Set NSSC-I Event Flag 2 to prevent high-voltage turn-on. Insert SQL to ensure that the SBC is off when the flag is set, and for qasi_states ACS start/end = WFHROPER, DOOR start/end=OPEN, HCOR start/end=HOLD, LAMP start/end=HOLD, and WCOR start/end=HOLD. ------------------------------------------------------------------------------------------------------------------------------------ 11162( 3) - 08/29/07 06:51 - [ 7] Summary Form for Proposal 11162 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures SBC NONE ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/SBC S/C ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM DATA ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements AFTER A1 BY 2 Orbits TO 5.5 Orbits; SPEC COM INSTR EJFLAG2CLR; SPEC COM INSTR EJFLAG2; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F140LP PR110L ------------------------------------------------------------------------------------------------------------------------------------ Target Names V-EF-ERI DARK ------------------------------------------------------------------------------------------------------------------------------------