13668( 6) - 20-Apr-2015 18:58:54 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 13668 Version: 6 Check-in Time: 20-Apr-2015 18:58:54 STScI Edit Number: 4 Title Deep Search for Small Satellites of Eris and Makemake ------------------------------------------------------------------------------------ Type Cycle GO 22 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Marc W. Buie Southwest Research Institute Y CoI: Dr. Keith S. Noll NASA Goddard Space Flight Center N CoI: Dr. William M. Grundy Lowell Observatory N ------------------------------------------------------------------------------------ Abstract Recent HST observations searching deeper than ever before have discovered a very distinct family of small, faint, circumbinary satellites around Pluto and Charon. Pluto has looked like the oddball of the Solar System many times in the past, with its inclined and eccentric transneptunian orbit, its enormous satellite Charon, and its volatile ice rich surface composition. But in each of these matters, subsequent discoveries revealed that Pluto was not unique, merely the first of an entirely new class of objects. This proposal aims to determine if Pluto's family of small faint satellites is also non-unique, through unprecedentedly deep imaging of Eris and Makemake, the two other most Pluto-like bodies in the Kuiper belt. ------------------------------------------------------------------------------------ Observations Description ------------------------ We are observing (136199) Eris and (136472) Makemake looking for faint companions using observing procedures used successfully for the Pluto system. Our proposed observatations will improve on prior work in two fundamental ways. First, we plan a longer integration time that will get to a much fainter limiting magnitude. Each visit will take two orbits and we will take six ~730-sec exposures (three per orbit) and two short navigation images. A single visit stack nets an aggregate exposure time of ~4400 seconds and will yield an optimal SNR of 14 for an object of V=28 (assuming a G8V spectrum and average zodial light and background). This improvement will get us one magnitude deeper for Makemake and Eris. We will dither by small integer pixel amounts between images within a visit to help remove any potential detector artifacts. The second improvement comes from applying lessons learned while searching for faint satellites around Pluto. The biggest challenge to searching the inner regions is removing the confusion caused by the PSF of the primary and secondary objects (if present). The strategy used by Showalter and Buie was to take pairs of visits with controlled geometry. By design, Pluto and Charon were in the same relative position in raw pixel coordinates between the epochs and a difference of the two image stacks almost perfectly removes these two bright central objects. This technique led to the discovery of the fifth satellite around Pluto. That this new satellite is roughly V=27 attests to the sensitivity achieved. In the case of Pluto, the residual noise in the difference image is higher than any object on our list merely because the 13668( 6) - 20-Apr-2015 18:58:54 - [ 2] central object is not as bright. We can expect both changes to contribute to a much more thorough and deeper search than any done to date. Our basic observational pattern will use four orbits per object grouped into two visits with two orbits each. Each visit will lead to a deep stack and the pair will be used to search for a satellite that moves relative to the primary. A key component of the observing strategy is to maintain useful sensitivity to the motion of any putative satellites between the two visits. If the interval is too short there will not be enough time for detecting the motion though our technique would still reveal the presence of a satellite. Our survey is designed to cover out to 20% of the Hill radius. Larger distances are not expected to be stable. This threshold sets the minimum velocity that we have to accommodate. The time between visits is set to 2-3 days for Makemake and 3-4 days for Eris to ensure a minimum of 100 mas of satellite motion between visits at the outer edge of the stability region. We require a small roll between the two visits so that any object in the system will move relative to any PSF artifacts. This roll needs to be just a few degrees to facilitate the observations. Making the roll offset too large will make the observations difficult to schedule. These observations are specifically designed to find new satellites but will not, by themselves, do a very good job of determining orbits. It will remain for later work to followup any objects discovered. ------------------------------------------------------------------------------------ 13668( 6) - 20-Apr-2015 18:58:54 - [ 3] TARGET LIST Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 TARGET NAME: ERIS ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: DWARF-PLANET Eris system ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 TARGET POSITION LEVEL 2 STD=ERIS ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 WINDOWS ------------------------------------------------------------------------------------------------------------------------------------ DATA COMMENTS V = 18.7 +/- .1 Ephemeris Center: EARTH ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 2 TARGET NAME: MAKEMAKE ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: DWARF-PLANET Makemake system ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 TARGET POSITION LEVEL 2 STD=MAKEMAKE ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 WINDOWS ------------------------------------------------------------------------------------------------------------------------------------ DATA COMMENTS V = 16.9 +/- .1 Ephemeris Center: EARTH ------------------------------------------------------------------------------------------------------------------------------------ 13668( 6) - 20-Apr-2015 18:58:54 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-UVIS-DITHER-LINE Pattern_Purpose DITHER Number_Of_Points 3 Point_Spacing 0.290 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 46.84 Angle_Between_Sides Center_Pattern NO Pattern_Comments: This pattern is believed to be a half-pixel dithering pattern for purposes of sub-samping the image while being constructed to follow the distortion of the camera. The point spacing was multipled by 2 to make it an integer pixel pattern. This pattern is our ultimate goal so that a given target will fall in the same place relative to a unit pixel throughout all observations within a visit. ------------------------------------------------------------------------------------------------------------------------------------ 13668( 6) - 20-Apr-2015 18:58:54 - [ 5] Visit: 01 Visit Requirements: BETWEEN 10-NOV-2014:00:00:00 AND 20-FEB-2015:00:00:00; Period 7.89358 D AND ZERO-PHASE HJD2456934.0 On Hold Comments: Additional Comments: Each visit is designed to collect a deep integration (two orbits per visit) on the target. For Eris, there are additional timing constraints. This constraint ensures that the observations of the known satellite, Dysnomia, will serve to break the mirror ambiguity on its current orbit. Without the timing constraint we would only have a 25% chance of getting the desired observation. Basically, the constraint serves to get this visit at a particular orbital longitude. The additional loose timing constraint restricts the observations to occur somewhat near opposition. This ensures a useful motion of the target relative to the background stars while also giving the best image scale and target brightness. 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 ERIS WFC3/UVI ACCUM UVIS2 F350LP CR-SPLIT=NO 1 80 S (80 PHASE 0.873 TO 0.127 S S) ------------------------------------------------------------------------------------------------------------------------------------ 2 ERIS WFC3/UVI ACCUM UVIS2 F350LP CR-SPLIT=NO 1 720 S PATTERN 1 2 S (2160 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 ERIS WFC3/UVI ACCUM UVIS2 F350LP CR-SPLIT=NO 1 720 S PATTERN 1 3 S (2160 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 ERIS WFC3/UVI ACCUM UVIS2 F350LP CR-SPLIT=NO 1 80 S (80 POS TARG 0, 0 S S) ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ ERIS 1 WFC3/UVI ACCUM UVIS2 F350LP none none none none 1 N/A S ERIS 2 WFC3/UVI ACCUM UVIS2 F350LP 1 none none none 1 N/A S ERIS 2 WFC3/UVI ACCUM UVIS2 F350LP 2 none none none 1 N/A S ERIS 2 WFC3/UVI ACCUM UVIS2 F350LP 3 none none none 1 N/A S ERIS 3 WFC3/UVI ACCUM UVIS2 F350LP 1 none none none 2 N/A S ERIS 3 WFC3/UVI ACCUM UVIS2 F350LP 2 none none none 2 N/A S ERIS 3 WFC3/UVI ACCUM UVIS2 F350LP 3 none none none 2 N/A S ERIS 4 WFC3/UVI ACCUM UVIS2 F350LP none none none none 2 N/A S 13668( 6) - 20-Apr-2015 18:58:54 - [ 6] Visit: 02 Visit Requirements: ORIENT 5D TO 6D FROM 01; AFTER 01 BY 3 D TO 4 D On Hold Comments: Additional Comments: The second epoch is required to find a satellite moving relative to the primary object. The timing window is set to capture useful motion for an object at 20% of the Hill radius. Objects closer in will be moving faster. The relative roll is used to move the satellite system relative to the PSF between epochs. The minimal dithers are calculated for integer pixel shifts of the field (accounting for distortion) so that faint objects fall in the same place relative to a unit pixel in all images within a visit. 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 ERIS WFC3/UVI ACCUM UVIS2 F350LP CR-SPLIT=NO 1 80 S (80 S S) ------------------------------------------------------------------------------------------------------------------------------------ 2 ERIS WFC3/UVI ACCUM UVIS2 F350LP CR-SPLIT=NO 1 720 S PATTERN 1 2 S (2160 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 ERIS WFC3/UVI ACCUM UVIS2 F350LP CR-SPLIT=NO 1 720 S PATTERN 1 3 S (2160 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 ERIS WFC3/UVI ACCUM UVIS2 F350LP CR-SPLIT=NO 1 80 S (80 S S) ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ ERIS 1 WFC3/UVI ACCUM UVIS2 F350LP none none none none 1 N/A S ERIS 2 WFC3/UVI ACCUM UVIS2 F350LP 1 none none none 1 N/A S ERIS 2 WFC3/UVI ACCUM UVIS2 F350LP 2 none none none 1 N/A S ERIS 2 WFC3/UVI ACCUM UVIS2 F350LP 3 none none none 1 N/A S ERIS 3 WFC3/UVI ACCUM UVIS2 F350LP 1 none none none 2 N/A S ERIS 3 WFC3/UVI ACCUM UVIS2 F350LP 2 none none none 2 N/A S ERIS 3 WFC3/UVI ACCUM UVIS2 F350LP 3 none none none 2 N/A S ERIS 4 WFC3/UVI ACCUM UVIS2 F350LP none none none none 2 N/A S 13668( 6) - 20-Apr-2015 18:58:54 - [ 7] Visit: 03 Visit Requirements: ORIENT 149D TO 149 D; BETWEEN 01-MAR-2015 AND 01-JUN-2015 On Hold Comments: Additional Comments: Each visit is designed to collect a deep integration (two orbits per visit) on the target. The loose timing constraint restricts the observations to occur somewhat near opposition. This ensures a useful motion of the target relative to the background stars while also giving the best image scale and target brightness. 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 MAKEMAKE WFC3/UVI ACCUM UVIS2 F350LP CR-SPLIT=NO, FLASH=10 1 12 S (12 GS ACQ SCENARIO BASE1B3 S S) ------------------------------------------------------------------------------------------------------------------------------------ 2 MAKEMAKE WFC3/UVI ACCUM UVIS2 F350LP CR-SPLIT=NO 1 725 S PATTERN 1 2 S (2175 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 MAKEMAKE WFC3/UVI ACCUM UVIS2 F350LP CR-SPLIT=NO 1 725 S PATTERN 1 3 S (2175 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 MAKEMAKE WFC3/UVI ACCUM UVIS2 F350LP CR-SPLIT=NO, FLASH=10 1 12 S (12 S S) ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ MAKEMAKE 1 WFC3/UVI ACCUM UVIS2 F350LP none none none none 1 N/A S MAKEMAKE 2 WFC3/UVI ACCUM UVIS2 F350LP 1 none none none 1 N/A S MAKEMAKE 2 WFC3/UVI ACCUM UVIS2 F350LP 2 none none none 1 N/A S MAKEMAKE 2 WFC3/UVI ACCUM UVIS2 F350LP 3 none none none 1 N/A S MAKEMAKE 3 WFC3/UVI ACCUM UVIS2 F350LP 1 none none none 2 N/A S MAKEMAKE 3 WFC3/UVI ACCUM UVIS2 F350LP 2 none none none 2 N/A S MAKEMAKE 3 WFC3/UVI ACCUM UVIS2 F350LP 3 none none none 2 N/A S MAKEMAKE 4 WFC3/UVI ACCUM UVIS2 F350LP none none none none 2 N/A S 13668( 6) - 20-Apr-2015 18:58:54 - [ 8] Visit: 04 Visit Requirements: ORIENT 155D TO 155 D; AFTER 03 BY 2 D TO 3 D On Hold Comments: Additional Comments: The second epoch is required to find a satellite moving relative to the primary object. The timing window is set to capture useful motion for an object at 20% of the Hill radius. The relative roll is used to move the satellite system relative to the PSF between epochs. 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 MAKEMAKE WFC3/UVI ACCUM UVIS2 F350LP CR-SPLIT=NO, FLASH=10 1 12 S (12 GS ACQ SCENARIO BASE1B3 S S) ------------------------------------------------------------------------------------------------------------------------------------ 2 MAKEMAKE WFC3/UVI ACCUM UVIS2 F350LP CR-SPLIT=NO 1 725 S PATTERN 1 2 S (2175 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 MAKEMAKE WFC3/UVI ACCUM UVIS2 F350LP CR-SPLIT=NO 1 725 S PATTERN 1 3 S (2175 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 MAKEMAKE WFC3/UVI ACCUM UVIS2 F350LP CR-SPLIT=NO, FLASH=10 1 12 S (12 S S) ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ MAKEMAKE 1 WFC3/UVI ACCUM UVIS2 F350LP none none none none 1 N/A S MAKEMAKE 2 WFC3/UVI ACCUM UVIS2 F350LP 1 none none none 1 N/A S MAKEMAKE 2 WFC3/UVI ACCUM UVIS2 F350LP 2 none none none 1 N/A S MAKEMAKE 2 WFC3/UVI ACCUM UVIS2 F350LP 3 none none none 1 N/A S MAKEMAKE 3 WFC3/UVI ACCUM UVIS2 F350LP 1 none none none 2 N/A S MAKEMAKE 3 WFC3/UVI ACCUM UVIS2 F350LP 2 none none none 2 N/A S MAKEMAKE 3 WFC3/UVI ACCUM UVIS2 F350LP 3 none none none 2 N/A S MAKEMAKE 4 WFC3/UVI ACCUM UVIS2 F350LP none none none none 2 N/A S 13668( 6) - 20-Apr-2015 18:58:54 - [ 9] Summary Form for Proposal 13668 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO, FLASH=10 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements AFTER 01 BY 3 D TO 4 D, AFTER 03 BY 2 D TO 3 D, BETWEEN 01-MAR-2015 AND 01-JUN-2015, BETWEEN 10-NOV-2014:00:00:00 AND 20-FEB-2015:00:00:00, GS ACQ SCENARIO BASE1B3, ORIENT 149D TO 149 D, ORIENT 155D TO 155 D, ORIENT 5D TO 6D FROM 01, PATTERN 1 2, PATTERN 1 3, PHASE 0.873 TO 0.127, POS TARG 0, 0, Period 7.89358 D AND ZERO-PHASE HJD2456934.0 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F350LP ------------------------------------------------------------------------------------------------------------------------------------ Target Names ERIS, MAKEMAKE ------------------------------------------------------------------------------------------------------------------------------------