15171( 5) - 05-Jan-2018 21:59:21 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 15171 Version: 5 Check-in Time: 05-Jan-2018 21:59:21 STScI Edit Number: 0 Title The rotation period, orbit, and mass of Eris' satellite Dysnomia ------------------------------------------------------------------------------------ Type Cycle GO 25 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Bryan Jason Holler Space Telescope Science Institute Y CoI: Ms. Catherine Gosmeyer Space Telescope Science Institute N CoI: Dr. John A. Stansberry Space Telescope Science Institute N CoI: Dr. Leslie A. Young Southwest Research Institute N CoI: Dr. Marc W. Buie Southwest Research Institute N ------------------------------------------------------------------------------------ Abstract Almost 80 satellite systems have been identified in the trans-Neptunian region in the outer Solar System. These systems fall into two classes: equal mass, wide separation binaries and large primaries with relatively small satellites. The existence of these two distinct classes suggests different formation mechanisms of capture and giant impact, respectively, but there is no way to confirm this without more in-depth observations of a given system. Little is known about the majority of these satellite systems besides the orbital period and the relative brightness of the components. The orbital period provides the total system mass but does nothing to constrain the masses of the individual components. The mass and rotation period of the satellite can provide valuable information about the tidal state and thus the formation mechanism of the second class of binary systems. Previous observations of large trans-Neptunian objects (TNOs) with multiple satellites point to formation by giant impact, but never before has this kind of investigation been performed for a large TNO with only one satellite. In this work, we propose to observe Eris and its satellite Dysnomia with the WFC3 instrument to provide useful constraints on the mass Dysnomia, calculate Dysnomia's rotation period, and compute an improved orbit solution for Dysnomia, with the ultimate goal of understanding the origin of this and other large TNO binary systems. ------------------------------------------------------------------------------------ Observations Description ------------------------ These observations of Eris and its satellite, Dysnomia, are designed to provide data for two separate investigations: constructing a rotation light curve of Dysnomia and measuring the wobble of Eris. Data for a third investigation, a new calculation of Dysnomia's orbit, come from the the observations that satisfy the other two investigations. To measure the wobble of Eris, the motion of Eris around the system barycenter due to the gravitational influence of Dysnomia, a majority of the orbits are timed to coincide with the maximum elongation of Dysnomia; the times of maximum elongation were extrapolated from Brown and Schaller (2007). Al six orbits are planned to occur within one orbital period of Dysnomia (15.774 days) to avoid the effects of changing phase angle. Two of the six orbits in this program are timed to coincide with one maximum elongation, while two more are timed to coincide with the opposite maximum elongation. We place 3-7 HST orbits between the two orbits at each 15171( 5) - 05-Jan-2018 21:59:21 - [ 2] maximum elongation. The two maximum elongation sets are separated by ~7.9 days (about half of a rotation period). The remaining two orbits are set up to be made at some point in a large range between the maximum elongations (one on either side of Dysnomia's orbit). The large ranges for these two orbits satisfy two goals: enable more flexible scheduling and mitigate aliasing in the determination of Dysnomia's rotation period. Photometry will be performed on all the images to extract the flux from Dysnomia and construct a rotational light curve. Additionally, the short time between the two orbits at each maximum elongation serve the purpose of testing for short (~5-12 hour) periods. Relative astrometry between Eris and Dysnomia in each image will be used to compute an orbital solution for Dysnomia. In order to obtain enough stars for the absolute astrometry required to measure Eris' wobble, a full readout of the WFC3/UVIS detector is required. This means the minimum time for each image is 348 seconds to prevent a loss of time for a buffer dump. Four of these images are planned using the WFC-UVIS-DITHER-BOX, a four-point box dither used for sub-sampling the PSF. Each box dither is followed by one 585-second image to fill out the orbit; some leeway is left so as not to fill the entire orbit and therefore open up the scheduling options. Eris saturates in the 585-second images, but is not saturated in the 348-second images, allowing for the possibility of obtaining photometric measurements of Eris for construction of a rotational light curve. Large orientation ranges are provided to prevent Dysnomia from falling in the same columns as Eris, especially for the 585-second images where Eris saturates and may bleed into nearby pixels in the columns. The orientation ranges are not meant to avoid the diffraction spikes, although this was the original plan; such constraints, combined with the timing constraints, placed significant constraints on the observations as a whole and rendered them unschedulable. ------------------------------------------------------------------------------------ 15171( 5) - 05-Jan-2018 21:59:21 - [ 3] TARGET LIST Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 2 TARGET NAME: ERIS-OFFSET ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: DWARF-PLANET Eris ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 TARGET POSITION LEVEL 2 STD=ERIS TYPE=POS_ANGLE, RAD=20, ANG=225, REF=NORTH ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 WINDOWS ------------------------------------------------------------------------------------------------------------------------------------ DATA COMMENTS V = 18.7 Ephemeris Center: EARTH Extended: NO ------------------------------------------------------------------------------------------------------------------------------------ 15171( 5) - 05-Jan-2018 21:59:21 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-UVIS-DITHER-BOX Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.173 Line_Spacing 0.112 Coordinate_Frame POS-TARG Pattern_Orient 23.884 Angle_Between_Sides 81.785 Center_Pattern YES ------------------------------------------------------------------------------------------------------------------------------------ 15171( 5) - 05-Jan-2018 21:59:21 - [ 5] Visit: 01 (Maximum elongation 1-1) Visit Requirements: ORIENT 61D TO 90 D; Period 7.887 D AND ZERO-PHASE HJD2458032.92355; SEQ 01, 02, 03, 04, 05, 06 WITHIN 15.774 D On Hold Comments: Additional Comments: 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-OFFSET WFC3/UVI ACCUM UVIS2 F606W 1 348 S PHASE 0 TO 0.05; PATTERN S (1392 S) 1 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 ERIS-OFFSET WFC3/UVI ACCUM UVIS2 F606W 1 585 S (585 PHASE 0 TO 0.05 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-OFFSET 1 WFC3/UVI ACCUM UVIS2 F606W 1 none none none 1 N/A S ERIS-OFFSET 1 WFC3/UVI ACCUM UVIS2 F606W 2 none none none 1 N/A S ERIS-OFFSET 1 WFC3/UVI ACCUM UVIS2 F606W 3 none none none 1 N/A S ERIS-OFFSET 1 WFC3/UVI ACCUM UVIS2 F606W 4 none none none 1 N/A S ERIS-OFFSET 2 WFC3/UVI ACCUM UVIS2 F606W none none none none 1 N/A S 15171( 5) - 05-Jan-2018 21:59:21 - [ 6] Visit: 02 (Maximum elongation 1-2) Visit Requirements: ORIENT 61D TO 90 D; AFTER 01 BY 3 Orbits TO 7 Orbits On Hold Comments: Additional Comments: 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-OFFSET WFC3/UVI ACCUM UVIS2 F606W 1 348 S PATTERN 1 1 S (1392 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 ERIS-OFFSET WFC3/UVI ACCUM UVIS2 F606W 1 585 S (585 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-OFFSET 1 WFC3/UVI ACCUM UVIS2 F606W 1 none none none 1 N/A S ERIS-OFFSET 1 WFC3/UVI ACCUM UVIS2 F606W 2 none none none 1 N/A S ERIS-OFFSET 1 WFC3/UVI ACCUM UVIS2 F606W 3 none none none 1 N/A S ERIS-OFFSET 1 WFC3/UVI ACCUM UVIS2 F606W 4 none none none 1 N/A S ERIS-OFFSET 2 WFC3/UVI ACCUM UVIS2 F606W none none none none 1 N/A S 15171( 5) - 05-Jan-2018 21:59:21 - [ 7] Visit: 03 (Floater 1) Visit Requirements: ORIENT 61D TO 90 D; AFTER 01 BY 26 Orbits TO 95 Orbits On Hold Comments: Additional Comments: 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-OFFSET WFC3/UVI ACCUM UVIS2 F606W 1 348 S PATTERN 1 1 S (1392 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 ERIS-OFFSET WFC3/UVI ACCUM UVIS2 F606W 1 585 S (585 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-OFFSET 1 WFC3/UVI ACCUM UVIS2 F606W 1 none none none 1 N/A S ERIS-OFFSET 1 WFC3/UVI ACCUM UVIS2 F606W 2 none none none 1 N/A S ERIS-OFFSET 1 WFC3/UVI ACCUM UVIS2 F606W 3 none none none 1 N/A S ERIS-OFFSET 1 WFC3/UVI ACCUM UVIS2 F606W 4 none none none 1 N/A S ERIS-OFFSET 2 WFC3/UVI ACCUM UVIS2 F606W none none none none 1 N/A S 15171( 5) - 05-Jan-2018 21:59:21 - [ 8] Visit: 04 (Maximum elongation 2-1) Visit Requirements: ORIENT 61D TO 90 D; AFTER 01 BY 115 Orbits TO 121 Orbits On Hold Comments: Additional Comments: 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-OFFSET WFC3/UVI ACCUM UVIS2 F606W 1 348 S PATTERN 1 1 S (1392 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 ERIS-OFFSET WFC3/UVI ACCUM UVIS2 F606W 1 585 S (585 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-OFFSET 1 WFC3/UVI ACCUM UVIS2 F606W 1 none none none 1 N/A S ERIS-OFFSET 1 WFC3/UVI ACCUM UVIS2 F606W 2 none none none 1 N/A S ERIS-OFFSET 1 WFC3/UVI ACCUM UVIS2 F606W 3 none none none 1 N/A S ERIS-OFFSET 1 WFC3/UVI ACCUM UVIS2 F606W 4 none none none 1 N/A S ERIS-OFFSET 2 WFC3/UVI ACCUM UVIS2 F606W none none none none 1 N/A S 15171( 5) - 05-Jan-2018 21:59:21 - [ 9] Visit: 05 (Maximum elongation 2-2) Visit Requirements: ORIENT 61D TO 90 D; AFTER 01 BY 138 Orbits TO 142 Orbits On Hold Comments: Additional Comments: 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-OFFSET WFC3/UVI ACCUM UVIS2 F606W 1 348 S PATTERN 1 1 S (1392 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 ERIS-OFFSET WFC3/UVI ACCUM UVIS2 F606W 1 585 S (585 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-OFFSET 1 WFC3/UVI ACCUM UVIS2 F606W 1 none none none 1 N/A S ERIS-OFFSET 1 WFC3/UVI ACCUM UVIS2 F606W 2 none none none 1 N/A S ERIS-OFFSET 1 WFC3/UVI ACCUM UVIS2 F606W 3 none none none 1 N/A S ERIS-OFFSET 1 WFC3/UVI ACCUM UVIS2 F606W 4 none none none 1 N/A S ERIS-OFFSET 2 WFC3/UVI ACCUM UVIS2 F606W none none none none 1 N/A S 15171( 5) - 05-Jan-2018 21:59:21 - [ 10] Visit: 06 (Floater 2) Visit Requirements: ORIENT 61D TO 90 D; AFTER 01 BY 161 Orbits TO 213 Orbits On Hold Comments: Additional Comments: 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-OFFSET WFC3/UVI ACCUM UVIS2 F606W 1 348 S PATTERN 1 1 S (1392 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 ERIS-OFFSET WFC3/UVI ACCUM UVIS2 F606W 1 585 S (585 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-OFFSET 1 WFC3/UVI ACCUM UVIS2 F606W 1 none none none 1 N/A S ERIS-OFFSET 1 WFC3/UVI ACCUM UVIS2 F606W 2 none none none 1 N/A S ERIS-OFFSET 1 WFC3/UVI ACCUM UVIS2 F606W 3 none none none 1 N/A S ERIS-OFFSET 1 WFC3/UVI ACCUM UVIS2 F606W 4 none none none 1 N/A S ERIS-OFFSET 2 WFC3/UVI ACCUM UVIS2 F606W none none none none 1 N/A S 15171( 5) - 05-Jan-2018 21:59:21 - [ 11] Visit: 53 (Floater 1) Visit Requirements: ORIENT 61D TO 90 D; BETWEEN 18-JAN-2018:00:00:00 AND 24-JAN-2018:00:00:00; BETWEEN 03-FEB-2018:00:00:00 AND 09-FEB-2018:00:00:00; BETWEEN 18-FEB-2018:00:00:00 AND 24-FEB-2018:00:00:00 On Hold Comments: Additional Comments: 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-OFFSET WFC3/UVI ACCUM UVIS2 F606W 1 348 S PATTERN 1 1 S (1392 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 ERIS-OFFSET WFC3/UVI ACCUM UVIS2 F606W 1 585 S (585 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-OFFSET 1 WFC3/UVI ACCUM UVIS2 F606W 1 none none none 1 N/A S ERIS-OFFSET 1 WFC3/UVI ACCUM UVIS2 F606W 2 none none none 1 N/A S ERIS-OFFSET 1 WFC3/UVI ACCUM UVIS2 F606W 3 none none none 1 N/A S ERIS-OFFSET 1 WFC3/UVI ACCUM UVIS2 F606W 4 none none none 1 N/A S ERIS-OFFSET 2 WFC3/UVI ACCUM UVIS2 F606W none none none none 1 N/A S 15171( 5) - 05-Jan-2018 21:59:21 - [ 12] Summary Form for Proposal 15171 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements AFTER 01 BY 115 Orbits TO 121 Orbits, AFTER 01 BY 138 Orbits TO 142 Orbits, AFTER 01 BY 161 Orbits TO 213 Orbits, AFTER 01 BY 26 Orbits TO 95 Orbits, AFTER 01 BY 3 Orbits TO 7 Orbits, BETWEEN 03-FEB-2018:00:00:00 AND 09-FEB-2018:00:00:00, BETWEEN 18-FEB-2018:00:00:00 AND 24-FEB-2018:00:00:00, BETWEEN 18-JAN-2018:00:00:00 AND 24-JAN-2018:00:00:00, ORIENT 61D TO 90 D, PATTERN 1 1, PHASE 0 TO 0.05, Period 7.887 D AND ZERO-PHASE HJD2458032.92355, SEQ 01, 02, 03, 04, 05, 06 WITHIN 15.774 D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F606W ------------------------------------------------------------------------------------------------------------------------------------ Target Names ERIS-OFFSET ------------------------------------------------------------------------------------------------------------------------------------