15405( 15) - 18-Dec-2017 17:41:31 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 15405 Version: 15 Check-in Time: 18-Dec-2017 17:41:31 STScI Edit Number: 3 Title Which way home? Finding the origin of our Solar System's first interstellar visitor ------------------------------------------------------------------------------------ Type Cycle GO/DD 25 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Karen J. Meech University of Hawaii Y CoI: Dr. Marc W. Buie Southwest Research Institute Y CoI: Marco Micheli ESA SSA-NEO Coordination Centre N CoI: Dr. Jacqueline Keane University of Hawaii N CoI: Dr. Jan Kleyna University of Hawaii N CoI: Olivier Raoul Hainaut European Southern Observatory - Germany N CoI: Dr. Kenneth Chambers University of Hawaii N CoI: Dr. Harald Ebeling University of Hawaii N ------------------------------------------------------------------------------------ Abstract We request HST/WFC3/UVIS observations of A/2017 U1, a recently discovered fast moving and fast fading object that appears to originate from outside the Solar System. Rapid follow-up observations from the ground established the object's orbit as hyperbolic and thus ruled out that A/2017 U1 is a comet or asteroid. The proposed observations are critical to (a) determine the object's rotation period in order to allow observations to be performed at maximal brightness, and (b) obtain precise astrometry along an extended arc length in order to identify the region from which this object originated. A/2017 U1 is the first known interloper from outside the Solar System, and the observations proposed here play a pivotal role in determining its origin. ------------------------------------------------------------------------------------ Observations Description ------------------------ The proposed observation consists of two components that serve tightly related purposes: 1) Extend the astrometric arc in order to permit a refined orbit estimation that may allow us to uncover where the target originated. 2) Obtain critical light curve observations as the object is fading to provide accurate predictions of the rotational phase for our ongoing follow-up observations. To achieve the first goal, we split our observation into three visits, distributed evenly over a 40-day period in order to maximize the observed arc of the interloper's orbit. The beginning of this period, and hence the time of the first visit, is set by the requirement to align HST's astrometric observations with those performed with groundbased facilities, which results in a date of November 22, 2017 (or within a day thereof) for the first visit. The end of the 40-day period, and hence the time of the third visit, is defined by the date at which our target is predicted to have faded to V=27.5 which we consider the limiting magnitude for a credible detection with HST in a single orbit. We expect this to occur on January 01, 2018, but stress that adjustments in our photometric model may alter this prediction by a few days. The second 15405( 15) - 18-Dec-2017 17:41:31 - [ 2] visit should be scheduled near the midpoint between the first and the third visit in order to provide the best possible constraints on the target's highly eccentric orbit. Again, some flexibility is required to allow adjustment as the result of improvements in our model predictions. To achieve the second goal, we allocate three orbits to the first visit, and one orbit each to the subsequent second and third visit. The longer, first visit aims to sample the target's light curve at high precision and over a sufficiently long time to tightly constrain both amplitude and period, both of which are crucial parameters of the photometric model that underlies the predictions driving the timing of visits two and three. All observations will be performed with WFC3/UVIS and the F350LP filter in order to maximize system throughput. Since ours is a moving target, no dithering is required. We do, however, split each orbit into 5 subexposures using CR-SPLIT in order to allow efficient removal of cosmic rays and limit the track length of GAIA reference stars in the field that form the basis of our astrometric solution. Since our target is located at high Galactic latitude, the surface density of reference stars is low; we therefore request additional flexibility to allow scheduling of all visits (within the aforementioned windows) such that the number of GAIA stars is maximized. ------------------------------------------------------------------------------------ 15405( 15) - 18-Dec-2017 17:41:31 - [ 3] TARGET LIST Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 TARGET NAME: A-2017-U1 ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: ASTEROID Interstellar Object ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 TARGET POSITION LEVEL 2 TYPE=COMET, Q=0.2544189102683901, E=1.197091100469663, I=122.600523808621, O=24.60311659652012, W=241.5361324795846, T=09-SEP-2017:11:19:55, TTimeScale=TDB, EQUINOX=J2000, EPOCH=27-OCT-2017:00:00:00, EpochTimeScale=TDB ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 WINDOWS ------------------------------------------------------------------------------------------------------------------------------------ DATA COMMENTS V = 27.5 Ephemeris Center: EARTH ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 2 TARGET NAME: A-2017-U1-UPDATED ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: ASTEROID Interstellar Object ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 TARGET POSITION LEVEL 2 TYPE=COMET, Q=0.2553352156734523, E=1.1994907679102, I=122.6864296097109, O=24.59924632942247, W=241.7015187109427, T=09-SEP-2017:11:46:05, TTimeScale=TDB, EQUINOX=J2000, EPOCH=31-OCT-2017:00:00:00, EpochTimeScale=TDB ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 WINDOWS ------------------------------------------------------------------------------------------------------------------------------------ DATA COMMENTS V = 27.5 orbital elements update from JPL on Nov. 29 Ephemeris Center: EARTH ------------------------------------------------------------------------------------------------------------------------------------ 15405( 15) - 18-Dec-2017 17:41:31 - [ 4] TARGET LIST Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 3 TARGET NAME: OUMUAMUA ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: ASTEROID Interstellar Asteroid OUMUAMUA ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 TARGET POSITION LEVEL 2 TYPE=COMET, Q=0.2558123336343649, E=1.200914723821507, I=122.7325277932375, O=24.59699783461255, W=241.7946554840634, T=09-SEP-2017:12:12:09, TTimeScale=TDB, EQUINOX=J2000, EPOCH=01-JAN-2018:00:00:00, EpochTimeScale=TDB ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 WINDOWS ------------------------------------------------------------------------------------------------------------------------------------ DATA COMMENTS V = 27.5 +/- 2.5 Ephemeris Center: EARTH ------------------------------------------------------------------------------------------------------------------------------------ 15405( 15) - 18-Dec-2017 17:41:31 - [ 5] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type LINE Pattern_Purpose OTHER Number_Of_Points 5 Point_Spacing .030 Line_Spacing Coordinate_Frame CELESTIAL Pattern_Orient 0 Angle_Between_Sides Center_Pattern YES Pattern_Comments: This is a small fractional pixel dither for nearly non-redundant pixels between frames on the target. ------------------------------------------------------------------------------------------------------------------------------------ 15405( 15) - 18-Dec-2017 17:41:31 - [ 6] Visit: 01 (Epoch 1 part 1) Visit Requirements: ORIENT 51D TO 53 D; BETWEEN 21-NOV-2017:00:00:00 AND 21-NOV-2017:06:15:00 On Hold Comments: Additional Comments: This visit is intended to be scheduled as soon as possible without being a disruptive turn-around. Otherwise the timing is not critical but candidate times for scheduling need to be checked for stellar contamination and for having sufficient numbers of Gaia reference stars. This visit is the timing anchor for visits 2 and 3. 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 A-2017-U1 WFC3/UVI ACCUM UVIS2 F350LP 1 380 S POS TARG 16.000, 12.960; S (1900 S) SEQ 1 NON-INT; PATTERN 1 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 | ------------------------------------------------------------------------------------------------------------------------------------ A-2017-U1 1 WFC3/UVI ACCUM UVIS2 F350LP 1 none none none 1 N/A S A-2017-U1 1 WFC3/UVI ACCUM UVIS2 F350LP 2 none none none 1 N/A S A-2017-U1 1 WFC3/UVI ACCUM UVIS2 F350LP 3 none none none 1 N/A S A-2017-U1 1 WFC3/UVI ACCUM UVIS2 F350LP 4 none none none 1 N/A S A-2017-U1 1 WFC3/UVI ACCUM UVIS2 F350LP 5 none none none 1 N/A S 15405( 15) - 18-Dec-2017 17:41:31 - [ 7] Visit: 02 (Epoch 1 part 2) Visit Requirements: ORIENT 50D TO 52 D; AFTER 01 BY 0.8 Orbits TO 1.2 Orbits; BETWEEN 21-NOV-2017:00:00:00 AND 21-NOV-2017:06:15:00 On Hold Comments: Additional Comments: This visit should be close in time to visit 1. The timing applied here is an initial guess and may need to be modified slightly as more lightcurve information becomes available. This initial request is for this visit to be consecutive to visit 1. However, it could also be consecutive with visit 3 if that works better. 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 A-2017-U1 WFC3/UVI ACCUM UVIS2 F350LP 1 380 S POS TARG 32, 0; GS ACQ S (1900 S) SCENARIO BASE1B3; SEQ 1 NON-INT; PATTERN 1 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 | ------------------------------------------------------------------------------------------------------------------------------------ A-2017-U1 1 WFC3/UVI ACCUM UVIS2 F350LP 1 none none none 1 N/A S A-2017-U1 1 WFC3/UVI ACCUM UVIS2 F350LP 2 none none none 1 N/A S A-2017-U1 1 WFC3/UVI ACCUM UVIS2 F350LP 3 none none none 1 N/A S A-2017-U1 1 WFC3/UVI ACCUM UVIS2 F350LP 4 none none none 1 N/A S A-2017-U1 1 WFC3/UVI ACCUM UVIS2 F350LP 5 none none none 1 N/A S 15405( 15) - 18-Dec-2017 17:41:31 - [ 8] Visit: 03 (Epoch 1 part 3) Visit Requirements: ORIENT 85D TO 87 D; BETWEEN 22-NOV-2017:12:00:00 AND 22-NOV-2017:13:45:00 On Hold Comments: Additional Comments: This visit should be close in time to visit 1. The timing applied here is an initial guess and may need to be modified slightly as more lightcurve information becomes available. This initial request is based on a rotational period of 4 hours and is intended to run 5 orbits after visit 1. 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 A-2017-U1 WFC3/UVI ACCUM UVIS2 F350LP 1 380 S POS TARG 24.000, 0.000; S (1900 S) SEQ 1 NON-INT; PATTERN 1 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 | ------------------------------------------------------------------------------------------------------------------------------------ A-2017-U1 1 WFC3/UVI ACCUM UVIS2 F350LP 1 none none none 1 N/A S A-2017-U1 1 WFC3/UVI ACCUM UVIS2 F350LP 2 none none none 1 N/A S A-2017-U1 1 WFC3/UVI ACCUM UVIS2 F350LP 3 none none none 1 N/A S A-2017-U1 1 WFC3/UVI ACCUM UVIS2 F350LP 4 none none none 1 N/A S A-2017-U1 1 WFC3/UVI ACCUM UVIS2 F350LP 5 none none none 1 N/A S 15405( 15) - 18-Dec-2017 17:41:31 - [ 9] Visit: 04 (Epoch 2) Visit Requirements: BETWEEN 11-DEC-2017:00:00:00 AND 13-DEC-2017:00:00:00 On Hold Comments: Additional Comments: This timing for this visit is roughly half way between visit 1 and 5. The only thing critical about the timing is to get this data for rotational phase refinements to support scheduling the last visit. There is more latitude in the timing than indicated if there is a problem with this request. 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 A-2017-U1-U WFC3/UVI ACCUM UVIS2 F350LP 1 380 S SEQ 1 NON-INT; PATTERN 1 PDATED S (1900 S) 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 | ------------------------------------------------------------------------------------------------------------------------------------ A-2017-U1-UPDATED 1 WFC3/UVI ACCUM UVIS2 F350LP 1 none none none 1 N/A S A-2017-U1-UPDATED 1 WFC3/UVI ACCUM UVIS2 F350LP 2 none none none 1 N/A S A-2017-U1-UPDATED 1 WFC3/UVI ACCUM UVIS2 F350LP 3 none none none 1 N/A S A-2017-U1-UPDATED 1 WFC3/UVI ACCUM UVIS2 F350LP 4 none none none 1 N/A S A-2017-U1-UPDATED 1 WFC3/UVI ACCUM UVIS2 F350LP 5 none none none 1 N/A S 15405( 15) - 18-Dec-2017 17:41:31 - [ 10] Visit: 05 (Epoch 3) Visit Requirements: BETWEEN 01-JAN-2018:00:00:00 AND 03-JAN-2018:00:00:00 On Hold Comments: Additional Comments: This timing for this visit is set when we anticipate the target will reach V=27.5 at maximum light. The final scheduling for this will depend on updates provided by the other visits. 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 OUMUAMUA WFC3/UVI ACCUM UVIS2 F350LP 1 380 S POS TARG 32.0, -6.8; SEQ S (1900 S) 1 NON-INT; PATTERN 1 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 | ------------------------------------------------------------------------------------------------------------------------------------ OUMUAMUA 1 WFC3/UVI ACCUM UVIS2 F350LP 1 none none none 1 N/A S OUMUAMUA 1 WFC3/UVI ACCUM UVIS2 F350LP 2 none none none 1 N/A S OUMUAMUA 1 WFC3/UVI ACCUM UVIS2 F350LP 3 none none none 1 N/A S OUMUAMUA 1 WFC3/UVI ACCUM UVIS2 F350LP 4 none none none 1 N/A S OUMUAMUA 1 WFC3/UVI ACCUM UVIS2 F350LP 5 none none none 1 N/A S 15405( 15) - 18-Dec-2017 17:41:31 - [ 11] Summary Form for Proposal 15405 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements AFTER 01 BY 0.8 Orbits TO 1.2 Orbits, BETWEEN 01-JAN-2018:00:00:00 AND 03-JAN-2018:00:00:00, BETWEEN 11-DEC-2017:00:00:00 AND 13-DEC-2017:00:00:00, BETWEEN 21-NOV-2017:00:00:00 AND 21-NOV-2017:06:15:00, BETWEEN 22-NOV-2017:12:00:00 AND 22-NOV-2017:13:45:00, GS ACQ SCENARIO BASE1B3, ORIENT 50D TO 52 D, ORIENT 51D TO 53 D, ORIENT 85D TO 87 D, PATTERN 1 1, POS TARG 16.000, 12.960, POS TARG 24.000, 0.000, POS TARG 32, 0, POS TARG 32.0, -6.8, SEQ 1 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F350LP ------------------------------------------------------------------------------------------------------------------------------------ Target Names A-2017-U1, A-2017-U1-UPDATED, OUMUAMUA ------------------------------------------------------------------------------------------------------------------------------------