16707( 4) - 06-Jan-2023 20:08:01 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 16707 Version: 4 Check-in Time: 06-Jan-2023 20:08:01 STScI Edit Number: 1 Title Precision astrometry with STIS to confirm the orbital motion of HD 106906b ------------------------------------------------------------------------------------ Type Cycle GO 29 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Paul George Kalas University of California - Berkeley Y CoI: Dr. Robert J De Rosa European Southern Observatory - Chile N CoI: Meiji Nguyen Space Telescope Science Institute N ------------------------------------------------------------------------------------ Abstract The 15 Myr old spectroscopic binary HD 106906 represents a unique laboratory for studying the early dynamical evolution of planetary systems because a gas giant exoplanet has been directly imaged exterior to a central planetary system and a distorted debris disk. Several groups have proposed that the planet has been ejected from its formation site near the binary and dynamically shapes the outer disk structure, much like the hypothetical Planet Nine in our solar system is thought to control the orbital architecture of detached Kuiper Belt Objects. A key test of this hypothesis is to measure the orbital elements of HD 106906b which requires exquisite astrometric precision over many years given its 737 au separation from the binary. Using multi-epoch HST imaging with ACS, WFC3 and STIS where background stars detected with Gaia are used as an astrometric reference frame, Nguyen et al. (2021) recently measured orbital motion and contrained the orbit of HD 106906b. The findings were consistent with the hypothesis that the planet perturbs the disk. However, the result strongly depends on a single ACS/HRC point from 2004 that cannot be reproduced given that the camera is no longer functional. Here we propose to reproduce their 2017 STIS observations in Cycle 29, five years after the planet was first imaged with STIS. The sky-plane motion over this interval is expected to be greater than 3-sigma of the astrometric uncertainty. These observations will serve as a critical validation using the same instrument for two epochs of astrometry and will refine the estimated posteriors of the planetary orbital elements. ------------------------------------------------------------------------------------ Observations Description ------------------------ (1) To mitigate the effects of uncorrected geometric distortion, we aim to place HD 106906b in the central region of the STIS field. This is achieved by occulting the star at the WEDGEB1.8 position and using the specified ORIENTs. (2) HD 106906 is a bright star (mv = 7.8 mag) and its PSF halo interferes with the detection of its debris disk as well as the planet located at 7.1'' radius from the star. To achieve PSF subtraction we will image the science target at two roll angles. (3) We image at the WEDGEB1.8 position, and also at a POS-TARG X=-0.5" away from this position, thus achieving additional dithering for PSF analysis. (4) The best PSF subtractions occur when the the orbits are executed 16707( 4) - 06-Jan-2023 20:08:01 - [ 2] consecutively. Therefore, in Visit 01 we specify a timing SEQUENCE which should have consecutive orbits and not be interrupted by other types of observations. ------------------------------------------------------------------------------------ 16707( 4) - 06-Jan-2023 20:08:01 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HD-106906 STAR, DISK, EXTRA-SOLAR RA=12H17M53.1914S +/- 0.1", J2000 V = 8.89 PLANET, EXTRA-SOLAR DEC=-55D58'31.89" +/- 0.1" PLANETARY SYSTEM, F3-F9 Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000.0 -0.004648284006755771 -0.012872 0.0096774 ------------------------------------------------------------------------------------------------------------------------------------ 16707( 4) - 06-Jan-2023 20:08:01 - [ 4] Visit: 01 Visit Requirements: ORIENT 320.0D TO 320.1 D; SEQ 01, 02 WITHIN 1.1 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 HD-106906 STIS/CCD ACQ F25ND3 MIRROR 1 1.0 S (1 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 HD-106906 STIS/CCD ACCUM WEDGEB1.8 MIRROR CR-SPLIT=3, GAIN=4 1 960 S (960 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 HD-106906 STIS/CCD ACCUM WEDGEB1.8 MIRROR CR-SPLIT=3, GAIN=4 1 960 S (960 POS TARG -0.5, 0 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 HD-106906 STIS/CCD ACCUM WEDGEB1.8 MIRROR CR-SPLIT=3, GAIN=4 1 180 S (180 POS TARG -17, 0 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 | ------------------------------------------------------------------------------------------------------------------------------------ HD-106906 1 STIS/CCD ACQ F25ND3 MIRROR none none none none 1 N/A HD-106906 2 STIS/CCD ACCUM WEDGEB1. MIRROR none none none 1 1 N/A 8 HD-106906 2 STIS/CCD ACCUM WEDGEB1. MIRROR none none none 2 1 N/A 8 HD-106906 2 STIS/CCD ACCUM WEDGEB1. MIRROR none none none 3 1 N/A 8 HD-106906 3 STIS/CCD ACCUM WEDGEB1. MIRROR none none none 1 1 N/A 8 HD-106906 3 STIS/CCD ACCUM WEDGEB1. MIRROR none none none 2 1 N/A 8 HD-106906 3 STIS/CCD ACCUM WEDGEB1. MIRROR none none none 3 1 N/A 8 HD-106906 4 STIS/CCD ACCUM WEDGEB1. MIRROR none none none 1 1 N/A 8 HD-106906 4 STIS/CCD ACCUM WEDGEB1. MIRROR none none none 2 1 N/A 8 HD-106906 4 STIS/CCD ACCUM WEDGEB1. MIRROR none none none 3 1 N/A 8 16707( 4) - 06-Jan-2023 20:08:01 - [ 5] Visit: 02 Visit Requirements: ORIENT 338.5D TO 338.6 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 HD-106906 STIS/CCD ACQ F25ND3 MIRROR 1 1.0 S (1 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 HD-106906 STIS/CCD ACCUM WEDGEB1.8 MIRROR CR-SPLIT=3, GAIN=4 1 960 S (960 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 HD-106906 STIS/CCD ACCUM WEDGEB1.8 MIRROR CR-SPLIT=3, GAIN=4 1 960 S (960 POS TARG -0.5, 0 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 HD-106906 STIS/CCD ACCUM WEDGEB1.8 MIRROR CR-SPLIT=3, GAIN=4 1 180 S (180 POS TARG -17, 0 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 | ------------------------------------------------------------------------------------------------------------------------------------ HD-106906 1 STIS/CCD ACQ F25ND3 MIRROR none none none none 1 N/A HD-106906 2 STIS/CCD ACCUM WEDGEB1. MIRROR none none none 1 1 N/A 8 HD-106906 2 STIS/CCD ACCUM WEDGEB1. MIRROR none none none 2 1 N/A 8 HD-106906 2 STIS/CCD ACCUM WEDGEB1. MIRROR none none none 3 1 N/A 8 HD-106906 3 STIS/CCD ACCUM WEDGEB1. MIRROR none none none 1 1 N/A 8 HD-106906 3 STIS/CCD ACCUM WEDGEB1. MIRROR none none none 2 1 N/A 8 HD-106906 3 STIS/CCD ACCUM WEDGEB1. MIRROR none none none 3 1 N/A 8 HD-106906 4 STIS/CCD ACCUM WEDGEB1. MIRROR none none none 1 1 N/A 8 HD-106906 4 STIS/CCD ACCUM WEDGEB1. MIRROR none none none 2 1 N/A 8 HD-106906 4 STIS/CCD ACCUM WEDGEB1. MIRROR none none none 3 1 N/A 8 16707( 4) - 06-Jan-2023 20:08:01 - [ 6] Summary Form for Proposal 16707 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F25ND3, WEDGEB1.8 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, ACQ ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=3, GAIN=4 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 320.0D TO 320.1 D, ORIENT 338.5D TO 338.6 D, POS TARG -0.5, 0, POS TARG -17, 0, SEQ 01, 02 WITHIN 1.1 Orbits ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD-106906 ------------------------------------------------------------------------------------------------------------------------------------