0 Assigned ID: 798 ----- Attempting Submission 1 (Fri Apr 07 19:40:22 GMT 2017) ----- I adjusted all of the ORIENT RANGE values and the ORIENT FROM values so that they reflect all acceptable possibilities, instead of just the preferred ranges that were given in the first phase 2 submission. This resubmission provides maximum flexibility in scheduling this program. -669419703 ----- Attempting Submission 1 (Wed Jul 19 22:02:07 GMT 2017) ----- ----- Attempting Submission 2 (Mon Aug 28 19:18:45 GMT 2017) ----- One of the key questions concerning exoplanetary systems is why some are dynamically cold, such as TRAPPIST-1, whereas others are dynamically hot, with highly eccentric planets and/or perturbed debris disks. Dynamical theory describes a variety of plausible mechanisms, but few can be empirically tested since the critical dynamical evolution that sets the final planetary architecture is short-lived. One rare system available for testing dynamical upheaval scenarios is the 400 Myr-old Fomalhaut system. In Cycle 22 we coronagraphically studied Fomalhaut C, which is a wide M-dwarf companion to Fomalhaut A, in order to test our prediction that the unresolved, Herschel-detected debris disk around Fomalhaut C may be highly perturbed because of a recent close interaction with Fomalhaut A. Using HST/STIS we discovered a highly asymmetric feature extending northward of Fomalhaut C by 3" that resembles our model of a dynamically hot disk. However, it may be a background galaxy and the definitive test of its physical relationship to Fomalhaut C is to demonstrate common proper motion. Using Keck adaptive optics follow-up observations in J band, we did not detect the feature, and hence follow-up HST observations are the only way to test for common proper motion. Here we request a very small program to revisit Fomalhaut C with STIS in order to validate the initial discovery as a debris disk (1" proper motion between HST epochs). The astrophysical significance is demonstrating that the Fomalhaut system is a valuable case for studying dynamical upheavals via stellar encounters that are inferred to occur in the evolution of many other planetary systems. Our observing plan builds on the successful Cycle 22 observing sequence (GO-13725). The absolute roll constraints are chosen so that the circumstellar feature (PA = 0 degrees) will not intersect the diffraction spikes or BAR5. Scheduling windows appear to be available through the end of November 2017. Fomalhaut C will be occulted at the bent finger with width ~0.3". The bent finger (BAR 5) is a newly supported coronagraphic mode for STIS that is ideal for fainter targets such as Fomalhaut C (Gaspar & Schneider, GO-12923). Two orbits of integration on Fomalhaut C will be executed at two different telescope ORIENTs separated from each other by 25-30 degrees, with ORIENTs selected to avoid having the disk feature behind a diffraction spike or the finger obscuration. A GROUP WITHIN 1.9 orbits is specified in order to achieve two contiguous, non-interrupted orbits to achieve PSF stability (needed for PSF subtraction during data reduction). To go to BAR5, the acquision is on BAR10 and each exposure has a POS TARG X = 16.34596, Y = -7.20172 arcsec. Though a BAR5 aperture is available in the APT, from Cycle 22 we know that the BAR10 acquision combined with this POS TARG places the target at the tip of the bent finger instead of farther down the bent finger (closer to the right edge of the CCD). Planets and Planet Formation 6 false false false false false false SUPPORTED STAR DISK This object was generated by the targetselector and retrieved from the SIMBAD database. J2000 J2000 STIS/CCD Imaging Yes No BAR5 STIS/CCD Imaging Yes No BAR5 1503947245015 /private/var/folders/xt/qjmnp0112nl6r_37xv8_kg1c0000gn/T/OPVisit3195560569033994127.xml Timing link suitability includes constraints ([Group (01 02) Within 0.1 days]) The scheduling data was generated by CASM 25.2. CASM was run in Phase II mode. 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