0 Assigned ID: 1605 ----- Attempting Submission 1 (Mon Oct 16 23:15:26 GMT 2017) ----- Be very careful mixing POS TARG and Center_Pattern = Yes Be very careful mixing POS TARG and Center_Pattern = Yes try orient link again 1993212752 ----- Attempting Submission 1 (Fri Nov 03 22:37:44 GMT 2017) ----- HST Phase II Proposal 15406 (Comet.apt) successfully submitted. Receipt: # 15406-1 ----- Attempting Submission 2 (Sun Nov 05 21:24:43 GMT 2017) ----- ----- Attempting Submission 3 (Wed Nov 15 00:21:33 GMT 2017) ----- ----- Attempting Submission 4 (Wed Nov 15 18:52:18 GMT 2017) ----- ----- Attempting Submission 5 (Thu Jan 18 18:09:31 GMT 2018) ----- ----- Attempting Submission 6 (Tue Jan 23 16:18:26 GMT 2018) ----- HST Phase II Proposal 15406 (15406.apt) successfully submitted. Receipt: # 15406-6 ----- Attempting Submission 7 (Tue Jan 23 16:26:06 GMT 2018) ----- HST Phase II Proposal 15406 (15406.apt) successfully submitted. Receipt: # 15406-7 ----- Attempting Submission 8 (Tue Jan 23 16:51:56 GMT 2018) ----- ----- Attempting Submission 9 (Wed Jan 24 18:58:20 GMT 2018) ----- ----- Attempting Submission 10 (Mon Jan 29 20:42:17 GMT 2018) ----- ----- Attempting Submission 11 (Tue Jan 30 21:55:07 GMT 2018) ----- ----- Attempting Submission 12 (Wed Jan 31 16:59:32 GMT 2018) ----- HST Phase II Proposal 15406 (15406.apt) successfully submitted. Receipt: # 15406-12 ----- Attempting Submission 13 (Thu Feb 01 16:13:39 GMT 2018) ----- Your proposal could not be saved. Submission aborted. ----- Attempting Submission 14 (Thu Feb 01 16:25:14 GMT 2018) ----- HST Phase II Proposal 15406 (15406.apt) successfully submitted. Receipt: # 15406-14 ----- Attempting Submission 15 (Thu Feb 01 16:41:53 GMT 2018) ----- The nested pattern that includes a POS-TARG offset is correct as specified. Cause and characteristics of the major outburst of comet C/2017 O1 (ASASSN) We seek to observe comet C/2017 O1 (ASASSN), which remained undetected even at a distance from the Sun of only a few a.u., but is currently undergoing a major outburst (dm~5). We aim to search for near-nucleus fragments and, if they are present, determine their size distribution down to <10m, investigate the total mass of ejected material, and identify the cause of the outburst by measuring fragment velocities and searching for color variations among the fragments. C/2017 O1 provides a unique opportunity to collect observational evidence of the origins and evolution of comets, as only a handful of long-period comets that have had outbursts this large have been studied in detail. We propose a single-orbit observation in November to establish whether fragmentation occurred; only if fragments are detected, we request two additional single-orbit observations in intervals of a few days to determine the fragments' velocity and evolution. Should fragments be found to move too slowly to allow velocity determinations from the resulting dataset, we request a final set of two 1-orbit visits in February 2018 when the fragments' separation has increased. Regardless of whether splitting occurred or not, the requested observations will allow us to explore the inner coma for any structures or jets that could reveal the physical mechanism behind the outburst, thus adding an important datapoint to a currently still very small sample of well studied cometary outbursts. As such, the proposed project will provide fresh insights into a class of objects that are central to our understanding of the physical and chemical evolution of the solar system. This single-orbit observation is meant to establish whether fragmentation is the cause of the outburst and to search for differences in color between any fragments, if present. If fragments are detected, two additional visits will be requested in order to measure the fragments' velocities. The present observation is designed to (a) detect the nucleus as well as any fragments, using the high throughput of the F350LP filter and the excellent angular resolution of WFC3/UVIS, and (b) to explore the presence of color variations by obtaining photometry in a much redder, high-throughput bandpass, namely the F110W filter in the WFC3/IR channel. Both parts of this exploration take about approximately equal parts of this single-orbit observation; dithering is applied to the extent allowed by the constraints set by the need to dump buffers. The sole visit of this observation needs to be scheduled within the Nov 29 - Dec 3, 2017 window within which projection effects are minimal, thereby allowing fragments to be detected if present. The optimal time within this window, determined by the requirement that a sufficient number of reference stars (and no bright stars) fall within the field of view, is still under investigation. Solar System 0 SUPPORTED SOLAR SYSTEM COMET Comet undergoing major outburst, possibly due to fragmentation TYPE=COMET,Q=1.49871313,E=0.9965450,I=39.84913,O=25.81029,W=20.90731,T=14-OCT-2017:18:49:20,TTimeScale=UTC,EQUINOX=J2000,EPOCH=01-NOV-2017:00:00:00,EpochTimeScale=UTC,A1=0,A2=0,A3=0 EARTH WFC3/UVIS Imaging No No F350LP WFC3/IR Imaging No No F110W WFC3/UVIS Imaging No No F350LP WFC3/IR Imaging No No F110W WFC3/UVIS Imaging No No F350LP WFC3/IR Imaging No No F110W WFC3/UVIS Imaging No No F350LP WFC3/IR Imaging No No F110W WFC3/UVIS Imaging No No F350LP WFC3/IR Imaging No No F110W POS-TARG DITHER 0.135 This is a small fractional pixel dither for non-redundant pixels between frames on the target. LINE false false 3 46.84 WFC3-UVIS-DITHER-LINE-3PT 1 false POS-TARG DITHER 0.572 LINE 0.365 false false 74.653 4 18.528 WFC3-IR-DITHER-BOX-MIN 3 false POS-TARG DITHER DITHER 4 5.183 WFC3-IR-DITHER-BOX-MIN false 74.653 true 0.365 0.572 2 41.859 POS-TARG WFC3-IR-DITHER-BLOB 18.528 4 true POS-TARG MOSAIC DITHER 2 2.414 WFC3-UVIS-DITHER-LINE false true 0.145 2 85.759 POS-TARG WFC3-UVIS-GAP-LINE 46.84 5 true Using ephemeris for target 15406-01-C2017-O1 ephemeris data for target 15406-01-C2017-O1 does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 17.213 to 19.091. ephemeris interval: 17.304 to 19.305 The scheduling data was generated by CASM 25.2. CASM was run in Phase II mode. We request scheduling of this observation in the 2017.335:00:16:14 slot. 1512087374000 138.5 (Tic-Visit :proposal-id 15406 :visit-id "01" :proposal-version -1 :trans-version "20171009" :date "16-Jan-2018 08:42:27.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 1632272 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15406 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15406 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2867 :al-overhead-at-end 0 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3202 :pcs-gap 0 ) true 1 0 Using ephemeris for target 15406-02-C2017-O1 ephemeris data for target 15406-02-C2017-O1 does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 17.305 to 19.091. ephemeris interval: 17.365 to 20.001 The scheduling data was generated by CASM 25.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 15406 :visit-id "02" :proposal-version -1 :trans-version "20171009" :date "24-Jan-2018 08:56:28.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 1810544 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15406 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15406 :visit-id "02" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2814 :al-overhead-at-end 0 :internal-dur-at-end 582 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3202 :pcs-gap 0 ) false 1 0 Using ephemeris for target 15406-03-C2017-O1 ephemeris data for target 15406-03-C2017-O1 does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 17.305 to 19.091. ephemeris interval: 17.365 to 20.001 The scheduling data was generated by CASM 25.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 15406 :visit-id "03" :proposal-version -1 :trans-version "20171009" :date "30-Jan-2018 11:53:49.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 1443744 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15406 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15406 :visit-id "03" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2866 :al-overhead-at-end 0 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3202 :pcs-gap 0 ) false 1 0