visit 3 on singles ----- Submission 6 (Tue Apr 11 19:21:33 GMT 2006) ----- Phase II Proposal 10992 (10992) successfully submitted. ----- Submission 7 (Tue Apr 11 20:07:49 GMT 2006) ----- Phase II Proposal 10992 (10992) successfully submitted. ----- Submission 8 (Tue Apr 11 20:58:16 GMT 2006) ----- Phase II Proposal 10992 (10992) successfully submitted. ----- Submission 9 (Tue Apr 11 21:06:02 GMT 2006) ----- Phase II Proposal 10992 (10992) successfully submitted. ----- Submission 10 (Tue Apr 11 21:26:34 GMT 2006) ----- Phase II Proposal 10992 (10992) successfully submitted. ----- Submission 11 (Tue Apr 11 21:44:16 GMT 2006) ----- Phase II Proposal 10992 (10992) successfully submitted. ----- Submission 12 (Tue Apr 11 21:58:24 GMT 2006) ----- ----- Submission 13 (Mon Apr 17 13:17:59 GMT 2006) ----- no processing Investigating the Disintegration of Comet 73P/Schwassmann-Wachmann 3 The performance of the comet 73P/Schwassmann-Wachmann 3 during its current apparition is vastly surpassing all of our original expectations. Thus, the currently approved Hubble program to observe this comet (GO-10625) is no longer adequate, and we propose a 5-orbit DD program to perform an intensive investigation of the 3 brightest fragments, all of which are showing evidence for ongoing disruption. The Hubble observations of 73P/SW3 will produce the most detailed views possible of the regions surrounding these 3 fragments, thereby yielding important new insights into cometary disruption, which is one of the principal mechanisms by which cometary nuclei expire. The combination of Hubble and Spitzer data, the latter from a recently approved Spitzer DD program, should provide the most extensive investigation yet of a cometary disruption event.
The observing program that addresses the objectives discussed above consists of: -3 orbits of ACS/WFC imaging of the B-fragment -1 orbit of ACS/WFC imaging of the C-fragment -1 orbit of ACS/WFC imaging of the G-fragment 3 orbits are needed for the B fragment to study the dynamics of any large sub-fragments currently being shed. The acceleration of objects as small as ~10-20~m can be probed by taking 3 observations spaced over ~3-5 days. (At a speed of ~1 m/s, a fragment travels ~86 km/day, or 7 WFC pix/day.) There is no strict timing constraint on the 3 orbits; they simply need to be spread over a few day period. 1 ACS/WFC orbit for each fragment should be enough to capture regions where the trail is spatially separated from the tail, at least to the east of the nucleus. The individual nuclei (C, B, G) should easily be detectable in the ACS/WFC, and the areal coverage is 54x larger for the WFC compared to the HRC, so the WFC casts a much wider net for debris than does the HRC. The ACS/WFC has enough sensitivity to obtain color information (at least B and R) on all 3 nuclei. Long exposures through F606W, taken in the same orbit, will be obtained for the deep survey of the debris field. In other words, we will follow a similar strategy to that used for our already-approved HRC program, except that we will not be attempting to measure the lightcurves of the fragments, which would take too much time. Detailed planning for Hubble observations of 73P/SW3-C has already been performed by Alison Vick, the Program Coordinator for our cycle~14 program on the comet (GO-10625). She found that single-guide-star tracking is possible during the week of April~17$^{th}$ and that Hubble observations during the following weeks are essentially impossible. She identified 9 different orbits between April 17$^{th}$ and April 19$^{th}$ when observations centered on the C-fragment could be scheduled. At least one of those orbits can be used for one of the visits (\ie of the C fragment). The large offsets between the different fragments means that new feasibility studies must be performed for the other 4 orbits. Note, however, that the rates of motion of all the fragments are essentially identical to that of the C-fragment, so it should be possible to find 4 other orbits where the planned observations can be scheduled. We will take a series of dithered exposures (probably a 4-point dither) to cover the WFC interchip gap and to mitigate the effect of anomalous pixels. SOLAR SYSTEM 0 false 0.0 false false false false false SUPPORTED SOLAR SYSTEM COMET Comet-73P-SW3-C TYPE=COMET,Q=0.93915457500755,E=0.69335804611058,I=11.39051090327332,O=69.90136109280597,W=198.7932324156269,T=06-JUN-2006:22:49:39,EQUINOX=J2000,EPOCH=10-APR-2006:00:00:00 SOLAR SYSTEM COMET Comet-73P-SW3-B TYPE=COMET,Q=0.9391157229472108,E=0.6934916836020937,I=11.39051308660114,O=69.90139070323583,W=198.7859088085189,T=07-JUN-2006:22:03:37,EQUINOX=J2000,EPOCH=07-APR-2006:00:00:00 SOLAR SYSTEM COMET Comet-73P-SW3-G TYPE=COMET,Q=0.93909821038298,E=0.69414229676781,I=11.3940447594551,O=69.91657236735139,W=198.7681551135105,T=08-JUN-2006:02:03:49,EQUINOX=J2000,EPOCH=07-APR-2006:00:00:00 ACS/WFC Imaging No No F475W ACS/WFC Imaging No No F555W ACS/WFC Imaging No No F625W ACS/WFC Imaging No No F606W ACS/WFC Imaging No No F475W ACS/WFC Imaging No No F555W ACS/WFC Imaging No No F625W ACS/WFC Imaging No No F606W ACS/WFC Imaging No No F475W ACS/WFC Imaging No No F555W ACS/WFC Imaging No No F625W ACS/WFC Imaging No No F606W (Tic-Visit :proposal-id 10992 :visit-id "02" :proposal-version -1 :trans-version "20060322" :date "11-Apr-2006 15:00:00.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 1421120 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10992 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10992 :visit-id "02" :orbit-number 1 :pcs-time 269 :si-vis-utilization 2600 :al-overhead-at-end 0 :internal-dur-at-end 349 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3132 :pcs-gap 0 ) false 1 0 /private/tmp/OPVisit46731.xml (Tic-Visit :proposal-id 10992 :visit-id "03" :proposal-version -1 :trans-version "20060322" :date "11-Apr-2006 15:00:05.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 1421120 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10992 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10992 :visit-id "03" :orbit-number 1 :pcs-time 269 :si-vis-utilization 2650 :al-overhead-at-end 0 :internal-dur-at-end 349 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3132 :pcs-gap 0 ) false 1 0 /private/tmp/OPVisit46732.xml (Tic-Visit :proposal-id 10992 :visit-id "04" :proposal-version -1 :trans-version "20060322" :date "11-Apr-2006 16:14:59.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 1421120 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10992 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10992 :visit-id "04" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2600 :al-overhead-at-end 0 :internal-dur-at-end 349 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3236 :pcs-gap 0 ) false 1 0 /private/tmp/OPVisit46736.xml (Tic-Visit :proposal-id 10992 :visit-id "05" :proposal-version -1 :trans-version "20060322" :date "11-Apr-2006 16:23:48.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 1421120 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10992 :visit-id "05" :obset-id "05" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10992 :visit-id "05" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2600 :al-overhead-at-end 0 :internal-dur-at-end 349 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3236 :pcs-gap 0 ) false 1 0 /private/tmp/OPVisit46738.xml (Tic-Visit :proposal-id 10992 :visit-id "06" :proposal-version -1 :trans-version "20060322" :date "11-Apr-2006 16:23:37.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 1421120 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10992 :visit-id "06" :obset-id "06" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10992 :visit-id "06" :orbit-number 1 :pcs-time 269 :si-vis-utilization 2600 :al-overhead-at-end 0 :internal-dur-at-end 349 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3236 :pcs-gap 0 ) true 1 0 /private/tmp/OPVisit46737.xml