We propose to image asteroid 4 Vesta throughout one complete rotation during its opposition and close approach to Earth in May of 2007 in four filters for the purposes of improving knowledge of its spin pole, size, shape, albedo and composition across its surface. We will conduct a satellite search. Multi-filter imaging will extend the range of photometric mapping into the southern hemisphere where a large basin exists, and will extend compositional mapping further into the southern hemisphere than previous observations. The results will improve our understanding of protoplanetary processes and support scientific planning for NASA's Dawn mission to orbit Vesta 2011.

We plan to image asteroid 4 Vesta through one complete rotation during its opposition and close approach to Earth in May of 2007 in four broad band filters for the purposes of improving knowledge of its spin pole, size, shape, albedo and composition across its surface. We will conduct a search for satellites. Multi-filter imaging at this opposition will extend the range of photometric mapping into the southern hemisphere of Vesta where a large basin exists, and will extend compositional mapping further into the southern hemisphere than previous observations. The results will improve our understanding of protoplanetary processes and support scientific planning for NASA's Dawn mission to orbit Vesta in 2011. none none Time critical observing: Our primary objective of dense longitudinal mapping of Vesta is achieved with seven visits to Vesta. The first four visits are sequential and occur within 4 orbits. There is a gap of 31 orbits from the start of the first visit, then the last three visits are sequential. This spacing gives complete and fairly uniformly spaced longitudinal coverage and is controlled by the rotation period of Vesta (5.342 hrs) relative to the orbital period of HST. Observations can begin on May 14th. Obsrving earlier, we lose spatial resolution. We want to complete our observations before May 20th, 2:00 hr, as the phase function begins its opposition surge at 6 degrees. We want to observe at phase angle values larger than 6 degrees. We will be able to constrain a roughness parameter with photometric modeling when we observe at phase angle between 7-9 degrees. We can meet the objective of aquiring albedo maps if the observations are scheduled between May 17 and June 4, 2007, but we lose the information on surface roughness. So we prefer to complete observations by May 20th. SOLAR SYSTEM 12 false 0.0 false false false false false false SUPPORTED SOLAR SYSTEM We are targeting the southern hemisphere of Vesta (maximum southern sub-Earth latitude). First priority: Albedo maps Acquire complete rotational coverage in as few orbits as possible. Observe at large enough phase angle to constrain the roughness and avoid opposition surge, between 7-9 degrees. Achieve high spatial resolution which changes by less than 2/3 pixel in this observing window. Second priority: Satellite search The uncertainty in the V magnitude is theoretically 0.01 magnitudes. source of these data is JPL Small-Body Database. http://ssd.jpl.nasa.gov/sbdb.cgi The acquisition uncertainty is most likely driven by uncertainty in the position of the guide stars. surface brightness 4.33 mag/arcsec2, B-V=0.782 +/- 0.020, U-B= 0.492 +/-0.030 ASTEROID Asteroid Vesta TYPE=ASTEROID,A=2.36195625573717,E=0.08936578245846,I=7.13379759216282,O=103.9183796862978,W=150.1801484597885,M=341.5920160475586,EQUINOX=J2000,EPOCH=10-APR-2007:00:00:00 PHASE OF VESTA FROM EARTH BETWEEN 7.0 10.0, RANGE VESTA EARTH LT 1.1814, RANGE VESTA EARTH GT 1.159 ACS/HRC Imaging No No F814W ACS/HRC Imaging No No F555W ACS/HRC Imaging No No F330W ACS/HRC Imaging No No F220W The most important factor is to achieve complete and uniform rotational coverage. This can be done by separating the start of visit 4 from the start of visit 5 by 31 orbits. If these two visits are more than 31 orbits apart, the range in phase angle and spatial resolution become problematic to the mapping. Note that this value has been revised from the old value in the original Phase II proposal, which has been updated here accordingly. (Tic-Visit :proposal-id 501 :visit-id "01" :proposal-version -1 :trans-version "20070108" :date "26-Apr-2007 16:03:54.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "26" :si-bright-earth-limb-angle 20.0 :data-volume 672240 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 501 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 501 :visit-id "01" :orbit-number 1 :pcs-time 269 :si-vis-utilization 2709 :al-overhead-at-end 120 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3132 :pcs-gap 0 ) false 1 0 The most important factor is to achieve complete and uniform rotational coverage. This can be done by separating the start of visit 4 from the start of visit 5 by 31 orbits. If the visits are more than 31 orbits apart, the range in phase angle and spatial resolution become problematic to the mapping. Note that this value has been revised from the old value in the original Phase II proposal, which has been updated here accordingly. (Tic-Visit :proposal-id 501 :visit-id "02" :proposal-version -1 :trans-version "20070108" :date "26-Apr-2007 16:03:57.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "26" :si-bright-earth-limb-angle 20.0 :data-volume 672240 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 501 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 501 :visit-id "02" :orbit-number 1 :pcs-time 269 :si-vis-utilization 2709 :al-overhead-at-end 120 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3132 :pcs-gap 0 ) false 1 0 The most important factor is to achieve complete and uniform rotational coverage. This can be done by separating the start of visit 4 from the start of visit 5 by 31 orbits. If the visits are more than 31 orbits apart, the range in phase angle and spatial resolution become problematic to the mapping. Note that this value has been revised from the old value in the original Phase II proposal, which has been updated here accordingly. (Tic-Visit :proposal-id 501 :visit-id "03" :proposal-version -1 :trans-version "20070108" :date "26-Apr-2007 16:03:59.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "26" :si-bright-earth-limb-angle 20.0 :data-volume 672240 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 501 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 501 :visit-id "03" :orbit-number 1 :pcs-time 269 :si-vis-utilization 2709 :al-overhead-at-end 120 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3132 :pcs-gap 0 ) false 1 0 The most important factor is to achieve complete and uniform rotational coverage. This can be done by separating the start of visit 4 from the start of visit 5 by (exactly) 31 orbits. If the visits are more than 31 orbits apart, the range in phase angle and spatial resolution become problematic to the mapping. Note that this value has been revised from the old value in the original Phase II proposal, which has been updated here accordingly. (Tic-Visit :proposal-id 501 :visit-id "04" :proposal-version -1 :trans-version "20070108" :date "26-Apr-2007 16:04:01.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "26" :si-bright-earth-limb-angle 20.0 :data-volume 717056 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 501 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 501 :visit-id "04" :orbit-number 1 :pcs-time 269 :si-vis-utilization 2769 :al-overhead-at-end 120 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3132 :pcs-gap 0 ) false 1 0 In order to get complete longitudinal coverage of Vesta, which rotates in 5.342 hrs, it is necessary to begin the start of visit 5, 31 orbits after the start of visit 4. (Tic-Visit :proposal-id 501 :visit-id "05" :proposal-version -1 :trans-version "20070108" :date "26-Apr-2007 16:04:03.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "26" :si-bright-earth-limb-angle 20.0 :data-volume 627424 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 501 :visit-id "05" :obset-id "05" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 501 :visit-id "05" :orbit-number 1 :pcs-time 269 :si-vis-utilization 2589 :al-overhead-at-end 120 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3132 :pcs-gap 0 ) false 1 0 This visit should follow after visit 5 (Tic-Visit :proposal-id 501 :visit-id "06" :proposal-version -1 :trans-version "20070108" :date "26-Apr-2007 16:04:07.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "26" :si-bright-earth-limb-angle 20.0 :data-volume 672240 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 501 :visit-id "06" :obset-id "06" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 501 :visit-id "06" :orbit-number 1 :pcs-time 269 :si-vis-utilization 2709 :al-overhead-at-end 120 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3132 :pcs-gap 0 ) false 1 0 This visit should follow after visit 6. (Tic-Visit :proposal-id 501 :visit-id "07" :proposal-version -1 :trans-version "20070108" :date "26-Apr-2007 16:04:09.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "26" :si-bright-earth-limb-angle 20.0 :data-volume 672240 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 501 :visit-id "07" :obset-id "07" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 501 :visit-id "07" :orbit-number 1 :pcs-time 269 :si-vis-utilization 2769 :al-overhead-at-end 120 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3132 :pcs-gap 0 ) false 1 0