The only changes with respect to previous submission: SAME POS AS for the six exposures with the ACS ramp filter deleted and instead entered x- and y- coordinates into the positions manually. It is the same pointing but expressed in a different way. APT gave no errors previously, nor this time, and I could not find a note in the Phase II Manual that SAME POS AS could interfere with ACS ramp filters. Please copy comments to erich@lpl.arizona.edu ----- Submission 1 (Wed Oct 20 00:47:24 GMT 2004) ----- Phase II Proposal 10423 (neptuneacs) successfully submitted. ----- Submission 1 (Wed Oct 20 18:04:17 GMT 2004) ----- Imaging of Neptune's Evolving Atmosphere Neptune's disk-integrated reflectivity flux has risen steadily over the past decade, and has now reached unprecedented levels. Near-IR images of Neptune made with the Keck AO system in late 2003 show that the amount and distribution of cloud activity is also unprecedented. In 1994, HST images suggested that increased cloud activity on the disk was correlated with the formation of a new northern Great Dark Spot (GDS) and the dissipation of the Voyager GDS. Great Dark Spots are only detectable with HST blue-wavelength images. In Cycle 12, no ACS or WFPC2 images of Neptune were obtained, and exactly two STIS Neptune images were obtained (broad-band only). The observations proposed here will reveal the visible-wavelength component of the banded structure, and also show whether the unusual activity is linked to the evolution of one or more Great Dark Spots.
Longitudinal Coverage: To fully map Neptune in longitude, four samples are required separated in time by 4-5 hours (i.e., every third orbit). This spacing yields images at about roughly a quarter of the planet's atmospheric rotation period (~18 hours on average). Camera and Filter Selection: We propose to use ACS/HRC. Our filter selection and observing strategy are designed to elucidate the vertical and horizontal aerosol distribution in Neptune's troposphere and lower stratosphere. Filter choices and the observing sequence are based on our experience with WFPC2 images of Neptune and ACS/HRC images of Uranus. We use 11 filters once during each of our four visits in order to record discrete features. Our remaining three filters are expected to primarly record zonal features and thus we only use them once or twice. Exposure times and order of exposures are adjusted to maximize efficiency. Our exposure times are expected to generally yield 50,000-100,000 detected photons per pixel for the brightest features. For filters that cannot reach these signal levels in less than 240 seconds, we set exposure times at 240 seconds to limit rotational smear and cosmic rays. We request that the four visits be separated by 4-5 hours (three orbits), corresponding to just over 90 degrees rotation of Neptune; this ensures adequate longitudinal coverage for vertical aerosol measurements of discrete features. If the SAA interferes with the temporal sampling, the last exposures of each visit may be delayed into the following orbit. We hope that our observations can be scheduled within four months of opposition (August 8, 2005) in order to maximize the apparent diameter of Neptune. SOLAR SYSTEM 12 false 0.0 false false false false false SUPPORTED SOLAR SYSTEM PLANET NEPTUNE STD=NEPTUNE ACS/HRC Imaging No No F250W /var/tmp/OPVisit10882.xml (Tic-Visit :proposal-id 10423 :visit-id "01" :proposal-version -1 :trans-version "20041107" :date "08-Mar-2005 12:05:22.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 220816 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10423 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10423 :visit-id "01" :orbit-number 1 :pcs-time 365 :si-vis-utilization 2186 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3236 :pcs-gap 0 ) (Tic-Orbit :proposal-id 10423 :visit-id "01" :orbit-number 2 :pcs-time 300 :si-vis-utilization 629 :al-overhead-at-end 0 :internal-dur-at-end 280 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3236 :pcs-gap 0 ) true 2 0 /var/tmp/OPVisit40816.xml (Tic-Visit :proposal-id 10423 :visit-id "02" :proposal-version -1 :trans-version "20040225" :date "20-Oct-2004 11:55:25.0" :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 220816 :tdrss-contact-duration 0 ) (Tic-Obset :proposal-id 10423 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10423 :visit-id "02" :orbit-number 1 :pcs-time 365 :si-vis-utilization 2806 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3200 :pcs-gap 0 ) true -1 -1 /var/tmp/OPVisit40817.xml (Tic-Visit :proposal-id 10423 :visit-id "03" :proposal-version -1 :trans-version "20040225" :date "20-Oct-2004 11:55:43.0" :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 220816 :tdrss-contact-duration 0 ) (Tic-Obset :proposal-id 10423 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10423 :visit-id "03" :orbit-number 1 :pcs-time 365 :si-vis-utilization 2805 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3200 :pcs-gap 0 ) true -1 -1 /var/tmp/OPVisit40818.xml (Tic-Visit :proposal-id 10423 :visit-id "04" :proposal-version -1 :trans-version "20040225" :date "20-Oct-2004 11:52:15.0" :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 220816 :tdrss-contact-duration 0 ) (Tic-Obset :proposal-id 10423 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10423 :visit-id "04" :orbit-number 1 :pcs-time 365 :si-vis-utilization 2806 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3200 :pcs-gap 0 ) true -1 -1 /var/tmp/OPVisit40815.xml