----- Submission 1 (Mon May 12 21:21:22 GMT 2003) ----- From molecules to aerosols: observing the haze creation process during Titan's polar summer Our Cycle 11 observations of Titan at southern summer solstice reveal unexpected complexity and an opportunity for science that has not previously been possible. Titan currently has a polar hood below 65 degrees S. The polar hood is dark in the visible relative to the southern mid-latitudes, as is Titan's northern hemisphere. In the UV and near-IR, the hood is spectrally distinct from the better-known north-south asymmetry, indicating a different formation mechanism. The nature of the relation between the southern summer hood and the northern spring equinox polar hood observed by Voyager is uncertain. We propose a set of ultraviolet and supporting observations to demonstrate the nature of temporal changes in the hood and to look for expected stratospheric absorbing gasses. The gasses are precursors to Titan's aerosols; the polar hood may be an early stage of aerosol evolution. Our observations will provide important constraints on the chemistry and dynamics of Titan's stratosphere at summer solstice. The chance to follow-up our observations of the polar hood will allow us to assess the processes and changes that are occurring now, so that Cassini observations of the polar regions will not need to be interpreted in isolation from seasonal context.
ACS: near 2D phase angle before opposition for consistency with 2002 observations. Orbit 1: GSA, then single ACS/SBC image with F165LP filter for expected S/N of 6. Orbits 2-3: re-acquisition, followed by CRSPLIT exposure with F220W, followed by 4-point dither set using F250W, F330W, F435W, and F475W. The dither set is spread over 2 orbits. After the dither set, CRSPLIT images are acquired with F502N, F550M, and F892N. Any exposure times can be modified up or down to fit different visibility periods. STIS: the observations are assumed to be near opposition based on the narrow ORIENT requirement (51+-5, or 231+-5). After acquisition (using parameters that have been used previously), the first orbit is used for a single spectrum oriented to Titan's north-south axis with G230L, the NUV MAMA, and the 0.5 arcsec slit. The second orbit has a dither with G430L starting at the center of flux and moving outward. No recenter is needed due to symmetry. After that pattern, a dither with G750L and higher sampling density is used, also from the center outward. Any change in exposure time should be applied first to the G230L or G430L exposures, as needed. SOLAR SYSTEM 12 false false false false SUPPORTED SOLAR SYSTEM SURF(U) = 9.8, SURF(B) = 9.1, SURF(V) = 7.8 SATELLITE Satellite Titan STD=SATURN STD=TITAN PHASE OF TITAN FROM EARTH BETWEEN 0.0 2.1 SOLAR SYSTEM SURF(U) = 9.8, SURF(B) = 9.1, SURF(V) = 7.8 SATELLITE Satellite Titan STD=SATURN STD=TITAN false false DITHER No center-pattern is used intentionally. STIS-PERP-TO-SLIT false 0.0 1 POS-TARG 0.1 90.0 MOSAIC 4 STIS-ALONG-SLIT POS-TARG false false DITHER No center-pattern is used intentionally. STIS-PERP-TO-SLIT false 0.0 2 POS-TARG 0.05 90.0 MOSAIC 7 STIS-ALONG-SLIT POS-TARG false false ACS-HRC-DITHER-BOX false 19.89 3 0.15 DITHER 4 LINE POS-TARG /var/tmp/OPVisit10822.xml Can waive the BEFORE requirement if needed, but partially compromises comparison with 2002 data. (Tic-Visit :proposal-id 9745 :visit-id "01" :proposal-version -1 :trans-version "20030908" :date "02-Oct-2003 14:49:49.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 4 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 515360 :tdrss-contact-duration 0 ) (Tic-Obset :proposal-id 9745 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 9745 :visit-id "01" :orbit-number 1 :pcs-time 365 :si-vis-utilization 2390 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3056 :pcs-gap 0 ) (Tic-Orbit :proposal-id 9745 :visit-id "01" :orbit-number 2 :pcs-time 300 :si-vis-utilization 2750 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3056 :pcs-gap 0 ) (Tic-Orbit :proposal-id 9745 :visit-id "01" :orbit-number 3 :pcs-time 300 :si-vis-utilization 392 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3056 :pcs-gap 0 ) (Tic-Orbit :proposal-id 9745 :visit-id "01" :orbit-number 4 :pcs-time 300 :si-vis-utilization 2690 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3056 :pcs-gap 0 ) true Can open orientation constraints if need -- please consult PI first. (Tic-Visit :proposal-id 9745 :visit-id "02" :proposal-version -1 :trans-version "20030422" :date "12-May-2003 15:19:41.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 242672 :tdrss-contact-duration 0 ) (Tic-Obset :proposal-id 9745 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 9745 :visit-id "02" :orbit-number 1 :pcs-time 365 :si-vis-utilization 2638 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3004 :pcs-gap 0 ) (Tic-Orbit :proposal-id 9745 :visit-id "02" :orbit-number 2 :pcs-time 291 :si-vis-utilization 2705 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3004 :pcs-gap 0 ) true