Distant comets and Centaurs often show cometary activity and outbursts well beyond 3 AU, the boundary of the sublimation zone of water. Super-volatiles (most likely CO, but possibly CH4, N2, or S2) are suspected to be responsible, but have never been detected in distant comets in the UV. We will obtain FUV spectra of active bodies to cover important CO emission bands. We plan two sets of observations: comet 29P/Schwassmann-Wachmann at 6 AU, whose outbursts are too short to capture as a Target of Opportunity, but which also shows persistent cometary activity in quiescence; and Target of Opportunity observations of the Centaur 2060 Chiron (at ~15.5 AU) in outburst.

TOO observations of Chiron, after continued brightening beyond 0.7 visual magnitudes. 3 consecutive orbits, with grating G160M at central wavelength 1589? and 1623?. Scheduled observations of 29P/SW-1 with the same grating configuration; three separate 1-orbit visits staggered at 15+ day intervals, in order to improve chances of catching at least one outburst. SOLAR SYSTEM 12 false 0.0 0.0 false false false false false false SUPPORTED SOLAR SYSTEM Orbital elements retreived from JPL Small-Body Database Browser, http://ssd.jpl.nasa.gov/sbdb.cgi#top on 1/21/2010 Date of solution: 2009-Oct-06 16:17:00; based on 1104 observations Formal errors in sky coordinates through 2010: <= 0.18", from JPL Horizons ephemeris generator, http://ssd.jpl.nasa.gov/horizons.cgi 8R at 1510A ASTEROID ASTEROID 2060 CHIRON TYPE=ASTEROID,A=13.70387092426883,E=.378760177032046,I=6.929747024642194,O=209.3385535947615,W=339.898328429563,M=98.72903822472631,EQUINOX=J2000,EPOCH=04-JAN-2010:00:00:00 EARTH SOLAR SYSTEM Orbital elements retreived from JPL Small-Body Database Browser, http://ssd.jpl.nasa.gov/sbdb.cgi#top on 1/21/2010 Date of solution: 2010-Jan-08 12:05:58; based on 12538 observations Formal errors in sky coordinates through 2010: <= 0.08", from JPL Horizons ephemeris generator, http://ssd.jpl.nasa.gov/horizons.cgi 1.5R at 1510A COMET COMET 29P/SW1 TYPE=COMET,Q=5.7177821417888301525067,E=0.0449990221280341870513,I=9.3946369470700457071643,O=312.634502088065,W=48.16939670906947,T=30-JUN-2004:09:21:17,EQUINOX=J2000,EPOCH=10-JAN-2009:00:00:00 EARTH COS/FUV Spectroscopic No No G140L COS/FUV Spectroscopic No No G140L Using ephemeris for target 11536-01-2060-CHIRON ephemeris data for target 11536-01-2060-CHIRON does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 08.245 to 11.091. ephemeris interval: 10.090 to 12.092 The scheduling data was generated by CASM 18.1. CASM was run in Phase II mode. Oh hold as Target of Opportunity waiting for outburst. 1275752878000 248.02956788728443 (Tic-Visit :proposal-id 11536 :visit-id "01" :proposal-version -1 :trans-version "20100218" :date "25-May-2010 11:23:47.0" :trans-errors '(:WARNINGS 1 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 3 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 843840 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11536 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11536 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2867 :al-overhead-at-end 0 :internal-dur-at-end 107 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3182 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11536 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 2959 :al-overhead-at-end 0 :internal-dur-at-end 116 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3182 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11536 :visit-id "01" :orbit-number 3 :pcs-time 222 :si-vis-utilization 2957 :al-overhead-at-end 0 :internal-dur-at-end 428 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3182 :pcs-gap 0 ) true 3 1 Acquisition time from ETC COS.A219019, assuming 19th magnitude point source with solar spectrum and average airglow, S/N = 40. ETC COS67398: 2" diameter (1" radius), 18th magnitude = 19.2 mags per sq arcsec, 8 R = 2.0e-16 erg/cm^2/s/sq. arcsec @ 1510? (5? wide band). Calculated buffer time is 2/3 of 93000s Using ephemeris for target 11536-02-29P-SW1 ephemeris data for target 11536-02-29P-SW1 does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 08.245 to 11.091. ephemeris interval: 10.090 to 12.092 Timing link suitability includes constraints ([03 After 02 by 15.0 to 300.0 days]) The scheduling data was generated by CASM 18.1. CASM was run in Phase II mode. 1274116491000 108.17872045110221 (Tic-Visit :proposal-id 11536 :visit-id "02" :proposal-version -1 :trans-version "20100218" :date "27-Apr-2010 11:42:24.0" :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 238176 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11536 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Obset :proposal-id 11536 :visit-id "02" :obset-id "A2" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11536 :visit-id "02" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2841 :al-overhead-at-end 0 :internal-dur-at-end 428 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3234 :pcs-gap 0 ) true 1 0 Visible context image, to check comet morphology/brightness/activity level. Use F606W filter for maximum signal; comet spectrum from 4500 - 6500 A is largely flat. use 3x3 binning to - minimize overhead time, to get most UV spectroscopy time available, while still viewing field larger than expected comet nucleus (~1+ arcmin) - reduce readout noise, thereby maximizing S/N for faint comet coma Comet nucleus (up to 50km, viewed from 5.2+ AU) is unresolved even without binning. Coma covers ~ 1+ arcmin in visible images, ETC COS78955: approx. as point source, solar-type spectrum at max 13th magnitude, 2.5 R within 1" diameter: 5e-17 erg/cm^2/s @ 1510 A. Calculated buffer time is 2/3 of 93000s, even with high airglow. We will be safe even with very large outburst. Using ephemeris for target 11536-03-29P-SW1 ephemeris data for target 11536-03-29P-SW1 does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 08.245 to 11.091. ephemeris interval: 10.090 to 12.092 Timing link suitability includes constraints ([03 After 02 by 15.0 to 300.0 days] [04 After 03 by 15.0 to 300.0 days]) The scheduling data was generated by CASM 18.1. CASM was run in Phase II mode. (Tic-Visit :proposal-id 11536 :visit-id "03" :proposal-version -1 :trans-version "20100218" :date "27-Apr-2010 11:42:33.0" :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 238176 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11536 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Obset :proposal-id 11536 :visit-id "03" :obset-id "A3" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11536 :visit-id "03" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2841 :al-overhead-at-end 0 :internal-dur-at-end 428 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3234 :pcs-gap 0 ) false 1 0 ETC COS78955: approx. as point source, solar-type spectrum at max 13th magnitude, 2.5 R within 1" diameter: 5e-17 erg/cm^2/s @ 1510 A. Calculated buffer time is 2/3 of 93000s, even with high airglow. We will be safe even with very large outburst. Using ephemeris for target 11536-04-29P-SW1 ephemeris data for target 11536-04-29P-SW1 does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 08.245 to 11.091. ephemeris interval: 10.090 to 12.092 Timing link suitability includes constraints ([04 After 03 by 15.0 to 300.0 days]) The scheduling data was generated by CASM 18.1. CASM was run in Phase II mode. (Tic-Visit :proposal-id 11536 :visit-id "04" :proposal-version -1 :trans-version "20100218" :date "27-Apr-2010 11:42:41.0" :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 238176 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11536 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Obset :proposal-id 11536 :visit-id "04" :obset-id "A4" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11536 :visit-id "04" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2841 :al-overhead-at-end 0 :internal-dur-at-end 428 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3234 :pcs-gap 0 ) true 1 0 ETC COS78955: approx. as point source, solar-type spectrum at max 13th magnitude, 2.5 R within 1" diameter: 5e-17 erg/cm^2/s @ 1510 A. Calculated buffer time is 2/3 of 93000s, even with high airglow. We will be safe even with very large outburst.