0Assigned ID: 464
----- Attempting Submission 1 (Fri Apr 10 13:45:11 GMT 2015) -----This target is not used in this proposal.
COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details.
COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details.
COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details.
COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details.
COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details.
POS TARG OUTSIDE OF APERTURE NO ORIENT
POS TARG OUTSIDE OF APERTURE
POS TARG OUTSIDE OF APERTURE NO ORIENT
POS TARG OUTSIDE OF APERTURE
COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details.
COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details.
COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details.
COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details.
COS FUV PSA science exposures with extended targets have special calibration limitations. See "Errors and Warnings" for more details.- New target acquisition mode (August 2016 - after recommendation from John Debes)
- updated target offsets
- September 2016: Cenwave changed from 1291 A to 1327 A to cover SI 1429 A line-1810075598----- Attempting Submission 1 (Thu Jul 09 10:38:58 GMT 2015) -----
----- Attempting Submission 2 (Thu Jul 16 19:06:45 GMT 2015) -----
----- Attempting Submission 3 (Mon Aug 10 14:34:15 GMT 2015) -----
----- Attempting Submission 4 (Thu May 19 09:04:30 GMT 2016) -----
HST Phase II Proposal 14106 (ceres_phase2b.apt) successfully submitted.
Receipt: # 14106-4
----- Attempting Submission 5 (Thu May 19 13:47:11 GMT 2016) -----
----- Attempting Submission 6 (Mon Aug 15 19:28:27 GMT 2016) -----
----- Attempting Submission 7 (Thu Sep 29 12:38:26 GMT 2016) -----Revision maybe requiredProbing Ceres' exosphere and water vapor outgassingEvidence is mounting that Ceres is a geophysically active icy world. The Herschel telescope measured water vapor above two surface regions and first-view images by the Dawn spacecraft suggest active outgassing above bright, intriguing surface features. Dawn will be in orbit probing the interior and surface of Ceres at least until the end of 2015. The high sensitivity and high resolution of COS provide the unique possibility to obtain supporting FUV spectra to constrain Ceres' exosphere and outgassing. We propose 5 consecutive orbits in the COS G130M mode to measure atomic emissions from O, H and possible trace species in the exosphere. During the ~7.5-hour long visit Ceres' active regions will be targeted on the dayside. Observed diurnal variations will be used to independently differentiate between sublimation and liquid reservoir source regions and detected exospheric signals will be related to surface features characterized by Dawn.We use the COS G130M mode centered at 1291 A for the two wavelength ranges of 1134 A to 1274 A (Segment A) and 1291 A 1431 A (Segment B) that include the most important oxygen lines at 1304 and observe over almost one full Ceres rotation period (7.5 hours out of 9.1 hours).
We will locate Ceres with a small offset of ~0.5 arcsec in the lower part of the 2.5 arcsec pinhole in order to be able to simultaneously measure both Ceres and the sky background.Solar System12falsetruefalsefalsefalsefalseSUPPORTEDSOLAR SYSTEMYESThe diameter of Ceres is roughly 0.6 arcsec in the sky near Ceres opposition, so that it falls just in the category of extended sources for COS. The CERES-ACQ target does not have observing window requirements, while the CERES target (for the science exposures) includes "CML OF CERES" requirements.DWARF-PLANETDWARF-PLANET CERESSTD=CERESEARTHSOLAR SYSTEMYESThe diameter of Ceres is roughly 0.6 arcsec in the sky near Ceres opposition, so that it falls just in the category of extended sources for COS. The CERES-ACQ target does not have observing window requirements, while the CERES target (for the science exposures) includes "CML OF CERES" requirements.DWARF-PLANETOFFSET DWARF-PLANET CERESSTD=CERESNOT CML OF CERES-ACQ FROM EARTH BETWEEN 340 20EARTHSOLAR SYSTEMYESThe diameter of Ceres is roughly 0.6 arcsec in the sky near Ceres opposition, so that it falls just in the category of extended sources for COS.DWARF-PLANETOFFSET DWARF-PLANET CERESSTD=CERESEARTHCOS/FUVSpectroscopicNoNoG130M1291Using ephemeris for target 14106-01-CERESephemeris data for target 14106-01-CERES does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 15.207 to 17.213. ephemeris interval: 16.213 to 18.213The scheduling data was generated by CASM 24.2.CASM was run in Phase II mode.- For acquisition, we use only ACQ/IMAGE with Mirror A assuming that the coordinates of Ceres are known with an accuracy smaller than 0.4''. The ETC yields SNR=40 in 0.0234 seconds for the normalized solar spectrum and the exposure time of 5 second should give good margin.
- For the science exposures, the target has an offset of y = -0.5'' to locate Ceres in the lower half of the aperture. This way we can analyze the sky background only in the upper half of the detector. Ceres is located in the lower half, as the upper half might suffer a gain-sag from the previous lifetime
position on the COS detector. The gain-sag might affect the sky background, but the primarily targeted OI lines fall on segment A, which is less strongly
affected.
- We take 2 science exposures per orbit cycling consecutively through the FP-POS positions.144058404900052.5(Tic-Visit
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)true50For the ETC, a SED of Ceres' surface brightness between 1200 and 4200 A was generated with a solar spectrum for average solar wind acitivity from UARS. The spectrum was scaled to Ceres' distance to the sun of ~2.9 AU during the observation and with an interpolated geometric albedo based on the albedo values from Li et al., 2006, Icarus.
The ETC run for extended source yield a SNR of 40 after 1.1 seconds, so we choose 10 seconds for a sufficient margin.
A imaging ETC run (not TA) was also performed: COS.ta.727578ETC buffer time calculations yields times larger than exposure time of ~1200 sec, so buffer time is set to exposure timeETC buffer time calculations yields times larger than exposure time of ~1200 sec, so buffer time is set to exposure timeETC buffer time calculations yields times larger than exposure time of ~1200 sec, so buffer time is set to exposure timeETC buffer time calculations yields times larger than exposure time of ~1200 sec, so buffer time is set to exposure timeUsing ephemeris for target 14106-02-CERES-COPYephemeris data for target 14106-02-CERES-COPY does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 15.207 to 17.244. ephemeris interval: 16.244 to 18.244The scheduling data was generated by CASM 24.2.CASM was run in Phase II mode./private/var/folders/t4/6rz943fx6js3czpmlz79sbrc0000gq/T/OPVisit5898964722099486228.xml- For the science exposures, the target has an offset of y = -1.85'' to locate Ceres just outside the aperture allowing an location error of 0.3". This way we get only the signal from the exosphere without contributions from bright surface reflected light.
- The last science exposure target 20" away from Ceres to get a comparable sky background (minimal exosphere contributions)
- We cycle consecutively through the FP-POS positions, repeating POS=4 in the fifth exposure.(Tic-Visit
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The ETC run for extended source yield a SNR of 40 after 1.1 seconds, so we choose 10 seconds for a sufficient margin.
A imaging ETC run (not TA) was also performed: COS.ta.727578ETC buffer time calculations yields times larger than exposure time of ~1200 sec, so buffer time is set to exposure timeETC buffer time calculations yields times larger than exposure time of ~1200 sec, so buffer time is set to exposure timeETC buffer time calculations yields times larger than exposure time of ~1200 sec, so buffer time is set to exposure timeETC buffer time calculations yields times larger than exposure time of ~1200 sec, so buffer time is set to exposure time