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Scientific paper
Jul 2008
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2008hst..prop11893w&link_type=abstract
HST Proposal ID #11893. Cycle 17
Other
Scientific paper
This proposal contains the steps for turning on and ramping up the COS FUV high voltage in a conservative manner after a HV anomalous shutdown. It is loosely modeled on COS proposal 11356, SMOV4 FUV Detector Initial Turn-on. It is divided into two distinct parts with the first consisting of a slow ramp-up with diagnostics and darks, followed by a ramp-down, HV off, and setting Flag 3. Time is allotted for UC Berkeley, COS Instrument Scientist, and engineering to examine data dumps, science exposures, and housekeeping telemetry. If all is well, the go-ahead will be given to clear Flag 3 and proceed with the second HV ramp-up. The second part consists of a normal ramp-up with diagnostics and darks, followed by a ramp-down, HV off, and setting Flag 3. Again, UC Berkeley, COS Instrument Scientist, and engineering will examine data dumps, science exposures, and housekeeping telemetry. If all is well, this time the go-ahead will be given to clear Flag 3 and precede with normal FUV science programs. Prior to the beginning of Visit 1, Flag 3 must be cleared by the ground via real-time commanding. This can be done as soon as the anomalous HV shutdown is understood and the go-ahead is given to proceed with the recovery. An outline of the visits and activities of each is presented below: 1} Uninhibit the DCE. This visit uninhibits the DCE {sets dce_FUVInhibitMode = FALSE and does some other CS cleanup}, takes diagnostic data {DCE RAM dump}, and transitions the FUV detector from Boot to Operate. {Boot will be the state of the detector after being Inhibited.} Special commanding is used to uninhibit the DCE and to dump the DCE RAM. Regular recon commanding is used for the Boot to Operate transition. 2} FUV HV turn-on and ramp to HVLOW. Special commanding will be used to execute the FUV Operate to HVLow reconfiguration. Diagnostics are taken {DCE RAM dumps} after each transition. 3} Dark exposure. A 1-hour dark exposure is taken followed by diagnostics {DCE RAM dump}. 4} Ramp FUV HV from HVLOW to HVNOM. Ramp the HV to its nominal value for each segment {178,175} during a 1000.0 second DARK exposure. Diagnostics are taken {DCE RAM dumps} after. 5} Dark exposure. A 2nd 1-hour dark exposure is taken followed by diagnostics {DCE RAM dump}. 6} Ramp the HV down and turn it off. Set Flag 3. UC Berkeley, COS Instrument Scientist, and engineering will examine data dumps, science exposures, and housekeeping telemetry. If all is well, this time the go-ahead will be given to proceed with the 2nd part that starts with Visit 11. It is requested that diagnostic and science data be fast-tracked to the Science Team. 11} Diagnostics are taken {DCE RAM dumps}. Flag 3 must be cleared by the ground via real-time commanding before the start of Visit 12. 12} FUV HV turn-on and ramp to HVLOW. Diagnostics are taken {DCE RAM dumps}. 13} Dark exposure. A 1-hour dark exposure is taken followed by diagnostics {DCE RAM dump}. 14} Ramp FUV HV from HVLOW to HVNOM. Ramp the HV to its nominal value for each segment {178,175} during a 1000.0 second DARK exposure. Diagnostics are taken {DCE RAM dumps} after. 15} Dark exposure. A 2nd 1-hour dark exposure is taken followed by diagnostics {DCE RAM dump}. 16} Ramp the HV down and turn it off. Set Flag 3. UC Berkeley, COS Instrument Scientist, and engineering will examine data dumps, science exposures, and housekeeping telemetry. If all is well, this time the go-ahead will be given to clear Flag 3 and proceed with normal FUV science. It is requested that diagnostic and science data be fast-tracked to the Science Team. No FUV activities be scheduled within 48 hours after the completion of Visit 16 to allow for data analysis.;
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