COS SMOV Morning Update
29 June 2009
Agenda
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FUV HV Turn-on Visit 13 (of 13)
FUV Functional Test
FUV Darks Visits 4-11 (of 11)
Upcoming COS SMOV Timeline
COS FUV HV Turn-on:
Visit 13 (of 13) - normal HVLOW to HVNOM ramp
• On Fri 26 June:
– HV successfully taken in normal ramp from HVLOW (-4069 v) to nominal
HVNOM level (A/B HVNOM command levels = 178/175)
– Data collected after reaching HVNOM
• Background rates consistent with previous visits
• Summary: all normal and similar to previous data;
– FUV detector is ready for routine operation in SMOV
COS FUV Functional Test
• Program 11483: executed on Sat 27 June (UT):
– One lamp 1 D2 test exposure;
• verified SEGMENT=A only operation
• Nominal countrates
– Three PtNe lamp 1 exposures
• 1 exposure with each FUV grating
• Nominal countrates
– Three PtNe lamp 2 exposures
• 1 exposure with each FUV grating
• Count rates approximately 50% of lamp 1 values – nominal
– One PtNe lamp 1 exposure to initially evaluate OSM1 drift
• 3600 sec G160M 1600; 30-sec flashes every 240 sec (15 flashes)
• Nominal countrates
• Approximately 5 pixel drift over one hour
– Consistent with larger drift cases seen in ground testing
– Drift magnitude and characteristics correctable with pipeline algorithms
– Spectrum locations being analyzed for SMS 187 TA parameter uplink
• Summary: all normal and similar to previous data;
– FUV detector, gratings, and lamps ready for routine operation in SMOV
COS FUV Functional Test:
Preliminary OSM1 Drift Analysis – G160M
• One PtNe lamp 1 exposure to initially evaluate OSM1 drift
• 3600 sec G160M 1600; 30-sec flashes every 240 sec (15 flashes)
• Approximately 5 pixel drift over one hour
– Quicklook segment B drift curve shown below; segment A similar
• More detailed tracking exposures later in SMOV after optical alignment
COS FUV Darks: Initial 8 visits
• Program 11482: 11 visits planned in SMOV
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5 completed on Sat (visits 4-8); 3 completed on Sun (visits 9-11)
Varying approaches to SAA
All data obtained with pressure gauge OFF
Lower dark than with with gauge on
Some visits end at SAA; others have small impact-parameter
Pressure gauge off decreases counts by 33% (A) , 42% (B)
• 14/11 csp (1.62/1.44 ps/cm^2 for A/B, respectively
• Higher gain “bump” in dark PH is gone (as expected from TV experience)
– Most counts have low gain; easily discriminated in processing
• Summary: all nominal so far
COS FUV Darks: Orbit Tracks
COS FUV Darks: Pulse Height Distribution; Count Rate
COS FUV Darks: Cumulative Counts
• Segment B mid-line enhanced spots all very low gain; easily removed
Upcoming COS SMOV Timeline
• Day 180: Mon 29 June
– 11482: 2 visits of 11 (COS24) FUV darks
• 1148202 180:20:00:00 - 180:21:01:42
• 1148203 180:21:04:00 - 180:22:28:56
• Day 181: Tues 30 June
– 11482: last 1 visit of 11 (COS24) FUV darks
• 1148201 181:09:19:00 - 181:10:20:42