COS SMOV Morning Update
8 June 2009
Agenda
• COS FUV HV Turn-on Visits 3 and 4 (of 13)
– Ramp-up status
– Initial dark and PtNe wavecal lamp exposures
• COS NUV Functional Test (COS07) TAGFLASH analysis
• Upcoming COS SMOV Timeline
.
COS FUV HV Turn-on:
Visit 3 and 4 (of 13) HVLOW to first ramp level
• On Sat 6 June:
– HV successfully taken from HVLOW (-4069 v) to first specified ramp-up
level (-4916/-4869 v for segment A and B respectively)
– HV currents are normal on both segments
– QE grid and rear field talk backs are nominal
– HV current histograms dumped immediately after the HV ramp (visit 3) and
just before the drop back to HVLOW (visit 4) were normal.
• Neither show any indication of transient activity
• Recommended ops request to clear event flag 3, continue with
next step in FUV HV turn-on procedure (on Mon afternoon)
• Visit 3 dark exposure
– Nominal: dark files look normal, showing a uniform distribution of counts
(aside from the normal warm strip at the bottom of the B segment).
– Background rates are elevated relative to ground testing, not unexpected.
– At this voltage dark ~19 and 29 cps per A and B segment (~2.23 and 3.40
ct/s/cm2 )
• Roughly twice ground values; may increase with increasing voltage
– Pressure gauge is still ON; dark rate should decrease when turned off
COS FUV HV Turn-on:
Visit 3 and 4 (of 13) HVLOW to first ramp level
• Visit 3 PtNe wavecal lamp exposure: G160M
– Nominal: lamp functioned; nice spectrum on both segments; tight line
spots
– Gravity-release (GR), the 1-g to 0-g image shift, agrees well with Ball
(Delker) prediction of -8 pixels in USER Y(cross-dispersion).
– Pulse heights:
• At this voltage the photon pulse height distribution is peaking around bin
6 or 7 for both segments which is below our normal gain, as expected for
the lowered voltage, and will increase as we raise the voltage.
• NOTE: PHDs from both segments are nominally narrow ; we are losing
very few (if any) counts below our charge thresholds
– Plot of spectrum on next slide
COS FUV HV Turn-on:
Visit 3 G160M PtNe Wavecal Lamp Exposure
•
From pipeline _x1d file: upper figure: full spectrum ; Lower figure: 10 Angstrom extract
–
Lower fig: vertical lines on top scale indicate catalog line wavelengths and relative intensities
– Note: only a very small GR shift with respect to TV06 (calcos) wavelength scale
NUV Functional Test Analysis: OSM2 drift and
TAGLFASH
•
•
.
No significant OSM2 drift in one 3600 sec exposure; maximum amplitude
0.4 pixel on order of cross-correlation uncertainty
No measurable scattered light from WCA flashes in PSA extraction area
NUV Image Locations and TA Sub-arrays
•
Current NUV WCA
MIRRORA and
MIRRORB image
locations near TVAC 06
locations.
•
IMCAL TA Boxes (subarrays) in good initial
location.
•
ACQ/IMAGE TA
Boxes OK, but could be
moved in +X (detector)
for optimal coverage.
11467 backgrounds
possible slide – in development
• Background sample from 3600 sec TAGFLASH exposure
– 30-sec duration internal PtNe lamp flashes every 240 sec
– sample signal from PSA extraction boxes in 100 sec bins; look for differences
contamination from WCA during flashes
– Calcuate equivalent dark from entire detector
– Track of spacecraft during exposure
• With MAMA at 22-23C we get ~65 CPS background – still
much better than predicted.
.
Upcoming COS SMOV Timeline
• Day 159: Mon 08 June
– 11356 visit 5 of 13 (COS23) FUV HV Turn-on
• ramp from HVLOW to second specified ramp value(seg A/B: -5010/4963v), dump DCE, wave , dark exp
• OPS request required: clear NSSC-1 COS event flag 3 set in 1135604
• 1135605 159:17:32:15 - 159:18:07:43
• No event flag set; leave SI at HV level for 4 hours; then execute 1135606
– Contingency OPS request in place to place FUV in INHIBIT if anomaly
• science data
– 11356 visit 6 of 13 (COS23) FUV HV Turn-on
• After 4-hour wait at first specified ramp value, dump DCE RAM, return
to HVLOW
• sets event flag 3
• 1135606 159:23:23:01 - 159:23:24:37
• OPS request required: clear NSSC-1 COS event flag 3 prior to visit 7
– 11466: 2 visits of 11 (COS05) NUV darks
• 1146608 159:06:58:00 - 159:07:59:34
• 1146609 159:20:19:00 - 159:21:20:34
Upcoming COS SMOV Timeline
• Day 160: Tues 09 June
– 11466: 2 visits of 11 (COS05) NUV darks
• 1146611 160:07:27:34 - 160:08:29:08
• 1146610 160:20:16:00 - 160:21:17:34
Upcoming COS SMOV Timeline
• Day 161: Wed 08 June
– 11356 visit 7 of 13 (COS23) FUV HV Turn-on
• ramp from HVLOW to third specified ramp value, dump DCE, wave ,
dark exp
• OPS request required: clear NSSC-1 COS event flag 3 set in 1135606
• 1135607 161:19:24:25 - 161:20:01:53
• No event flag set; leave SI at HV level for 4 hours; then execute 1135608
– Contingency OPS request in place to place FUV in INHIBIT if anomaly
• science data
– 11356 visit 8 of 13 (COS23) FUV HV Turn-on
• After 4-hour wait at first specified ramp value, dump DCE RAM, return
to HVLOW
• sets event flag 3
• 1135608 161:23:39:25 - 161:23:41:01
• OPS request required: clear NSSC-1 COS event flag 3 prior to visit 9