Second Meeting of the IACHEC Contamination WG
10th IACHEC Meeting, Fragrant Hill Hotel, Beijing, China
20 April 2015 14:00-16:00
Attendees
- Doug, Eric, Wei, Vadim, Paul, Kallol, Herman
Agenda
- summary by Eric (~ 5 min)
- presentations (~ 60-75 min)
- Kallol: ASTROSAT SXT plans
organization of contamination white paper (~ 45-60 min) - Eric Miller, Contamination WG Summary
Notes
- Kallol described briefly the ASTROSAT LET (?) contam mitigation
- one month before LET door opens
- epoxy of one instrument is big concern, so might wait longer
- Herman provided just the depth of C,O edge, not total tau at the edge
- will give Eric total tau, but it will be modeled, not measured
- Doug
- accelerated accumulation since 2012 can only be explained by a source that is increasing
- uses CALDB values since that's the best compromise between clusters and grating contamination measurements
- first source is going down exponentially to a constant rate, second is going up exponentially
- uses empirical temperature of the OBA (Optical Bench Assembly) which is level at first and then seems to go up exponentially
- Herman wonders why it doesn't go up linearly, since presumably it's being heated because thermal blanket is being destroyed by particulates
- maybe it was flat until heaters were turned off, and it went up and is now approaching a linear dependence
- based on model of OBA temp going up exponentially, source rate goes up 30x in next 5 years
- also volatility is very well constrained, under same temp change assumption, because of spatial dependence on OBF and ACIS-S vs. ACIS-I
- higher volatility than initial stuff that built up
- Herman mentioned Rosetta which tracked contamination
- paper from several years ago, will try to track it down
- used mass spectrometer to measure the atmosphere around the spacecraft en route
- Herman
- early and late contanimant are oxygen-rich, midtimes is oxygen poor
- fluorine has been pretty constant
- Eric
- compare Henke and Verner cross-sections
- white paper
- ran out of time for discussion
- Eric will prepare a skeleton paper, with sections for Suzaku/XIS filled in as example
- Eric and Herman will talk about this at MIT over the summer
- focus on current missions: tracking, monitoring, calibration
Action Items
- A/I 1 DUE: March 30: Eric will ask Astro-H folks about any updates
- A/I 2 DUE: March 30: Eric will ask ASTROSAT folks to join (Kallol Mukerjee)
- A/I 3 DUE: March 30: Eric will update the multi-mission plot with the information he has on ACIS,XIS,MOS and send it to Steve S. for display at EPIC cal meeting
- A/I 4 DUE: April 13: Herman, Steve S., Eric will send Eric tau_c, tau_o for instruments vs. time (XIS,ACIS,MOS) and space (XIS,ACIS)
- A/I 5 DUE: 2015 August 30: Steve S. will look up possible environmental effects to explain MOS1/2 differences
- A/I 6 DUE: 2015 August 30: Steve S. will ask about RGS contamination update, include slide
- A/I 7 DUE: 2015 August 30: Eric: make differential rate plot, showing rate of build-up for Suzaku
- A/I 8 DUE: 2015 August 30: Eric: combine RXJ1856 data and see if H has changed for Suzaku
- A/I 9 DUE: 2015 August 30: Eric & Herman will discuss this at MIT, prepare a skeleton manuscript with example text for Suzaku XIS
- A/I 10 DUE: 2015 August 30: Eric will compare the Henke and Verner cross-sections to see if this makes a difference for CCD instruments
