...
- 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 me 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
- uses empirical temperature of the OBA (Optical Bench Assembly) which is level at first and then seems to go up exponentially
- 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
...