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Is the all sky raw gamma rate about 20 Hz? So 10 Hz after "transient" or "source" cuts? Dominated by the Milky Way diffuse? The whole sky is 40 k square degrees. Milky Way maybe 5k square degrees?
So a W.A.G. for the gamma rate in the ROI is 10Hz*30/5k = 0.06 Hz, that is, 3 or 4 photons per minute. For the larger ROI's needed for gtlike, the rate is higher.
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So now the analyst checks the time sequence of events without GPS lock in his data sample. He finds sequences of a few events here and there, and either says "times are probably fine for my slow, faint pulsar, I'll keep all the data" or he says "I'm a paranoid perfectionist working on a high precision analysis, I'll throw them away" and either way it doesn't amount to much. *\[anders\] I suppose I'm paranoid here, but if we have been out of lock for some time and the photons you see are on the tail of that then the only thing you can say is that we have only been out of lock for N minutes (which would be the last time we pointed in that direction, assuming the photons from the previous pass were locked). If that is good enough (and I should be able to answer my own question with all the information available, but I'm lazy) then there is no problem. Of course, having the accumulated out-of-lock time makes all this much simpler (with the only exception being if we start a run with no lock).* |
-OR- the analyst find a sequence of hundreds of photons without GPS time lock, and he starts to calculate maximum drift. Or he checks the Vela peak position using Marianne's IRFmon tools. Or he just throws them away.
Anything wrong with my reasoning? David.
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