...
| Wiki Markup |
|---|
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).* <span style="color: #cc3333"><strong><em>(See Dave S reply#2, below.)</em></strong></span> |
-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.
Dave S reply #2 Good point Anders -- I hadn't thought about the >1/2 orbit that the ROI is out of sight. Well then... if you don't have the accumulated out-of-lock time, then either you toss the few events that don't have GPS lock when the ROI first returned to view (presuming that it was a short outage and that the GPS comes back soon) ; or you do the Vela-check that the times are okay.
Of course, this is getting more complicated, because Joe User didn't think that he needed to keep track of where he was in the orbit when he was validating his times. So now the time sequence I mentioned about has to be plotted versus theta (photon angle from the LAT z-axis) or something like that.
I've always said that we'd like to have the accumulated time. You & yours have said a different times that it's do-able, or too much of a pain. So I think I've always said that if we can have it, great, and if we can't, then Joe User will have to figure something else out.
I (or rather, we the Pulsar group) was asked to formulate a clear request to the ST keepers, so that Davi d Band could then refuse or implement. So... I'm not quite sure how to proceed.