[Crater-team] Proper Processing of CRaTER Data (1-second shift?)

[Mark D Looper]

Hello—

                Hrm – I have never done any analyses that require lining up the HK or lro_spice files with one-second accuracy; I just need to know altitude and attitude, which change little in 1 second, as opposed to Jody’s mapping work that needs a precise ground track, say.  However, with regard to the PRI and SEC files, I list the number of PRI events per second of day based on the timestamps in the L2_PRI files and compare that with the number of good events at each second in the L1_SEC files based on those timestamps.  For the vast majority of the 86400 seconds each day, these two counts agree; a couple of times a day they differ by one, except on days when the calibration pulser is active, when there are usually a couple of hundred that disagree.  (I’d have to go back and look at the bigger SEP events, if you have days about which you’re particularly concerned).  These are just for the set of all valid events, as counted by the instrument and with the count reconstructed by me from the PHA events; I also strip counts per second for individual detectors and for coincidence rates, if you want me to go back and compare those with the sensor-reported rates.  Can’t help with HK or lro_spice, though, I’m afraid.

Thanks—
--Mark

p.s. Is the telecon on today?  Do we default to “yes” or “no” if no announcement is sent out?

Mark D. Looper
Space Sciences Department
The Aerospace Corporation
M/S M2-260
P.O. Box 92957
Los Angeles, CA 90009-2957
Mobile: 310-529-3406
Voicemail: 310-336-6302
Publications: https://www.loopers.org/curvitae.html

From: Crater-team <crater-team-bounces at lists.sr.unh.edu> on behalf of Anthony Case <tonycase at cfa.harvard.edu>
Date: Wednesday, June 24, 2020 at 4:44 AM
To: "crater-team at lists.sr.unh.edu" <crater-team at lists.sr.unh.edu>
Subject: [Crater-team] Proper Processing of CRaTER Data (1-second shift?)

Hi all,

I'm hoping somebody can remind me of the proper time-synching of PRI, SEC, HK, and lro_spice files.

As I recall, the primary science packets are tagged with the time of the second in which they are *sent*, meaning that the data were actually recorded during the prior second.  So to properly compare with secondary science to get the configuration of the instrument, you need to compare the primary science data from second "n" to the secondary science from second "n-1".

Is this time shift accounted for in the L2 files? Or do I need to do that myself?

Does the same shift need to happen with the lro_spice files and housekeeping files?

Tony



---------------------------------------------------------------------

Anthony Case

Astrophysicist

High Energy Astrophysics Division (HEAD/SSXG)

Center for Astrophysics | Harvard & Smithsonian

Cell: (617) 304 0768

60 Garden Street | MS 58 | Cambridge, MA 02138
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