[vsnet-chat 2533] CBA (California) observation times are ~correct

[Lew Cook <lcoo@yahoo.com>]

Several photometrists are finding errors in observation times from a
software bug and corrections are going to be issued by them. 

I use Richard Berry's Photomet v.27 for reductions. I checked it
against the calculated JD in my Excel spreadsheet SunTime.xls (which
calculates JD in addition to heliocentric corrections). The times
reported by Photomet are correct within the clock accuracy of the
computer to the mid point of the exposures. 

I make checks of the clock every couple of hours with NIST, as errors
of several seconds in the computer clock may accumulate throughout
the night. I divide the data up so that the clock error is less than
3 seconds for my reported data. Heliocentric corrections are usually
not made in data reported out to VS-Net, CBA archive or AAVSO.

If anyone wants to use the spreadsheet it is available free from the
descriptive page

http://vsnet.geocities.com/lcoo/SUNTime.htm


=====
Regards, Lew 
http://vsnet.geocities.com/lcoo/
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