ISIS calculating JD-MID as 0 ?

[Robin Leadbeater]

There is a report of JD-MID being calculated as 0 (thus failing to upload to the AAVSO database)
https://www.aavso.org/comment/71413#comment-71413
I have not seen this problem myself so I wondered if anyone had seen something similar.

Thanks
Robin

[David Boyd]

Robin,
I have read the fits headers of several hundred spectra in the ARAS database in the course of preparing the Eruptive Stars Newsletters. Until recently these have been prepared almost exclusively by ISIS. Except for a very few spectra in the early days of ISIS these have all had a JD-MID keyword correctly filled. More recently observers have started using BASS and Demetra. Initially neither of these included a JD-MID keyword in the header. Although this is not a BeSS keyword, the authors of both software have indicated they will include JD-MID in their output. Strictly speaking it would be better to calculate JD from DATE-OBS and EXPTIME (or DATE-END), which I assume is what ISIS does, as these are both BeSS keywords.
David

[Robin Leadbeater]

Thanks David,

It is good to know there is no evidence of a bug. According to the change log, JD-MID was added in version v4.4.0 in 2012 so I guess that would tally with what you saw. The submission to the AAVSO database failed as there was a zero value rather than being left blank which would not have been a problem. (AAVSO apparently use the value if it is present or calculate it if it is missing.) It turned out though that the header of the problem spectrum had a number of other zero values including JD-OBS so it looks like there was a specific unidentified one off problem with this reduction in ISIS.

Cheers
Robin