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Trying to do it
I have a big list that all of you sent and am trying to work through
it. Please send answers by number so that I can be sure what you are
responding to. Note that I have several different versions of the same
item. Which one should I use? I suspect that some formats are more
universal than others. I am just going through the lists that you all
submitted and asking questions where I do not understand. Some of them are
pretty dumb. There is obviously a convention about quotes. I thought all
numbers had to be single or double quoted?:
1a) DATE-OBS = 2001-03-05t10:06 / Start of exposure
What time do I use here. Local time? If so what do I do when DST comes in.
1b)DATE-OBS = '13/07/97' / Date of observation
1c) DATE-OBS = / UT at which exposure started
1d)DATE-OBS = '2001-03-04T02:08:09' /UT date of exposure start
OK, I seem to have four possibilities from four suggestions. What should I
use. Note that 1b) in single quotes where the previous one was
unquoted. My guess is 1d) But what do I know.
3A) EQUINOX = 1997.6 /
3B)EPOCH = 1997.6 /
Where do I get these? How do I calculate them? Note again, these are
4)EXPOSURE /no format suggested
EXPTIME /asks for both
EXPTIME 15.000 /Exposure time in seconds , no format
Should I put in both. What is the format required.
5) USHUT = '16:34:45.0' /UT of shutter open
How does this differ from DATE-OBS
6) GAIN '7.5' / electrons per ADU
I can't detect any system for when the ' ' or " " are used and when they
7) I now have a formula which give me JD and MJD which I think I
understand. Cary just sent me a C snippet which I could decode.
8) I am not in such good shape for ST, GST, etc.. I seem to need to know
the days since Jan 0.0 2001. This seems to call for some code snippet
where it has been worked out.
9) WCS keywords have been requested. I have no idea how to compute these
10) From the same request:
DATE-OBS = '13/07/97'
HDR_REV = '2001-Mar-05'
What form do we want to use for dates? I am a confirmed "Little Endian" so
I like to write dates as 20010305.234 for 2001-Mar-05. What does fits expect?
I am sure I will have more questions as I actually try to do the
Please be sure to refer to the number in your reply.