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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 
unquoted.

4)EXPOSURE                           /no format suggested
    EXPTIME                                /asks for both
    EXPTIME     15.000             /Exposure time in seconds , no format 
indicated

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 
are not.

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 
values.

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 
implementation.  Sigh!

Please be sure to refer to the number in your reply.

Tom Droege