RE: double checking dates on Disk 18

["Creager, Robert S" <CreagRS@LOUISVILLE.STORTEK.COM>]

Tom,

The latest version of downfits I sent you removes the DATE-OBS keyword since
it was off by one hour from your system time.  Since I didn't know what
CFITSIO was doing, I just removed it...

Cheers,
Rob

> -----Original Message-----
> From: Tom Droege [mailto:tdroege@veriomail.com]
> Sent: Friday, May 25, 2001 8:36 PM
> To: Stupendous Man; tass@listserv.wwa.com
> Subject: Re: double checking dates on Disk 18
> 
> 
> One reason for sending out this data was to that problems 
> like this could 
> be fixed.  This reminds me that there is still another error.
> 
> OK, disk 18a was from a run which started at local date 010412 at 
> 23:22.  This puts it on the 13th universal time (I think).  
> So DATE-OBS 
> looks right as to date.  Note that I compute DATE-OBS.  There 
> is also DATE 
> in the fits header that is computed by Rob.  It differs from 
> my DATE-OBS by 
> one hour.  We are yet to settle who is right.  There is also 
> a UT in the 
> fits header which I compute so (not surprisingly) it agrees 
> with DATE-OBS.
> 
> Rob computes the hiraxxxxxxx.fits label, which I then 
> normally use to write 
> the range of files on the CD faces.
> 
> So to answer your questions:
> 
> The run started at 23:22 local time on April 12, 2001.  Disk 
> 18a was made 
> from the second data disk I took that night so it would have 
> started at 
> about 01:12 on April 13th.
> 
> There is a two day gap before 16b which I have starting on 
> the evening of 
> the 15th with no time in the log.
> 
> I note that I never write enough things in the log.  One 
> thing we should 
> develop is a log sheet with blanks to fill in.  One thing I have been 
> trying to do for these runs is to set the computer clock to a few 
> seconds.  I do this at least every few days over this run.  
> It was seldom 
> out by more than a few seconds.
> 
> I hope that this helps.
> 
> Tom Droege
> 
> 
> At 05:33 PM 5/25/01 -0400, you wrote:
> 
> >   Tom,
> >
> >     I've been examining the Disk 18 data.  I see an inconsistency
> >in the dates.  The FITS header records a UT date and time, for
> >example:
> >
> >        data disk 18a   hira2011752.fits    says
> >                        DATE-OBS= '2001-04-13T06:02:55'
> >
> >     Now, April 13 06:02:55 UT corresponds to Julian Date 
> 2452012.752.
> >I've checked this in two different ways.
> >
> >     But the name of the file, "hira2011752.fits", would indicate
> >that it was taken on Julian Date 2452011.752.  That's one day
> >earlier than the date indicated by the FITS header values.
> >
> >     Perhaps this has been noted already.  But could you please
> >double-check for me the following:
> >
> >        data disk 18a   has data which indicate clouds early and
> >                        mostly clear skies late in the night.
> >                        There is a three-day gap between it and
> >                        data disk 18b.
> >
> >        Could you tell me exactly when you took the data on disk 18a?
> >
> >
> >     If you can say, "the night starting Thursday, April 12,"
> >or "the night starting Friday, April 13", it will help me to
> >make sure that I'm interpreting things properly.  At the moment,
> >I'm using the FITS header values, and ignoring the file name.
> >
> >                                            Michael
> >
> >
> >
> 
>