Re: file naming

[<jbush@pucp.edu.pe>]

i second the motion

jamie


On Thu, 14 Jun 2001 aah@nofs.navy.mil wrote:

> Tom recently suggested that I take an active part
> in any file naming discussion, since I wrote a TN
> on the process a while back.  That technical note
> was concerning the Mark III data, a much more limited
> project.
>   My feelings towards the Mark IV have already been
> stated:
>   (a) files stored on CDROM should be in an 8x3 format
>       so that they obey the ISO 9660 standard.
>   (b) if you need more characters than that to uniquely
>       identify the data, then you should use a directory
>       structure on the CDROM.
>
> I've never been a great fan of including the 'time' as part
> of a file name; the number of characters necessary to obtain
> a unique name depends on the exposure length.  I have always
> been a great fan of a sequence number, so that automated
> processing tasks can easily access the files.
>   The ways most professional observatories name files
> usually falls into two categories:
>   (1) a filename based on the name of the observed field,
>       such as ngc4449.fit.  This can get long if you
>       start including filters, sequence numbers, on/off sky, etc.
>   (2) a filename based on the UT date plus a sequence
>       number.  Examples are y01d138.005, 990504.101,
>       j1520f233.fit (where the last one is based on the
>       last 4 digits of the Julian Date plus a 3-digit file number).
>
> So if I were to state a preference at this stage, I would
> suggest the following:
>   (1) use a directory structure on the disk, where the
>       upper level directory indicates the site.  How the
>       site is to be named is TBD; perhaps by the system
>       'name' like TOM, MIKE, etc.
>   (2) under the site directory, use a unique filename with
>       a sequential file number.  I would suggest
>          jddddxsss.fit
>          j  -- indicates following digits are Julian Date
>          dddd - last 4 digits Julian date (9999 days is longer than
>                these systems will run)
>          x  -- single character of filter name (bvri)
>          sss - 3 digits sequence number, starting at 000
>            (1000 files should be plenty for a Mark IV)
>
> My personal data is stored in a similar manner, though the
> file names look more like
>     yymmddfx.sss
>      yy - (year - 2000)
>      mm - month
>      dd - day
>      f  - filter name
>      x  - processing step (r=raw, d=darksub f=darksub&flatfield)
>      sss - sequence number
> but I understand that this does not uniquely identify the files
> as 'fits' and some processing programs can't handle it.  I prefer
> my format since I think in yymmdd instead of jdddd.
> Arne
>