Subject: Re: OBJECT names

From: kuin at homer.stx.com (Nicolaas Kuin)
Date: Tue, 5 May 1998 00:45:44 -0400 (EDT)

I believe that creative use of the OBJECT keyword as discussed here
should not have an impact on the OBJECT designation, which should 
follow the IAU designation recommendations.  The advantages of using 
consistent designations are large.  Adding other information in the 
keyword field makes the whole meaning of KEYWORD=VALUE weak and sloppy
and meaningless.

  There is no reason that Keck and Lick could not introduce their own
LICK_OBJ for a string like 
LICK_OBJ = 'NGC 1234, 400 s, blue filter, 1200 line grating'
which then could be put into the header. I would strongly suggest to 
have some software go over this string which would make an intelligent 
guess for other FITS keywords (like OBJECT, FILTER, GRATING, etc.) 
and ask the observer to approve the  insertion into the FITS header 
of the automatically generated FITS keywords. It seems to me that 
software's function is to make life easier in this way. 

  Paul Kuin

Steve Allen <sla at ucolick.borg> wrote 
|In article <199804171526.LAA06339 at fits.cv.nrao.edu>,
|Don Wells  <dwells at NRAO.EDU> wrote:
|>The text should also recommend that data systems which originate
|>OBJECT strings (e.g., telescope/instrument data systems) encourage
|>observers to use strings which conform to the recommendations of the
|>Designations Task Group of IAU Commission 5 (Astronomical Data). The
|>text should cite "IAU Recommendations for Nomenclature"
|><http://cdsweb.u-strasbg.fr/iau-spec.html>.
|
|Our data systems have always provided for the maximum possible FITS
|string length as the value for the object card.  Unfortunately, this
|opens the door for other forms of abuse.
|
|It is extremely commonplace for observers to set the string to something like
|OBJECT  = 'NGC 1234, 400 s, blue filter, 1200 line grating'
|This is done even though there may be other FITS keywords which contain
|the appended values.
|
|Indeed, there's movement to create a next-generation interface for
|Keck and Lick which will actually permit the observer to specify a set
|of keywords whose values are to be appended into the OBJECT string.
|
|Before we actually do this, I'd appreciate external commentary from
|the FITS community on the (lack of) merits of abusing the OBJECT
|keyword in this way.
|--------------------------------------------------------------- 
 Paul Kuin, Raytheon STX Corporation, 4400 Forbes Blvd., 
 Lanham, MD 20706, USA
 (301) 794-5195 <kuin at homer.stx.com>
 ---------------------------------------------------------------

---

From: pence at tetra.gsfc.nasa.gov (William Pence)
Date: Tue, 5 May 1998 13:23:34 -0400

Don Wells wrote on 17 April:

> I recommend that some additional text be appended to the single
> sentence associated with the 'OBJECT Keyword' entry on page 23 in
> Section 5.4.2.2 (Keywords Describing Observations).
> 
> This text should recommend that new software implementations which
> read and write FITS files should support OBJECT strings with lengths
> of at least 26 characters, and preferably 32 (maybe 36?) characters.

Would there be any objections to recommending that software support
strings up to the maximum 68 character length?  Why introduce an
arbitrary shorter limit?  In fact, instead of just adding a
recommendation for only the OBJECT keyword, a more general way to
handle this would be to add a couple sentences to the end of section
5.2.1 (which defines character string keywords) which says something to
the effect:

"The maximum allowed length of a keyword string is 68 characters (with
the opening and closing quote characters in columns 11 and 80,
respectively).  Software which reads or writes any character string
keyword should support strings up to this maximum length."

-Bill Pence

---

From: pence at tetra.gsfc.nasa.gov (William Pence)
Date: Tue, 5 May 1998 18:08:37 -0400

Nicolaas Kuin wrote:

> which then could be put into the header.

I'd agree that it would be better to invent a new keyword to record the
user's observation title, (OBSTITLE?) and reserve OBJECT for its
intended purpose, which is to give the name of the object observed and
nothing more.

-Bill Pence

---

From: arots at xebec.harvard.edu (Arnold Rots)
Date: Mon, 11 May 1998 17:02:04 -0400 (EDT)

I agree that it is absolutely essential that the syntax of OBJECT be
regulated to conform to the Committee 5 guidelines - or at least to
something the name resolvers can be reasonably expected to handle.

For AXAF, we have designated the keyword TITLE to contain the proposal
title, but in principle it could be used for any kind of "junky"
information, like suggested below, at the discretion of the project
that generates the FITS files.

  - Arnold Rots

> intended purpose, which is to give the name of the object observed and

--------------------------------------------------------------------------
Arnold H. Rots                                         AXAF Science Center
Smithsonian Astrophysical Observatory                tel:  +1 617 496 7701
60 Garden Street, MS 81                              fax:  +1 617 495 7356
Cambridge, MA 02138                             arots at head-cfa.harvard.edu
USA                                     http://hea-www.harvard.edu/~arots/
--------------------------------------------------------------------------