(IAAC) Thoughts on Data Sources (was: Basel 11B etc, etc.)

At 02:30 PM 3/13/98 UT, Sue French wrote:

Hi everyone,

Would you allow me to wax philosophical for a moment?

There has been some discussion about the observation of objects in
"obscure" catalogs and the like of late, and I wanted to pass along a URL
that I thought might be interesting:


This is Brian Skiff's article of a couple years ago, called "M is for
Messier...", and discusses the wide variety of data sources available on
amateur observable DSO's.

In the web version of the article, it seems that the conclusions that Brian
was trying to lead us to were a little washed out, sort of like a dim
galaxy in a light polluted sky. But I think the general point of the
article is that there are certain recognized "default" catalogs that should
be used when an object is represented in them. For example, an NGC galaxy
that is also an Arp Peculiar galaxy should be identified by its NGC number.
Failing that, an Arp Galaxy that is in, e.g., the PGC should use the latter
designator, since the PGC is more recent and a more reliable data source
than the Arp catalog. 

The reason I bring this up is that soon, if not already, the
netastrocatalog, either collectively or by fiat of Lew, will need to figure
out how to handle these objects that are represented only in a few of the
more obscure catalogs. It seems to me that cross referencing within the
astrocatalog can be done by using some rudimentary lookup tables to figure
out what belongs where. If certain principal catalogs were agreed upon, all
objects could be primary keyed to their designations in that catalog, along
with xref keys to their designations in other catalogs. Standard data, such
as position et al, should be gleaned from the primary catalog, as that
catalog should be chosen with the reliability of its data in mind.

With open clusters, the situation is a little difficult. There is no
remotely comprehensive catalog of opens, which incidentally speaks to a
possible amateur contribution to the literature.... In fact, there is no
ready location of even the common open cluster catalogs in electronic
format (I have in mind the Collinder, Dolidze, Tombaugh, etc opens in mind
here). The Lynga Open Cluster Data catalog has a heck of a lot of these
opens in it, but not all of them - there are Dolidze and Tombaugh clusters
that are not found in Lynga, for example, and there may be Collinder, etc,
clusters in the same manner. For the moment, the wide variety of data
sources for open clusters represents a big problem for amateurs in general.
The only thing to do about it is to continue with the accepted practice -
that is, call these things Collinder X or Dolidze Y until something better
comes along.

Incidentally, if anyone has any open cluster catalogs in electronic format
(which are not on the ADS server), I would be very grateful to have a copy.

Now, about the specific question:

>	Here's one I am currently trying to puzzle out.  I've got an article in to 
>S&T on Hercules.  It includes the carbon poor planetary DoDz 1 which in the 
>professional literature is referred to as DDDM-1 or DdDm-1 (all three being 
>abbreviations for Dolidze-Dzimselejsvili).  

Not all the professional literature designates it as such. It is also known
as KO 1 and IRAS 16385+3848, among others, such as ---

>I just got my Megastar 4.0 
>upgrade, and DoDz 1 is no longer plotted as a planetary in Hercules, but 
>instead as an open cluster in Aries.  

This situation in part was what prompted the IAU to lay down some rules
some years ago for the creation of new catalogs of celestial objects. Two
different catalogs, for two different kinds of objects, containing
identical or similar prefixes, designators, and authors, is bound to lead
to confusion.

>The planetary in Hercules now has the 
>label PNG61.9+41.3.  

Though there is a syntax error in this designation (see below), this is its
designation in the now standard Strasbourg-ESO Catalog of Galactic
Planetary Nebula (Acker A., Ochsenbein F., Stenholm B., Tylenda R., Marcout
J., Schohn C., European Southern Observatory -- ISBN 3-923524-41-2 (1992)).
This catalog is available at:


Almost all current work on planetary nebulae now uses this catalog, both in
the professional and amateur communities. As you noted, Megastar now uses
it, as does SkyMap, I believe Guide, and so on. I do not know if atlases
such as Uranometria or Millennium use it or not.

>Perhaps someone decided that the DoDz 1 designation was 
>incorrectly applied to the planetary.  

The decision in general to abandon the DDDM planetaries in favor of
Strasbourg-ESO has to do with the reliability and datedness of the
information in the DDDM, compared to that of the Strasbourg-ESO. If you are
fluent in the Jargon File as I am, you will understand when I say that the
DDDM catalog is considered "crufty".

>After all, most DoDz objects are OCs.  
>But since there is a lot of litterature out there calling this planetary 
>DDDM-1, it seems awkward to change it. Which object should really bear this 

The open cluster should retain the discoverer's designation, because (I
presume) there is no better designation for it to have. There *is* a better
designation for the planetary DDDM 1 to have.

>Are they both going to share the same designation?  

That would lead to confusion, as you have shown!

My opinion about planetary nebulae, which I plagiarize directly from Brian
Skiff, is that they should be designated by their Strasbourg-ESO
designators followed by the designation of its original discoverer. That is
to say, your example of DDDM 1 should be designated as:

PN G61.9+41.3 = DDDM 1

Note that there should be a space between the PN and the G, but no space
between the G and the designator. Megastar does this incorrectly, as does
most everyone and everything I have seen outside of the professional

Similarly, your recently posted observation of Jonckheere 900 should be
listed (under the new scheme) as:

PN G194.2+02.5 = Jonckheere 900

Incidentally, your referring to it as Jonkherre 900 (PK 194+2.1) is not
only using two outdated and questionable catalogs for it, but it is also
syntactically incorrect! The older PK designations do not use a period
between 2 and 1 as in the designation given; a space is used instead. The
period is a "MOL-ism", as Brian calls it; that is, an incorrect usage
inspired by the incorrect usage in the old "Master List of Nonstellar
Optical Astronomical Objects" - very old, incidentally, and entirely
superseded; the MOL should not be used any longer even by us amateurs.

If I were you, I would change your galleys to refer to the planetary as PN
G61.9+41.3 = DDDM 1; not only will you set a good precedent among the
amateur community (and as a leader in that community, I assume you seek to
do so), but your professional readers will know what you are talking about
and respect the fact you are using reliable, up to date information. Also,
amateurs armed with SkyMap or Megastar will know what to look for in those
programs, rather than searching for DDDM 1 and finding an o/c in some other
constellation. Finally, amateurs without these resources will benefit
greatly by the improved position listed in Strasbourg-ESO, versus the
position in the 1966 catalog of Dolidze et al. That's just my *opinion*,
though, and it is your article, so do what you wish.

As far as the netastrocatalog is concerned, it seems to me that some rules
for designating objects should be laid down before I begin to submit a
couple old observations of Lynds nebulae and obscure planetaries done with
the 31" at Warren Rupp Observatory. A "meta-code" example of these rules
might be as follows:

If the object is in the Messier catalog, it is designated as such, jump to
a routine to find xrefs into the other recognized catalogs.

If it is in the NGC, designate as such, xref.

If it is in the IC, designate as such, xref.

If an open not in the M, NGC, IC, use observer's catalog of choice; check
whether it is in Lynga catalog and xref accordingly.

If a planetary not in M, NGC, IC, use Strasbourg-ESO as designator and xref.

If it is a planetary in M, NGC, IC, check Strasbourg-ESO for xref'ing.

If a galaxy not in M, NGC, IC, use UGC, PGC, RC3 (in that order of
preference?), xref.

Other appropriate code.

All this could be coded pretty easily (even by an unskilled programmer like
myself) since all of the catalogs other than M and NGC-IC have cross
referencing tables already set up. Since they are all available from ADS,
making lookup tables based on these xref tables should be pretty simple.
Scripting this before the IAAC gets really active (some other mailing lists
I am on generate > 100 messages a day) would probably save the
current/future listowner and hostmaster a lot of time.

Thoughts, anyone? I'm just speaking off the top of my head for the most
part here, but what do you all think? Sue, I am especially interested to
hear what you think of the current state of PNe designations.

Jeff Medkeff          | Acting Assistant Coordinator
Rockland Observatory  | Association of Lunar and Planetary
Sierra Vista, Arizona | Observers, Solar Section

On the web at http://shutter.vet.ohio-state.edu/