Information concerning the FTP file (mcneilpn.txt).  This data file contains 

all the PN's in Jay's list.  Each record (1 planetary nebulae per database record)is comma-delimited

text so that the entire file can be imported into a database program such as

Microsoft ACCESS or FileMaker Pro.  There is an additional note near the bottom

of this page explaining the field names.  The file has been successfully tested

in MS ACCESS 2000. Please notify me of any 'bugs' that you may come across in 

your application.  Thanks - Doug Snyder ( douglas@blackskies.com)

Planetary Nebulae Observer's Home Page ( http://www.blackskies.com)



THE MOST COMMONLY SOUGHT AFTER PLANETARY NEBULAE

(KNOWN, POSSIBLE, AND MISCLASSIFIED)

By: Jay McNeil



    In my opinion, planetary nebulae compose one of the most intriguing classifications of

objects in the entire sky.  This is primarily due to the fact that so many of these gaseous

stellar ejection's have been misclassified in the past by well-informed professional

astronomers who were very dedicated to the study of such objects.  Recent studies and

observations of the spectra, expansion velocities, and non-visual emissions of planetaries

and their corresponding central stars have shown that many objects previously classified

as planetary nebulae are actually symbiotic and Be stars, reflection nebulae, HII regions,

Wolf-Rayet ejections, and even galaxies.

However, similar studies have also shown a number of misclassified celestial objects

mentioned above to actually be planetary nebulae.  Furthermore, a few objects have been

known to alternate between classifications over a period of time (Ex: Abell 21), and many

amateurs (myself included) know what this can do to a search for valuable information

on such an object.

For this and many other reasons, I have taken the time to compile a variety of information

on a host of known, possible, and misclassified planetary nebulae for use by the typical 

amateur astronomer.  The following list consists of over 450 objects scattered throughout

the sky, and the only true requirement for the list is that each included object must have a 

declination greater than -60 degrees.  This is because of my Houston, Texas residency and 

the fact that I will probably observe Abell 47 with my naked eye before I can afford an 

observing trip below the equator.  Otherwise, the list contains what I call "the most commonly 

sought after planetary nebulae." 

By all means, this does not imply that the list is conclusive of all observable planetaries in the sky.  

On the contrary, every object in the list has at one time or another been questioned by myself or 

others as being possibly observable.  Of course, not all included objects are visually observable 

with present amateur equipment, and a very few will possibly never be visually detected with any

 size telescope.  In my opinion, however, a negative observation of a 17.0 magnitude planetary with 

a surface brightness of 16.5 magnitudes per square arc minute is not an unsuccessful observation, 

as long as I am confident that I have pushed my observing skills, my equipment, and my skies to 

their limits!

    The list is an excellent companion for those who wish to go beyond the typical list of up

to about 100 observable planetaries found in a lot of amateur material.  Furthermore, the

list can present quite a challenge to even the most experienced observer.  Indeed, anyone 

who has observed over 400 of these objects has accomplished a significant feat.  

Every possible cross-reference at my disposal was included in the listing (IRAS and EUVE

designations were usually omitted), and most were spelled out to avoid the confusion of

acronyms and abbreviations.  The few that were not spelled out are explained below.  

The right ascension and declination of each object is included with 2000.0 coordinates.  

   The magnitude of each object, if found, was included.   Even though most of the 

magnitudes listed are photographic (these are most commonly found in professional literature), 

some of them are in fact visual estimates (these are noted by a following "v").  However, do not 

be offended by seemingly high magnitude estimates when observing planetary nebulae.  

When using published magnitudes for observing such extended and diffuse objects as some 

planetaries, it is very easy to overlook many easily observable

objects based upon the predicted visual magnitude limits of your equipment. Furthermore, 

magnitude(visual and/or photographic) is not nearly as important as the surface brightness of a 

non-stellar object when at the telescope. The included list of magnitudes, therefore, is only used 

as a very general reference by myself.  For example, I found the 16.4 magnitude Abell 77 to be a 

fairly easy target for my 16" f/5.1 on a good night less than 90 miles from Houston,Texas.  Of course, 

the proper usage of narrow-band filters with any telescope will greatly increase the number of planetaries

visible under any observable sky conditions.  The sizes included in the list are generally visual sizes, 

however some may actually differ from observable sizes due to a lot of the data being compiled 

from professional literature.  The included classification of each planetary is based upon the planetary 

nebulae classification system set forth by Vorontsov-Vel'yaminov, which is described below.  

Also included in each listing is the constellation in which the object resides and the Uranometria 

2000.0 page # on which the object should be located. 

A few of the objects will have to be hand plotted, and some of these are well worth the effort

 (Ex: Abell 12).  The visual magnitude of the central star of each planetary was included if available. 

 However, there are presently many acceptable ways to measure the brightness of such 

gas-enshrouded stars, and with each different procedure a different magnitude estimate results.  

I would therefore suggest using this list of central star magnitudes as a general reference.

    My reasons for including a number of possible and misclassified planetary nebulae are

based upon the alternating classifications previously mentioned, which correspond to our

technological advances and new theories on the role that planetaries play in stellar evolution, 

and for convenience when cross-referencing.  Furthermore, many of such misclassified 

planetaries have very interesting visual histories (Ex: has anyone seen the "real" IC 2120 lately?). 

Also, a great deal of data was compiled from a number of various resources for this project.  

These resources range from professional journals and databases 

(to which amateurs have limited access) to personal observing notes of my own; 

therefore, some of the included data may not seem to be very relative to what can actually be observed.  

This is exactly why I urge every active observer to find out how many of these objects are observable, 

regardless of telescope size.  After all, the only unsuccessful observation is the observation 

not attempted.  If you feel that you have made a spectacular or otherwise unusual observation 

of any lesser-known planetary nebula or related object, then feel free to contact me.  

I know that a lot of these objects, that were until recently considered out of the amateur's league, 

are actually very acceptable in such an observing program, and this presents quite a challenge to 

any observer like myself.



Jay McNeil

icnebula@primenet.com



Note concerning the number of designations in the comma-delimited file (mcneilpn.txt): 

The number of  'names', or designations in the text data file is limited to SIX.  Some of the

 PN's in Jay's list are assigned up to a dozen different designations.  I have limited it to six

 to allow a uniform assignment of fields in the event that the text data is imported into a database

 (i.e., MS ACCESS).  There are 15 fields in the data file, six of which are for different designations.  

THE FIRST RECORD IN THE DATA FILE CONTAINS THE FIELD NAMES.  The field names are:

Name(1),Name(2),Name(3),Name(4),Name(5),Name(6),RA2000,Dec2000,Mag,Size(arc sec),Class,Con,URA,CenStar,Notes.  

This note has been added by Doug Snyder.(douglas@blackskies.com)

                                                                  

  Notes:  IC = Index Catalogue

             NGC = New General Catalogue

             PK = Perek & Kohoutek Catalogue

             V-V = Vorontsov-Vel'yaminov(1961)

             VV = Vorontsov-Vel'yaminov(1962)

             MINK = Minkowski

             ARO = Algonquin Radio Observatory Catalogue(Higgs)

             ESO = European Southern Observatory(Holmberg, Lauberts, Schuster, West)

             IRAS = Infrared Astronomical Satellite(Joint IRAS Working Group)

             MSCL = misclassified planetary nebula

             aka = "also known as"

             R = radio diameter

             B = Johnson's B filter magnitude(~3800-5500 Angstroms)

             V = visual magnitude

             P = photographic magnitude

             N = near-infrared magnitude(1.25um)

             v = variable magnitude

             

             I = stellar

             II = smooth disc

                    A = brighter towards center

                    B = uniform brightness

                    C = traces of ring structure

             III = irregular disc

                     A = very irregular brightness distribution

                     B = traces of ring structure

             IV = ring structure

             V = irregular form

             VI = anomalous form



THE MOST COMMONLY SOUGHT AFTER PLANETARY NEBULAE

(KNOWN, POSSIBLE, AND MISCLASSIFIED)

DATA COMPILED BY: JAY MCNEIL