NGC_ORIG/IC_ORIG(M0): Dreyer's Original NGC/IC Catalogs (19930419)
FILES:
ngc_orig.m0 (7823 entries)
ic_orig.m0 (5387 entries)
CONTENTS: Dreyer's Original NGC/IC Catalogs
DATASET: These files come in HyperSky dataset M-7, version 19930419. Availability on HyperSky CD-ROM: Vol. 1 (1993).
DESCRIPTION: These datasets contain HyperSky versions of J.L.E. Dreyer's original New General Catalog (NGC) and its Index Catalog (IC) supplements. The HyperSky files are based on machine-readable source files (made available through Willmann-Bell) which were manually transcribed from the original NGC/IC.
If you use these HyperSky files, you are STRONGLY FORWARNED that errors will exist in them. First, the source files contain only the original NGC/IC catalog data. They do not include any corrections appearing in the original NGC/IC catalog notes, nor other corrections supplied by later observers and catalogs. Second, it is very likely that at least some errors have been introduced during the transcription process. Because of such error sources, the best way to use these files is in combination with other HyperSky datasets based on more recent reliable catalogs. HyperSky dataset M-6 (the HyperSky NGC/IC composite catalog) provides a convenient way to do this, since it collects into one dataset all NGC/IC information currently available in the various major astronomical catalogs used by HyperSky.
When using these files with other datasets such as the NGC/IC composite catalog, it is best to load the these (original NGC/IC) files first, followed by any others. If loaded in this order, field symbols for later catalogs will overlay any original NGC/IC objects they match with the correct colors, leaving unmatched original NGC/IC objects obvious in their typically bright white color. In this way, original NGC/IC objects which are unmatched, and thus are questionable, will stand out.
DATA: The HyperSky composite datafiles contain the following data from the contributing catalogs:
POSITION: Right Ascension and Declination are based on the 1860 NGC/IC catalog values, precessed to equinox 2000.
MAG: Since the few magnitudes mentioned in the original NGC/IC are not in a programmatically decipherable form, no magnitudes appear in the HyperSky MAG column for these files.
TYPE: With a few simple exceptions (mainly star clusters), it was not possible to decode NGC/IC objects types in a systematic way from the object descriptions. This is especially true of galaxies, which were in fact not recognized as such when the original NGC/IC was completed. Consequently, most NGC/IC objects will not have a HyperSky type code.
IDENTIFICATION: The NGC or IC catalog number.
COMMENTS: The following catalog information is presented when available in comments following the object identification line:
* Object Description: This will always be the first object comment line. It will contain Dreyer's original object descriptive, modified only as necessary to fit within simple text characters. Each description will generally consist of a series of comma-separated abbreviations, such as those in the following list:
ab=about; alm=almost; att=attached; b=brighter; bet=between biN=binuclear; bn=brightest on North side; bs=brightest on South side bp=brightest on preceding side; bf=brightest on following side B=bright; c=considerably; chev=chevelure; co=coarse; com=cometic comp=companion; conn=connected; C=compressed; Cl=cluster
d=diameter; def=defined; dif=diffused; diffic=difficult dist=distance,distant; D=double; e=extremely, excessively ee=very extremely; er=easily resolvable; exc=excentric E=extended; f=following(eastward); F=faint; g=gradually gr=group; i=irregular; iF=irregular figure; inv=involved,involving
l=little,long; L=large; m=magnitude,much; M=middle,in the middle n=north; neb=nebula; nebs=nebulous; neby=nebulosity nf=north following; np=north preceding; ns=north-south; nr=near N=nucleus; p=preceding(westward); pf=preceding-following p=pretty(before F,B,L,S); pg=pretty gradually; pm=pretty much
ps=pretty suddenly; plan=planetary nebula; prob=probably; P=poor in stars; r=resolvable; rr=partially resolved R=round; RR=exactly round; Ri=rich in stars; s=south,suddenly sf=south following; sp=south preceding; sc=scattered sev=several; st=stars; stell=stellar; susp=suspected
S=small; S*=small star; trap=trapezium; triN=trinuclear v=very; vv=VERY; var=variable; *=single star *10=10th magnitude star; *7-8=7-8th magnitude star **=double star; ***=triple star; !=remarkable; !=very remarkable !!!=extremely remarkable; st 9...=stars 9th magnitude and fainter st 9...13=stars of magnitude 9 to 13
Dreyer's descriptions include some geometric symbols which are not reproducible in text. Substitutions have been made for these as follows:
PN=planetary nebula (replaces open circle) GC,Gl,Gc=globular cluster (replaces crossed circle)
An "Fi" at the end of a description refers to a "figure" or sketch in the original catalog. Also, in almost all cases, a single asterisk (*) at the end of a description does indicate a star, but instead indicates that further notes exist on the object Dreyer's catalogs. These notes are not included in the HyperSky files.
An excellant commentary on Dreyer's descriptions appears in NGC2000, (available through Sky Publishing Corp) which also provides modern corrected positions for many NGC/IC objects.
* Catalog identifications: Dreyer's NGC entries cross-referenced several still earlier catalogs. These references have been retained on lines following the description. The prefixes used are HyperSky-specific, added for clarification; they do not appear in Dreyer's catalogs:
HGC: number from John Herschel's "General Catalogue of Nebulae", (1864, 5079 objects) which combined observations of both John and his father William Herschel.
JH: John Herschel's own object identification number.
WH: William Herschel's object classification, which placed each object into one of 8 lists, each list representing a particular sub-catagory:
Class I : Bright nebulae
Class II : Faint nebulae
Class III : Very faint nebulae
Class IV : Planetary nebulae
Class V : Very large nebulae
Class VI : Very compressed and rich clusters of stars
Class VII : Compressed clusters of small and large stars
Class VIII : Coarsely scattered clusters of stars
Note that the above cross-references are prefixed separately only in the HyperSky NGC file. In the HyperSky IC file, any such references are merged into the more general observer notes described below.
* Observer notes: A line beginning with "Obs:", contains Dreyer's references to various observers connected with inclusion of the object in the NGC/IC. Many of these notes contain abbreviations. For example, d'A refers to the observer H.L. d'Arrest. No comprehensive explanation of these abbreviations is offered here.