Historically-aware NGC/IC Positions and Notes

Here are current versions of my NGC/IC position and notes files. I have finished my main sweep through the catalogues, checking identifications and finding accurate positions from modern sources. Most recently, I have added Gaia DR2 positions for nearly 12,000 of the included objects in these files. As always, I update these files at irregular intervals. Check back occasionally for updates. Latest updates:

What's new.

The addition of the Gaia positions is essentially complete, so I am now turning to other data: detailed types, diameters, magnitudes and colors, radial velocities, and other relevant data. This has led to my work on bringing the data for the RC3 galaxies up to date; see the RC3 directory for the latest on that. I've prepared a new version of RC3 with accurate positions for all the included galaxies, and other revised data.

I will of course be on the lookout for bugs still lurking in the files. One of interest that lately came to light is that IC 809 is identical to IC 3672. This suggests that we need to compare IC1 to IC2 to search for additional identities.

I am also adding accurate positions from PanSTARRS (and other reliable sources) as I continue to work on the data. (I have done the first 900 NGC objects, and a few dozen random IC objects as well.) The PanSTARRS positions, at their observation epochs, are nearly as accurate as those from Gaia DR2, though the stars do lack proper motions in the first PanSTARRS release. While this is now a background task, it has still resulted in many more-accurate positions for the NGC and IC objects.

Some of this introduction from a few months ago is still relevant, so here it is.

Here are some still-relevant notes from previous releases, updated as needed:

What's here:

If you want the main portion of all this -- including my extensive comments about nearby objects, original positions, cross-identifications, some magnitudes and diameters, and so forth -- just download the *.all and *intro.html files. You'll also want at least one set of the mean position files, too, probably the J2000.0 set (ic2000.pos, ngc2000.pos, and notngc2000.pos), though the B1950.0 set may still be of some historical interest for comparing with the mid-twentieth century catalogues I started working with in the early 1960s. See the NGC/IC positions introductory file for more information.

As I mentioned above, if you need positions and identifications for just the NGC and IC objects themselves, you may download ngconly.dat and iconly.dat, both in this directory.

If you are as interested in the history of the discovery of these objects as I am, or if you are curious why I chose the object I did to carry the NGC or IC number, then you will want to consult the Notes files: Notes on the NGC objects and Notes on the IC objects.

The current file layout still carries a hint of historical baggage. I started the project over three decades ago on computers with small and slow RAM and hard drives, so working with short files and 80-character lines was not just more efficient, it was even necessary. I also worked in the equinox B1950.0 as that was the reference equinox for virtually all of my sources. In March of 2014, I finally switched to J2000.0, and now work in that equinox with all 7840 NGC objects in a single file, and all 5386 IC objects in another. The 80-character line limit has been broken, too, at least in the position files. Aside from that, the format remains the same as it has been for the past third of a century.

All the files are 7-bit ASCII, by the way, with UNIX line-endings. I work now on a Macintosh running OS X, version 10.11.6, "El Capitan". This gives me access to almost all of my long-time UNIX tools as well as the GCC Fortran compiler (I'm currently using version 6.1.0) for building the tools and programs I use to manipulate the data.

Creative Commons License
NGC/IC Positions and Notes by Harold G. Corwin, Jr. is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.

This means that you are welcomed to use the Positions and Notes in any way you like (and you may correct any mistakes!), but please do acknowledge their origin. And if you find mistakes, please do let me know so that I can fix them, too.

Data and Images

Scattered throughout the J2000.0 base files and the notes files are data (primarily types, magnitudes, and diameters) and cross-identifications for the NGC/IC objects. The most recent data addition (aside from the Gaia DR2 positions) has been for the clusters and nebulae in the two Magellanic Clouds. Unlike the data given in the various catalogues I've authored and co-authored over the years, these data are neither complete nor homogeneous. I shall get to this eventually.

In the meantime, if you need data beyond identifications and accurate positions for the NGC and IC objects, you will want to consult

Note that a few of Wolfgang's identifications are different from mine. Compare the positions for an object to be sure that it really is the same one in each list. If they are different, please read my notes for my interpretation of the problem.

Finally, I am pleased to call your attention to Courtney Seligman's Celestial Atlas pages featuring images and notes for many celestial objects, including NGC and IC objects. In particular, many of the images -- some processed by Courtney himself -- are not only beautifully spectacular, but demonstrate the essential characteristics of the objects very well. Courtney is also tracing the history of every object; this is a welcomed and independent check on the work that those of us involved in the NGC and ICs have done over the past decades.

Latest update, this file: 9 June 2020.