Project Mission

(Detailed Explanation)

The NGC/IC Project is an attempt to correctly identify all of the original NGC and IC objects, starting with the original discoverer's notes and working forward in time to encompass the work of contemporary astronomers, both professional and amateur, such that the identity of each of the NGC and IC objects is known with as much certainty as we can reasonably bring to it from the existing historical record.

In so doing, we shall collect images for each object and assemble basic data for the objects -- positions, classifications, photometric parameters (magnitudes, diameters, position angles, colors, etc), and distances -- insofar as the data are accessible.

J.L.E. Dreyer published the New General Catalogue in 1888 as an attempt to collect in one place a complete list of all nebulae and star clusters known at the time. In 1895 and 1908, he published supplements to the NGC which he called the Index Catalogues. Nearly all of the bright, large, nearby non-stellar celestial objects have entries in one of these three catalogues. Thus, the catalogue numbers -- preceded by the catalogue acronyms, NGC and IC -- are still frequently used by astronomers to refer to these objects.

Dreyer collected observations for the objects from whatever sources were available to him. While he did extensive intercomparison of positions from different sources, he was working with lists of data from different observers using telescopes of vastly different apertures (from 2 inches to 72 inches!), working under greatly different conditions. The data are heterogeneous, to say the least. They are also frequently wrong (not through any fault of Dreyer's; he was a careful and excellect transcriber) and just as frequently contradictory. Many NGC/IC numbers have been found to refer to stars, double stars, or multiple stars, and many NGC/IC positions point to blank regions of sky. There are also many cases of two or more NGC/IC numbers clearly refering to the same object.

Attempts have been made to reobserve all the NGC objects, and to remove the errors in the catalogue. The IC objects are generally smaller and fainter, so have generally received less attention, but some work has been done on them, too. Unfortunately, almost all of these previous efforts have depended exclusively on the positions and brief descriptions published in the NGC and ICs themselves.

It has been clear for some time that the original publications, from which Dreyer collected the data, are a rich source of additional information about the objects. Micrometrically measured positions, for example, are frequently given not just as reduced Right Ascensions and Declinations, but as the actual offsets from the reference stars. Identify the reference star, and the observed object is usually obvious. Similarly, many observers made extensive notes about, and even sketches of, stars near the nebulae or clusters. Again, identify the stars, and the object is obvious even if its published position is only approximate.

So, we are making use of that rich 18th and 19th century literature to track down as many of the nebulae and star clusters as we can. In addition, we are visually reobserving as many of the objects as needed to see if we can reproduce the appearance of the nebulae and clusters as recorded by our predecessors. Could they have indeed seen the objects they claimed they could? If so, why are the data not better than they have come down to us today?

The project is approximate 80% done at the moment (summer 1996), and we expect to complete it within the next decade. However, we have imposed no time limits on ourselves, knowing full well that the previous attempts to correct the NGC and ICs have foundered on the shoals of impatience and deadlines.

So, we think that publishing our results electronically as we collect them will get them out to our audience much sooner than waiting until we can publish a complete printed catalogue and atlas. In addition, by presenting interim results, we hope that other curious astronomers and historians will be able to catch the errors that we inevitably make. Thus, the catalogue can only become "cleaner" as time goes on.

Who are we? Our group presently includes professional as well as amateur astronomers. Most of us live and work in North America, but one observer is in Australia. Members were chosen based upon their multitude of talents, skills, and interests which are interacting to handle different aspects of the work. Each of us is following our own inclinations in tracking down the correct data and identity of the objects -- our major goal is to have fun doing this project. It will get done when it gets done. And if others find it of some interest, so much the better.

This Web page is still relatively new, and is currently very incomplete. We are adding data to it as we can, and we invite you to revisit whenever you wish. At the moment, chances are good that your favorite object will have new data the next time you come back to it. If not, let us know, and we'll pop that object to the top of our queue.

Finally, we'd like to invite any interested astronomers to help us along the way. The goal is to have some fun while we're doing all of this. We are also specifically not interested in making any money from this project -- this is a hobby for us, nothing more. Shortly, we will be publishing a page of objects which are "puzzles". It will take a lot of work to track these NGC and IC objects down, and we'll take all the help we can get. So, if you've a mind to, send us your observations, your research, and your thoughts, as we give all contributors full credit for their findings. Who knows....You may just help us solve a 100+ year old puzzle!

Harold G. Corwin, Jr.