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
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.