- Q.: How do I read that 19-digit REFCODE of yours?
NED reference codes are 19-character strings of the form:
Unused characters are padded with dots ".".
The fields within the string are as follows:
|YYYY||The four digits of the year
|PUBLN||The journal code, left-justified
within the five-digit field|
| ||The codes for those journals regularly entered into NED
|A&A..||Astronomy and Astrophysics|
|A&AS.||Astronomy and Astrophysics Supplement Series|
|ApJS.||Astrophysical Journal Supplement Series|
|ARep.||Astronomy Reports (formerly Soviet Astronomy)|
|AstL.||Astronomy Letters (formerly Soviet Astronomy Letters)
|MNRAS||Monthly Notices of the Royal Astronomical Society
|PASP.||Publications of the Astronomical Society of the
|PASJ.||Publications of the Astronomical Society of Japan
|VVVV||Volume number of the journal,
right-justified within the four-digit field|
|M||Tie-breaker code. Where ambiguity is
possible (e.g. between the main journal section, |
| ||and the "letters" section of a journal), the following
characters or digits in this field break the ambiguity:|
|L||Letters sections in various journals
|p||Pink pages in MNRAS (changed to "L" in 1993)
|1, 2, ..., 9,||Issue numbers 1 through 0, then "a"
through "o", within the same volume of a journal|
| 0, a, b, c,||(e.g. Sky and Telescope, Physics
| ..., o|
|A, B, ...||Issue designations used by the publisher
within the same volume, where each issue starts with page one|
| OR |
|Two or more articles appearing on the same page
within a single issue of a journal
|(e.g. Nature, IAU Circulars) are lettered successively
beginning with A - Z|
|PPPP||Starting page number of the article,
|A||First letter of the first author's last
name, or a ":" when no authors are specified for a reference|
More information on reference codes is available in a
paper by members of the NED and SIMBAD groups.
- Q.: What do the notations like "NED01", "ID",
and "NOTES02" mean?
- A.: These are suffixes which we add to a root name to
distinguish physically separate objects which do not
otherwise carry separate names. For example, UGC 01562
is a double galaxy, but has only one entry in UGC. In
order to include both galaxies in NED with unique names,
we add the notation "NED01" and "NED02" to "UGC 01562".
Similarly, we add "NOTES01" to UGC 01562 to refer to a
galaxy included only in the UGC Notes for UGC 01562.
We typically use the "ID" suffix to indicate that a
non-optical source (e.g. an infrared source) has been
associated with an otherwise unnamed physical object,
usually a galaxy. An example is "IRAS 00182+1130".
This has been identified as a galaxy, but not given
a separate name. The "ID" notation makes it clear that
the object has been reclassified from its original type.
Other suffixes that we use include "COM" for a nearby companion,
not necessarily physically connected to the main object (e.g. "3C 227 COM01"),
"ABS" for an absorption line system seen along the line of sight
to a background object (e.g. "[HB89] 1727+502 ABS01"), and "ARC" for
gravitationally-lensed arcs usually found in rich clusters
(e.g. "ABELL 0164 ARC01").
- Q.: I would like to add a table to my paper with a
list of background galaxies and their coordinates. What nomenclature
should I use?
The IAU recommendations for nomenclature
are presented at the CDS site
How to refer to a source or designate a new one.
Here is a summary.
There are three basic categories of names presently in use.
- acronym + coordinate-based names
- acronym + sequential number
- special format
The "acronym" should be one which makes sense for your program so that
future researchers can easily recognize the origin. For example, the
acronym could be the
last-name initials of the first few authors, or an imaginative scheme
to indicate how or why the objects were discovered.
You should be sure to clearly define the acronym in your paper.
You may also register the acronym with the IAU at the CDS site
Proposal for Registering a New Acronym.
Coordinate-based names may be based on B1950 or J2000 coordinates.
If the latter, a "J" must precede the name. For example, a galaxy
with J2000 (or ICRS) coordinates of 12h 34m
56.7s, +76d 54m 32s
would be given a name like "GALCAT J123456.7+765432".
Note that coordinate-based names without a leading "B" or "J" are
ALWAYS interpreted as B1950, NOT J2000.
Whatever name you choose for your objects, it is vital that you
include coordinates for the objects to insure that other observers can
locate them on the sky. Positional uncertainties are helpful, too.
- Q.: Some object names have the form "xxx T1-001",
but I don't see any T1 in the paper. Where does the "T1" come from?
There are instances where NED has to create a
name for an object, but two or more tables in
a reference re-use the sequential numbers. Thus,
there is ambiguity between similarly named objects
in different tables from the same paper. To provide
uniqueness, NED sometimes adds a "T1-", or "A1-"
before the number to indicate "Table 1" or "Appendix 1".
This is not done for every paper, but if there is a need
to differentiate between redundant names, this technique
is sometimes used.
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