http://www.iau.org Commission B2 Working Group on Designations

Helpful Hints:
Description of the Formats

This document details the symbols used in formatting the sequence of astronomical designations, and provide examples of use (and misuse).

Contents:


1  Inventory of the formats

i
Symbols Meaning
- dash or hyphen
+ sign (+ or -)
+BB.b Degrees of galactic latitude (as many decimals as lowercase b 's)
+DDd Degrees of declination (as many decimals as lowercase d 's)
AA Uppercase-only text (as many letters as A 's)
aa alphabetic text (as many letters as a 's)
CCC Constellation 3-letter abbreviation (Official list)
B Introduces the coordinates based on B1950 Equinox
D Tens of degrees of declination
DD May be degrees of declination (in principle preceded by a sign), or Day-in-month numeral
DD.dd Day-in-month and fractions of day (as many decimals as lowercase d 's)
DDD.d Right ascension expressed in decimal degrees (as many decimals as lowercase d 's)
FF Field number (as many digits as F 's)
G introduces the Galactic coordinates (optional)
HH.hh Hours of right ascension (as many decimals as lowercase h 's)
J Introduces the coordinates based on J2000 Equinox (and ICRS)
LLL.l Degrees of galactic longitude (as many decimals as lowercase l 's)
M May be units of minute (range 0 to 9) if followed by SS , m or a decimal point; represents tens of minutes (range 0 to 5) otherwise
MM May be minutes (of hour or degree), or month numeral
MMm Minutes of right ascension or declination, (as many decimals as lowercase m 's)
NNN Ordinal number (as many digits as N 's)
NN.N Ordinal number with inserted numbers (as many digits as N 's)
RRR Roman numeral (as many R 's as maximal length)
S May be units of seconds (range 0 to 9) if followed by s or a decimal point; represents tens of seconds (range 0 to 5) otherwise
SS.s Seconds of right ascension or declination, (as many decimals as lowercase s 's)
VVV Velocity in km/s (as many digits as V 's)
VVV.v Velocity in km/s with decimals
Z Redshift (as many digits as Z 's)
Z.z Redshift with decimals
vvv Volume number
W A letter indicating one of the 4 directions (N, S, E or W)
WW Letters indicating one of the 4 directions (NE, NW, SE, SW)
xxxx.x Offset along x-axis from some reference position in any kind of unit (pixel, arcsec, mm, etc)
YYYY Year (YY when 2 digits, YYYY when 4 digits)
yyyy.y Offset along y-axis from some reference position in any kind of unit (pixel, arcsec, mm, etc)
{NGC|IC} One of the alternatives listed between the curly braces { ... } and separated by the vertical bars | — here either the text NGC or the text IC . An empty text is possible as e.g. {Q|G|} means either the letter Q , the letter G , or nothing.
Note: it is possible to use 2 dots .. to indicate a range of letter, e.g. {A..E} is equivalent to {A|B|C|D|E} . To specify a upper- or lower-case letter in the range A to E, one can write {A..E|a..e}   (modified in November 2006)


2  Typical formats (usual or recommended)

Format Example Remarks
Running number
NNN... HD  
Declination zone
+DD NNN BD-28 2411  
  Sk-69 72 Not Sk72-69
Equatorial coordinates
HHMM+DD PKS  
HHMM+DDd PKS  
BHHMM+DD PSR  
BHHMM+DDd PKS  
JHHMM+DDMM PSR  
  PKS  
HHMMm+DDMM IRAS Point Source Cat.
HHMM.m+DDMM 1E (IPC)
HHMMSS+DDMMSS 6C  
HHMMSS.s+DDMMSS 1E (HRI)
BHHMMSS.s+DDMMSS 6C  
JHHMMSS.ss+DDMMSS.s SDSS  
Galactic coordinates
LLL.ℓ+BB.b+VVV HVC  
GLLL.ℓ+BB.b PN  
Field
FFF-NNNN LP hyphens are recommended
  ESO  
FFFF-NNNNN GSC  
Constellation
CCC YYYY Nova  
Year or Date
YYYYA SN 1987A  
YYYYaa SN 1993aj  
YYMMDDA GRB 991216 γ-ray burst
YYYY MMM DDA GB 1979 Nov 05A  


3  Misleading formats (obsolete or confusing)

Format Remarks
NN+DD Sk 72-69   instead of Sk-69 72
HHNDA Pawsey (1955P1), First use of the coordinates in the format
+DD.NN as in OB to OZ (1967S1)
+DNN.N any combination where the point does not mean a decimal point or the declination is in tens of degrees
HH.MM.m.NN GN by Neckel (1985NV), any combination where the point does not mean a decimal point
HHMM+DD.N where the point does not mean a decimal point (e.g. Glazar)
HHMM+DDM truncating to tens of arc minutes in declination is strongly discouraged, use +DDd or +DD.d instead.
HHMM+DDdd Don't use hundredths of degrees, but the sexagesimal division +DDMM
MMSS+MMSS Do not omit the leading HH and DD