Norma is another of those relatively insignificant constellations in the
Southern Hemisphere. Invented by Nicolas Louis de Lacaille in the
mid-eighteenth century, the constellation
represents a scientific instrument, "the level". The original name was
"Norma et Regula" (the level and the square).
Since Lacaille's time, the principle stars of Norma have been
redistributed, leaving it with fewer Bayer
Epsilon Normae is a fixed binary: 4.8, 7.5; PA 335, separation
22.8". Both of these stars also have a spectroscopic companion.
Iota1 Normae is a multiple. AB is a rapid binary with
an orbit of 26.9 years. The current values are
5.2, 5.8; PA 228º, and separation 0.4".
Component C: 8.0, PA 243º, separation 11.1".
Norma has three variables of possible interest:
Mu Normae is an alpha Cygni type variable: 4.87-4.98.
R Normae is a Mira-type variable: 6.5-13.9, with a period of
507.5 days. The next maximum is scheduled for the last week of February
1997; in 2001 the maximum should occur in the last week of April.
S Normae is a well-known cepheid with a range from 6.1 to 6.8
magnitude, every 9.75 days. It is found in the NGC 6087 cluster (see
Deep Sky Objects:
Norma has several fine deep sky objects, including a notable planetary nebula.
NGC 6067 is a cluster of about a hundred tenth-magnitude stars.
This cluster is in the same field as kappa Normae, just to the north of
NGC 6087 is another cluster, some 3500 light years away, comprised of
forty or so stars, ranging from 7-10 magnitude. The group is a little ove 2º east of
iota1; it includes the cepheid variable S Normae.
Sp 1 is a planetary nebula, rather bright and perfectly circular with a 13 magnitude star in its centre. The planetary nebula is five degrees west-southwest of gamma2 Normae.
For a more detailed appreciation of Norma, visit the Binocular Section.