Discovered by Pierre Méchain on August 29-30, 1780.
[PT 1818 p. 447-448, SP2 p. 600]
The 72nd of the Connoissance. [M 72 = NGC 6981]
"1805, 7 feet telescope. With a power of 80 the stars may just be perceived."
"1783, 1810, 10 feet telescope. With 150 fairly resolved."
"1784, 1788, 20 feet telescope. A cluster of very small stars."
"1810, large 10 feet telescope. A globular cluster; its diameter is 2' 40"."
"1810, Oct. 30, 40 feet telescope. A beautiful cluster of stars."
[For further particulars see above, 1814]
By the observation with the 7 feet telescope, the profundity of this cluster
must be of the 243d order.
[Unpublished Observations of Messier's Nebulae and Clusters.
Scientific Papers, Vol. 2, p. 659]
1810, Oct 30, Review. 40 feet. Having been about 20 minutes at the telescope
to prepare the eye properly for seeing critical objects, the 72nd of the
Connois. came into the field. It is a very bright object. It is a
cluster of stars of a round figure, but the very faint stars on the outside
of these sorts of clusters are generally a little dispersed so as to deviate
from a very perfect circular form; the telescopes which have the greatest
light shew this best. It is very gradually extremely condensed in the center,
but with much attention even there the stars may be distinguished. Power 280.
There are many stars in the field of view with it, butthey are of many
magnitudes and totally different from the excessively small [faint] ones
which compose the cluster. It is not possible to form an idea of the number
of stars that may be in such a cluster, but I think we cannot estimate them
by hundreds. The diameter is about 1/5 of the field = 1' 53.6". -
10 feet telescope. I viewed the same object. The contrast is very striking,
it appear eF [extremely faint].
Sweep 363 (August 6, 1831)
RA 20h 44m 5.8s, NPD 103d 10' 9s (1830.0)
pB; v compressed cluster; irreg R; barely resolved; vgbM; 3' diam; many
straggling stars near, but none so small as those of the cluster.
Pretty bright; very compressed cluster; irregularly round; barely resolved;
very gradually brighter toward the middle; resolved into very small [faint]
stars; many straggling stars near, but none so small as those of the cluster.
Sweep 34 (July 31, 1826)
RA 20h 44m 6.5s, NPD 103d 10' 13s (1830.0)
F; R; 2' diam; gbM; r, but I do not see the stars separated enough to count
them. Sky beautiful. Has a * 9m 30 deg sf, dist 3'. Is rather an
insignificant object.
Faint; round; 2' diameter; gradually brighter toward the middle; resolvable
[mottled, not resolved], but I do not see the stars separated enough to count
them. Sky beautiful. Has a star of 9th magnitude 30 degrees sf, distance 3'.
Is rather an insignificant object.
October 4, 1810. 40-feet telescope. Space-penetrating power 191.68. Magnifying power 280. Having been a sufficient time at the telescope to prepare the eye properly for seeing minute objects, the 72d of the Connoissance des Temps [Messier's Catalog] came into the field. It is a very bright object.This cluster is followed, at about 5m difference AR and 7' to the southward, by a trio of 10th-magnitude stars in a poor field: this is No. 73 of Messier's list, also registered in 1780.
It is a cluster of stars of a round figure, but the very faint stars on the outside of globular clusters are generally little dispersed, so as to deviate from a perfectly circular form. The telescopes which have the greatest light show this best. It is very gradually extremely condensated in the centre, but with much attention, even there, the stars may be distinguished.
There are many stars in the field of view with it, but they are of several magnitudes, totally different from the excessively small [faint] ones which compose the cluster. It is not possible to form an idea of the number of stars that may be in such a cluster: but I think we cannot estimate them by hundreds. The diameter of the cluster is about one-fifth of the field, which gives 1' 53".6.
Last Modification: March 30, 2005