Universe Today
Description:
History of Observation:
"The first [nebula] is between the left heel of Serpentarius [Ophiuchus] and the bow of Sagittarius, to the west of a star cluster which is located in this place in the sky, and which appears the same at eyesight, rather resembling the nebula of Cancer [Praesepe, M44]: That nebula has exactly the shape of an equilateral triangle, a bit elongated, and the turning point to the south-west. I have observed it with a refractor of 18 to 20 feet [FL], and it always appeared to me nebulous and transparent; it touches with its base a rather beautiful star, seen in the refractor, and which is the brightest of all those which compose the star cluster I have mentioned. The right ascension of this star is for the beginning of 1748, 266d 44' 22" [17h 46m 57s], its southern declination, 25d 8' 10", its [ecliptical] longitude, 26d 45' 00", and its southern [ecliptical] latitude 1d 30' 00".
"I also have determined, in the same night [May 23 to 24, 1764], the position of a small star cluster which one sees in the form of a nebula, if one views it with an ordinary [non-achromatic] refractor of 3 feet [FL], but when employing a good instrument one notices a large quantity of small stars: near this cluster is a rather brilliant star which is surrounded by a very faint light: this is the ninth star of Sagittarius, of seventh magnitude, according to the catalog of Flamsteed: this cluster appears in an elongated shape which extends from North-East to South-West. I observed its position during its passage of the Meridian, comparing it with the star Delta Sagittarii, and I determined its right ascension as 267d 29' 30", and its declination as 24d 21' 10" south. This star cluster could have an extension, from North-East to South-West, of about 30 minutes of arc."