Universe Today
moreDescription:
History of Observation:
"Beautiful Nebula discovered between the Balance [Libra] & the Serpent [Serpens], near the star in the Serpent, of 6th magnitude, which is the 5th according to the Catalog of Flamsteed [5 Ser]: it doesn't contain any star; it is round, & one sees it very well, in a fine [clear dark] sky, with an ordinary refractor of 1-foot."
"The night of May 23 to 24, 1764, I have discovered a beautiful nebula in the constellation of Serpens, near the star of sixth magnitude; the fifth according to the catalog of Flamsteed. That nebula doesn't contain any star; it is round, and could have a diameter of 3 arc minutes; one can see it very well, under a good sky, with an ordinary [non-achromatic] refractor of one foot [FL]. I have observed that nebula in the Meridian, and I have compared it to the star Alpha Serpentis. Its position was right ascension 226d 39' 4", and its declination 2d 57' 16" north. On March 11, 1769, at about four o'clock in the morning, I have reviewed that nebula with a good Gregorian telescope of 30 pouces, which magnified 104 times, and I have ensured that it doesn't contain any star."
"With a magnifying power of 250, it is all resolved into stars: they are very close, and the appearance is beautiful. With 600, perfectly resolved. There is a considerable star not far from the middle; another not far from one side, but out of the cluster; another pretty bright one; a great number of small ones. Here we have a case where the penetrating power of 20 fell short, when 29 resolved the nebula completely. This object requires also great magnifying power to shew the stars of it well; but that power had before been tried, in the 7-feet, as far as 460, without success, and could only give an indication of its being composed of stars; whereas the lower magnifying power of 250, with a greater penetrating power, in the 10-feet instrument, resolved the whole nebula into stars. I counted about 200 of them. The middle of it is so compressed that it is impossible to distinguish the stars."