Globular Cluster Messier 75

Messier 75
Messier 75: Image taken with the Hubble Space Telescope. © ESA/Hubble & NASA [215]

History

M 75 was discovered by French astronomer Pierre Méchain. Charles Messier reported: «A nebula without a star between Sagittarius and Capricorn's head: sighted by M Méchain on August 27th and 28th, 1780. M. Messier looked for him on October 5th and compared him to star no. 4 in Capricorn Flamsteed. It seemed to M. Messier that the nebula consisted only of small stars. M. Méchain reported a nebula without stars. M. Messier saw him on October 5th, but the moon was over the horizon. Only on the 18th could he determine his appearance and location.» [281]

Physical Properties

This globular cluster is of type I and has one of the densest core regions and is estimated to contain around 400'000 stars. Like most globular clusters, it is very old, around 13 billion years old, and is about 67'500 light years away from Earth. [215]

Revised+Historic NGC/IC, Version 22/9, © Dr. Wolfgang Steinicke [277]
DesignationNGC 6864
TypeGCL (I)
Right Ascension20h 06m 04.8s
Declination-21° 55' 15"
Diameter6.8 arcmin
Visual magnitude8.6 mag
Metric Distance20.900 kpc
Dreyer Descriptionglobular, B, pL, R, vmbMBN, rr
Identification, RemarksM 75, GCL 116, ESO 595-SC13

Finder Chart

M 75 lies in a rather star-poor region between the figures of the constellations Sagittarius and Capricornus. The star 4 Capricorni is 5.8 mag bright and barely visible to the eye. The globular cluster lies 2° 45' west of it at almost the same declination.

Chart Globular Cluster Messier 75
Globular Cluster Messier 75 in constellation Sagittarius. Chart created using SkySafari 6 Pro and STScI Digitized Sky Survey. [149, 160]

More Objects Nearby (±20°)

References

149SkySafari 6 Pro, Simulation Curriculum; skysafariastronomy.com
160The STScI Digitized Sky Survey; archive.stsci.edu/cgi-bin/dss_form
215Explore - The Night Sky | Hubble’s Messier Catalog; nasa.gov/content/goddard/hubble-s-messier-catalog (2020-12-31)
277«Historische Deep-Sky Kataloge» von Dr. Wolfgang Steinicke; klima-luft.de/steinicke (2021-02-17)
281«Catalogue Nébuleuses et des Amas D'Étoiles» Observées à Paris, par M. Messier, à l'Observatoire de la Marine, hôtel de Clugni, rue des Mathurins. «Connoissance des temps ou connoissance des mouvements célestes, pour l'année bissextile 1784 » Page 227; gallica.bnf.fr/ark:/12148/bpt6k6514280n/f235 (2021-02-21)