Globular Cluster Messier 68

Messier 68
Messier 68: Image taken with Hubble Space Telescope [245]

History

The globular cluster M 68 was discovered on April 9, 1780 by Charles Messier, who wrote: «Nebula without stars under the raven and the water snake; it is very weak, very difficult to see with the telescope; next to it is a star 6th magnitude.» [281] Wilhelm Herschel wrote: «A beautiful star cluster, extremely rich and so compressed that most of the stars are mixed together. it is nearly 3' wide and about 4' long, but mostly round, and there are very few stars scattered around.» [217]

Physical Properties

The distance from M 68 is about 10.3 kpc (33'600 light years) and it is moving towards us at about 93 km/s. The mass is 223'000 times that of the sun. [251] 50 variables were found in the star cluster. [282] [282]

«Revised New General Catalogue and Index Catalogue» Dr. Wolfgang Steinicke, 2021 [277]
DesignationNGC 4590
TypeGCL (X)
Right Ascension12h 39m 28.0s
Declination-26° 44' 32"
Diameter11.00 arcmin
Visual magnitude7.3 mag
Dreyer Descriptionglobular, L, eRi, vC, iR, rrr, st 12
IdentificationM 68, GCL 20, ESO 506-SC30

Galaxy PGC 42334

The small, faint galaxy PGC 42334 is only about 10 arc minutes away.

«Catalogue of Principal Galaxies (PGC)», Paturel et al. 1989 [144]
DesignationsPGC 42334: ESO 506-29, MCG 4-30-9
Right Ascension (J2000.0)12h 39m 16.3s
Declination (J2000.0)-26° 54' 41"
Morphological TypeSB
Dimensions1.2' x 1.1'
Visual Magnitude14.2 mag
Radial Velocity (HRV)2976 km/s
Position Angle°

Finder Chart

M 68 lies in the constellation Hydra. To find it, connect the stars Algorab (η Corvi) - Kraz (β Corvi) by 3.5 ° to the south. It is best seen from February to May.

Chart M 68
Chart created using SkySafari 6 Pro and STScI Digitized Sky Survey. [149, 160]

References

144Catalogue of Principal Galaxies (PGC); Paturel G., Fouque P., Bottinelli L., Gouguenheim L.; Astron. Astrophys. Suppl. Ser. 80, 299 (1989); cdsarc.unistra.fr/viz-bin/cat/VII/119 (2021-02-18)
149SkySafari 6 Pro, Simulation Curriculum; skysafariastronomy.com
160The STScI Digitized Sky Survey; archive.stsci.edu/cgi-bin/dss_form
217The Messier Catalog (SEDS); messier.seds.org (2021-01-01)
245Bucking the trend; esahubble.org/images/potw1921a (2021-01-22)
251«Young Radio Pulsars in Galactic Globular Clusters» Jason Boyles, Duncan R. Lorimer, Phil J. Turk, Robert Mnatsakanov, Ryan S. Lynch, Scott M. Ransom, Paulo C. Freire, Khris Belczynski; The Astrophysical Journal, Volume 742, Number 1; DOI:10.1088/0004-637X/742/1/51
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)
282«A Census of Variability in Globular Cluster M68 (NGC 4590)» N. Kains, A. Arellano Ferro, R. Figuera Jaimes, D. M. Bramich, J. Skottfelt, U. G. Jørgensen, Y. Tsapras, R. A. Street, P. Browne, M. Dominik, K. Horne, M. Hundertmark, S. Ipatov, C. Snodgrass, I. A. Steele, K.A. Alsubai, V. Bozza, S. Calchi Novati, S. Ciceri, G. D'Ago, P. Galianni, S.-H. Gu, K. Harpsøe, T.C. Hinse, D. Juncher, H. Korhonen, L. Mancini, A. Popovas, M. Rabus, S. Rahvar, J. Southworth, J. Surdej, C. Vilela, X.-B. Wang, O. Wertz; arXiv:1502.07345v1; DOI:10.1051/0004-6361/201424600