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TOPIC: Messier 72

Blobrana

L

Posts: 131433

Date: Aug 28 20:44 2014

Messier 72	Permalink

Messier 72 (also M72, NGC 6981 and GCl 118)is a magnitude +9.35 globular star cluster located 54,570 ± 1,170 light-years away in the constellation Aquarius. The cluster appears as a "cloudy spot" in amateurs 4 inch telescopes. More powerful optical instruments can see a grainy texture and the brightest stars of the cluster can be resolved in telescope apertures of 8 inches or more. The brightest star in the cluster has an apparent magnitude of +14.2 The cluster was discovered by French astronomer Pierre Francois Andre Mechain using a 3.5" refractor at Versailles on the 29th August 1780. Right Ascension 20h 53m 27.70s, Declination -12° 32' 14.3" French astronomer Charles Messier looked for it on the following October 4, and included it in his catalog. Both decided that it was a faint nebula rather than a cluster. With a larger instrument, British astronomer John Herschel called it a bright "cluster of stars of a round figure". Read more __________________

Blobrana

L

Posts: 131433

Date: Apr 10 01:29 2013

NGC 6981	Permalink

Title: EMCCD photometry reveals two new variable stars in the crowded central region of the globular cluster NGC 6981 Authors: Jesper Skottfelt, D. M. Bramich, R. Figuera Jaimes, U. G. Jørgensen, N. Kains, K. B. W Harpsoe, C. Liebig, M. T. Penny, K. A. Alsubai, J. M. Andersen, V. Bozza, P. Browne, S. Calchi Novati, Y. Damerdji, C. Diehl, M. Dominik, A. Elyiv, E. Giannini, F. Hessman, T. C. Hinse, M. Hundertmark, D. Juncher, E. Kerins, H. Korhonen, L. Mancini, R. Martin, M. Rabus, S. Rahvar, G. Scarpetta J. Southworth, C. Snodgrass, R. A. Street, J. Surdej, J. Tregloan-Reed, C. Vilela, A. Williams Two previously unknown variable stars in the crowded central region of the globular cluster NGC 6981 are presented. The observations were made using the Electron Multiplying CCD (EMCCD) camera at the Danish 1.54m Telescope at La Silla, Chile.The two variables were not previously detected by conventional CCD imaging because of their proximity to a bright star. This discovery demonstrates that EMCCDs are a powerful tool for performing high-precision time-series photometry in crowded fields and near bright stars, especially when combined with difference image analysis (DIA). Read more (433kb, PDF) __________________

Blobrana

L

Posts: 131433

Date: Oct 29 07:27 2011

Messier 72	Permalink

Messier 72 (also known as M72 or NGC 6981) is a globular cluster in the Aquarius constellation discovered by Pierre Méchain on August 29, 1780. Charles Messier looked for it on the following October 4 and 5, and included it in his catalogue. Both decided that it was a faint nebula rather than a cluster. Read more __________________

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