Globular Cluster in Ophiuchus

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M14: A globular cluster is a group of ancient stars (M14 is thought to be about 11.4 billion years old; by comparison, our sun is about 4.6 billion years old; our galaxy is about 13.5 billion years old, and the universe is thought to be 13.8 billion years old), gravitationally bound to each other, orbiting the core of its associated galaxy. Unusually, M14 is somewhat elliptical in shape; most globulars are spherical.

I like the dense star field M14 appears in; M14 is in line with the plane of the Milky Way, when viewed from Earth.

M14 is about 30,000 light years from Earth, and is about one-quarter of the angular size of the full moon when viewed from very dark skies; it is roughly 100 light years across. It shines at magnitude 7.9 (not visible with the naked eye, but easily seen with binoculars). It has a mass equal to about 1,000,000 times that of our sun, and contains as many as 300,000 stars (for comparison, there are estimated to be no more than 2,000 stars within 50 light years of earth, which is a bubble about that same size). M14 has an unusual number of variable stars.


Technical Information:

LRGB: 298:75:70:91; luminance layer consists of 52 five-minute images and 38 one-minute images; RG channels consist of the combination five-minute images, while B was a group of 6.5-minute images.

Equipment: RC Optical Systems 14.5 inch Ritchey-Chretien carbon fiber truss telescope, with ion-milled optics and RCOS field flattener, at about f/9, and an SBIG STX-16803 with internal filter wheel (SBIG filter set), guided by an SBIG AO-X, all riding on a Bisque Paramount ME German Equatorial Mount.

Image Acquisition/Camera Control: Maxim DL, controlled with ACP Expert/Scheduler, working in concert with TheSky X.

Processing: All images calibrated (darks, bias and sky flats), aligned, and combined in Pixinsight. Color combine in Pixinsight. Some finish work (background neutralization, color calibration, gradient removal, Multiscale Linear Transform, lessening the dynamic range) done in Pixinsight; some finish work (Neat Image noise reduction, LRGB combination, contrast and saturation adjustment) was done in Photoshop CC.

Location: Data acquired remotely from Sierra Remote Observatories, Auberry, California, USA.

Date: Images taken on many nights in May and June of 2020. Image posted July 9, 2020.

Date: Image scale of full-resolution image: 0.56 arcseconds per pixel.

Seeing: Generally good, with calibrated luminance images varying from 1.8 to 2.2 arcsecond FWHM

CCD Chip temperature: -25C

Copyright 2020 Mark de Regt

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