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The Skies of September, 2021

Sep 06 2021 01:57 PM | cookman in This Month

Highlights: Comet Journals, Martian Landers, Meteor Showers, Autumnal Equinox, Planet Plotting, September Moon Focus Constellations: Ursa Minor, Draco, Cepheus, Cassiopeia, Perseus, Camelopardalis, Ursa Major, Corona Borealis, Ophiuchus, Hercules, Lyra, Cygnus, Aquila, Pegasus, Andromeda

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BASIC EXTRAGALACTIC ASTRONOMY Part 9: Supermassive Black Hole and Host Galaxy Coevolution

Sep 01 2021 05:00 AM | rekokich in Articles

The only primary evidence available to an astronomer about a very remote object consists of photometric measurements, a spectrogram, and an image which is in many cases no more than a pinpoint of light. In this article we present basic cosmological concepts and simplified mathematical methods which allow an amateur to derive from this meager data a surprising number of physical properties of distant extragalactic objects with a precision of several percent within professional results.

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FIELD TEST: THE NOH CT-20 ALT-AZ MOUNT

Sep 01 2021 05:00 AM | BillP in User Reviews

After several weeks of field use of the NoH CT-20 mount for general astronomical observing with both my TSA-102 and APM-152 refractors, I found the operation and use of this mount to be highly intuitive in the field. The axis friction knobs are conveniently located and are tactile-distinctive from the saddle plate knobs that hold the telescope on the mount, so there was never any question in the dark as to which knob-type I was operating. Operation of the mount was also smooth and precise throughout the testing and general field observing sessions. At no time did I ever find that the CT-20 mount was anything but superlatively capable to handle even my large 6-inch f/8 refractor.

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Cosmic Challenge: A Trio of Binaries

Sep 01 2021 05:00 AM | PhilH in Phil Harrington's Cosmic Challenge

How close can two stars appear and still be resolvable as two? The single most important factor that influences the result is a telescope's aperture. All other things being equal, the larger the aperture, the finer the level of detail resolved. Of the many observational experiments that have been conducted to determine the resolution limits of telescopes, the two most often cited are the Rayleigh Criterion and the Dawes Limit.

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The Skies of August, 2021

Aug 02 2021 04:36 PM | cookman in This Month

Highlights: Comet Journal, Martian Landers, Meteor Showers, Planet Plotting, August Moon Focus Constellations: Ursa Minor, Draco, Cepheus, Cassiopeia, Camelopardalis, Ursa Major, Bootes, Corona Borealis, Ophiuchus, Hercules, Lyra, Cygnus, Aquila, Pegasus, Andromeda

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SkyTee-2 Alt/Az Mount Review

Aug 01 2021 05:00 AM | ScrewLoose in User Reviews

Overall, I think that this mount is good value for money and a good choice for my purposes. I'm confident that the mount will be more than adequate for my needs.

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Cosmic Challenge: Planetary Nebula GJJC-1

Aug 01 2021 05:00 AM | PhilH in Phil Harrington's Cosmic Challenge

What is your favorite globular cluster? Apart from those two southern hemisphere beauties, Omega (ω) Centauri and 47 Tucanae, my answer has to be M22 in Sagittarius. Admittedly, the star chains and "propeller" formation within M13 in Hercules (profiled in the July 2017 Cosmic Challenge) are visually intriguing. But there is just something about the remarkable richness of M22 and its surrounding star field that calls to me.

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The Skies of July, 2021

Jul 08 2021 08:57 AM | cookman in This Month

Highlights: Comet Journal, Martian Landers, Meteor Showers, Planet Plotting, July Moon Focus Constellations: Ursa Minor, Draco, Cepheus, Cassiopeia, Camelopardalis, Ursa Major, Coma Berenices, Virgo, Bootes, Corona Borealis, Hercules, Ophiuchus, Aquila, Lyra, Cygnus

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Restoring an Old Star-Liner Equatorial Mount

Jul 01 2021 05:04 AM | Ochad in Articles

I have owned a large Star-Liner Equatorial Mount with 2 inch axes for over 50 years and in that time it has held a homemade 8 inch f/7 Newtonian, a homemade12.5 inch f/8 Newtonian, a 14 inch SC, a 6 inch refractor, an ATM 10 inch true Cassegrain.

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Cosmic Challenge: Mons Hadley and Rima Hadley

Jul 01 2021 05:00 AM | PhilH in Phil Harrington's Cosmic Challenge

Fifty years ago this month, on July 30, 1971, Commander David Scott and Pilot James Irwin navigated their Apollo 15 lunar module, nicknamed Falcon, to land among the lunar Apennine mountains, while Alfred Worden remained in orbit aboard the command module, Endeavor. Scott and Irwin guided Falcon to a soft landing between the edge of a deep precipice and the base of a tall mountain to establish Hadley Base, as the landing site became known.

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