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BASIC EXTRAGALACTIC ASTRONOMY - Part 3: Luminosity Corrections, Cosmological Extinction, and Mas...
Jan 16 2020 09:50 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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Deep Sky Lucky Imaging
Jan 14 2020 01:53 PM |
CygnusBob
in CN Reports
Amateur astronomers have been using lucky imaging for planetary targets with great success. The basic strategy is to obtain a large number of short exposure images in order to “freeze” the turbulence and then select the sharpest images for alignment and integration. Short exposures are valuable because the biggest effect of turbulence for small telescopes is image jitter. For long exposures, the image jitter gets averaged out, just generating a blurred image. The problem with doing this with deep sky objects is that the number of photons collected in a 1/60 of a second is rather small in most cases. This makes it hard to determine an image shift accurately. However lucky imaging can still help sharpen DSO imagery.
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January 2020 Skies
Jan 12 2020 12:53 PM |
cookman
in This Month
Highlights: Comet Journal, Martian Landers, Meteor Showers, Longest Night?, Planet Plotting, January Moon Focus Constellations: Pegasus, Pisces, Andromeda, Aries, Perseus, Taurus, Orion, Gemini, Auriga, Cancer, Leo, Camelopardalis, Lynx, Ursa Major, Draco, Ursa Minor, Cepheus, Cassiopeia
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Cosmic Challenge: NGC 1535
Jan 01 2020 07:00 AM |
PhilH
in Phil Harrington's Cosmic Challenge
Planetary nebula NGC 1535 is a victim of circumstance. Take a look at its facts. Its bluish disk spans about a minute of arc, which is quite large as planetaries go, and shines brightly enough to be visible through giant binoculars. Its central star glows at magnitude 11.6, creating a surreal scene resembling a disembodied human eye, which led to the nickname "Cleopatra's Eye." Those in the know rate NGC 1535 as one of the sky's finest planetary nebulae. Yet this enticing target remains unknown to many backyard stargazers.
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Optimal Filtering for Deep Sky Lucky Imaging
Dec 15 2019 12:30 PM |
CygnusBob
in CN Reports
A paper that describes a method of noise reduction for DSO imagery that I have invented for Deep Sky Lucky Imaging. I am Dr. Robert Majewski, a retired engineer living in Las Vegas. I have M.S. and Ph.D. degrees in Physics from the University of Illinois. My career involved testing and calibrating a number of imaging electro-optical systems at the Hughes Aircraft Company and Raytheon Missile Systems. My hobbies include high resolution planetary imaging, exo-planet transits and deep sky imaging.
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My experience using two 80-millimeter long-focus refractors
Dec 13 2019 03:18 PM |
caussade
in Telescopes
The Orion and TMB refracting telescopes are both a joy to use, and will undoubtedly stay with me for life. I sometimes get offers to sell but have politely declined; as the reader will suspect, the thought of a sale has never entered my mind.
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GSO 8-inch TRUE CASSEGRAIN
Dec 13 2019 02:33 PM |
Larry Carlino
in Telescopes
GSO Cass can be regarded as somewhat of a specialist instrument. Its excellent overall optical quality, fine lunar and planetary performance, reasonable size and weight, and bargain price make it a fine choice where sterling deep-sky and rich-field capability are not a priority. It is a good alternative to much pricier 5 to 6-inch apochromatic refractors for both visual and ccd work. In the price- to- performance ratio, I don't see anything in its price range that comes close (except, perhaps for a high-quality long-focus Newtonian [but try to find one!]) as a dedicated lunar and planetary instrument.
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BASIC EXTRAGALACTIC ASTRONOMY - Part 2: Distance, Luminosity, and the Hubble Parameter
Dec 13 2019 02:13 PM |
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.
Read story →
BASIC EXTRAGALACTIC ASTRONOMY - Part 1: Redshift and Recession Velocity
Dec 13 2019 12:53 PM |
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.
Read story →
December 2019 Skies
Dec 12 2019 04:15 PM |
cookman
in This Month
Highlights: Comet Journal, Martian Landers, Meteor Showers, Winter Solstice, Planet Plotting, December Moon Focus Constellations: Pegasus, Pisces, Andromeda, Aries, Perseus, Taurus. Orion, Gemini, Auriga, Camelopardalis, Lynx, Ursa Major, Draco, Ursa Minor, Cepheus, Cassiopeia
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