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2015 RASC Observer's Guide

By Tom Trusock


Join us as Tom Trusock takes a look at the 107th version of the venerable RASC Observer's Handbook.


Recent Additions

  • Blue Skies, Red Sunsets & Company: Part 3:...

    Aug 03 2015 07:28 AM by Snickersnee

    The time between sunset and night's darkness is divided into three intervals based on how brightly the sky is illuminated.

     

    "Star light, star bright,

     First star I see tonight,

     I wish I may,

     I wish I might,

     Have the wish I wish tonight."

    This familiar nursery rhyme is actually a good definition of civil twilight, which starts at sunset and continues until the brightest stars are first seen. It's the common legal meaning of twilight, as there is still light for many outside "civil" activities and most streetlights haven't been turned on. Technically it ends when the sun is 6 degrees below the horizon, or about 25-30 minutes after sunset for temperate latitudes most times of the year. Sunlight still streams 20 miles up. Nautical twilight continues from this point until the horizon blends with the sky, when the sun is 12 degrees below the horizon, about 50-60 minutes after sunset. The sun is setting at the top of the atmosphere about 90 miles (140 km) above you. Marine navigation using traditional visual methods such as sextants becomes difficult, since many of them involve a clearly defined break between sea and sky. The last interval, called astronomical twilight, starts with the end of nautical twilight and goes until the sun gets to 18 degrees below the horizon. This is the time about 70-90 minutes after sunset when no sunlight, either direct or scattered, illuminates the atmosphere above the horizon.

  • The Baader ASTF White Light Solar Filter

    Aug 03 2015 06:28 AM by wapaolini

    Overall I am extremely pleased with the performance of the ASTF.  It exceeded my expectations and provided a white light solar view that was brighter and more detailed than the standard full aperture glass filter I have could provide. 

  • The Lederman Optical Array LOA-21 3D Eyepiece

    Aug 03 2015 07:54 AM by wapaolini

    The LOA-21s and the new technology they introduce to astronomical observing has provided that long awaited next leap I have been eagerly looking for in visual astronomy.

  • The Best Telephoto Lenses for Astrophotography

    Jun 27 2015 04:21 PM by rekokich

    Over the years, I have tried more than two dozen telephoto lenses, until I finally found three or four perfect solutions. But first, there are several general rules which must be understood.



This Month's Skies



Imaging/Sketching Contest


User Reviews

  • The Baader ASTF White Light Solar Filter

    Yesterday, 07:28 AM by wapaolini

    Overall I am extremely pleased with the performance of the ASTF.  It exceeded my expectations and provided a white light solar view that was brighter and more detailed than the standard full aperture glass filter I have could provide. 

  • The Lederman Optical Array LOA-21 3D Eyepiece

    Yesterday, 08:54 AM by wapaolini

    The LOA-21s and the new technology they introduce to astronomical observing has provided that long awaited next leap I have been eagerly looking for in visual astronomy.

  • Ghosts in the Machine: the Astro-Tech AT111EDT...

    Jun 13 2015 12:23 PM by jrbarnett

    The AT111EDT is a doubly haunted scope.  Haunted by the tragic, premature death of the illustrious designer of its optical group, and haunted also by the turbulent financial times into which it was born.  Will there be another run of this fabulous instrument?  I certainly hope so, but telescopes are a tough business, and the landscape of the refractor market in particular changes quickly.

  • My NexStar 5 Journey

    Jun 13 2015 11:29 AM by orion61

    How much do I love my NexStar 5? It could be the best scope I have ever owned. The SCT 5" in my opinion is the size of scope that gives good Planetary views, and DSO's start to be able to be studied in detail. It is also a nice non pain in the back weight wise.

  • Review of the William Optics 102 GT

    May 25 2015 12:22 PM by Perseus_m45

    Would I purchase this scope again?  Yes, I would.  Would I recommend it to a friend?  Yes, I would.  As I wrote earlier, the main reason I bought this scope was to step up my grab and go kit.  Often there just isn't time between the clouds to open up the observatory.  This scope will be parked on an alt-az mount, at the ready for the quick viewing slot that happens so much of the time here in western Pennsylvania.

  • Review- Printing Astro photos on Metal with Bay...

    Apr 16 2015 03:36 PM by ScenicCityPhoto

    I've printed on metallic paper, and with other metal printing companies, but have yet to find anything that is as stunning as the metal print presentation at Bay Photo. Most people that walk into my office immediately say, "WOW!". My AP photos are my own, not perfect, not veteran level perfect, just my own with my personal touch to the editing and presentation. I love the color that is out there, and I strive to show it in my photos.

  • 16” F/4.5 Teeter Stark Review

    Apr 15 2015 03:46 PM by donsell

    I could blame my observing partner Jim Kvasnicka for this.  We often observe together and look forward to the Nebraska Star Party each year.  At NSP 2014, Jim announced that he was going to buy a new premium 16 inch telescope.  That got me to start looking at the different options.

    So, after Jim’s announcement, I asked the Cloudy Nights forum participants if I’d be happy with upgrading my 12” Lightbridge by getting the mirror refigured and coated, getting a new plywood base and a Moonlite focuser, or should I go with Jim and get a new scope from a premium telescope maker.  Consensus was that I’d be happiest with a premium scope if I could afford it.

  • Vixen Ascot Super Wide 10x50 Binocular Review

    Apr 15 2015 12:02 PM by jvandyke

    Are the Vixen Ascot 10x50 the final answer to wide field astronomy?

    Although the wide field is thrilling, I am disappointed by Vixen's lack of quality control on the Chinese optics.  One pair had a blurry upper half, and the second pair could not focus sharply.  I would be reluctant to buy a pair without looking through them first.

  • My Odyssey

    Mar 21 2015 12:54 PM by Gil V

    I think what Coulter did was remarkable. They made the best they could with what they had, and brought large apertures to the public at an unheard-of price.

    All things considered, I am thrilled with my Odyssey.

  • Innovations Foresight On-Axis Guide and Starlig...

    Mar 17 2015 09:25 AM by GazingSkyward

    Would I recommend the ONAG?  Absolutely.  The benefits of near-infrared guiding on-axis are not simply theoretical, you can see them right there in your guide camera images and in the results that you take home at dawn.

  • The Celestron C80 ‘ Regal’ Spotting scope. And...

    Mar 21 2015 08:54 AM by waxinggibbous

    In summation, if you’re like me and get the shakes taking your expensive glass into the bush, then you can do much worse than the C80 Regal.

  • The Celestron C90 Maksutov Cassegrain Telescope

    Mar 02 2015 06:00 PM by skyaddict

    For those of you starting out in astronomy, or simply looking for a small portable telescope for quick looks and travel, the C90 deserves further investigation. Indeed, at the price, it is difficult to justify not buying one!

  • William Optics Zenithstar 71ED and Twilight I M...

    Feb 28 2015 11:53 AM by Ahab

    Wow, it’s a match made in heaven! I can observe at the zenith without compromising the controls or OT or going into contortions. As a unit it’s light enough to carry in and out of the house or for reasonable distances. It’s solid, stable and can fit in my car when broken down.

  • If you want to Master your craft, read Lessons...

    Jan 07 2015 12:29 PM by AstroDad

    Lessons from the Masters: Current Concepts in Astronomical Image Processing (Springer, 2013.) edited by Robert Gendler is an essential addition to library of every serious astrophotographer. Gendler, who edited this 387 page work is himself a Master of the art and science of astrophotography with a rich portfolio of astrophoto accolades and achievements, including 107 NASA APOD selections. Gendler is a physician by profession and therefore technically an "amateur" astronomer. However he routinely teams with the world's leading professional observatories to create masterful images from their exquisite data sets.

  • Celestron Ultima 80

    Dec 16 2014 06:54 PM by Gianluca67

    I had the opportunity to observe the sky with this spotting scope during my holidays last Summer. My Father in law happened to own the Celestron Ultima 80 for nature watching and shooting sport and had left the scope at his holiday house near the seaside where I spent my holidays with my family. The sky there is pretty good so you can see 5.0-5.5 magnitude stars with the unaided eye at the zenith.

  • 10 Micron GM1000HPS --- My Experience

    Dec 15 2014 01:54 PM by sayitfast

    My first setup was working OK for me. I had a Celestron 11 inch HD scope a Hyperstar, Atik camera and a Celestron CGEM mount. I was getting images that I thought were wonderful and was overall very happy. The one major pain point I had was set up time and accuracy of the mount using was not always a fast fun experience. I found the CGEM mount overall worked well but there were some things that frustrated me which I will not go into here. I also wanted to do more advanced imagery… namely Satellites and Comets and I wanted it to be as easy as possible of course.




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