Binocular Space Walk - From Sirius

 

A word about binocular observing

You don't need a telescope to observe the night sky. Everyone likes to just look up sometimes with the unaided eye. In a dark sky it's a spectacular view, which unfortunately is becoming harder to come by with our rampant light pollution and disregard for the value of seeing the Milky Way and millions of stars. 

Binoculars occupy a spot in between telescopes and the unaided eye. Most amateur astronomers have at least one pair of binoculars, because the view through binoculars differs so much from a telescopic view. For one thing, the field of view is much greater. Second, it requires almost no setup and expensive equipment, although you can pay a lot for high end binoculars. Third, binoculars are easy to pack and easy to point. And lastly, binoculars will show many more stars than the unaided eye, even in more light-polluted areas. 

Nikon AE 10x50

This Space Walk is designed for binoculars. A good size binocular for astronomy is the 10x50, which means it magnifies 10 times more than the unaided eye, and has 50mm objective lenses. This size is not too heavy to hand hold and still keep steady and not get too tired, although they do vary in weight. Some oft-recommended value-priced binoculars for astronomy are the Nikon 10x50 Action Extreme ATB (around $180) and the Oberwerk 10x50 Deluxe (around $200). I have the Meade Masterclass Pro ED 10x56 and they are a bargain when they go on sale around $250. If these are outside of your budget, try the Nikon Aculon A211 10x50 (around $120) or the Bushnell Legacy WP 10x50 (around $105). See a recent Cloudy Nights discussion on binoculars or another CN discussion for more options. If you will be observing with glasses, look for eye relief of at least 17mm, and preferably more.

The second piece of equipment is a reclining chair. I recommend getting a "zero gravity chair." This will allow you to lie back and observe even very high in the sky in comfort. See my article on building a binocular chair mount for a zero gravity chair mount to maximize your viewing experience.

Sirius will be our starting point

This Space Walk complements the Binocular Space Walk - Winter. At the end of that one, I noted that there are many good clusters around Sirius that we didn't cover. The only star cluster covered in both is M41, and that's well worth looking at again! As with the Winter binocular Space Walk, you will need a good unobstructed view to the south. The darker the sky, the better, without the Moon in the sky, as even a crescent Moon will wash out the view a bit.

Familiarize yourself with the chart below in the comfort (and warmth) of your home before you go out observing. This will help in navigating along with the audio guide.

When you first sit down outside with your binoculars, make sure they are in good focus. 

1.  Get a medium bright star (about 4th to 6th magnitude) in the field of view  Closing your right eye and looking only through the left eyepiece, use the main focus knob to get it as sharp as possible.
2. Keeping on the same star, and without changing the main focus setting, close your left eye and looking only through the right eyepiece, use the diopter adjustment ring on the right eyepiece to focus for your right eye. (The diopter ring usually has a + and - on it and a few hash marks.)
3. Double check that the binoculars are in focus for both your eyes.

Link to the mp3 audio file. Download the file to the device you will be using to listen to it in the field.

Binocular Space Walk Among the Stars - From Sirius - audio

Chart to accompany the Binocular Space Walk. Review this prior to observing with your binoculars.

Chart 1: Sirius and the surrounding objects

Chart adapted from Cartes du Ciel.

For detailed information on how binoculars work and what to look when choosing binoculars for astronomy, see Phil Harrington's presentation for the Northern Virginia Astronomy Club from Jan. 2022.

Phil's website is www.philharrington.net.