Sangamon Astronomical Society

05/22/2026

Mark your calendars now for NCRAL 2027, next year's regional "event of the year" hosted by the Milwaukee Astronomical Society.

05/07/2026

Circumpolar Stars
Some stars never set, others never rise

Stars between the celestial equator and the Zenith are above the horizon for more than 12 hours.
Stars on the celestial equator are above the horizon for 12 hours.
Stars between the celestial equator and the declination at geographic south are above the horizon for less than 12 hours.
Stars farther south than "90º minus your latitude" are circumpolar south and never rise.

Declination of the zenith equals your latitude

Stars farther north than your latitude (i.e., zenith declination) are circumpolar north and never set.

Polaris' altitude in degrees equals your latitude

04/19/2026

Binocular Double Star Observing Program

https://www.astroleague.org/binocular-double-star-observing-program/

Effective Binocular Observing ...
Binoculars must be precisely focused.
Binoculars must be held steady. Mounted on a tripod is best.
Adequate dark adaption is needed. Wait at least 15 minutes in the dark before meaningful observing begins. 30 minutes is better.
Glare from a bright primary interferes with spotting a dim secondary. The greater the magnitude difference, the greater the difficulty splitting them.
Steady atmospheric seeing is desired.
Best observed when the double star has an altitude higher than 30º.

04/10/2026

Coma Berenices Open Cluster
aka Melotte 111

Easily visible in the early evening from mid March through July.

The two-dimensional celestial dome is deceiving in regard to the true spacing of stars in three-dimensional space.

Melotte 111 is thought to have over 40 stellar members, most being below naked eye visibility down to 9th and 10th magnitude.

The galaxies shown are typically 150,000 times farther than the Coma Bernices Open Cluster (Melotte 111).

Gamma, the brightest member, is not a true member of the cluster, but a foreground star.

The brighter stars of the cluster are on the order of 10-20 light-years apart from each other.

The volume is filled with 5 times as many stars as shown, but most of those are fainter than 8th magnitude.

02/21/2026

B35: A Deep, Dark Nebulae
Test your observing skill at low magnification

Appearing as a dark hole in the winter's sky, B35 is a dark nebulae with relatively high opacity.

How to find B35:
1. Look for the bright star Betelgeuse in the northeast corner of Orion.
2. 6º northwest of Betelgeuse is 3.4 magnitude Lambda Orionis, primary star of the "Orion's Head Nebula," also known as Collinder 69.
3. Midway between Betelgeuse and Lambda hides B 35.

How to view B35:
• Use a low magnification.
• Transparent, dark skies are a must.
• Must be able to distinguish small differences in contrast.
• View when no moon is present.
• Best seen near culmination.

01/03/2026

12/31/2025

12/05/2025

M33:
A Marriage of Sketching and Imaging

What happens when you sketch what you image?

The very large galaxy M33 – with an apparent diameter of 1º – can be difficult to spot even with binoculars.

Its location is not hard to find, however. It lies 40% between the 2nd magnitude stars Beta Andromedae and Alpha Arietis (Hamal).

Telescopes larger than 10 inches in aperture begin to hint at its fantastic spiral structure and reveal its immense emission nebula NGC 604 as a small faint blur on the northeastern edge of M33. It appears quite detached from the central core of the galaxy.

What lies just at the edge of visibility can be confirmed and better understood with an image. NGC 604 is found in the outer, wispy regions of M33. Other knots of nebulosity can be seen as well.

12/01/2025

The relative planetary positions in December.

11/20/2025

If you have binoculars, check out one of the many binocular observing programs from the Astronomical League. Programs include ✨Messier objects, 🌙lunar, ⭐️⭐️double stars, variable stars!✨

Binocular Buying Basics

Because they show an upright image, and are easy to aim, binoculars are very useful for examining any 5–7º degree portion of the sky. They are perfect for scanning the Milky Way – its bright regions, its dark bays, and its misty glows. Plus, hundreds of objects are visible. In fact, some objects need the low power – and wide field – only a good pair of binoculars can provide.

Buy quality optics with the best glass you can afford. For instance, BAK-4 glass prisms give better light transmission than BA-7 prisms, and, therefore, are more desirable – but are more costly. A good pair of binoculars will give you a lifetime of enjoyment – take good care of them!

Porro Prisms or Roof Prisms? Binoculars with Porro prisms have the traditional zig-zag shape and those with roof prisms have straight barrels. Porro prisms give better light transmission than most roof prisms, and, therefore, are better suited for astronomy.

Coatings? Yes! Coatings help improve the transmission of light through the binoculars. You want binoculars with fully multi-coated optics to give the best possible light transmission. Look for a slight purplish tint when light glints off the front lens.

What size is best? It is a matter of light collecting ability vs. weight. When evaluating binoculars, two numbers are given, 10x50 for example. The first number is the magnification. The second is the diameter of the objective (front) lenses expressed in millimeters. Glasses larger than 50 mm might be good, but will be heavier and likely require support such as a tripod. Glasses smaller than 50 mm will give dimmer night sky scenes. Anything less than 7 magnification will show images too small, larger than 10 power will likely be too heavy and will have a smaller field.

Exit Pupil. The diameter of the truncated cone of light at the focal point is the exit pupil and should match your eye's pupil diameter. Too large EP – not all the light enters the eye. Too small EP – a dimmer image. The diameter of the exit pupil equals the objective lens diameter divided by the magnification. The eye's pupil under dark conditions has a diameter of about 5 mm (or smaller) for older adults, 7 mm for young adults. 10x50 binoculars have a 5 mm exit pupil, which is nearly ideal for older adults.

Field of view. Common fields are 5-7º. Wider fields result in heavier, more costly binoculars, and may suffer from edge distortions.

Extras. Shock resistant, waterproof, and gas filled glasses are beneficial. And a standard tripod screw socket is almost essential. Don't forget a comfortable strap, a carrying case, lens caps, and warranties.