December 2022

Looking Up with FT&O

"Why can't we have a 'flash mob' star party?"

Maybe you remember Steve Fast. He ran the membership table a decade or so ago. After that, he headed up Field Trip & Observing. Steve’s flash mob comment was about the annual picnic, which once again, had been cancelled due to weather.

GuideStar Cover January 2023

by Loyd Overcash

IC-434 The Horsehead Nebula, Fort Davis, Texas

Exposure was 135 minutes taken in 5 minute subs with my 14.5 RC and the ZWO-2600mc camera in Bin 3 Gain 300

Stargazing Basics Tips to Go

by Jim King

Learn the basics, then work on getting better and having more fun

BARLOW LENS: This type of lens which you install in your telescope's focuser (and then put an eyepiece into) increases the effective focal length of a telescope and magnifies its image. A 2x Barlow doubles the focal length and the eyepiece will provide twice the power. If you choose the eyepieces carefully, adding a Barlow can give you a much wider range of magnifications.

BINOCULARS: High-quality binoculars should be part of every observer's kit. For magnification, choose 7x, 8x or 10x. The front lenses should be at least 50 mm across. Smaller ones don't collect enough light. If your budget can stand it, check into Image Stabilized (Canon, Fuginon) binoculars to avoid having to rely on the availability of a tripod. I have the Canon 10X30s image stabilized which are a true "grab and go" accessory for astronomy, bird-watching, etc.

CIRCUMPOLAR STAR: This term describes a star that always lies above an observer's day or season. At the equator, no star is circumpolar. At the North or South Pole, all stars are circumpolar. At any other latitude, a star whose declination is greater than 90 degrees minus the observer's latitude will be circumpolar.

Telescope Primer: The Refractor

by Will Sager


Figure 1. A refractor telescope (aka “yard cannon”). (source:


If you own a telescope, you probably looked first at a refractor (Figure 1). It is the quintessential telescope and if you see a telescope in a cartoon, it is probably one of these. This is first telescope invented, often attributed to Gallileo Galilei in 1609 although opticians in the Netherlands probably made similar instruments a few years before. But Galileo pointed his telescope skyward, extensively documenting his observations, and became the first telescopic astronomer. Galileo’s telescope used an objective lens to focus light on an eyepiece lens, which is the basic description of this type of scope. There are many different refractor telescopes, so a beginner can get confused without some background. The goal here is to provide the reader with some details to help understand refractor telescopes and their designs.

Getting You Exposed Part 1: Total Exposure Time

by Don Selle


Exposure in daylight photography is a pretty cut and dried subject. You need to set the exposure time required to fully illuminate the scene you are shooting while achieving a specific effect or look in your image. With your DSLR or smartphone, the exposure is pretty much automatic. The algorithm is built into the camera. Truth be told, the vast majority of picture takers never get outside the boundaries of the camera’s automatic settings.

Not so with astro-imaging. Dedicated astro-cameras have very simple, open-ended controls, there really are no boundaries or standards when it comes to exposure time. Even with a DSLR there is no guide to tell you what settings to use for exposing your individual subframes, nor for how many subframes you should take (total exposure time) to have a well exposed final image.

While astronomy image capture software will allow you to specify all of the parameters for exposing your subframes, and some even allow you to specify fairly complex image capture sequences, to the best of my knowledge, there is no built-in exposure algorithm here either. There are a few tools out there that will help you to calculate things like optimum subframe exposure times, and SharpCap’s Smart Histogram function which can help you to visualize your exposure sequence, but that’s as far as things go today.


Spot the Messenger: Observe Mercury

by David Prosper

Spot the Messenger: Observe Mercury

image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie

Mercury can be one of the brightest planets in the sky - but also easy to miss! Why is that? Since it orbits so close to the Sun, observing Mercury is trickier than the rest of the "bright planets" in our solar system: Venus, Mars, Jupiter, and Saturn. Mercury always appears near our Sun from our Earth-bound point of view, making it easy to miss in the glare of the Sun or behind small obstructions along the horizon. That's why prime Mercury viewing happens either right before sunrise or right after sunset; when the Sun is blocked by the horizon, Mercury's shine can then briefly pierce the glow of twilight.

Getting Started in Observing

Membership Renewals and New Member Adds on Hold

Hello all,

We’re almost done with our website migration, so to make sure we transition everything over properly, we’re putting all membership renewals and new member processing on hold until January 9. Editors note: A number of members are testing the renewal process and the new member joining process. Please bear with us as we get through the migration. We will announce when you may renew your membership when the migration is over. Thank you very much for your cooperation.

Joe Khalaf
HAS President

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