Field of View - February 2021

Original article appears in GuideStar February, 2021.


by Don Selle

HAS Guidestar Editor

HAS MW.jpgIf you are new to amateur astronomy, you may have noticed that as a group, amateur astronomers use the words observe or observation more than most people. If you are now saying “yeah I had noticed that” you are very observant yourself, and If you hadn’t noticed, don’t worry, amateur astronomy will help make you a better observer.

But what does it mean to observe or be observant? can help here. To observe is

   *   to see, watch, perceive, or notice

   *  to regard with attention, especially so as to see or learn something

   *  to watch, view, or note for a scientific, official, or other special purpose.

For visual astronomers, observing is the name of the game. Accomplished visual observers will see more and dimmer details than those just starting out. They also use the “O” word all of the time, more so than astro-photographers typically do.

But don’t be fooled, accomplished astro-photographers are also very keen observers. That’s how they have become accomplished. They have improved their finished images over time by observing the data they capture, learning what it takes to gather the best data possible, and what works best when assembling a finished image.

So how does one learn to become a better observer? For visual observers, learning about and understanding night vision is very important, since you cannot see dim low contrast objects until your eyes are at their highest low light sensitivity. Working with more experienced observers, you learn to develop a technique for looking through the eyepiece so that you maximize you chances of a successful observation. Using your averted vision so the most low light sensitive part of your retina is engaged, and keeping your gaze slowly sweeping the FOV are key skills to learn.

While these skills are essential, so is learning and understanding what you are looking through and the characteristics of what you are looking for, your intended target. The quality of the night sky has a huge influence on what you can observe, as does the size of your telescope objective, and your choice of eyepiece and other observing aids like filters.

What exactly does a clear dark sky look like? What is sky transparency and seeing?  How can these factors be estimated for the sky in a particular location on a given night? How do the type of objects you are attempting to observe, their characteristics like size, overall and surface brightness affect your probability of making a successful observation?  How can you use this information and estimates of sky quality to modify your observing plan so your time under the sky is well spent?

For astro-photographers, learning the capabilities of their imaging system, and how best to use it is analogous to learning about night vision and how to use it. Knowing the characteristics of their intended target as well as the quality of the night sky are also key factors in determining how successful their night of imaging will be.

By now, especially if you are being observant, you have figured out the point of this column. You only need to look at the definition above to understand one of the beautiful things about amateur astronomy. Inherent in one of our most common activities, astronomical observing, is the process of learning something.

We all must learn how to observe, and to become more proficient, we must learn about what we are observing. The very next step is to put the knowledge gained into the context of the cosmos and our place in it. This opens the door to a myriad of other opportunities to learn about basic physics, astrophysics, cosmology planetary science and more, as well as the history of ideas and of astronomical discovery. Amateur astronomy is a gateway and an invitation to life-long learning about the universe we live in.

To become an astronomical observer is to learn to see the world in a totally different way. When we start looking up at the night sky to learn the constellations, we are taking the same first steps on a path that has been created by countless other astronomers since antiquity, who started the same way. By their collective observations over the centuries, they added to the collected body of human knowledge, and by doing so, changed our view of ourselves and the cosmos. 

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