Welcome to Houston Astronomical Society

In good company, you are, as you spend your time here with members. Here is one: Leland Dolan. Leland stayed with us a long time but he had to go away to where we all will go one day. Leland thought highly of us, has left a gift for us...

Perhaps one reason I was picked as historian, is that I tend to dwell a lot on the past. I still think of my early years as an amateur astronomer as the “good old days”. The chief difference between, say 1960 and now, is that I could observe a number of Messier objects from my yard, and yet I lived only a quarter mile from the University of St. Thomas. For observing or photographing the Milky Way, I would spend the night at my parents’ home, only a couple of miles west of Memorial Park. Nowadays, to go anywhere where one can observe deep sky objects, requires that two or three hours be spent travelling to and from the observing site...

Many, maybe most of you, have at least dabbled in the famous Messier Catalogue as a good deep-sky starting point for your observing efforts.  The problem with Charlie Messier is that his catalogue has as a primary purpose, the identification and location of objects that looked suspiciously like comets through his 3.5-inch telescope.  After all, he was a world-renowned comet chaser. He did not want to waste his time looking at/for things that looked like, but were not, comets...

Part 1 of Getting You Exposed, dealt with the concept of Total Exposure time and Exposure Value. It also provided some rules of thumb to help you estimate the Total Exposure time required for various types of targets using your own imaging rig. Having a good idea of the Total Exposure is certainly essential for acquiring high quality data on the low light level targets we image, but it is only one factor we need to consider...