Status of The Amateur Sky Survey: 02 Jan 2001

Tom Droege

There is not a big turnover on this list, so most of you probably know what is going on. This message is for newer members of the list for which the last several messages must have seemed like pure gibberish.

The Amateur Sky Survey is an informal group interested in making all sky photometric measurements of the stars. Photometric means "how bright". But it means more than that. It means "how bright" measured in a way that is useful to professional astronomers. The result is that we give up on sensitivity in order to measure brightness through calibrated filters.

To do this, I am building a bunch of telescope systems. These are then given away to those that I think might operate them, take good data, and process it to a catalog that it useful to astronomers. This project is not funded. I just buy stuff and try to build telescopes.

The systems consist of a computer controlled mount with two 400 mm f/4 five element refractor telescopes. These have been designed and built to optimize the design for accurate photometry. Each telescope has a 2k x 2k CCD camera and electronics to read it out. Both cameras can be read out in 46 seconds. A commercial value for one of these systems is $25,000 to $50,000.

Each camera covers a 4 x 4 degree field. It is possible to take 20 or so exposures per hour. Assuming 80 good nights a year and 6 operating hours a night (good locations will get more), a system can cover about 60,000 square degrees a year in two filters. This is enough to get an average of 3 measurements on each star in a hemisphere. If we get a dozen or so systems spread north and south, then we can cover all the stars in the sky to our sensitivity (about mag 15) 20 or so times a year in each of two filters.

The above is just a possible plan. There are no rules so different operators will alter their programs to optimize what is interesting to them. There will be no directive from above telling us what to do.

I am building telescopes and giving them away for the obvious advantages of a standard survey camera design. Anyone can join in this work. If you have a telescope and a ccd camera and want to work with us, you are welcome. We are a bit technical, and the kitchen gets hot at times. No one will tell you what to do. But if you want to measure stars, then you have found a home. The group will have it's ideas of what constitutes good data. But so will you. We are working at science, and we will work it out.

The prototype has been working here in Chicago for a year or so, and the first two systems have been recently delivered to Flagstaff AZ and Rochester, NY. We should get four more systems out this year.

We hope to start taking real science data this year.

Do not be bashful about making posts to this list. But don't make stupid posts frequently. This is not a list to discuss relativity, or black holes, or to bash astrology. This is a working list. We consciously try here to expose the process that goes on in any University science project. I find that what goes on in the discussions of this list is little different that what goes on at science meetings at Fermilab. (The High Energy Physics laboratory from which I retired). If you really work on this project, you will do the same sort of thing that is done for the experimental part of a PhD program. We have many good advisors who will keep you on the right track if you ask for help. We discuss here the work of building telescopes, analyzing data, finding/writing programs to analyze data, classifying stars, write papers, etc.. Our home page is at