Tuesday, November 25, 2014

Astronomy Tools - Computers

Computers are very important to Astronomers. In so many ways, this tool has worked its way into just about every aspect from data storage and data analysis to automatically running a specific list of commands from across the world.
Chances are, you know what a computer is - how else are you able to read this! There are essentially three types of computers:
  • A computer running Microsoft Windows
  • A computer running Macintosh OS X (or some variant)
  • A computer running Linux or Unix
The professionals prefer to use Unix or Linux, mostly because all the work and software design for governmentally funded programs exists on the Unix platform. A perfect example is the Image Reduction and Analysis Facility (IRAF). This software is 100% free (paid by U.S. Tax dollars) and is by far the best software to use for any Astronomy related project. The problem is it can be notoriously difficult to use, and it only just began to support the Windows based computer.
This section will briefly introduce how computers are used, and are divided into the following sections:
There is an enormous amount of data available on the Internet, so much so that you probably don't need a telescope. Chances are, any deep sky object of interest has already been imaged. In addition,professional research articles are also available but you have to know where to look.
If you browse the web long enough, you will probably find them but I have already been there as a requisite for my coursework in Astronomy.
Film is rarely used by professional Astronomers today. Most of the previous plate film that has been captured has been digitized (and available online through the MAST website).
Images are captured by CCD camera. Usually, exposures are handled by computer software. The Astronomer programs the variables like exposure duration, filter selection, capture of the BIAS and Flat frames (for calibration - see the Astrophotography section for more details) and the software does the rest.
After image capture, the data is saved always as a FITS file. FITS stands for Flexible Image Transport System. This file type is standard everywhere and allows important header information from the CCD camera to be retained. Additionally, the image is unaltered and is in its native 16 bit format.
Once captured, software is used to combine, calibrate, enhance, save-as, whatever you can think of. There are several choices available.
Most, if not all, of these software packages provide CCD control and processing. However, don't be surprised if you see a fellow amateur astronomer (or professional) have more than one of these packages installed on their system.
Just about all telescope manufacturer makes a line of telescopes with a computerized mount. While not at all necessary, a computer controlled mount can save a load of time but there are power requirements to be considered. This section will assume a home observatory or computer controlled telescope from the patio (in other words, AC power is available).
A computer controlled telescope works in tandem with CCD software. Just about every planetarium software has an advanced or professional level software that is capable of controlling your Meade, Celestron, or even custom made electronic mount using what is called ASCOM standards - which is nothing more than an open source language used by Astronomers.
Telescope control really just controls the telescope mount. The CCDsoftware works in tandem with the telescope control software to:
  • Ensure accuracy by tracking a guide star
  • Focuses the eyepiece
  • Captures the image
CCD software was discussed in the section above. Here is a list of a few programs that offer a complete package, or telescope control.
  • ASCOM Standards for Astronomy - This is the language used by computer control and CCD control software
  • DC-3 Dreams - A new company that offers a very nice, and complete, telescope control package.
  • TheSky by Software Bisque - A very nice planetarium package that also controls a telescope quite well. Works well with their CCDSoft software.
There are probably others but these seem to be the most popular among amateur astronomers. The professionals will use custom made software.
Planetarium software shows what the night sky will look from any location on Earth at (just about) any time. Many of the software makers include extra features like bonus video CD's, telescope control, online star updates, list of current events (in Astronomy). There is a wide variety available, and they are all good. Some are more difficult to use than others, but they all show the positions of the stars is excellent precision.
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