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With the once in a lifetime opportunity to see Venus crossing the Sun having passed at the start of this month, I thought it would be quite topical to write about free- and open-source software, and my new hobby, astronomy.
Having recently taken an interest in astronomy, I decided that my software should be free and/or open source where possible. Thankfully, it seems that Linux isn’t left short when it comes to astronomy applications.
Sky Maps
The one thing that Linux isn’t short on is sky-mapping software. The idea behind these pieces of software is to load up a database of known stars, constellations, nebulae, etc, and show you where they are right now. Also, in most of these applications, you can fast-forward and rewind time. I quite often use the fast-forward feature to see where a particular star/planet will be at a particular time of night.
Quite probably the most widely used is Stellarium (www.stellarium.org).
It’s very polished and has a lovely plug-in system - which includes plug-ins to simulate telescope viewing and a plug-in to remote control a motorized scope. Its only downside is that it won’t run on older machines/laptops. But, never fear.
Kstars (edu.kde.org/kstars) will run on older hardware and, while not as fancy looking as Stellarium, and being KDE-based (which might upset some purists out there), it’s certainly up for the job of showing you stars and controlling your telescope. It also has some nice features not in Stellarium - such as being able to right-click on stars, view images from the Internet, and add notes/log entries. Both Stellarium and Kstars are in most repositories.
A more technical looking application is Aladin (ladin.u-strasbg.fr). I’ve used it only briefly while working through an Open University course, and, while it certainly has some nice layering/technical features, it is certainly used by the professionals since it can load the industry standard FITS files. One thing I have to say, though, is that it is Java based, so you’ll need to have Java installed on your system to use it. But, since it’s Java, you can actually use the application on their website without downloading it.
Another equally scientific-looking (and tricky to use) app is XEphem (www.clearskyinstitute.com/xephem). It does need compiling from source, though, but, if you look around the Internet enough, you’ll find a pre-compiled RPM that you can convert to DEB by using the ‘Alien’ terminal command.
Space Simulator
A space simulator differs from a sky map in that you can zoom out into the milky way and see the planets, their placements, and their orbits. Celestia (www.shatters.net/celestia) seems to be the one that most people use, and is in most repos.
But, like everything on Linux, there’s an alternative, OpenUniverse (www.openuniverse.org). Which, while looking nice, doesn’t seem to have been updated in a while.
Image Stacking
These applications veer into astrophotography. While most people will use a DSLR camera worth several hundred pounds, you can get surprisingly good results using a basic digital camera (even a webcam), hundreds of images, and some nice software. Most folks swear by Registax, which is, unfortunately, Windows only, but I’ll come to that later since Linux native apps is what we really want.
While not the most user friendly, AstroStack (www.astrostack.com) allows you to ‘stack’ images (or frames from a video if you buy the full version), which it will combine into one image which should, in theory, have more detail in it. Its downside is that it’s a bit slow as it’s written in Java.
Another step up the ladder of complexity is ImageJ (imagej.nih.gov/ij). It’s primarily used by scientists and, after looking at it briefly, I can see why. It’s certainly powerful (albeit that it too is written in Java), but it’s really not all that user friendly.
AviStack (www.avistack.de) is another image/video stacking tool which runs on Linux, but it requires the user to sign up for and install the IDL VM, which, at over 200MB, turned me off right away. Many people swear by it, but they’re probably Windows users who don’t need the IDL VM (whatever it may be).
wxAstroCapture (arnholm.org/astro/software/wxAstroCapture/) isn’t technically an application for stacking images, but for taking images to stack. It recognises and connects to most webcams allowing more advanced features such as long exposures (if supported by your webcam) and image/video capture. While it seems to have an active Yahoo! Group (http://tech.groups.yahoo.com/group/wxAstroCapture/), the application hasn’t been updated since the time of 10.x (and shows screens from Kubuntu 8.x), but it’s still a firm favorite.
Scope Control
These are applications which have been recommended to me. I don’t have a motorized telescope, so I can’t vouch for their user friendliness, or lack of.
OpenPHD (code.google.com/p/open-phd-guiding)
Device Control Device (pygtkindiclient.sourceforge.net)
EQ Polar Alignment (code.google.com/p/eq-polar-alignment)
If you’d like to write a follow-up piece to this about motorized mounts, feel free!
Android
No article on astronomy would be complete without mentioning several of the helpful Android apps that are out there in the wild.
Sky Map (http://goo.gl/ryhaV) is pretty much a pocket sky map. You can use the GPS and/or internal tilt sensors in your Android device to show which star you're holding your phone up to.
SkEye (http://goo.gl/KY5Xt) is pretty similar to Sky Map, but lets you scan across the sky without waving your device around your head, and can, according to the creator, be ‘strapped to your OTA’ to be used as a ‘PUSHTO guide’. Not something I’ve tried.
AstroPanel (http://goo.gl/HXS1a) is last, but not least. It’s a small app that (when given your location) will give you a weather forecast for several days ahead with astronomical information such as moon/general visibility and cloud cover.
Next month, I’ll discuss a quick way of remote viewing your scope - which can also be used to remotely control your webcam/telescope from a warm and cosy place.
Sources: Stargazers Lounge Forum http://stargazerslounge.com