Aladin is an interactive sky atlas enabling users to visualise and explore a host of astronomical images and data.
Or, if that sounds too complicated, you could just use it to look at gorgeous pictures of deep space. Which works for us.
As long as you have Java, there’s no setup required. Aladin is a single executable, and you can just download it and run on Windows, Linux and Mac.
Experts can then enter an object or coordinates in the Location box to start viewing.
If you’re an astro-novice, click the DSS or SDSS buttons beneath the Location box to load a particular survey– a set of astronomical imagery.
You already know the viewing basics. Aladin might start with a 3D sphere; click, hold and drag spins the sphere in 3D space; when you see something interesting, shift it to the centre of the screen, and spin the mouse wheel to zoom in and out.
It doesn’t take long to discover stars, cloud shapes, new galaxies. These won’t be at HD resolution, especially if you’ve zoomed in a long way, but there’s still plenty of spectacular views on offer. Use Ctrl+C to copy or File > Save to save the best.
If the resolution isn’t high enough for you, use a multiview button (at the bottom of the screen) to split it into 2 or 4 panes. Each of these can then be used as an independent viewer.
This isn’t just about the pictures, of course. If you’re interested, Aladin can also tell you more about what you’re looking at.
To get started, click File > Load Catalog > Simbad > Submit. Aladin uses the Simbad service to retrieve data about the objects you’re looking at, and overlays links for each one on the screen. Click one to highlight it, and optionally view more technical details online.
We’ve not even started to discuss what the program offers serious users, but to give you some idea, here’s the developer’s “Main features” list:
Zoom; Pan; Rotate; Overlays; Multi-views; Many projections (Sin, Tan, Aitoff, Mollweide, etc); Any coordinate systems (FK4, FK5, ICRS, GAL, SGAL, ECL); No image size limit; Million source overlays, Most of astronomical formats (images: HiPS, FITS, PDS, HEALPix map, JPEG, PNG; cubes (HiPS, FITS); tables: HiPS, FITS, VOTable, S-extractor, IPAC TBL, ASCII, etc; regions: XML, STC, DS9, IDL); Powerful tool boxes (images: color map, contours, crop, re-encode, color composition, pixel computation, resampling, astrometrical calibration, mosaic, photometric measurements, etc; Catalogs: filter, split, merge, x-match, scatter plot, etc); VO standards: JSAMP, CS, SSA, SIA, etc; Extendable: plugins, VOApp interface; Fully scriptable.
Just keep in mind that you don’t have to delve into any of that, if it seems too complicated– the basic viewing features are simple, straightforward, and justify the download all on their own.
Aladin is a free application for Windows, Linux and Mac (Java required).