Introducing Nightlight.

FITS visualization for the Mac, by Demitri Muna.

The answer to the question, “What’s in this FITS file?” should not be “Let me open Python.”


Nightlight is a new desktop application whose aim is to bring a modern interface to FITS files with the polish and design people expect from applications they use every day. By making it a native Macintosh application, one is able to leverage cutting edge frameworks that enable GPU acceleration, multithreading, interactive touch interfaces, real-time image processing, desktop metadata indexing, and more. These kinds of features and user experience are simply not possible when using cross-platform environments.

Astronomers are much more concerned with how easy it is to visualize and access FITS data than the order of the bytes on disk.

Few astronomers are fond of the FITS format (note the discussions of migrating to HDF or creating something new altogether). The reason for this is not the specific format itself (when was the last time you heard an argument – or even acknowledgement – of the byte order of jpegs or PDFs?), but the tools available for FITS files. A file format or specification is only as good as the best tools that use them. (Which is not to say that FITS does not need to be updated.)

The user interface. (Design matters.)

When first launched, Nightlight uses Spotlight to find all of the FITS files on your computer (and automatically keeps the list up to date). No need to be concerned about which directory a file is in. Nightlight uses the header to identify the source of the file (e.g. the SDSS survey), and uses the appropriate logo for the file when possible.

Nightlight’s file browser graphically presents FITS files as a list of HDUs. At a glance, you can quickly see the HDU type and its dimensions. Viewing the data is only a click away.


Selecting a filename shows a thumbnail view of all of the HDUs in the file. The thumbnails displayed here are of three images and a table. A 1D image isn’t useful to display with the height of a single pixel across the screen; instead it’s displayed as a plot.

Even in this thumbnail view, the table is interactive: hover the mouse over a column name (on the left), and the column on the right displays its values.

A yellow badge tells you that the file failed a fitsverify scan. It even contains the report.

Nightlight. Fall in love with FITS files all over again for the first time.

Nightlight is a new platform for astronomical visualization. Rather multiple surveys or projects spending the (limited) resources reinventing the wheel, surveys can instead concentrate on the complex visualization that is specific to their data by funding a plug-in for their data.

For more information about Nightlight or to enquire about funding further development, please contact Demitri Muna (demitri -at-

Nighlight has been submitted to the Mac App Store and is currently under review!