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. FITS (flexible image transport system) is the standard file format used by professional astronomers. Nightlight is designed to answer the question, “What is in this FITS file?” without requiring a line of code.


• view the structure of a FITS file at a glance
• displays all image and table HDUs
• thumbnail view of all HDUs
• metadata “card” view for table columns
• supports an unlimited number of table rows and columns
• inspector panels for image views
• supports WCS (world coordinate system) overlays for ten coordinate systems
• pinch and zoom image magnification for trackpad users
• FITS headers displayed in a floating panel
• Nightlight uses Spotlight to find all the FITS files on your computer for you

New features will be continually added. Features will be determined and prioritized by Nightlight users. A feature voting system will be available soon.

While I have tested hundreds of files, it’s impossible to have tested every FITS file available. If you have any problem viewing a particular file, please contact me and I will do my best to address it.

Custom visualizations for your telescope, instrument, or survey are available. Contact me for details.

More information about Nightlight can be found here:

• Nightlight web site:, including the FAQ:
• @nightlightviz on Twitter
• contact Demitri Muna at

Want to talk about Nightlight? Join the discussion group here:!forum/nightlight-discuss

Note: This version of Nightlight only supports macOS 10.12. Nightlight will support earlier systems pending further testing.

What’s New

Version 1.0.1

New in version 1.0.1:
• Nightlight now supports macOS 10.10-10.12.
• 2D images that look like 2D spectra now displayed as plots in thumbnail views.
• fitsverify now called as an external process (now won’t crash Nightlight).
• Better handling/display of edge cases of several data types.
• Fixed display of tool tips in table views.
• Null values now correctly displayed in table column card views.
• Numerous small user interface fixes.


Demitri Muna
14.5 MB

OS X 10.10 or later, 64-bit processor



Age Rating
Rated 4+
© 2011-2018 Demitri Muna


  • Family Sharing

    Up to six family members will be able to use this app with Family Sharing enabled.