View FITS files in your browser
The picture format of observatories, space telescopes and backyard astrophotography. Open one right here, stretched so faint galaxies show. Nothing leaves your device.
Or drop it anywhere on this page
What you'll see
Your picture opens stretched for your screen, as astronomy apps show it, with what the telescope and camera noted.
- Auto stretched from its own levels • Bayer data in color
- Every image and plane a page
- Show details • Object, telescope, camera, exposure and filter
- Export • Save as PNG or JPEG
About FITS
Astronomers made FITS in 1981 to move pictures between observatories, and NASA, ESA and every observatory still use it. Hubble's and Webb's images come as FITS, and so do the frames N.I.N.A. and SharpCap save at backyard telescopes.
A FITS file is a header of plain text cards, like EXPTIME = 300 and OBJECT = 'M42', then the pixels as 8 to 64 bit numbers, far more levels than a screen shows. One file can hold several images, a cube of planes, and tables beside them.
Filepeek reads it in your browser and stretches it the way astronomy apps do, from the picture's own levels, so faint nebulae show without burning the stars. A color camera's Bayer data is turned into color, every image and plane is a page, Show details gives the object, the telescope, the camera, the exposure, the filter and where it points, and Export saves PNG or JPEG.
Flexible Image Transport System
.fits • .fts
Format
- MIME type
- image/fits
- Made by
- Astronomers at NRAO and Kitt Peak, now the IAU
- Released
- 1981
Inside the file
- Pixels
- 8 to 64 bit integers or floats
- Header
- Text cards, like EXPTIME and OBJECT
- Holds
- Images, cubes and tables
- Color
- Bayer data or three planes
Opens in every browser
No browser shows FITS by itself. Filepeek opens it in Chrome, Edge, Firefox and Safari.
- YouChromeOpens through Filepeek
- YouEdgeOpens through Filepeek
- YouFirefoxOpens through Filepeek
- YouSafariOpens through Filepeek
Apps that open FITS
- WindowsSiril and SAOImageDS9, free • PixInsight
- MacSiril and SAOImageDS9, free • PixInsight
- iPhone and iPadNo app built in opens it
- AndroidNo app built in opens it
Questions
How do I open a FITS file?
Drop it on this page or press Peek a FITS. It opens stretched for your screen, with nothing to install.
Why is my FITS image black in other apps?
Telescope cameras record far more levels than a screen shows, and the sky's faint light sits in the lowest few. Apps that show the numbers as they are show black, so Filepeek stretches the picture from its own levels, as astronomy apps do. The file stays as it was.
Why does my color camera's picture show gray?
A color camera records a Bayer pattern, one color for each pixel. When the header names it, as BAYERPAT, Filepeek turns it into color. Without it the picture shows gray, as the sensor saw it.
Can I see where the telescope pointed?
Yes. Show details lists the object, its right ascension and declination, the telescope, the camera, the exposure, the filter, the gain and the sensor temperature, when the header has them.
Does it open .fit and .fts files?
Yes. A .fts is a FITS, and a FITS named .fit opens too, by its first bytes. Garmin's .fit files are workouts, not pictures.
Does it open compressed FITS?
Pictures packed with fpack, usually named .fz, aren't read, and say so. Unpacking them with funpack gives a FITS that opens here.