• display FITS images, binary tables, data cubes, and multi-extension files
• colormaps, scaling, pan, zoom, binning, blending, print, export ...
• region support: create, manipulate, import, export, ...
• drag and drop images, regions, catalogs
• server-side and local analysis using the JS9 public API
• control JS9 using scripts from the Linux shell or Python
• runs on Macs, Linux, Windows, iPads, iPhones, ...
• runs as a Desktop app, in all modern browsers, mobile apps are coming ...
• utilizes WebAssembly, if present (FITS processing at near native speed!)

Go to JS9 web site and drag a FITS data file onto the JS9 display:

http://js9.si.edu

The JS9 web site also contains on-line documentation, demos, and release downloads.

For many users, there is no need to install: simply use the JS9 web site to display your data. You can even upload your FITS files to the web site and run our server-side analysis.

Installing JS9 allows you to create your own web pages, tailor site parameters, and add your own local and server analysis tasks. Grab the latest version from JS9 on GitHub:

git clone https://github.com/ericmandel/js9

Load a local page into your browser:

file:///path/to/js9/js9.html

(NB: Chrome needs to run with the --allow-file-access-from-files switch to use the file URI.)

For Desktop use, install Electron.js and generate js9 script:

./mkjs9 -q

Use the js9 script to start the Desktop app and load an image:

js9 -a ~/data/m13.fits

For more advanced support (web-based support, support for handling large files), build the JS9 helper and install JS9 in a web directory:

# configure location to install the JS9 web files,
# where to find cfitsio library and include files,
# where to install programs and scripts,
# what sort of helper to build:
./configure --with-webdir=[path_to_web_install] \
            --with-cfitsio=[path_to_cfitsio]    \
            --prefix=[path_to_prog_install]     \
            --with-helper=nodejs

# the usual ...
make
make install

# start helper
cd path_to_web_install
node js9Helper.js 1>js9node.log 2>&1 &

The js9 script allows you to control a JS9 web page from the Linux command line using the JS9 Public API (scripting requires installation of JS9 and either node.js or Electron.js):

js9 Load chandra.fits '{"scale":"log","colormap":"red","contrast":5.78,"bias":0.15}'
js9 Load spitzer.fits '{"scale":"log","colormap":"blue","contrast":6.3,"bias":0.54}'
js9 ReprojectData chandra.fits

Python users can install pyjs9:

git clone https://github.com/ericmandel/pyjs9
...
import pyjs9
j = pyjs9.JS9()
j.Load('chandra.fits', '{"scale":"log","colormap":"red","contrast":5.78,"bias":0.15}')
j.Load('spitzer.fits', '{"scale":"log","colormap":"blue","contrast":6.3,"bias":0.54}')
j.ReprojectData('chandra.fits')

JS9 is distributed under the terms of The MIT License.

Eric Mandel, Alexey Vikhlinin

Harvard-Smithsonian Center for Astrophysics