There are quite a few servers which offer images of either user-selected
or observed sections of the sky (sometimes called "postage stamps").
Current servers and client browsers mostly deal with simple single-wavelength
FITS images with
World Coordinate
System (WCS) sky coordinate to pixel transforms encoded in their
headers. See
Mark Calabretta and Eric Greisen's paper
- SkyView,
a versatile Mosaic-based, multi-wavelength image server, has been
implemented at NASA/Goddard. It also returns a FITS file with WCS information.
The SkyView Basic
Form lets you select center coordinates, a sky survey, and image
projection, size, and brightness scaling.
The
SkyView Advanced Form adds exact image size specification in pixels
and degrees, catalog overlays, multi-color image overlays, and
contouring.
- DSS
(Digitized Sky Survey):
The
STScI Catalogs and Surveys Group
scanned the astrophotographic plates of the Palomer Observatory Sky Survey (POSS) and the
Sothern Sky Atlas (SERC) to make images of the entire sky an high resolution. Extracts
from the DSS1 and its followup DSS2 survey are available from many sources:
The
SAO Digitized Sky Survey Server
forms-based server retrieves FITS or GIF images within the Harvard-Smithsonian
Center for Astrophysics.
-
Aladin Interactive Sky Atlas
An interactive software sky atlas visualizing digitized images of
any part of the sky, with superimposed entries from astronomical catalogs.
- Telescope Image Archives:
HST
(Hubble Space Telescope at STScI)
[ESO]
(Hubble Space Telescope at ST-ECF)
[CFHT]
MAST
(Multimission Archive at Space Telescope)
NOAO Image Gallery
ESO Science Archive Facility
ESO + HST Querator
-
Super Cosmos Sky Surveys
FITS or GIF images from sky survey plates taken with the UK
Schmidt telescope (UKST), the ESO Schmidt, and the Palomar Schmidt,
scanned by the SuperCOSMOS advanced photographic plate digitising machine.
- ADIL: The
Astronomy Digital Image Library
is a collection of astronomical, research-ready images, browsable and
downloadable in FITS format.
-
The Galaxy Catalog: Digital images of 113 nearby galaxies
in several passbands (FITS, GIF, JPEG) and color (JPEG) from Princeton.
- VLA: The
NRAO/VLA Sky Survey,
a survey of the sky north of -40 declination at wavelength of 20 cm,
is being served by NRAO.
FIRST
(Faint Images of the Radio Sky at Twenty-centimeters) is
a project designed to produce the radio equivalent of the Palomar Observatory
Sky Survey over 10,000 square degrees of the North Galactic Cap.
- IPAC: The source for infrared images
The
Quick Look 2MASS Atlas images cover the entire sky at J, H, and K.
They also serve the entire sky a longer IR wavelengths through the
IRAS Sky Survey Atlas (ISSA).
The
IRAS Galaxy Atlas,
containing 60 and 100 micron data of the galactic plane and several other
regions, can return FITS images.
If you know what IRAS plate you are looking for, the entire ISSA plate
sets for the
southern
hemisphere
and the
northern
hemisphere are online.
- ROSAT:
The ROSAT X-Ray All-Sky Survey has images of the entire sky in
various formats.
- PDS:
In addition to the
Planetary Data System Planetary Image Atlas,
NASA's PDS archive has spacecraft images of
the Moon and
Mars, with
Venus and
Jupiter coming.
- SkyMorph
SkyMorph enables searches for variable, moving or transient objects.
It provides convenient access to optical images and catalogs generated by
the Near Earth Asteroid Tracking (NEAT) program These include more than
67,000 CCD images covering a large fraction of the sky.
-
USNO Flagstaff Station Integrated Image and Catalogue Archive Service
This facility allows you to extract catalogue data from the USNO-A2.0
and/or ACT Catalogues and plot up finder charts from these lists. In
addition, we have available the raw images from scanning the major
photographic surveys. You can overplot the catalogue data onto the
images, as well as overplot your own additional markers.
-
Galaxy Stock Images and Photos
They cost money to buy and use, but you can browse through this extensive
collection of astronomical and space imagery for free.
Accessing archived data now
International Virtual Observatories
Setting up the protocols to make all online astronomical data accessible
- SAOimage,
originally written by Mike vanHilst of SAO, has been revised by Doug Mink,
also at SAO, to display WCS information with FITS or IRAF images, including
plate solutions in the format used by the Digital Sky Survey, as well as
the all proposed standard FITS WCS formats using Mark Calabretta's
WCSLIB subroutine library. It is available by anonymous
ftp from
ftp://cfa-ftp.harvard.edu/pub/gsc/SAOimage/.
The same WCS subroutines are used in ds9, SKYCAT and SAOtng.
- DS9 is
SAO's latest astronomical data visualization application and runs on many
different platforms, including displays with most standard depths. There
is an
online reference manual.
- The European Southern Observatory's
SKYCAT tool not only
tracks in WCS, but can overplot catalogs retrieved over the network.
- NASA Goddard's FV
program displays both FITS images and tables. It runs under Microsoft Windows
95 or NT as well as on any Unix platform.
- SAOtng, by
Eric Mandel at SAO, is evolved from SAOimage and is based on the IRAF Ximtool.
Use of the X Public Access mechanism makes it easily extensible.
- FITSview,
by Bill Cotton of NRAO, displays FITS images on PC's running
Microsoft Windows 3.x or 95,
Macintoshes,
as well as
Unix machines.
It is available as source or compiled executable binaries for all of these
different operationing systems and includes very good online help.
- IPAC's Skyview
(no capital V) program can deal with WCS, but needs a better browsing interface.
- Doug Mink's
Skymap
has extensive overlay capabilities, despite a rudimentary image display,
Browsing adaptations will soon be made.
- ATV
is an interactive image-display tool for IDL from
Aaron Barth.
- The Java-based Horizon
Image Data Browser was developed at NCSA using WCSLIB.
A Test
If you have the line
image/x-fits fit fits fts FIT FITS
in your mime.types file and a browser set up to deal with the
image/x-fits mime type by an entry something like this in a mailcap file
image/x-fits; saoimage -fits %s
you should be able to retrieve and display a FITS image of M51 like the one
at the top of this page from
http://tdc-www.harvard.edu/postage_stamp/wpix.fits
If you are using SAOimage, click on histeq to histogram-equalize the image
and get a good picture of the galaxy M51.
Other settings in your mailcap or helper file to make sure your browser recognizes
FITS images should include
image/fits; saoimage -fits %s
application/fits; saoimage -fits %s
application/fits-image; saoimage -fits %s
saoimage may be replaced with your favorite FITS viewer:
skycat, saotng, fitsview or xfitsview, ds9, or even xv.
Graphically Editing FITS images
A
FITS-reading plug-in for Adobe Photoshop
is available, but it can read 8- and 16-bit integer images only.
There is also a plug-in
for the GIMP open-source image processing
package, and ImageMagick also
reads and writes FITS files.
The widely-available
PBMPlus and
NetPBM
graphics toolkits can be used to convert FITS files to other formats
or vice versa.
