What's New in SkyView?
Older news (prior to May 2007)
- April 28, 2008
- SkyView now has a blog
that we will be using to make announcements of what's happening in SkyView.
We hope that with this new format we can provide you with more timely insight
into changes in SkyView and to engage you in helping us to know how
we can improve SkyView.
We do not anticipate updating this page further, but we anticipate more frequent
updates to our blog. Please join us there and let us know what you think.
- April 25, 2008
- We've discovered a bug in the smoothing routine used in SkyView.
if the image contains NaNs, they convert all pixels to their right
to NaNs also. A fix will be installed Monday April 26.
- March 31, 2008
- SkyView will be unavailable from 8:00am-5:00pm EST on Saturday April 5, 2008 due to a network system upgrade. We apologize for the inconvenience.
- February 28, 2008
- A bug associated with the ClipIntensive keyword was fixed. When an output
image oversampled the survey data, output pixels whose area was entirely contained within
a single input pixel were not being normalized by the area of the output pixel.
- February 26, 2008
- The BAT surveys uncovered a error in SkyView's processing of the
LONPOLE keyword. The effect was that for these surveys the third of the sky
nearest the galctic poles was rotated by 180 in RA. The galactic plane was
unaffected. This error has been corrected. We apologize for the error.
The BAT data is served as six images similar to the COBE quadralaterized cube data
except that each facet uses a zenithal equal area projection. The WCS
specification indicates that the default LONPOLE for images at the pole
is different than for images at other latitudes and SkyView handled this
situation incorrectly. The effect was that for the two BAT images
for each BAT survey that were at the poles, the images were incorrectly
rotated by an extra 180 degrees.
The downloadable SkyView-in-a-Jar application jar file and the jar file used for the SkyView
website are now the same so changes will instantly be available to
all SkyView users.
- February 15, 2008
- The SkyView servers have just upgraded to version 1.6 of Java.
This should improve performance somewhat but should not otherwise
affect the system.
- February 13, 2008
The SUMSS radio survey has been updated, filling most of the remaining holes
coverage south of declination -30. The SUMSS survey is now considered complete
though there are a few remaining gaps.
The Swift BAT All-Sky Flux and Significance Surveys have been updated. Images can now be generated for four separate energy channels as well as the full energy range. The 4 energy channels are: 14-24, 24-50, 50-100, and 100-195 keV. Each of these is represented as separate survey, and an averaged survey over all bands is also given. See the Survey documentation for details.
- February 11, 2008
- Brian McLean at ST ScI has sent us a complete set of the latest astrometry
for the DSS and DSS2 images. The astrometry from 263 plates is different
from what was included in the distribution we received from ST a few months ago.
In a few cases the differences are significant and can shift images substantially.
These updated astrometry
files have been installed in the SkyView DSS area. The 263 plates are approximately
3% of the total number of plates.
- February 11, 2008
- After an extended absence, the NEAT/SkyMorph survey is once again available
for use in SkyView. This survey links to images taken by the Near Earth
Asteroid Tracking program. There are currently more than 600,000 images available
in the NEAT archive. NEAT images are randomly scattered on the sky and SkyView
treats these differently from other surveys. SkyView looks for a recent image
near the requested image center and resamples only that one image, no mosaicking
of multiple images is done. Thus NEAT images
are restricted by the size of the original NEAT data (about 1.5 degrees).
More flexible access to the NEAT archive, including the ability to get all of the
images at a given point, and also to track moving objects is avilable at
the SkyMorph web site.
- February 6, 2008
- The SDSS team has corrected the error in their DR6 simple image access
service and SkyView is once again using this latest release.
Sergei Goshko at Sky-Map.org has found five more DSS plates with out of date
astrometry in the DSS distribution. These are
The astrometry files for these plates have been updated.
|Plate||Survey||Approx J2000 position |
After a few reports of DSS tiles which could not be decompressed from
Sergei Goshko, SkyView attempted to decompress every DSS and DSS2 tile in
its archive. 19 tiles were found to have have problems.
Brian McLean from ST ScI has sent corrected tiles for nine of these.
The affected tiles are:
Many thanks to Sergei and Brian for helping to clean up these rare problems with
DSS data. To understand the scope of these problems with the DSS note that the
total number of DSS and DSS2 plates is about 7300 with about 6 million tiles in all.
- February 5, 2008
- An error in the metadata of the nH survey has been corrected. This
might have caused requests for this service which did not include the center of the
image to fail.
- February 4, 2008
- We have noted a problem with the Simple Image Access service
used to access SDSS DR6 data after a user noted that the SDSS didn't
seem to work. Some coordinate information returned by the SDSS
has the RA and Dec switched. SkyView has reverted to the DR5 until this problem
- January 31, 2008
- The Swift Burst and Transient (BAT) All-Sky survey has been released and is now available through the SkyView
web site. These surveys, with about 10' resolution, straddle the boundary between the X-ray and gamma-ray regimes and we've currently classified
them as gamma-ray, but that may change in the future. The current surveys use 9 months of BAT data.
The data comprise four bands, the scalar images sum the data from all four bands.
Two surveys are included one giving the flux observed, and the other the significance of the detection
at a given location. Further surveys based upon longer time periods may be released in the future.
- January 30, 2008
- The astrometry for the DSS2R image XS046 (including the region near RA=300., Dec=-73.) has been corrected.
- December 26, 2007
- Due to an increase in batch jobs requesting very large images a time limit of 20 minutes is now in place for SkyView batch processing to prevent web server overload. Please note that the SkyView In A Jar download is available for generation of large images. If you have questions or comments please contact us.
The astrometry for the DSS2R image XP340 (including the region near 20h30m, +40d) has been updated.
- December 5, 2007
- Permission problems on some of the files in the DSS2R caused
many queries of this survey to fail. The permissions have been fixed.
- November 20, 2007
The DSS2R survey is now being served as a local survey from
SkyView. All DSS surveys are now local.
- November 19, 2007
Incorrect FITS headers for several DSS data files have been corrected.
The headers for regions XI188 (DSS2IR), XE618 (DSSR), XP232 (DSS2R) have been updated.
- November 7, 2007
that shows the mouse coordinates. Leading 0's in the fractions
of seconds in sexagesimal coordinates were being omitted.
Most commonly this was in the RA. E.g.,
10 10 10.01 would be shown as 10 10 10.1
however it could affect either RA's or Dec's when users
specified very small fields of view.
This bug has been fixed and the format of the displayed coordinates
has been slightly modified.
- October 16, 2007
A bug in SkyView Simple Image Access outputs was fixed. The NAXES
and NAXIS columns were incorrectly specified.
- October 2, 2007
- The system upgrade scheduled for September 28 was postponed and is now
scheduled for 9pm EDT Saturday, October 6 through 1am Sunday, October 7. SkyView was be intermittently unavailable during that time. We apologize for any inconvenience.
- September 24, 2007
- Now that the new SkyView hardware and software has been
stable for several months we have removed access to the old SkyView
site. Old versions of the software will no longer be maintained.
Please let us know
if you have any questions or concerns.
- September 4, 2007
- The DSS1R, DSS1B and DSS2B surveys are
now all being served using local data (along
with the DSS2IR which had transitioned earlier).
Unfortnately a few of the files for the DSS2R survey
are missing, so that will continue to use HST MAST
source data for a while.
Illustrating one of the reasons why we getting local
copies of the data,
the HST MAST service which provides
DSS data seems to be down today. Users will
still be able to get DSS2R data from regions which
have been cached in earlier SkyView requests.
The names of the DSS1B and DSS1R surveys are somewhat
confusing since they really only contain information
from Palomar Observatory Sky Surveys, and thus have
coverage for declination > -30. These may be
changed to POSS1R and POSS1B at some future date
though the old names will continue to be supported.
- August 21, 2007
- A bug in the SkyView VO SIA service was corrected.
The <DATA> element was missing in the VOTable returned.
- August 8, 2007
- The latest release (DR6) of the Sloan Digital Sky Survey (SDSS) covering over 9,583 square degrees of the sky in the optical wavelength is now available through SkyView. The latest coverage map and more information can be found at the SDSS site.
A reported problem generating images via the Batch interface using the old
syntax, specifically SFACTR=Default, has been fixed. A fix was also made
to correctly generate remote survey images that have Brightness
- July 26, 2007
- An updated version of the SkyView web
interface has been released. The major new change
is that users can now run their mouse over an image
and the pixel and celestial coordinates will be shown.
Users click to freeze the coordinate update. A 'Zoom'
link retrieves an image at the selected coordinates with
a scale 1/2 the current image. Users can use the Back
button to unzoom.
Small changes were also made to logging and
to support some common misspellings of projection names.
- July 26, 2007
- The DSS2 IR survey is now being served locally from
the SkyView server rather than through downloads
from ST MAST. Image generation should be much faster especially
for larger regions.
The other DSS2 surveys should be served
locally within a couple of weeks.
- July 18, 2007
- Now that the new SkyView site has been functional and stable for a couple of months we will be phasing out the old interfaces. The target date to remove access to these pages is September 21, 2007.
- July 17, 2007
- The 0034.5 MHz GEETEE low-frequency radio survey has
been rebuilt for use in the new versions of SkyView.
The WCS used in this new version is consistent with the
observed overlaps in the original GEETEE image tiles and the
indicated centroids of the images. There are some inconsistencies
between the descriptions of the images and their WCS's
We are contacting the original authors of this
survey to ensure that we've gotten the correct solution in
place for this data.
- July 17, 2007
- During the reboot from the scheduled down-time on July 13-14
several disks failed. The main SkyView service was restored by
the evening of July 14 but the old SkyView interface was
still refering to data on the old disks till the morning of
Tuesday July 17 when it was switched to a working disk.
- July 11, 2007
- Skyview will be unavailable from 6:00pm Friday July 13 through Saturday July 14 due to electrical work that is necessary to maintain servers. We apologize for the inconvenience.
- June 27, 2007
- Problems with retrieving 2MASS images were traced
to an external Web site being down. 2MASS data and catalog
retrieval requests both use an XML format named VOTable
and the formal description of this format is provided via
a URL. The Java parsing of these files tried to retrieve
this description file, but unfortunately the site hosting
it was not available. We have disabled the linking
to this external site and 2MASS and catalog requests
should now be working.
- June 26, 2007
- New version of SkyView JAR installed.
A fix was made to correct the translation of old SkyView syntax
values for the batch interface.
The NEAT survey has been temporarily removed from the list
of available surveys while we work on image generation problems.
- June 25, 2007
- A problem with the 2MASS survey caches has been
reported (thanks to Dieter Shertl) and is now corrected.
The file names used in the 2MASS cache were not guaranteed to be
unique over the entire sky. E.g., a 2MASS source file named
ji0610056.fits.gz would be generated around both
RA,Dec=(4.5,-7) and at (9.5,-73).
If users asked for data for both of these regions then the
second request tried to reuse an inappropriate image and failed.
If the output image used multiple inputs, then this problem
could leave parts of the output image blank. To correct
this the cache files no include the coadd-key as well as the
file name returned from 2MASS which should make the file
names unique. We apologize for the error.
To correct this error all cached 2MASS images have been deleted
since the coadd-key is not available from the image. Retrieval
of 2MASS data may slow somewhat until the cache data is recovered.
- June 21, 2007
- Arc projection has been added to the Projection options on the web Query Form. Also, the EUVE surveys which had mysteriously disappeared from the Query Form have returned. We apologize for any inconvenience.
- June 18, 2007
- New version of SkyView JAR installed.
- Added Arc projection (the choices on the Web site
should be added shortly, but this is available immediately
in Batch mode).
changes to the 2MASS SIA service so that 2MASS
images are available (this changed earlier today).
- Changed the way DSS1B, DSS2B, DSS1R, DSS2R and DSS2IR
surveys are handled. These surveys are handled as tiled
downloads from the ST ScI server. An approximate solution
for the tile in a standard gnomonic (TAN) projection is
given with the tile and SkyView had been using that
solution. However we find that errors of ~2" are possible
in that projection and now these surveys use the DSS-style
Larger tiles are now retrieved near the poles to accommodate
problems when the actual observation was rotated with
respect the the nominal coordinate frame.
- When a user asks for an inverted color table, the
displayed color table will also change.
- A number of other changes including removal of
redundant and incorrect entries in the survey documentation
and better logging facilities.
- June 13, 2007
- SkyView was unavailable for a short period this afternoon
just after 2:00pm EST when severe weather caused the SkyView
machines to shut down.
- June 12, 2007
- Some errors in dealing with data near (with a few degrees)
of the poles in the DSS2 surveys have been identified.
Some of the WCS information returned from ST ScI is incorrect
and also at the poles the tiles retrieved are sometimes too
small to address possible large rotations. Modifications to
the DSS2ImageGenerator and XML descriptions will be made later
this week to address this problem.
- The skys address for SkyView is now being
translated to the same address as skyview and the old
SkyView hardware is no longer visible to the public.
The old SkyView interfaces will continue to be
supported for a while but we anticipate phasing them
out this summer.
- June 8, 2007
- The transition of the skys.gsfc.nasa.gov address to our
new machines is now scheduled for noon, Tuesday, June 12.
Please let us know if you have any concerns or issues
with this transition. After this transition the two
addresses skys and skyview will be treated as aliases, so
that data generated under one address will be retrievable under
- June 7, 2007
- Most Internet Explorer 7 browser issues have been resolved.
Please let us know if you see any problems.
- Users who have problems with the standard form may wish to
- June 5, 2007
- Handling of images where there are no survey data in the
area has been changed for Batch processing. Batch requests
were receiving an HTML document not a FITS file. Now an
empty FITS file is returned. The FITS keyword SV_ERROR is
set to indicate that no image data was found.
- Futher enhancements to the gridding algorithms should
ensure that images in Car projections will be grid properly
regardless of the origin of the image. The grid interval
selections have been tweaked to make better choices at
some image sizes.
- June 1, 2007
- SDSS surveys are unavailable (except for small cached
areas) due to problems at the SDSS sites. As soon as the
SDSS archives come up access through SkyView will be restored.
- A bug in the gridding algorithms was fixed. The grid values
for RA were occasionally being selected at inappropriate intervals such
that the grid value was not exact. E.g., a grid line labeled 6h10.1
minutes might actually be 6h10.1333333 minutes. Incorrect grid
should generally be detectable by looking at the differences between
the grid values. In the most common case every third grid interval
will be larger.
- May 26, 2007
- Uploaded updated version of SUMMS files from U.Sydney and
created updated SUMMS survey description file pointing to the
data. The coverage of the survey
is much improved.
- May 24, 2007
- Version 2.3 of SkyView-in-a-Jar released in the JAR directory.
This version will support the new SkyView Web site starting
May 29, 2007.
- May 17, 2007
- Very Low-frequency Sky Survey
added. This is a 74 Mhz VLA survey of the sky north of -30 degrees
with about 1' resolution. The survey is currently about 95% complete.
- May 2007
The new Java based SkyView engine has been released along with
new SkyView hardware.
More complete information on this is given in our transition document which discusses
the schedule and implications the major
SkyView upgrade conducted from May-September 2007.
Direct all questions regarding SkyView to our Feedback Page
SkyView has been developed with generous support from the NASA AISR
and ADP programs (P.I. Thomas A. McGlynn)
under the auspices of the High Energy
Astrophysics Science Archive Research Center (HEASARC) at the NASA/
Astrophysics Science Division.
We gratefully acknowledge the support of NASA and contributors
of SkyView surveys.