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What's New from May 2007 through April 2008

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 has found five more DSS plates with out of date astrometry in the DSS distribution. These are
PlateSurveyApprox J2000 position
The astrometry files for these plates have been updated.

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 is resolved.
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
Brian Skiff reported an error in the SkyView JavaScript code 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 Scaling applied.

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 mor ning 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).
  • Addresses 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 WCS.
    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 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 the other.
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 try the non-JavaScript version of the form.
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.

Older news (prior to May 2007)

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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/ GSFC Astrophysics Science Division.

We gratefully acknowledge the support of NASA and contributors of SkyView surveys.

A service of the Astrophysics Science Division at NASA/ GSFC
and the High Energy Astrophysics Division of the Smithsonian Astrophysical Observatory (SAO)

HEASARC Director: Dr. Alan P. Smale
HEASARC Associate Director: Dr. Roger Brissenden
Responsible NASA Official: Phil Newman
Web Curator: Laura McDonald

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