The remote system that serves 2MASS data was down for scheduled maintenance for a couple hours today. As of 3:50pm EST service has been restored and 2MASS data is again available in SkyView. We apologize for any inconvenience.
Archive for the ‘Uncategorized’ Category
SkyView 2MASS data interruption March 1, 2011
Tuesday, March 1st, 2011Clip resampling of intensive quantities in SkyView
Friday, February 11th, 2011The SkyView web page now has two different options for using the Clip resampler. The clip resampler computes the overlaps between the user image’s output pixels and the original survey pixels and adds up the contributions from each overlap. The default behavior sets the output pixel to the sum of all of the inputs. This is the only option that used to be available in the Web interface. Using this option if you could integrate over exactly the same region of the sky in both the input and output images, you’d get exactly the same number: flux is exactly conserved.
This makes sense when what is being measured is an extensive quantity like counts or flux. If the output pixels are bigger than the input pixels, then the values in those pixels should typically be bigger too.
Often however, the original data are an intensive measurement: the size of the pixels should not directly affect the values we place in them. E.g., the map might be of temperature or intensity. The temperature at some point should not be proportional to the size of the pixel. If you select the new Clip (Intensive) sampler, the output pixels will the averages over the overlapped pixels in the input. So the output values will not depend directly upon the size of the pixels.
If you are using SkyView-in-a-Jar, this option has always been available with the combination of settings
sampler=Clip ClipIntensive
and we’re now making the choice available on the web as well.
Recent SkyView Availability issues
Wednesday, September 1st, 2010SkyView experienced two separate outages the last two days. 2MASS data were unavailable most of Tuesday due to the downtime of the remote system hosting the 2MASS survey data. The problems were resolved and 2MASS data are now available again in SkyView.
We also experienced image generation problems due to heavy usage that caused our temporary storage space to be depleted. We have tweaked the processes that clean out this area. As a result FITS files and specifically large ones will not be stored as long as they have been in the past. We will monitor the storage area to see if we can make the files available for a longer period of time and will look into possibly creating a larger storage area.
SkyView moved to new VM architecture
Tuesday, August 3rd, 2010The operational SkyView machines have been moved to a virtualized environment. The numeric IP address for SkyView has been changed to 129.164.179.52. This actually points to a load balancer on top of several virtual machines. The new machines are already being used inside Goddard, and the change should propagate throughout the rest of the web over the next day or so as domain name servers refresh their caches. The address skys.gsfc.nasa.gov points to the same location.
So far there have been no problems reported in the transition. All surveys and services, including the SkyMorph NEAT archive and VO access should be available. Please let us know if you notice any anomalies.
SkyView on Flickr
Monday, June 7th, 2010A set of beautiful images mostly using RGB overlays from the DSS surveys has been put up at in a SkyView Flickr group. Flickr allows comments and tags on images. Perhaps Flickr is where the SkyView image gallery should go?
Timeouts for SIA requests.
Wednesday, April 14th, 2010This morning we ran into a problem where too many SkyView requests were running simultaneously and so we had to reject some image requests. One of the reasons this happens is that SkyView accesses some data from remote services using the Virtual Observatory Simple Image Access (SIA) protocol. If those services are unavailable our requests can hang and build up on the system. Today we implemented a timeout for such requests of 15 seconds. There is also a new option, SIATimeout, that can be set when using the SkyView JAR file.
SkyView Blog Housekeeping
Tuesday, October 27th, 2009We have upgraded our blog software and all seems normal. Let us know if you see otherwise.