Posts Tagged ‘surveys’

SkyView Allsky Images from Gamma-ray to Radio

Tuesday, April 26th, 2011

We have been thinking of ways to add more educational aspects to the SkyView website and our first step was to create a slide show of survey data that cover the entire sky. This first image set is in equatorial coordinates and we hope to add galactic images soon and then interactive enhancements as time permits. Of course the first lesson we learn from these images is that the sky looks different in different wavelengths. We also see that certain celestial features come and go. This is typically dependent on the process by which the radiation is emitted.

We hope that these images are interesting to SkyView users. Let us know if you have any comments.

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Posted in Notices | 12 Comments »

SkyView Fermi LAT Surveys

Monday, February 28th, 2011

We have just released two gamma-ray all-sky surveys based upon the Fermi LAT weekly data. Fermi images go much deeper and have somewhat higher resolution than the old EGRET surveys. Fermi is also sensitive to gamma-rays at significantly higher energies, up to 300 GeV.

The two surveys cover the bands 0.1-5.4 GeV and 5.4-300 GeV. There are many more counts in the lower energy survey and many more sources are apparent there. The surveys are generated from the weekly exposure maps and photon lists supplied by the Fermi LAT team. The exposures are summed together to create an overall exposure map and the photon lists are combined and resampled in 1/8 degree pixels in a Cartesian projection. The combined exposure at the center of each of these pixels is then sampled and weighted by the size of the pixel to get the normalized exposure. The ratio of the counts to the weighted is used to get the intensity of the pixel. Currently we are only providing the intensity maps but we can also include the counts and exposure maps if there is interest. We also hope to provide a 3-D Fermi survey with perhaps 10 energy bands.

Fermi’s new hard band extends SkyView‘s frequency coverage a full decade above the previous upper limit.

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Posted in Announce | No Comments »

SkyView updates GALEX survey

Wednesday, February 16th, 2011

Galaxy Evolution Explorer (GALEX) surveys have been updated to use the GALEX GR6 release. As mentioned in a previous post GR6 improvements include more sky coverage and a bit better calibration. Image generation for GALEX may be slow for a period of time as the data file caches get rebuilt. More GALEX mission information can be found at the Space Telescope Science Institute GALEX page.

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Posted in Announce, Notices | 4 Comments »

New SkyView Survey: WMAP

Wednesday, May 13th, 2009

Microwave data from the WMAP (Wilkinson Microwave Anisotropy Probe) mission are now available in SkyView. WMAP is the first fine-resolution (0.2 degree) all-sky map of Cosmic Microwave Background (CMB) radiation. For more information see our Survey Information page and the WMAP archive site.

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Posted in Announce, releases | 2 Comments »

GALEX survey available!

Thursday, May 8th, 2008

SkyView now includes data from GALEX. This is a major new survey for us. GALEX provides high resolution images in the ultraviolet for about a quarter of the sky. This fills a substantial hole in the resolution/regime coverage for SkyView. The GALEX data are accessed through the Web from MAST. Currently the fourth release of GALEX data (GR4) is being ingested and we will update the survey description to include new data as it becomes available.

By default GALEX uses a different image finder than other surveys. When it needs to choose which input image to sample for a given output pixel, it looks only at images whose center is under some maximum radius from the position of the output pixel and then chooses the one of those with the longest exposure time. The maximum radius is currently set to 0.58 degrees. These settings can be overridden if you use the SkyView-in-a-Jar locally, but are fixed for the Web interface.

M81 3 Color image: Red: DSS2R, Green: GALEXNear, Blue: GALEXFar
A three color image of M81 with Red=DSS2R, Green=GALEX Near, Blue=GALEX Far

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Posted in Notices, releases | 1 Comment »

New RASS Diffuse Emission maps

Tuesday, April 29th, 2008

A new survey including seven bands of data from the ROSAT All Sky Survey data has been added to SkyView. The RASS Background 1-7 data show the entire sky in diffuse X-ray emission. Point sources have been subtracted out. This new survey replaces the RASS 1/4, RASS 3/4 and RASS 1.5 KeV maps. Those data are still available but we no longer display the survey names on the Web page. You can still access them through the batch interfaces or using the Jar file. The new data sets have better spatial and energy resolution and were built by the Steve Snowden who also created the earlier maps.

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Posted in Documentation, releases | No Comments »