The information displayed below web form query image results now includes the coordinates of the requested center in decimal format. This applies to queries where the entered position is in any format other than decimal (object name, coordinates in sexagesimal format, etc). We thought this additional image information might be helpful.
We have added an Image Gallery to the site and we welcome your SkyView images. Just click the Add to Gallery button below your generated images and they will be added to the gallery and included in the pool of images that are randomly displayed on the main SkyView page. The button will appear if your image is below a set size limit. Images will stay in the Image Gallery until we start running out of storage space at which time we will remove older images.
So if you have created a image that you would like to share please do so! And let us know if you have any questions or comments.
One of the major functions of SkyView is mosaicking multiple images together. Occasionally you may be interested in finding out which source image was used for a given pixel. The FITS header indicates which images were used somewhere, but normally that’s all the information you can get.
Recently we added a new class skyview.process.IDMosaic. You can use this class to get exact pixel source information when using SkyView (in local mode). To any request add the setting mosaicker=skyview.process.IDMosaic. This will generate an output FITS file where each pixel is the index of the image used to create it. You can compare this file with the file generated using the normal mosaicker to understand exactly how your image was generated.
SkyView treats a number of projections (Aitoff, Cartesian, Sansom-Flamsteed/Sinusoidal) as fixed projections. Regardless of the position you specify, the sky is projected to the plane in the same way. All that your coordinate entry changes is the center of the image you get. Thus if you ask for an image near the pole in a Cartesian projection, you’ll find that there’s a large distortion since you are near a singularity in the projection. By contrast, projections like the Tangent and Sine projections are centered at the position you specify: that’s the point of minimum distortion.
If you wanted to make an Aitoff or Cartesian map really centered on some point other than the coordinate origin, older versions of SkyView couldn’t help you. With the version we’re releasing today, you can specify the new RefCoords setting. It takes a pair of decimal coordinates and uses that as the coordinate center for fixed projections. E.g., use RefCoords=0.,90. Position=0.,90. projection=Ait to ask for an Aitoff projection centered around the pole. Note that you still need to specify a position.