Recently we’ve been updating and systematizing some of the metadata we have on SkyView surveys, trying to make sure that we have consistent, quantitative description of each one. Some of the key metadata are the resolution of the survey on the sky, sensitivity and sky coverage. It’s quite difficult to provide single numbers for these in a consistent way. E.g., for lots of surveys the resolution varies depending upon where you are. In some cases it even depends upon the spectrum of the source.
So take this with a grain (or maybe even a spoonful) of salt, but here’s a graph of the nominal resolution of SkyView’s surveys as a function of wavelength.
The surveys span about 18 orders of magnitude in frequency. That’s pretty amazing. If you want to get a sense of how big that range is, consider the ratio of the distance to the nearest stars to your height… An immense difference — but only 1% of the range of SkyView‘s frequency coverage!
Looking at the graph we can split surveys into three categories based on their resolution: High resolution surveys have better than 10″ resolution. Most of these are concentrated near the optical, but there are a couple of outliers. Medium resolution surveys, with resolutions of about 1’ are the most common. These surveys have resolution comparable to our eyes. A fair number of surveys have resolutions of a degree or more. This doesn’t necessarily mean they are less valuable. Sometimes you want to look at the forest and not the trees.