Havin fun in the deep sky

kw: astronomy, surveys, pastimes

Among my favorite images from my involvement with The Galaxy Zoo Hubble is this one of AHZ2000ke7, a distant (2.26 GLy or 0.7 GPc) spiral galaxy near the boundary of Leo and Sextans.


Its dimensions are about 7"x10", and it is located at RH 9:59:57 and Dec +1°59'14" (Decimal: 149.9891 and 1.9872). Ten arc seconds at this distance works out to about 110,000 light-years across, making this galaxy very close in size to the Milky Way. This image is about 44" across, and every visible object is a galaxy. I decided to see to what extent it is shown in Google Sky. An image to about the same scale is shown here:


Most of Google Sky is from Sloan (SDSS) images and other earth-bound imaging. Viewing through the atmosphere, even at mile-high elevations such as the Sloan's location, seldom exceeds 0.3" resolution, so this image is probably among the best earth-bound views available. Most of Google Sky is intended (At least so far) for viewing at about a 10x smaller scale, such as this view, centered on the same galaxy, but 7'20" across:


As before, everything visible in this image is a galaxy. The resolution is about 1" per pixel, so it corresponds to the view at about 300x through a telescope larger than 8 inches. However, you'd be hard put to see these galaxies visually, even through a larger telescope, because they are quite faint. A "rich field" telescope at 300x would be a 60-inch, such as the McDonald telescope in Texas. The digital detectors in modern telescopes reach far beyond what the eye can see. If we back off another factor of ten, Google Sky shows us a view like this:


This image is just over a degree across, and represents the view at 30x, though with greater sensitivity than the eye. Now, nearly everything shown is a star in the Milky Way. Considering how hard it is for an amateur to get good views approaching 300x, and how much harder it is to take pictures with such resolution, I find Google Sky is a great resource for "desktop astronomy", and Galaxy Zoo gives me the deepest views available, though of objects the survey directors find interesting. There's a great deal of beauty "out there."