Wednesday, November 9, 2011

M2

M2 is a few degrees south of M15, a little smaller, and a tiny bit dimmer. It's still very easy to find in binoculars.

Just to the south of M2 are several more globulars-I may be able to catch them in a few days right after dusk and before they dip below the horizon.

This shot is 10 minutes at ISO 3200. The exposure for the last two pictures is not needed in order to get the clusters to show brightly; unlike remote galaxies, these are part of the Milky Way and are much brighter. Instead, I use the exposure time to kill light pollution and moonlight.

At first glance, the last two pics look like there may have been a focus problem. Actually, the focus is essentially perfect. Last night was very clear, but the seeing was awful. Because of wind and turbulence in the air, stars with twinkling madly. Twinkling is actually the effect we see when the image of a star appears to shift around a lot; under magnification, it's much easier to see that the brightness stays the same, but the apparent position moves around. In a longer exposure, that makes stars look blobbish. Even Jupiter was twinkling; it takes some pretty bad air to make planets do that.

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