Lulin (02-19-2009)

This is Comet Lulin on the morning of February 19, at about 7:00 a.m. U.T., or 1 a.m. Central Standard Time. This image was taken through the AT66ED and the WO 0.8x reducer ff II with the XTi, and is 32 x 17" processed in Nebulosity and PSE7, unguided.

Lulin passed not just through a field of stars, but also through a field of galaxies. In this next image, the galaxies are labeled (some of the galaxies are pretty faint; you may have to adjust your monitor to see them) (I have also labeled two of the brighter stars near the center of the image):
The galaxies are a long way off, of course. Comet Lulin is speeding through our solar system. the stars in the image are relatively nearby in our galaxy. NGC4697, the brightest of these other galaxies, is probably 35 million and may be 50 million light years away. NGC 4697 has attracted attention because its X-ray output is high; see images in X-ray here. NGC 4602 and its neighbor NGC 4604 are probably around 41 million light years out. One study I read suggested that NGC 4691 is nearly 72 million light years away. PGC42868 is way out there, but no one knows how far.

Of course, Lulin itself does not look like a streak of light, but it is moving so fast that an exposure of any length requires that one either stop the stars or stop the comet. The images above stop the stars. Here is one that stops the comet and lets the stars move. Each of these images represents the passage of about ten minutes. In other folks' exposures, Lulin has a tail. In fact, it has one pointing toward the sun and one pointing away. My skies were too light-polluted to record either tail, however, and this is more or less just the comet's nucleus.