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25. M5, globular cluster
Notes: M5 is 13 billion years old, which is even older than M13 (19) at 11.5 billion years. By comparison, the open Double Cluster NGC 884, 869 (6) is estimated to be only 12.5 million years old and the open M11 Wild Duck Cluster (20) only 220 million years old. M5 is estimated to have between 100,000 and 500,000 stars, of which we can see only a few hundreds in this image. It appears that the globular clusters are like very small sub-galaxies that congealed within our own galaxy when it was forming, while the open clusters are, by comparison, sparse and recent, generated by forces sweeping across and impacting the dust in the spirals.
Technical notes: The weather was clear and quiet. There was a gibbous moon in the SSE. We set the integration time to 0.5 sec and found a good guide star. The histogram at 2 min exposures was skewed left, but lengthening the exposure time would have washed out the core and the sky as well due to the bright moon. We lost a few exposures when the target passed over a tree. At about 11:15 Gary heard the growling of what sounded like a very large cat a few yards up the hill. Mindfull that a camper on the Yuba river had been attacked by a mountain lion early that morning* and that the Yuba river was only two miles away, and that a lion had been seen on his lot the previous week, he jumped and dropped his flashlight. He picked it up and was scanning the hill when the animal yowled/screeched. He took the point and retreated into the house, leaving the scope to complete the subexposures.
*"Cat attack, Mountain lion goes after man near Yuba River" The Union, July 3, 2012, p. 1.
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