Observation Log - July 31, 2001

Observation Log - July 31, 2001 - Tinton Falls, NJ

A VERY nice night, except for the bright moon which set after midnight. Temperature was cool, probably in the 50's. Had some dew... heaters did a good job until NGC7768, then the 12" LX200 dewed up a bit. I blew it off with a hair dryer, and put on the dew shield and continued. Configuration on the LX200 was Crayford/f.3.3 reducer/baffled T-adapter/MX516 with no filters. Took darks and flats after the session was over.

	First up was M13, the Great Cluster in Hercules. This object is magnitude 5.9, and is 20' in diameter. The age is given as 14 billion years, and the distance is given as 26,000 light years. This globular is about 150 light years in diameter. This image was made from 21 one-minute images taken between 10:33 and 10:57 p.m. the evening of July 30, 2001. The images were calibrated, flattened, then aligned and composited in MaxIm. That image was enhanced with a Digital Development filter (Kernel, low-pass, more), and an unsharp mask (FFT, low- pass, hard). The histogram was changed to lognormal, and the resulting image was finished with a contrast stretch. Here is the same image resampled to be twice as large.
	Next up was M92, another globular cluster in Hercules. This object is magnitude 6.5, and is 14' in diameter. The distance is 28,000 light years, and the extent is 110 light years in diameter. This image was made from 19 one-minute images taken between 11:03 and 11:25 p.m. the evening of July 30, 2001. The images were calibrated, flattened, then aligned and composited in MaxIm. That image was enhanced with a Digital Development filter (Kernel, low-pass), and an unsharp mask (FFT, low-pass, hard). The resulting image was finished with a contrast stretch. Here is the same image resampled to be twice as large.
	Seeing was so good tonight I wanted to test it with this image of NGC7319, Stephan's Quintet, galaxies in Pegasus, magnitudes 12.6 to 15.3, group diameter about 3'.5. Main components are, from the right side going counterclockwise: NGC 7317, m13.6 42" x 30"; NGC 7318A, m13.4 1'.6 x 1'.2; NGC 7318B, m13.1 1'.9 x 1'.2; NGC 7319, m13.1 1'.6 x 1'.2; (left away from group) NGC 7320C, M15.3 24"; (bottom) NGC 7320, m12.6 1'.9 x 1'.0. The exposures for this composite were taken between 11:33 p.m. and 1:22 a.m. the morning of July 31, 2001. A total of 76 frames were used, with a total integration time of 76 minutes. The images were calibrated with dark and bias frames, and flat fields, then composited in MaxIm. That image was enhanced with a Digital Development (Kernel, low-pass), and an unsharp mask (Kernel, low-pass, hard) Here is the same image resampled to be twice as large. While I had all those images, I took the opportunity to make some images showing how exposure time improves astronomical photos. Here are the frames, all processed and composited in the same way, and stretched to have the same background level: 5 minutes 10 minutes 15 minutes 20 minutes 30 minutes 45 minutes 76 minutes It's easy to see the improvement in detail, limiting magnitude and noise as the integration time lengthens.
	Next up was NGC7817, a galaxy in Pegasus, magnitude 11.8, dimensions 3'.5 x 1'.0, and a distance of 110 million light years. This image was made from 45 one-minute images taken between 01:25 and 02:25 a.m. the morning of July 31, 2001. The images were calibrated, flattened, then aligned and composited in MaxIm. That image was enhanced with a Digital Development filter (Kernel, low-pass), and an unsharp mask (FFT, low-pass, hard). The resulting image was finished with a contrast stretch. Here is the same image resampled to be twice as large.
	The next target was NGC7768, the brightest member of a galaxy cluster (Abell 2666) in Pegasus. The prominent galaxy is magnitude 12.3, dimensions 1'.6 x 1'.3, and a surface brightness of 13.4 mags/sq arcmin. To the upper right is NGC7765, mag 14.5, 42" x 42", sb 14.8. The spindle below is NGC7767, mag 13.5, 1'.0 x 0'.2, sb 13.9. There are several other unidentified galaxies in this frame as well. This image was made from 58 one-minute images taken between 02:34 and 04:28 a.m. the morning of July 31, 2001. The telescope dewed up in the middle of this one, and had to be dried and refocused to continue. The images were calibrated, then aligned and composited in MaxIm. That image was enhanced with a Digital Development filter (Kernel, low-pass), and an unsharp mask (FFT, low-pass, hard). The resulting image was finished with a contrast stretch. Here is the same image resampled to be twice as large.
	With a little time to kill before morning twilight and flats, I took a few images of M31, the Andromeda Galaxy. From these I made two little mosaics. The larger is made from 5 2-minute integrations, and the smaller from 2 2-minute integrations. These were just for fun, but they show some detail in the dark lanes.