Observation Log - July 23, 2001

Observation Log - July 23, 2001 - Tinton Falls, NJ

[Tonight was an interesting session, with temps in the low 50's. Configuration on the Meade 12" LX200 was Crayford, 1.25" visual back, and the MX516 with no filters. I took the telescope up to Ernie's place in New York over the weekend, so I set up and did a drift alignment. I forgot to put on the focal reducer tonight, so I decided to image some planetary nebula that could stand the f/10 120" configuration. I had clouds come in after 3:00 am, and didn't have time to take calibration frames. So I left the telescope in this configuration during the day, and took the calibration frames during the next evening's twilight. I didn't have time to do new darks, so I'll use those taken at Ernie's as the temperature was pretty close to the same.

This session started out as a test of the new USB interface I just received to use with my MX516 camera. The system worked quite well in some aspects. The focus mode is terrific, and the faster downloading (<2 seconds vs 11 seconds on the old interface) make taking centering and other test shots a breeze. Problems came when the new control software doesn't have the same feature set as the older version. The new software can't take an automatic sequence of photos. And it can't do some kinds of contrast enhancements on the fly. Basically it's useless until those features are added back in. They say that the AstroArt software has the USB upgrade now, so I'll try that later on. Also, had problem with the software crashing, and it sometimes wouldn't recognize the camera. Also, the new software doesn't save the images in quite the same format as the old, making it impossible to cross-use images taken with both systems. -GW]

First up was M57, the Ring Nebula, a planetary nebula in Lyra. This object is magnitude 8.8, and is 76" in diameter. The central star is magnitude 15.2, and the distance is given variously as 1,400 to 2,000 light years. Also known as PK63+13.1. This image was made from seven one-minute images taken between 11:50 and 1:08 a.m. the morning of July 23, 2001, all using the new USB interface. Those seven images were chosen as the best of about 20 that I saved during the course of the night. The images were left uncalibrated, as the USB image formats didn't match the formats taken under the older software, which I had used to capture the calibration frames. The images were aligned and composited in MaxIm, then a Digital Development filter (FFT, low-pass, hard) was applied. Next I used an unsharp mask (FFT, low-pass, hard.) The resulting image was finished with a contrast enhancement and resampled to twice the original size. I've lately gotten a couple of questions regarding the limiting magnitude of my photos. M57 makes a nice test, as I was able to find a trustworthy magnitude chart of the surrounding stars. Here is a highly stretched version of my image. You can tell that the limiting magnitude of this photo is about 19.4, and that was attained at f/10 with a seven-minute exposure.

Next was NGC6826, the Blinking Planetary, a planetary nebula in Cygnus. This object is magnitude 8.8, and is 25" in diameter. The central star is magnitude 10.4, and the distance is given as 3,300 light years. Also known as PK83+12.1. This image was made from 11 one-minute images taken between 1:13 and 1:54 a.m. the morning of July 23, 2001, all using the old camera interface. The images were calibrated, aligned and composited in MaxIm, then a Digital Development filter (FFT, low-pass, hard) was applied. Next I used an unsharp mask (FFT, low- pass, hard.) The resulting image was finished with a contrast enhancement and resampled to twice the original scale.

The last object of the night was NGC6905, a planetary nebula in Delphinus. This object is magnitude 11.1, and is 40" in diameter. The central star is magnitude 15.7, and the distance is 4,200 light years. Also known as PK61+9.1. This image was made from 25 one-minute images taken between 2:02 and 2:53 a.m. the morning of July 23, 2001, all using the old camera interface. The images were calibrated, aligned and composited in MaxIm, then a Digital Development filter (Kernel, low-pass, more) was applied. Next I used an unsharp mask (FFT, low- pass, hard.) The resulting image was finished with a contrast enhancement and resampled to twice the original scale. Here is a highly stretched version of the same photo that shows more detail in the outer parts of the planetary.