Splitting Airs

by Tom Campbell


January 31, 2003

ObserverTom Campbell
LocationIola, Kansas (Long: 95°24'W Lat: 37°55'N)
EquipmentDiscovery DHQ 8" dobsonian
Eyepieces1.25" Plössls - 25mm (49x), 15mm (81x), 10mm (122x), 6.5mm (188x), 4mm (305x)
Time9:15pm - 10:30pm CST (03:15-04:30 UT)
TransparencyClear (8/10)
SeeingModerately Stable (6/10)
WeatherTemperatures in the low 30s. There was no wind.

Observing Summary

Although clear, I knew that tonight wasn't the best for observing. Temperatures were beginning to drop, and the stars were really twinkling. Regardless, I set up anyway. I've been trying to split the closer two components of Zeta Orionis for over a month now, without success. Tonight, Orion was high in the sky, but it was right over my house, meaning that the warm air currents coming from my chimney would have a negative effect on seeing.

It seemed to take forever for my telescope to cool down tonight. I set up about 8:00pm and the images were just starting to settle down a little by 9:30pm. I don't know whether the seeing was particularly bad, or whether the mirror was having trouble keeping up with the falling temperatures.

JupiterCancerGas Giant9:25pm CST
RA: 9h 3m 46sDec: +17° 40'Mag: -2.6
While waiting for the tube currents to settle down a bit, I focused my telescope on Jupiter. I was pleasantly surprised to see a shadow transit in progress. I had never witnessed one of these events in this telescope, and I wasn't sure whether or not it would be visible in my telescope. At 125x, some details could be seen in both equatorial bands, and Io's shadow is visible right in the center of the planet. The shadow appears as a pinprick of blackness right between both equatorial bands. Io itself couldn't be seen. At 305x, during moments of good seeing, a few dark gray streaks could be seen in the cloud zones. One of them was in the equatorial zone. The streaks were about 1/5 to 1/6 the diameter of Jupiter. Europa could be seen closing in on the gas giant.
ZetaOrionMultiple Star10:15pm CST
AlnitakRA: 5h 40m 45sDec: -1° 56'Mag: 2.0
This is a triple star system. The brightest two components are very close to each other. It took 305x and moments of good seeing before I was able to split them. Both appeared white, with one star a little fainter. The third star is much dimmer, and is easily separated at low magnification. It appeared blue-white and is at about a 130° angle to the brighter two components.

By this time, my eyepieces were fogging up pretty badly, and the outside of my sonotube had a light coating of frost. I called it a night. I didn't get to see many objects, but my main mission was accomplished, and I was able to see a nice shadow transit as a reward for my efforts.