A long dry spell

Ironically, a long dry spell in astronomy is usually, but certainly not always, caused by a long wet spell meteorologicaly. If not wet, cloudy at least. Such has been the case for the past, almost 3 months at Starlight Observatory. However, Friday night, September 4^th, it wasn't AS cloudy. A few stars were visible, but there was a definite layer of haze or high cloudiness. Nevertheless, it was the best we've had for a long time. So.... Observatory opened, camera connected, security light out (more or less... it kept coming back on. Maybe the batteries in the laser are getting weak. What laser you ask? Why, the one that I point at the photoelectric cell that turns the light on and off. If I'm able to hit the cell with the laser light, the light goes off. It sounds easy, but try hitting a 1 inch diameter target from 40 feet with a light beam on a creaky old camera tripod; sometimes that is where most of the night is spent!).

This was also an opportunity to try something new; in this case, I was going to spend most of the time recording photons on the Luminosity channel, with a minor amount of time on the Red, Green, and Blue channels. But, alas, the air was not steady. We apparently had a thunderstorm to our northeast; I could see the horizon lit up by the lightening flashes. It would seem that the outflow from the storm was causing the unsteady air. As a means of “tracking”, I use a 2^nd camera to monitor the position of a star. I then feed that information to an “autoguiding” program, which, in turn, sends correcting signals to the telescope mount to keep the star centered in it's tracking “box”. The tracking program displays the errors in tracking, which, on Friday night, were in the 2 to 3 arc-second range. The actual movement of the star was probably 5 to 6 arc-seconds, so I felt pretty good about getting down in the 2 to 3 range. This is where having a spare $35,000 or so would come in handy; I could afford a mount that could track better, say to within 1 arc-second. I don't see that happening any time soon, though.

Anyway, time to shoot. The target was M20, also know as the Trifid Nebula. This is a primarily emission nebula in the constellation of Sagittarius. I managed to get 3 three minute exposures on the Luminosity channel, and 1 three minute exposure in each of the Red, Green, and Blue channels. These four channels would be combined later, in the computer to form one color photo. “Well, what does it look like?” you ask. See for yourself.

M20, September 4, 2015

8” LX200GPS F10, QSI 683

Shot thru high cloudiness

Imaged in Nebulosity 3

Post processed in Nebulosity 3 and Paint Shop Pro 7

This was an interesting, to me, experiment. I wanted to see how well I could image through the high clouds or haze or whatever it was. It's far from a ”perfect” picture; I'm not using the Hubble Telescope and don't have government funding for the computers and software. But, for an amateur with my experience level, I think it's OK. I can, and so can you, see the cloudiness show up as what looks like a hazy background color instead of a really black background. Tracking wasn't perfect, but not terrible, considering. (The stars look basically round, which is an indicator of good tracking.) The colors are at least in the ballpark of what they should be, but there is an artificial look to the nebula, caused by the processing trying to remove the effect of the cloudiness. There were other processing artifacts that I had to remove manually.

The last thing I thought I would try to demonstrate is what the nebula would have looked like if seen through and eyepiece, ie, you were looking through the telescope instead of me taking an image. The following is an attempt to show you what you would see.

M20 as seen though an eyepiece at the telescope

There are a few things to note. First, and foremost, it's hard to see. There is a reason astronomers call these things “faint fuzzies”. The word nebula comes from Latin for cloud. Whisp of a cloud seems appropriate here. Second, the sky is not black. That's because of 1) the cloudiness, 2) light pollution (meaning the lights of all the surrounding cities shinning up, into the clouds and into the 3) water vapor (in the air, of course). All 3 of these things scatter the light, making a dim object dimmer, as well as removing the contrast between the object and its background. Polar bear in a snow storm type of thing.

Well, that' it for this entry. Maybe late September and October will bring better weather for astronomy. Thanks for staying awake this long...