Hydrogen Alpha glows red and doubly ionized Oxygen (O-III) glows green. The central star itself does not emit very much visible light so what we’re seeing is gasses that are excited by infrared or x-ray radiation. M27 has a visual brightness of magnitude 7.4 which makes it visible as a grey hourglass shape in small (80mm refractors, 114mm reflectors) telescopes at moderate magnifications. This is the same fate our star will have some 6 billion years from now. Several thousand years ago the parent start ejected its coronal mass and collapsed into the white dwarf in the center of the nebula. Yes, you can practice astrophotography in the city! This image was built from 41 minutes worth of 60 second sub-exposures stacked one on top of the other with some other frames to subtract various forms of noise.Īt an average estimated distance of 1,250 light years this planetary nebula is relatively close. Messier 27, the Dumbbell Nebula, taken from suburban Dallas on a night with 80% – 90% humidity with the object in the light dome of a massive shopping complex just a mile away. Cursory inspection of the first few raw frames showed some significant dust motes so I won’t pretend to get Hubble quality images out of this but I’ll do the best I can. It looks like each iteration of stacking will take about fourty-five minutes to an hour on my six-core computer so processing time will be a bit long on this one. Exposures longer than 60 seconds were completely washed out with wide, flat histograms which suggests large areas that are over exposed. Five seconds, ten, 25, 45, and 60 seconds. In the end there will be a total of approximately 180 frames in five different lengths. I took advantage of a very calm, very clear night and collected some 1,300 year old photons for your viewing pleasure.
It clears the house around 9:00 so with sunset at 6:30 or so, you can have your high accuracy drift alignment completed by the time Orion is visible over the houses. Its the end of the calendar year and Orion is high in the sky at a reasonably early hour for urban astronomy.
0 kommentar(er)
