NGC 7000, North America Nebula

NGC 7000 is an emission nebula, meaning that its gaseous hydrogen, oxygen and sulphur are strongly irradiated by ultraviolet light from a nearby star. This ionizes the nebula, causing its gasses to fluoresce in various wavelengths of red light. The star in this case is probably Deneb, the bright star marking the tail of the swan Cygnus. If Deneb is the UV-source, then the distance to NGC 700 is 1600 light years, only 300 light years farther than the much brighter Orion Nebula. The breadth of the North America Nebula is about 100 light years.

 

Noisy

Because of time constraints, the astrophotograph is processed without making flat and bias-frames to remove pixel and signal noise. Each of the 24 subframes (red, green, blue and luminance) were exposed only one minute, and there are six of each. That is why the image

suffers from vignetting and noise.

 

The Dark Side

At 59 degrees north latitude, the night sky reaches maximum darkness 27th August. This is the first night after 21st April when the sun sinks to more than 18 degrees below the horizon. Eighteen degrees is the minimum limit for astronomical night, because the upper reaches of atmosphere are not illuminated by the sun.

 

Always cloudy

The nights have been cloudy and rainy on the Isle of Rennes this summer and fall. The night of 4 September, however, was one of the rare clear and stabile nights we have had since last winter. Since the following day was a workday, exposures were fewer and shorter, and I had to sacrifice flat- and bias frames :-(

 


NGC 7000. Date: 5 Sept 2016, Loc: Rennesøy, Norway, Telescope: Esprit 120 ED, Camera: Apogee Alta U16M, Mount: ASA DDM160, Exposure: LRGB 6/6/6/6 min, Photographic field is 2.5 x 2.5 degrees.