This was my first attempt at photographing the central portion of the Orion Complex. This region contains the Orion Giant Molecular Cloud which envelops the constellation Orion but is directly observable only in the millimeter wavelength portion of the spectrum. In the visible regime, the sky from Orion eastward into Monoceros is chock full of diffuse nebulae, some of which are shown in this photo. In Orion’s sword are NGC 1976 (Orion Nebula) and NGC 1973,5,7 (Running Man Nebula). Near the left star in Orion’s belt, ζ Orionis, are NGC 2024 (Flame Nebula) and IC 434 with the less distant dark cloud, Bok 33, which together create the Horsehead Nebula.
This is a 168-second exposure at ISO 4000 using a 200mm lens at f/2.8. It was tracked but not guided, and the sky was clear but not especially dark, with a measured zenith V-mag of 21.5 per square arcsecond. I plan to re-image this region on the next good night using a series of many exposures to go deeper.
Monthly Archives: January 2017
Summer Milky Way
The summer Milky Way at Sierrita Observatory is a spectacular sight. These wide angle views show the southern Milky Way setting along the SSW horizon. The left image runs from Cepheus at the top, through the Galactic Bulge in Sagittarius, just above the horizon. About 1/4 the way down from the top is the constellation Cygnus, with NGC7000 (“North America Nebula”) glowing red to the left of the bright star, Alpha Cygni (Deneb). The other two images show the sky below Sagittarius. To the right of the Galactic Bulge, notice the dark region called the “Pipe Nebula” which actually consists of several contiguous galactic dust clouds known as Barnard objects.
In this compass direction, there is no human development all the way to the Gulf of California, but the sky brightness increases toward the horizon as we view a longer optical path length through the upper atmosphere. Emission from the upper atmosphere, or “airglow”, occurs from forbidden transitions of OⅠ λ6300 (red) and NⅡ λ5577 (green), and other species. [ref]. Very close to the horizon, however, the extinction rapidly increases from looking through the low elevation dust layer.
Left: 2016-09-03, Nikon D800e + 12mm fisheye, f/2.8, 156 seconds @ ISO 1600″
Middle: 2016-09-04, Nikon D800e + 14-24mm @ 20mm, f/2.8, 30 seconds @ ISO 2000
Right: 2016-08-27, Nikon D800e + 14-24mm @ 24mm, f/2.8, 95 seconds @ ISO 1600
Not shown above: Comparison with labeled objects in SkyGazer
Moonset, 31 Aug 2012
This image shows the moon setting behind Kitt Peak National Observatory as viewed form the observatory location. The national observatory is located on the next mountain range to the west of Sierrita Observatory.