Welcome to the first, of a new series of monthly blogs about astrophotography! I’m not going to focus on techniques or processing in depth, (see my Sky & Telescope Blog about that) but rather I want to talk about what targets or objects are out this time of year that might be worthy of your attention, with maybe a few high level tips about acquisition or processing.
Our first candidate for your consideration is the well known, and stunning target, the Horsehead Nebula (Barnard 33). The horsehead is an area of dust against a bright background of glowing hydrogen gas. This creates a silhouette if you will that is shaped like a horses head, or a knights chess piece. This area is quite bright photographically in both visible and narrowband wavelengths and a favorite target for expert imagers, but is also an excellent target for beginning astrophotographers.
Currently, the horsehead region is perfectly placed right as it get’s dark, high up in the eastern sky and can be imaged until about midnight early this month before it gets too low in the West. It is also easy to find, as the bright nebula where this lies is hanging right off the left most star in Orions belt, Alnitak (or Zeta Orionis).
This part of the sky is a wonderland for imagers, and almost any focal length optic and camera combination is capable of capturing stunning views. Perhaps the most iconic views of the area are wide field images spanning about one and a half degrees horizontally.
The star Alnitak is featured prominently on the left, just above another well known target, the Flame Nebula (NGC 2024). Very often you will see both the horsehead and flame captured together like this. This whole area is glowing brightly from ionized hydrogen gas, which creates a glorious backdrop to the shadowy puff of curling dust that looks like smoke rising from a hidden furnace. This area is so bright in fact, even an unmodified DSLR will pickup quite a bit of this red glow. Narrowband imagers with hydrogen alpha filters can capture amazing details in this shimmering curtain of light too, such as the image below which is only an a hours worth of total exposure time (Officina Stellare RH-200 600mm f/3, FLI Microline 16200 camera).
The entire region spans about a degree and a half, and can be captured with moderate focal lengths and APS-C sized chips. A smaller chip and/or a longer focal length will allow you to focus in primarily on the horsehead itself with an image like the first one in this blog. That image by the way is only three hours of data, captured with a small sensor (Sony 694 on a Starlight Xpress camera), and bit of focal length, 1200mm (Sky-Watcher Quattro 12″ f/4 imaging newtonian).
This is not a target that requires dozens of hours of integration time to capture all the details
available. A 600mm telescope with a DSLR (cropped or not) will capture the entire region very quickly, and many astrophotographers will use long DSLR lenses to capture large swaths of the Orion constellation, with the horsehead and great Orion nebula both featured.
There are a few hidden jewels too to look for too in this region. First, the star Alnitak is actually a double star with a small companion 50 Orionis. In my earliest attempts to shoot this area, I often stretched far too aggressively, and the bright star Alnitak would swell up quite large and swallow it’s companion. In your own images, or when looking at someone else’s, look for this tell tail sign of attention to detail in processing.
Often overlooked or glossed over too is NGC 2023, a reflection nebula to the lower left of the bigger celebrity here. This bluish reflection area looks like a tunnel to another world to me. The very bright star
HD 37903 powers this area and if I were superstitious, I’d swear I was looking down a tunnel into the next world (follow the light Carol Anne…). At longer focal lengths and smaller pixel scales (and good seeing!), there is a surprising amount of intricate and beautiful detail to be captured here too.
The winter sky is full of jewels like this. Catch the horsehead this month before it gallops away!