As March wears on, Winter targets in Orion start to fade off to the West, and objects in the Northern arm of the Milky Way sink low on the horizon earlier each night. Summer objects such as the Eagle, Trifid and Lagoon Nebula remain low, and appear closer to sunrise than sunset. There’s an awkward space between Winter and Summer targets for those who practice astrophotgraphy in wider fields. But there are targets for us to bridge that gap! Enter Galaxy Season. I’m still a newbie, but I’ve learned a lot in the past few months and look forward to the challenge and expectations I’ve set for myself.
Most of the galaxies in the night sky are tiny and perhaps best tackled in the scope range of f/8 to f/10. But that doesn’t mean you have to sit tight for two months, or buy a different scope. Despite the extra-large galaxies, M31 (Andromeda) and M33 (Triangulum) drifting lower, or ducking under the horizon line, there are plenty of targets we can dial in at f/4 or f/5. Check this out for some of the larger targets and galaxy groupings available in Spring.
Early Spring East/Southeast
This three galaxy set is easily captured in a single shot, but each is large enough to maintain good detail in each Galaxy. All three galaxies are presented at different angles, adding to the composition. It’s a good early Spring target that comes up high enough not long after sunset. There isn’t much value to adding H-alpha data to this set. It’s best to add a lot of RGB. This is just 1 hour of non-selective data (100% stacked in DSS) on the triplet. Four to six hours is my target on these objects.
The Virgo cluster trails behind Leo in the sky making it a good second target through Spring. Markarian’s Chain centers this cluster, consisting several primary galaxies arcing from corner to corner of the frame. A wider view of the area can present so many galaxies you will often lose count looking at an image. As true with the triplet, the size of these galaxies limits any useful data obtained from H-alpha imaging. Take a look at a field of view calculator such as the one from Astronomy Tools , or even the ones built into you planetary application like the example from Stellarium to see how you want to frame these object and get an idea of how many you can fit in a single shot.
Objects Surrounding Alkaid
M51, M101 and M106 are all galaxies split between Canes Venatici and Ursa Major constellations. They are all fairly easily located from Alkaid, the star that makes up the end of the Big Dipper’s handle. These objects are a little larger, and more defined than those in Leo or Virgo.
It’s easy to look at advanced images of these two interacting galaxies and wonder if they are real. Bright, well defined arms of the larger galaxy, sometimes labeled M51a, is eating the smaller. The object is photographed very often, but it’s always good to have you’re own take on it. There is a large benefit to the reds of this galaxy by incorporating H-alpha data. I grabbed a whole 3 test exposures in H-alpha when I was up way past my bedtime just to get an idea. I’m anxious to jump at this in April.
Even setups with a field of view max around 1.5 degrees and catch some good detail on M101. The relatively small object packs a punch and responds well to incorporated H-alpha data.
Still smaller than M101 the same field of view will present you with good detail and color along with some neighborhood friends if it’s framed up right in the center.
M81 & M82
These two galaxies are a perfect pair to line up in a single frame. M81, Bode’s Galaxy is about a 3/4 view while M82, the Cigar Galaxy is an edge-on view with jet’s of hydrogen spitting out from it’s center. H-alpha data is a must on this object to get the detail from the center of M82. They aren’t exactly circling on top of Polaris, but the are well above the horizon year-round for me. Early-to-mid Spring puts them at their highest at a decent hour. I usually catch them right after they cross the Meridian and keep going for about 90 degrees of their arc.
For someone who normally shoots deep sky objects, galaxies can be confusing. As you can see above with the Leo Triplet and M81 & M82, you can get results in no time, and without much effort, but there is a whole other level to imaging galaxies that requires just as much, if not more integration time than our dim DSO’s. When you see those images of M51, or even Andromeda with all of that blue detail, well they were mostly done with a mono camera and filters, but you absolutely can get color if you maintain a good dynamic range. Experiment of exposure length and ISO to capture dim arms without blowing out the bright core. Take some test exposures, and then take a whole lot more. I took over two hours on the Triplet last night, just to test the difference between ISO800 and ISO1600 on the dynamic range of the galaxies. The results were positive for me. I just think there is so much color and variance in brightness in galaxies that a drop in dynamic range is just lost data. When you’re planning your imaging session, double the time you think you need. You’ll thank yourself when you’re processing.
By the time you get trough these objects, it’ll be time to return to the DSO’s. The Eagle, Trifid and Lagoon will be calling you. The Wizard starts it’s climb back up into the NorthEast Sky. before you know it, Andromeda and the Triangulum are popping up over the tree line right when you wanted to go to bed, and you have another excuse to stay up way too late.
Clear Skies, Bleary Eyes – KA