Spring can be a dull season for casual, naked-eye stargazing in the Northern Hemisphere. Broad stretches of the sky are devoid of bright stars. Dim constellations completely disappear for an observer within or near a city. For the astrophotographer, though, it’s Galaxy Season. The Virgo and Coma superclusters of galaxies, completely invisible to the naked-eye, make for rich hunting in the telescope.
It’s a rare treat for a North Carolina astrophotographer to have two clear, moonless nights in the same April week. I tried to make the most of the opportunity by imaging two contrasting galaxies.
First up is galaxy NGC 2403, in the constellation Camelopardalis (the Giraffe). NGC 2403 is a “flocculent” – fluffy – spiral galaxy. Its arms are alive with bright clumps, which are sites of active star formation. NGC 2403 is about 57 million light years from Earth.
On the evening of April 12, I imaged the “Needle Galaxy,” NGC 4565. The Needle was the cover story for the May 2023 issue of Sky and Telescope magazine. Many astrophotographers have been posting images of it, for good reason. It’s a beautiful and unusual sight.
The Needle is a barred spiral galaxy, like our own Milky Way. We are looking at it edge-on. Even the casual observer will notice the galaxy’s large central bulge and the dark dust lanes that mark the edge of the galaxy’s disk. Closer inspection shows that the disk is slightly warped. The Needle’s companion galaxies are tugging on it and distorting the disk. We believe the same phenomenon is happening with the Milky Way.
The Needle lies in the constellation Coma Berenices (Berenice’s Hair), and is part of the Coma I galaxy cluster, about 50 million light years from Earth. Our line of sight to it is directly perpendicular to the plane of our galaxy, so our view is unobstructed by local dust and gas. (This is the opposite of the case for the Hidden Galaxy in my earlier post.)
Dozens of galaxies are visible in my original, full-resolution image. I highlighted here some members of a more distant galaxy cluster. The arrowed galaxies in cluster RX J1236.9+2550 and the star are magnitude 18 – fully 10,000 times dimmer than stars visible with the naked eye. It always amazes me that my backyard telescope can captures objects this dim and far away!
In contrast to the cold weather earlier in the week, April 12 was a quite comfortable evening for standing out under the stars. While the telescope worked its magic on the galaxy, I enjoyed several hours looking at the sky with my unaided eyes and with 7×50 binoculars. I tried to make out the dimmer, more unfamiliar constellations that I usually can’t see – Cancer, Leo Minor, Hydra, Coma, Libra, Serpens. It also surprised me to realize after midnight that I could see in the same sky both Gemini (a winter constellation) and Scorpius (a summer constellation) – one of those things I guess I just never thought about before.
Technical details for the images: Images taken north of Summerfield, NC in Bortle 4-5 skies. Explore Scientific ED127mm FCD-100 refractor, ZWO ASI 1600MM mono camera cooled to -10°C, filter wheel, guided tracking on an EQ6-R Pro mount. Luminance frames binned 1×1, 120-second exposures. RGB frames binned 2×2, 120-second exposures. For each target I used 54 Lum frames and 18 each of RGB. Darks and flats applied. Stacked and processed in Pixinsight.