Looking South

Galaxies and Clusters

The Moon had not yet risen on December 22nd when I saw a clear evening sky. One annoying neighbor light made sky darkness less than ideal. Also, at this time of year many nearby houses with bright Christmas lights add to suburban sky glow. At my location the worst light pollution conditions are at low southern altitudes where I planned to capture a few targets.

It was a cold 26 degrees when I carried Seestar outside to begin imaging. On nights like this I can do the initial Seestar setup inside before moving Seestar outside. In warm comfort I turn on the power, establish connection to my tablet, wait for any firmware updates to load, raise the viewing arm,  install the dew shield, and turn on the dew heater. It then takes only a few seconds to move Seestar outside, place it in its usual level spot, and immediately return inside to control the remaining initialization. I really appreciate how Seestar takes all of the suffering out of observing! 

The first southern sky target this night was galaxy NGC1300 in Eridanus. As the 30-minute exposure shown below progressed, I was thrilled to see this barred spiral galaxy gradually become visible in spite of considerable sky glow in that part of the sky. The small fuzzy ball to the upper right of NGC1300 is elliptical galaxy NGC 1297.

Next, I moved to capture a pair of interacting galaxies in Canis Major. Once again, a 30-minute exposure allowed the galaxies to eventually appear. The larger, more circular shaped galaxy is NGC2207. Close by to its lower left is smaller galaxy IC2163 which has been captured by NGC2207's gravity. IC2163 has actually passed by NGC2207 and will begin circling behind over the course of tens of million years. The two galaxies orbit each other and will eventually merge. It's incredible to be able to see this interaction even though the image is small! If you Google the Hubble Telescope image of these galaxies, you can see this interaction in amazing detail. 

The southern constellation Puppis contains two Messier objects I wanted to add to my collection. Where does that odd name come from? The ancient astronomer Ptolemy created a huge constellation of mostly southern stars called, Argo Navis - the ship of Jason and the Argonauts in their search for the Golden Fleece. Later, this original constellation was broken into three smaller parts called Carina, the keel, Vela, the sails, and Puppis, the stern. (Puppis is a Latin term.) M93 was the most impressive of two Puppis open clusters I captured this night. The 10-minute exposure is shown in the next picture.

Also in Puppis is relatively unremarkable open cluster M47 shown below. This is a 5-minute exposure.

Discouraged by light pollution to the south, I turned north toward Ursa Major which was beginning to rise to a decent altitude. There I targeted the unusual Messier object, M40, with a quick 5-minute exposure. M40 is not a galaxy, nebula, or star cluster. Instead, it's an optical double star - two stars not actually orbiting each other but coincidentally appearing close together along our line of sight. The upper star is about 1,000 light years away, and the lower star is 470 light years away. The angular separation of the stars is about 53 arc seconds. If you enlarge the image and follow a diagonal line starting with the star pair and moving upward, you can barely see two tiny galaxies. First along this diagonal line is NGC4290. Next is smaller NGC4284. As I understand it, Messier was looking for these fuzzy nebulae and added the double star to his catalog when he couldn't find the dim fuzzies.

As you can see in the image above, Seestar has no trouble resolving two stars separated by 53 arc seconds. I wondered how close two stars could be and still be seen by Seestar as separate. After a quick search through some of my Seestar images I found an example of two stars 14 arc seconds apart that were clearly separate. Maybe I'll find another pair slightly closer, but I doubt clear separations less than 10 arc seconds are possible. Nevertheless, Seestar's resolving power is remarkable for such a small aperture! 

After imaging M40 I went outside for a quick sky check and noticed hazy clouds forming in the north. The temperature had dropped to 23 degrees, and it was time to quit.