A few gems of the southern sky

In May 2021 I took a trip to Tivoli Farm, in Namibia. On that occasion I had a chance to use a 10” ASA astrograph (900 mm FL, f/3.6) sitting on an AP 1200 equatorial mount. Having always used refractors and slower catadioptrics (SCTs or RCs), this was my first time ever with a fast newtonian. The astrograph was fitted with an ASA electrical focuser. Focusing is always critical, even more so with fast scopes; additionally, the sheer thermal excursion typical of Namibian nights requires refocusing at least every three hours. ASA’s electrical focuser made my life much easier. 

This being my third astrophotography trip to Namibia after 2011 and 2019, I had already imaged the most popular objects of the southern sky, so I could focus my attention on somewhat more “exotic” stuff. Also, my first two trips had taken place in July and August, while this time around I traveled in early May, when the gems in the constellations of Carina, Puppis and Vela are still high enough above the horizon in the early evening.

I had a quite dense imaging program with different camera orientation depending on the target. Unfortunately I learned a bitter lesson: unless a precise angle reference is available (which was not my case), never ever change the camera’s orientation across images with scopes having a secondary mirror held by spider vanes, or you’ll end up with multiple diffraction spikes in the final images, which are really a royal pain in the *** to take out.

Now, without further ado, let’s move on to the photos, all of which were acquired with the above mentioned ASA astrograph, a Moravian G2-8300 CCD camera and a Baader Ha, L, R, G and B filter set. The respective exposure times are available by clicking the “I” icon next to each image. Let’s now start with three of the most famous open clusters of the southern sky: IC 2602 (aka the “Southern Pleiades”), NGC 4755 (the ubiquitous “Jewel Box” in constellation Crux) and NGC 2516, an open cluster in constellation Carina, not so famous as the previous two, but no less beautiful:

Let’s continue our “journey” with some galaxies, and in particular a cluster of galaxies, Abell S0805 in constellation Pavo. The brightest galaxy in the field is IC 4765, shining at magnitude 11 and with an apparent size of about 3.5 x 1.9 arcminutes. This beautiful image, which was plagued by the multiple spikes problem due to a change in camera orientation across subs, was processed by Edoardo Radice. Edoardo saved this image with his “PixInsight magic” :-)

Let’s now take a look at the main highlight of this report, the nebulas, mainly the ones located in constellations Carina and Puppis. The first is Gum 15, aka RCW 32, an emission nebula making up one of the brightest parts of the Vela molecular complex. This image was also processed by Edoardo Radice.

Let’s now move on to an image of an area very close to the Eta Carinae nebula, containing the NGC 3293 open cluster (on the left) and the nebula + open cluster NGC 3324 (on the right). The latter is also called the Gabriela Mistral nebula for its resemblance to the Chilean writer. The first version of this image is an Ha+RGB composite:

Then comes a version with the narrowband channel (Ha) only:

And, finally, a version with the Ha channel, from which all the stars have been removed via PixInsight’s Starnet++ process. This version offers a better view of the structures and tendrils of the Ha nebula:

Then we have a classic of the southern sky: NGC 3372, i.e. the Eta Carinae Nebula, probably the brightest emission nebula in the whole sky. Here we have a close-up of its central part. This image also comes in three versions: an Ha+RGB composite, one with the Ha channel only and a third one with a starless Ha channel, also obtained with Starnet++:

Let’s conclude our journey with a totally different type of nebula: Bernes 149, a reflection nebula  in constellation Scorpius nestled in a dark nebula which is part of the wider Lupus 3 molecular cloud.

Hope you liked my images. Can't wait to go back under that wonderful starry sky!