In April 2021 I posted here a new version of a capture made in July, 2020. Well, I was not entirely happy.
Then, I decided to do a new version. This means that the picture I’m posting today is at least the 3rd version of the same data. Ok, ok, sorry. I won’t be stalling. Here is the new (And hopefully the last) version:
Also, I made an annotated version, with the astrometric solution. What are your thoughts?
This is the equipment I used to capture this image:
Canon T6i (750D);
Nikon Nikkor 135mm f2.8 Ai with Canon EOS adapter;
The Eta Carinae is also the name of the star inside the nebula surrounding it. Whitin a mass of 100 to 150 times the mass of the Sun, this star is HUGE! It also is, probably, a binary star. What does that mean? That there is another star, in this case really smaller than the main star of the system, and also much hotter and with half the brightness. This binary system have a cloud of gas 400 times the size of our solar system, wich once was ejected by its bigger star.
The beautiful Eta Carinae Nebula
But back to the Eta Carinae Nebula! As an emission nebula, it shines mostly it the H-Alpha frequency of the electromagnetic spectrum. In other terms, the color mostly red cames from the atoms of hydrogen element, witch absorbs the UV light from the big blue and young stars of the cloud complex, to release this energy in a very specific frequency of 656.281 nm.
The Keyhole Nebula
In the center of the Eta Carinae Nebula is the Keyhole Nebula, a small, dark cloud of gas and dust with little arms brighting with fluorescing gas, in a beautiful constrast with the surrounding nebula.
But I wasn’t happy with the results, for two reasons. First of all, none of both images had enough SNR to bring all details I wanted. And second, this is a huge nebula, and even with my little 66mm f6 refractor, with more than 3×2 degrees of field of view, I couldn’t capture the entire greatness of the Eta Carinae Nebula.
On May 23, in a full moon, I got some hours of open skies and managed to capture all the light I needed: 4 panels with 1 hour of exposure each.
That seems like little exposure time, but with the Optolong L-Enhance, all those blue light of the full moon didn’t get in the way and I got some nice H-Alpha data.
How to do an astrophotography mosaic?
Well, although it may seems like a challenge, it went easier than I first thought.
First of all, I used N.I.N.A. to simulate the field of view, overlay and every other aspect of the mosaic. At the end, I have noticed that with 4 panels and with a safe 35% overlay betwen each one, I could get the entire Eta Carinae Nebula with some safe space at the sides.
Once all the data was captured, I used Pixinsight, first to substract the calibration frames and than to integrate every one of the panels individualy.
With all 4 panels properly integrated, I did a Photometric Color Calibration in each of then, taking care to properly measure the background level. It really helped a lot later to assemble the mosaic.
And finally I did a Dynamic Background Extraction in each panel to make sure no gradient would interfere on the assemble of the mosaic too.
With the four panels properly integrated, calibrated and everything else, I started using a sequence of the processes StarAlign and GradientMergeMosaic. To asure a good 4 panel mosaic, first I did 2 mosaics, with 2 panels each (2×1), and than I merged these 2 mosaics to end up with a 4 panel (2×2) mosaic.
More or less: Panel 1 + Panel 2 = Mosaic 1 Panel 3 + Panel 4 = Mosaic 2 And than: Mosaic 1 + Mosaic 2 = Full mosaic
If you want more detail about the process, please, leave a coment here and I will make a full tutorial. And if you don’t have Pixinsight, don’t worry! I’m sure you’ll be able to use Photoshop. 🙂
NGC 6334, the Cat’s Paw nebula is a faint emission nebula on the constellation of Scorpio.
That’s finally my last capture before I get my DSLR modified for astrophotography.
My setup for astrophotography is slowly getting the way I want!
Of course, my ideia was to shot an emission nebula hard to capture with a stock camera. If everything ends right, soon I’ll post a version of this same target, with some quite similar exposure, but with an astromoded Canon T6i. Wish me luck!
Well… the Cat’s Paw nebula is a hard target for Bortle 6 skies and a stock DSLR. Almost 3 hours of exposure and I hardly got some nebulosity. I hope it will change soon, as soon my camera come back and my Optolong L-Pro arrive.
The Crux constellation and the Coalsack Nebula (C99) are so close to each other that we can shot it through a 135mm and a cropped APS-C sensor.
And I finally did it! Let’s see how it ended.
The Crux constellation
The Crux constellation is probably the most known constellation of the southern hemisphere, and it’s easy to understand why. There are 4 stars, being the less brighter yet on magnitude 2.75, and disposed on a “cross” shape very easy to locate.
This constellation is full of surprises. Just to the left of the star called “Mimosa” (Beta Crucis) is the Jewel Box (NGC 4755), a beautiful, bright open cluster with stars of many colors.
The star Alfa Crucis, also known as “Magellanic Star”, is the brightest one, with 0,8 mag. This is also a multiple stelar system, with at least 3 stars.
The Coalsack Nebula (C99)
I don’t know why, but I just love dark nebulas. And the Coalsack is awesome! C99 is the biggest one seeing from earth, with dimensions of 7×5 degrees! It is HUGE!
I first discovered C99 a few years back, while I was on the firsts steps with astrophotography. I pointed my D5000 to the Crux with a tripod and toke some 15s shots. When I saw this huge shadow I couldn’t believe.
The picture itself
Shot it was pretty easy, to be fair. I started just after the sunset, but the first 4 frames was lost due to the INTENSE traffic of artificial sattelites. I should have thinking on that, right?
C/2020 F8 SWAN is a comet discovered on images of the SWAN camera, aboard of the SOHO spacecraft. Although it was imaged for the first time by the SWAN camera, was Michael Matiazzo, in Australia who first noticed it.
This little guy started to gain brightness very fast, and as soon I knew about his existence, I mounted my telescope and pointed to him.