Chasing the Eastern Veil Nebula

The next upgrade has arrived! This time it’s a ZWO ASI120MM Mini guide camera together with a Ganymedes 30mm F/4 guide scope.

Until now, my mount has basically been trusted to follow the stars on its own. A bold strategy considering that I wouldn’t even trust myself to walk past the tripod in the dark without supervision.

With the new guide scope and camera, I can finally start experimenting with autoguiding. The little ASI120MM Mini will keep an eye on a guide star while the software watches for tiny tracking errors and tells the mount to correct them. At least, that’s the theory. I’m sure the practical version will involve several hours of staring at guiding graphs, changing settings I don’t fully understand yet, and wondering why a perfectly innocent-looking number has suddenly turned red.

Still, this should be a pretty big step forward. Better tracking means I can start working towards longer exposures, hopefully getting sharper stars and collecting more of those faint details I’m constantly trying to drag out of the darkness.

Of course, adding a second telescope and camera to make the first telescope and camera work better also feels like I’ve reached an important milestone in astrophotography:

Solving problems by buying more things that create entirely new problems to solve. 😅

Can’t wait to get it mounted, calibrated and guiding under the stars. And, with any luck, eventually figure out what all those graphs actually mean.

With the preprocessing finished, it was time for registration: the part where Siril takes all my individual exposures and works out how they need to be aligned before they can eventually be stacked together.

In theory, this makes perfect sense. Even though the telescope was tracking the sky, every exposure is going to be positioned ever so slightly differently. Siril therefore looks for stars that appear in multiple images, matches them together and calculates how each frame needs to be shifted and rotated so everything lines up properly.

In practice, I pressed the button and was greeted by this.

Apparently Siril had discovered every star in the known universe and decided to draw a little orange circle around each one just to make absolutely sure I understood how many there were.

The console on the right then started enthusiastically throwing numbers at me:

Gaussian profiles… pair matches… inliers… rotation… FWHM…

Naturally, I studied all of this very carefully, nodded thoughtfully and concluded:

“Yes. Those are definitely numbers.”

What I do understand is that Siril is comparing the stars between my exposures and finding matching patterns. Those matches allow it to calculate the tiny differences between each frame and align them accurately. The occasional differently coloured markers are part of that matching process, while the sea of orange circles represents detected stars.

And judging by the number of circles on screen, I appear to have successfully photographed at least seventeen billion of them 😎

So while Siril continues doing some rather impressive mathematics in the background, my contribution to the registration process currently consists mainly of watching the console scroll past, looking for green text, and becoming slightly nervous whenever something appears in a different colour.

Green text = good. Red text = panic. Thousands of orange circles = apparently completely normal.

Astrophotography is becoming much easier now that I understand the technical terminology. 😅