Chasing the Western Veil Nebula

So after i did the polar alignment, I set the target in N.I.N.A. and slew to it. Added a new sequence and set all the settings, including the option to cool my camera (never used that before for some reason 😅). So before I triggered the sequence, I wanted at least one test shot to see if everything is still OK.

Well.. what can I say.. something went wrong. The preview was shot with the same settings I put in for the sequence, meaning this is a preview with 120s exposure time. Not exactly sure what happened, but I guess it’s not a good sign when you rush the setup as you can clearly see the stars are not round.

Since I don’t have any lighting in my backyard, nor that i have a head lamp I could put on, I came to realize I couldn’t re-setup my gear. Positive side effect is that I know my next purchase.. a new head lamp.

So today I wanted to try something different, since I noticed on several previous sessions that my initial polar alignment was quite off. Trying to aim the mount towards Polaris often gave quite a bit of alignment error.

So instead of bolting down the mount downwards on the tripod, I was thinking: “What if I just lock the mount first, do the initial Three Point Polar Alignment (TPPA) and adjust the Azimuth error by unlocking the mount.”

I should’ve thought about this earlier since it much easier to come within one arcminute then to move the whole tripod, and hoping the tripod stays leveled 😆

Shooting from my holiday address, Gato (the cat) was acting as my moral support this session.

When darkness came, and I was ready for my test shot. I noticed the same marginal drift that I had last session, and again with a decent polar alignment. I still went ahead with the session, but I’m now thinking that the pictures I shot during the last session wouldn’t be that useless if I didn’t disassemble my camera from my scope. But since I did disassemble them, I’m not sure if they are still useful since the darks, flats and biases would be from a different camera position.

It turns out, that such marginal drift is a logical consequence since I’m still not using guiding. It turns out that with my current gear an one arcsecond tracking error would result in a 0.32 pixel wide drift. Because this is quite small, this drift is only visible when you zoom in at the picture. So I guess my next target purchase is known: a guiding scope.

When looking at the results of this session, I noticed something strange happened. At one point the mount just stopped tracking, where the very first picture it happened just looks like the stars have a trail behind them. I had this once before on one of my very first sessions, not knowing better, I blamed it on my own skills.

But this time I looked into this to find out why this is happening, since it just looks weird. Specially since i threw away 75 pictures this session, which could have been 75 minutes of exposure. Which is a shame.

It turned out the nebula was crossing the meridian, and it seems to be that the toggle to flip the mount to meridian was not active in N.I.N.A. by default 😅

Searching for the settings that prevent the meridian flip, I saw these advanced settings of the mount, where it’s clearly visible that currently the mount stops tracking at 0 degrees before the meridian.

I switch the option to: Stop tracking at 5 degrees after meridian
This should give N.I.N.A. about 20 minutes to execute the flip, which should be more then enough.

Guess I will find out tonight, the forecast is again a clear night. I would like another 4 hours of total exposure time of using pictures that were taken with 60s exposure time each.

Then I would have a total exposure time of 10 hours with only the 60s exposure time per picture. This way I can create two different images:

• One stacked image of picture with each 60s exposure time
• One stacked image of pictures with 60s and 120s exposure time

This way I can see if the marginal drift of the 120s exposure time pictures have any effect on the final stacked images, and then the processed result.

A great night to shoot, and while setting up for tonights session I shot this picture of Polaris in Artificial Reality (AR).

If all goes well tonight, I should gather more then enough data to gain over ten hours of exposure time when I only use the 60s exposure photos.

Back at my home shooting again after 1.5 weeks of vacation, noticing my tree got quite a lot of new branches with leaves. So it will be a short session today, which is good enough for now anyway since I only need 65 more to hit the ten hours worth of data. I will get a few extra to have a surplus when during the stacking photos get rejected.

I do really need to cut this tree down.. it’s getting way too big for my small backyard anyway. And it will give much more view for longer shooting sessions 😇

When all the master files for the darks, biases and flats were created it was time to process all the lights images (which are the taken shots from all the sessions).

After converting, calibrating, registering and then creating the final stacked image with no rejections (the top image), it’s noticeable that there are fewer stars visible then when only one picture was loaded in Siril, which is normal. It also shows a bit more color as some stars already have a blue-ish glow to them.

Now the fun part is the auto stretch of Siril. Again, this is the pre-configured auto stretch in Siril that is quite aggressive and does not represent the final image.
But ooh boy.. the nebula is quite visible there. Even some dust clouds in the lower part of the image is visible. This is quite an exciting starting point for post processing 😄