Dear reader,

I am sharing my latest image and the story behind its acquisition. Autumn wasn’t favorable for astrophotography at my location. There were several clear nights in October and two in November ant that was it.

When I saw the forecast for three clear nights in December I started to plan. After some consideration I decided that I wanted to go for another mosaic. However this time I set a new goal - to make my biggest mosaic yet and go for a 6 panel mosaic – 3x2. The area of the sky that I chose was the Flaming Star, the Tadpoles, the Spider and the Fly and some faint nebulae from the Sharpless 2 catalogue.

I used NINA to plan the mosaic and my imaging sequence. In order to achieve the framing that I wanted I had to set the orientation of the camera to 35 degrees. I chose the panels to overlap with 10% and prepared all the details of the sequence. NINA made the needed orientation of the camera easy. The platesolving function shows it so I was able to get to 35 degrees fairly easy.

The first three clear nights in December were great – no clouds and conditions were perfect. The next two clear nights came after Christmas. During winter usually the Moon gets in the way of all the interesting targets in the sky. And this was the case for those two nights – the Moon was close so I got a nice gradient on my shots. I managed to capture the last panel in the beginning of January. On the next night I took three more hours – one for the last three panels for two of which I imaged close to the Moon.

And then came the processing… I carefully reviewed every frame and stacked every panel. The two panels that I acquired during the full Moon were the hardest to process. I tried several times. After the first and second attempts I found that the space looked like Swiss cheese – full of dark holes. I reviewed the individual frames again and found several more captures that included thin clouds. With those gone the things started to improve however one of the panels had severe gradients – almost like a dark reflection which I could not remove with DBE. Then the captures from the 7th night came to the rescue as they were taken during a moonless night. I used NormalizeScaleGradient to copy and apply the almost non-existent gradients from the 7th night to the ones with the severe gradient. After this processing step – things normalized.

In order to achieve a seamless mosaic I integrated the channels separately. Prior to stitching I used DBE to remove any gradients from the individual channels. Then after three of four processing attempts I reached to the version that you see above – which I think turned out ok (considering the short integration time of each panel) and which I really like.

I imaged with a HA/OIII narrowband filter and was surprised to see that I managed to capture the reflection nebula in the Flaming Star as well. I wasn’t expecting that.

The Tadpoles Nebula shows nice details. I love the cloud of HA which spans from the Flaming Star and reaches all the way to the distant bubble of SH-232.

My image also contains three star clusters – M36, M38 and NGC 1907. I can not find a catalogue number for the round emission nebula above M36. But it is an interesting looking one. Close to its upper end I think I can see a faint blue nebula – maybe reflection one.

Two very small planetary nebulae can be found if one examines the image at 100%. These are:
- PK173+03.1 – right inside SH2-232;
- PK172+00.1 – close to M38.

With the 6x2 image complete its resolution reached 17037x7614 or close to 130 megapixels. The .xisf file reached 1.5GB on my disk 😊

This project was fun and I like the result.

With the completion of this project I disassembled the RASA8 and prepared the C9.25. Now I am off to chasing galaxies and small PNs 😊 If only there were more clear and moonless nights…

CS,
Ivan