LDN 1089
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Francesco Meschia
Jul 31, 2025, 10:25:50 PMJul 31
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Hello SJAA imagers,
I’ve always found dark nebulae and molecular clouds very intriguing. In the northern hemisphere, Cepheus seems to be the mother lode of dark dust, and I’ve often found interesting targets within its boundaries – in 2019, for instance, out of the blue I got my first Astrobin IOTD with a picture of LDN 1235, the Dark Shark nebula.
Last weekend I went camping to a dark site to visit Cepheus again. This time, I had planned to image LDN 1089, the eastern portion of a large molecular cloud that from Draco juts into Cepheus. The shape of the cloud had triggered my pareidolia, conjuring in my mind the shape of a bird of prey taking off from a perch. But I knew that the challenge in imaging this bird would be the bright blue star Theta Cep, which –shining at magnitude 4.2– had the ability to turn my image into a blue haze, if transparency had declined during the night, or into a mess of reflections and flares if its light found anything shiny in my imaging train.
Fortunately, atmospheric transparency remained excellent throughout the night, and it appeared that I had done a decent job at flocking the inside of all my adapters, because I found no reflections. Total imaging time was somewhat limited due to the short summer night, but the sky appeared to be very dark, reading 21.60 mag/arcsec2 on my SQM, balancing things a bit in my favor.
I processed the data with PixInsight, where the main challenge was rendering Theta Cep while ensuring a smooth transition from its blue halo to the more muted colors of the surrounding dust. It turned out that the neural network in StarXTerminator was too conservative and considered a large portion of the star’s halo as part of the background. Due to the different type of processing needed by the dust and the stars, this created a jarring transition from blue to brown. It took some persuasion with masks and PixelMath to obtain a more reasonable separation, leading to what I hope is a more natural blend.
The full-resolution image, as well as the equipment and capture details, are on Astrobin at https://app.astrobin.com/i/gfwv5v. Comments, questions, and critique will be very welcome!
Thanks,
Francesco
I’ve always found dark nebulae and molecular clouds very intriguing. In the northern hemisphere, Cepheus seems to be the mother lode of dark dust, and I’ve often found interesting targets within its boundaries – in 2019, for instance, out of the blue I got my first Astrobin IOTD with a picture of LDN 1235, the Dark Shark nebula.
Last weekend I went camping to a dark site to visit Cepheus again. This time, I had planned to image LDN 1089, the eastern portion of a large molecular cloud that from Draco juts into Cepheus. The shape of the cloud had triggered my pareidolia, conjuring in my mind the shape of a bird of prey taking off from a perch. But I knew that the challenge in imaging this bird would be the bright blue star Theta Cep, which –shining at magnitude 4.2– had the ability to turn my image into a blue haze, if transparency had declined during the night, or into a mess of reflections and flares if its light found anything shiny in my imaging train.
Fortunately, atmospheric transparency remained excellent throughout the night, and it appeared that I had done a decent job at flocking the inside of all my adapters, because I found no reflections. Total imaging time was somewhat limited due to the short summer night, but the sky appeared to be very dark, reading 21.60 mag/arcsec2 on my SQM, balancing things a bit in my favor.
I processed the data with PixInsight, where the main challenge was rendering Theta Cep while ensuring a smooth transition from its blue halo to the more muted colors of the surrounding dust. It turned out that the neural network in StarXTerminator was too conservative and considered a large portion of the star’s halo as part of the background. Due to the different type of processing needed by the dust and the stars, this created a jarring transition from blue to brown. It took some persuasion with masks and PixelMath to obtain a more reasonable separation, leading to what I hope is a more natural blend.
The full-resolution image, as well as the equipment and capture details, are on Astrobin at https://app.astrobin.com/i/gfwv5v. Comments, questions, and critique will be very welcome!
Thanks,
Francesco
Sudhir Bud
Jul 31, 2025, 10:30:02 PMJul 31
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Wow! Terrific capture, Francesco.
Indeed, dark nebulae are quite intriguing.
-Sudhir
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Chris Gottbrath
Jul 31, 2025, 10:54:45 PMJul 31
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gorgeous
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Ian Clements
Aug 1, 2025, 12:57:04 AMAug 1
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On 7/31/25 19:25, Francesco Meschia
wrote:
Last weekend I went camping to a dark site to visit Cepheus again.
Congrats! What a nice image!
Stuart Heggie
Aug 1, 2025, 11:19:47 AMAug 1
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Francesco Meschia
Aug 1, 2025, 6:18:19 PMAug 1
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Stuart, Ian, Chris, Sudhir – thank you very much! I’m glad you liked it.
I haven’t had the time to write down the processing notes like I did for my two previous images, but I do want to do it. The processing that needed for Theta Cep is interesting.
Francesco
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Francesco Meschia
Aug 10, 2025, 8:48:16 PMAug 10
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And here’s the processing notes for the image: https://maketronica.wordpress.com/2025/08/03/ldn-1089/
Francesco
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