Chaos overhead – Crescent Nebula

Crescent Nebula or or NGC 6888 or Caldwell 27 hides a Wolf-Rayet type of star. According to NASA, “a massive, incredibly hot star that blasts substantial winds of particles out into space and can shed mass equal to that of our Sun in just 100,000 years.” So, this is a pre-supernova. Once it goes supernova, it might look like Veil nebula.

I am often puzzled as to how these deep sky objects get nicknamed. Why Crescent? Why not a bacteria? The reason turns out to be what it looked like to its discoverer in 1792. With the tech they had, it looked like a crescent moon, or perhaps a pair of crescent moons. To us, with our amateur tech, it looks like a bacteria or virus. I have also been wondering about all these catalogs, Messier, Caldwell, NGC….and then I came across a nice writeup.

Part way through imaging Crescent, we got our dual pass filter, Ha and Oiii. So, this was an aggregate of 7 hrs of Ha, 2 hrs of Oiii and then 4 hrs of the dual pass filter resulting in 11 hrs of Ha and 6 hrs of Oiii.

If the swan anatomy is to be compared with a human, then Crescent Nebula is right at the base of its throat, at its jugular notch.

Crescent also marks the end of exploration this year of Cygnus/Swan constellation. It had started with swan heart (Sadr), and then it had moved on to swan’s leg (North America), its wing (Veil) and now its throat, Crescent. Sadr was the first nebula with our narrow band filters simply because it was the first of the nebula season. And Crescent marked the first dual pass filter.

Written by locomotoring

September 18, 2026 at 8:35 pm

Posted in Uncategorized

Locomotoring