CTB1 or the Garlic Nebula

I was scrolling through Stellarium and noticed a very faint semi-circular object in the constellation Cassiopeia, not too far from the famous Bubble Nebula.

This object catalogue as CTB 1 or Abell 85, was originally listed in the famous Abell catalog of planetary nebula. Later discoveries by revealed that CTB 1 is actually a very faint supernova remnant, about the size of the full moon. It is not the most photographed object and I couldn't find many images on it.

The hydrogen-alpha shell is extremely faint, and was just barely visible in a 10-minute sub-exposure. Being in Bortle 7 didn't help either. Revealing the full circular shape was definitely going to be a challenge, so I spent three whole nights on this object for a total exposure time of 20 hours. I had to throw out 25% of it due to high clouds! It was worth it though. My image shows many fine filaments in the ionized gas and shell of this exploded star is ruptured on the bottom right side.

Equipment :

Mount  - SkyWatcher EQ6R Pro

Telescope - Orion 115mm EDT

Camera - ZWO ASI294MC Pro

Guiding Scope  - SVBony SV106

Guiding Camera - ZWO ASI120mm Mini

Acquisition - ZWO ASI Air Plus

Narrowband Filter - Optolong Lextreme


Exposure  - 10 min subs

Integration - 16hr 10 mins

Gain - 120

Bortle Scale - 7

Software  - Pixinsight, Photoshop