CTB 1/SNR G116.9+00.1 (“Garlic Nebula”, “Medulla Nebula”)

CTB-1 is in the constellation Cassiopeia (Cas) and is approximately 10,000 light-years from Earth, about 100 light-years in diameter, and is estimated to have formed about 10,000 years ago.  It is nearby several other emission nebulae: Sh2-170 (the dot in the Cosmic Question Mark), Sh2-168, and Sh2-173 to name a few.  In addition, there are two other SNRs in the frame: SNR G117.7+00.6 in the lower left of the frame, and SNR G116.5+01.1 in the upper left of the frame (although it’s not well defined).

CTB-1 has an interesting circular structure with many filamentary structures as well as a rupture in its shell (on the lower left of the SNR), has a slim and faint OIII signal on part of its shell, and is surrounded by additional nebulosity, both close to its shell and farther away.

CTB-1 was initially identified by George Abell as planetary nebula, Abell 85, but was later identified as a supernova remnant (G116.9+0.1) in 1972.  The CTB designation is from the Caltech Observatory list B catalogue. The designation Abell 85 is still used today.

I imaged this last year (I think), but wanted to get more time on the target since it has some very interesting detail.

Capture Dates: 10/1, 10/3, 10/5, 10/12, 10/18, and 10/19/24

Rig 1:
Stellarvue SVX90T Apochromatic Refractor @native 540mm fL (1.44”/px)
Guidescope/Cam: SV106 with ASI120mm mini
ASIAir Plus, ASI2600MM, ZWO AM5 mount, ZWO 7-position 2” filter wheel

Rig 2:
Askar 107PHQ with 0.7x reducer at fL = 524mm, f/4.9 (1.47”/px)
Guidescope/Cam: SV106 with ASI178mm
ASIAir Plus, ASI2600MM, ZWO AM5 mount, ZWO 7-position 2” filter wheel

Filters:
Antlia 3nm Narrowband H-alpha 2": 121×300″ [10:05]
Antlia 3nm Narrowband SII  2": 129×300″ [10:45]
Antlia 3nm Narrowband OIII 2": 187×300″ [15:45]
Antlia Pro V RGB 2” (for stars): 44x60s [0:44]

Total Integration Time: 37:09

Processed in PixInsight and Adobe Photoshop