by Anthony Ayiomamitis
The extended galactic supernova remnant CTB 1 in Cassiopeia is one of the closest SNR's known lying at a distance of about 9,800 light-years away. Measuring approximately 35.2 arcminutes in diameter and physically spanning 98 light-years across, this circular formation rich with filamentary structure lies immediately east of Caph (β-Cas, mag 2.26) and is characterized with dominant optical, x-ray and radio sources. CTB 1 was originally thought to be a large planetary nebula and was included by Abell in his catalog of planetary nebula (Abell 85) but it was suggested by van den Bergh in 1960 and comfirmed by Willis & Dickel in 1971 to be, in fact, not a planetary nebula but rather a galactic SNR. The northeast portion of the shell is discontinuous and studies have confirmed this shell rupture to be genuine and not an optical illusion and to extend up to 30' to the east and past the main shell. Also of interest is the stronger O-III emission on the western section of the shell and which coincides with scientific findings and is believed to represent "large-scale, incomplete shock cooling". Similarly, the greater contrast of the southern half of CTB 1 is consistent with scientific findings and which has been linked to the various dust clouds in the immediate area and also visible in the image above.
Technical Details:
Date: Sep 02-15, 2010
Location: Athens, Greece (38.2997° N, 23.7430° E)
Equipment: Takahashi FSQ-106/f5, AP 1200GTO GEM, SBIG ST-10XME, SBIG CFW10, Baader 7nm H-α, Baader 8nm S-II, Baader 8.5nm O-III, SBIG LRGB filters
Integrations: Ha-SII-OIII-LRGB @ 720:360:420:120:60:60:60 using 3-/6-/30-min subs, 1x1 binning, 2.65"/pixel, -17.5d C
Further details are available here.