CTB 1

CTB 1 is the supernova remnant G116.9+0.2 in the constellation Cassiopeia, and it is also known by the nickname Medulla Nebula. Radio surveys identified it in 1960 at 960 MHz. [NASA on CTB 1](https://www.nasa.gov/universe/nasas-fermi-satellite-clocks-cannonball-pulsar-speeding-through-space/)

Radio and optical studies put its main shell at roughly 34 to 35.5 arcminutes across, with a break or breakout toward the northeast. Optical observations show faint hydrogen-alpha and other emission-line filaments. [Monthly Notices of the Royal Astronomical Society](https://academic.oup.com/mnras/article-abstract/527/1/803/7333979)

Astronomers associate the fast pulsar PSR J0002+6216 with the explosion that created CTB 1 because its radio tail points back toward the remnant. NASA reports that it spins 8.7 times per second and moves at nearly 2.5 million miles per hour. [NASA Fermi article](https://www.nasa.gov/universe/nasas-fermi-satellite-clocks-cannonball-pulsar-speeding-through-space/)

CTB 1 is a very faint optical target, so ordinary visual observing is difficult even though the remnant spans about half a degree on the sky. Astrophotographers commonly use long exposures and narrowband filters to reveal its hydrogen-alpha and oxygen emission. [CTB 1 catalogue](https://www.mrao.cam.ac.uk/surveys/snrs-2019/snrs.G116.9%2B0.2.html)