NGC 300 (also known as Caldwell 70) is a spiral galaxy in the constellation Sculptor. It is one of the closest galaxies to the Local Group, and probably lies between the latter and the Sculptor Group. It is the brightest of the five main spirals in the direction of the Sculptor Group. It is inclined at an angle of 42° when viewed from Earth and shares many characteristics of the Triangulum Galaxy.
NGC 300-OT[]
On a CCD image obtained on May 14, 2008, amateur astronomer L.A.G. Berto Monard discovered a bright optical transient (OT) in NGC 300 that is designated NGC 300-OT. It is located at 00h 54m 34.55s , −37° 38′ 31.79″ in a spiral arm containing active star formation. Its broad-band magnitude was 14.3 in that image. An earlier image (from April 24, 2008), taken just after NGC 300 reemerged from behind the Sun, evidenced an already brightening OT at ~16.3 magnitude. No brightening was detected on a February 8, 2008 image or on any earlier ones. The transient's peak measured magnitude was 14.69 on May 15, 2008.
SN 2010da[]
On May 23, 2010, another transient object of 16th magnitude was discovered by Monard, denoted as SN 2010da. The optical transient was detected 15".9 west and 16".8 north the center of the galaxy at coordinates 00h 55m 04.86s -37° 41' 43.7.
The transient faded by 0.5-0.7 mag in 9 days, much faster than the 2008 transient in NGC 300.
Binary black hole system[]
The x-ray source at the core of NGC 300 is designated NGC 300 X-1. Astronomers speculate that NGC 300 X-1 is a new kind of Wolf-Rayet black hole binary system similar to the confirmed such system IC 10 X-1 in IC 10.