This X-ray Landmarks frame highlights a variety of X-ray objects, including X-ray binaries, supernova remnants, and active galaxies. The rectangular image is a magnification of the center of our Milky Way galaxy, which has a high density of X-ray stars. The Crab Nebula is in Taurus at ~RA 05h Dec 22°. The Large Magellanic Cloud is at ~RA 05h Dec -70° in Mensa\Dorado. NGC 4151 is in Canes Venatici at ~+RA 12h Dec +39°. Scorpius X-1 is at ~RA 16h Dec -15°. The center of the Milky Way in the frame is at ~RA 17h Dec -29°. Cygnus X-1 is at ~RA 20h Dec +35°. Cassiopeia A is at ~RA 23h Dec +58°. The point of view of the frame is in plane of the galaxy, at the 98° point looking edge on at the galaxy.
There are 88 official constellations that the International Astronomical Union (IAU) has used to divide the celestial sphere into 89 irregularly shaped boxes. The constellation Serpens is split into two separate sections, Serpens Caput (the snake's head) to the west and Serpens Cauda (the snake's tail) to the east. Using detectors placed above the Earth's atmosphere, X-radiation has been detected as incoming from each of these constellational areas. Searching for the first X-ray source per constellation is a history of science exercise that is still ongoing as the initial X-ray source for many of the constellations is questionable or unknown.
