what is the lockman hole? whats so special about it??

Answer 1

"A patch of the sky, lying roughly between the pointer stars of the Big Dipper (centered at R.A. 10h 45m, Dec. +58° 00'), with an area of 15 square degrees, that is almost free from absorption by neutral hydrogen gas in the Galaxy. Having the minimum column density of galactic hydrogen, it allows the most sensitive searches for extragalactic objects and, for this reason, is one of the best studied sky areas across a very wide range of wavelengths, from radio waves to gamma rays.'' -

http://www.daviddarling.info/encyclopedia/L/Lockman_Hole.html