Astronomy Picture of the Day . The X-Ray Sky . ... 1.01.1996 . ... Credit Copyright: NASA , HEAO-1 , Boldt (GSFC) and Garmire (Cal Tech/PSU), Skyview , Allen, Jahoda, Whitlock Explanation: What if you could see X-rays? ... This X-ray image of the entire sky was constructed with Skyview , using data from the first High Energy Astronomy Observatory (HEAO 1) , and plotted in a coordinate system centered on the galactic center with the north galactic pole at the top. ... January 1996 . ... 1995 1996 . ...