The High Energy Astrophysics Science Archive Research Center (HEASARC) is the primary archive for NASA missions
dealing with extremely energetic phenomena, from black holes to the Big Bang. Having recently merged with the Legacy
Archive for Microwave Background Data Analysis (LAMBDA), it includes data
obtained by NASA's high-energy astronomy missions from the extreme ultraviolet through gamma-ray bands, along with
missions that study the relic cosmic microwave background.
Enter positions, times, missions, ... to Browse.
Try ROSAT 3c273 to get ROSAT data on 3c273 or
chandra bii>80 status=archived to get archived Chandra
data near the north galactic pole. Use quotes around targets
that have embedded white space (e.g., 'ar lac').