Search constraints :

An ideal instrument for a Dyson sphere study is an all sky survey covering a wide wavelength band centered in the 10 micron regime equivalent to 300 degrees Kelvin. These two requirements were satisfied by the mid-eighties IRAS satellite. A central mission for IRAS was to study cosmic dust, so there was no premium on resolution and the mirror had only a 0.6 m diameter. Still, the performance was satisfactory for a Dyson Sphere survey. The sensitivity was 1 Jansky while the angular resolution was 1 minute. Starting from a 250,000 source sample sources were discarded if the IRAS flux quality for the 12 and 25 μm filters only corresponded to an upper limit. This left 10982 sources. The search focused on a temperature range of 100 to 600 �K leaving about 6521 sources. No cut was made on proximity to other sources. By doing this partial Dyson spheres were not ruled out. As noted on the Dyson Sphere look-alike page there are several natural surrogates that are difficult to rule out. Several cuts were used on the LRS sample to focus in on a Dyson Sphere signature. These included temperature, classification, and visual scans in SIMBAD. This led to a sample of 17 weak and ambiguous candidates..

