The millimeter transient sky is largely unexplored , with measurements limited to follow-up of objects detected at other wavelengths .
High-angular-resolution telescopes designed for measurement of the cosmic microwave background offer the possibility to discover new , unknown transient sources in this band , particularly the afterglows of unobserved gamma-ray bursts .
Here we use the 10-meter millimeter-wave South Pole Telescope , designed for the primary purpose of observing the cosmic microwave background at arcminute and larger angular scales , to conduct a search for such objects .
During the 2012–2013 season , the telescope was used to continuously observe a 100 \deg ^ { 2 } patch of sky centered at RA 23 h 30 m and declination -55 ^ { \circ } using the polarization-sensitive SPTpol camera in two bands centered at 95 and 150 GHz .
These 6000 hours of observations provided continuous monitoring for day- to month-scale millimeter-wave transient sources at the 10 mJy level .
One candidate object was observed with properties broadly consistent with a gamma-ray burst afterglow , but at a statistical significance too low ( p = 0.01 ) to confirm detection .