2018PASP..130a4504S

Time-series photometry taken from ground-based facilities is improved with the use of comparison stars due to the short timescales of atmospheric-induced variability. However, the sky is bright in the thermal infrared (3-5 µm), and the correspondingly small fields of view of available detectors make it highly unusual to have a calibration star in the same field as a science target. Here, we present a new method of obtaining differential photometry by simultaneously imaging a science target and a calibrator star, separated by <=2 amin, onto a 10 x 10 asec² field-of-view detector. We do this by taking advantage of the Large Binocular Telescope's (LBT) unique binocular design to point the two co-mounted telescopes apart and simultaneously obtain both targets in three sets of observations.
Result. indicate that the achievable scatter in L_S-band (λ_{c}=3.3µm) is at the percent level for bright targets and possibly better with heavier sampling and characterization of the systematics.