Daniel Guberman: Using UV-pass filters for bright Moon observations with MAGIC

Wednesday 29 Apr 2015, 13:00 → 14:00 Europe/Madrid

Seminar (IFAE)

Jelena Aleksic (IFAE), Joern Lange (IFAE Barcelona), Stefania Bordoni (IFAE)

The PMTs in the MAGIC cameras are designed to operate under moonlight, but they are limited to moon phases below 93% (300 Moon hours per year). As a result, MAGIC cannot be operated 2-3 days before and after Full Moon. We have selected commercial inexpensive UV-pass filters that reject ~ 80% of the moonlight and mounted them on light-weight frames that can be easily installed on the telescope cameras. With the UV filters the observation of sources down to an angular distance of 5 degrees to the Moon is possible even during Full Moon. Therefore, we can record 700 more Moon hours per year and extend the duty cycle of MAGIC by about 50%, including nights when VHE observations with IACTs are currently not feasible. Here we present the results from the tests that have been performed during the last year and evaluate a preliminary performance, in terms of sensitivity and energy threshold, of the telescopes equipped with the UV filter under different moonlight intensities.