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Contrib. Astron. Obs. Skalnatґ Pleso 43, 1 ­ 2, (2014) e

Mini-MegaTORTORA ­ multichannel system for wide-field optical monitoring with high temp oral resolution
V. Sasyuk1 , G. Beskin2 , S. Karp ov2 , S. Bondar3 , A. Perkov3 , E. Ivanov3 , E. Katkova3 and A. Shearer4
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Kazan Federal University, Russia Special Astrophysical Observatory of Russian Academy of Sciences, Russia 3 Insttitute for Precise Instrumentation, Russia 4 National University of Ireland, Galway, Ireland Received: November 4, 2013; Accepted: ???, 2014
Abstract. We report on a multi-ob jective and transforming 9-channel monitoring system, the Mini-MegaTORTORA (MMT-9). This system combines a wide field of view with a subsecond temporal resolution in the monitoring regime, and is able to reconfigure itself, in fractions of a second, to a followup mode which has better sensitivity and provides us with multi-color and polarimetric information on detected transients simultaneously. Key words: Instrumentation: photometers ­ Instrumentation: polarimeters ­ Techniques: high temporal resolution

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The systematic study of night sky variability on subsecond time scales still remains an important, but practically unsolved problem. The detection and investigation of rapid optical transients of various classes, both astrophysical and artificial, is an important task (Beskin et al., 2010, Beskin et al., 2013), which may be accomplished by means of continuous monitoring of the sky with wide-field optical cameras. Zolotukhin et al. (2004) and Karpov et al. (2005) demonstrated that it is possible to achieve the subsecond temporal resolution in a reasonably wide field with small telescopes equipped with fast CCDs, to perform fully automatic searching and classification of fast optical transients. A 9-channel system for wide-field monitoring of the sky with a subsecond temporal resolution was designed and is being manufactured (Karpov et al, 2013). The system is similar to the smaller, 6-channel (MMT-6) one we started to develop earlier (Karpov et al., 2012), and shares most of its constructive and operational properties. Each channel of Mini-MegaTORTORA consists of a Canon ob jective (diameter ­ 71 mm, lens aperture ­ 1/1.2), a 2560 x 2160 Andor Neo sCMOS detector (quantum efficiency 30-60% in the 4000-8000° A range) with a pixel size of 6.5 x 6.5 microns (which gives 15.5 per pixel angular resolution) and a frame rate of 10 frames per second. For photometric and polarimetric studies of the detected transients filters B, V, R and a polaroid are used. They are mounted behind the coelostat mirror. Its rotation to change FOV position (±20 degrees around two axes), as well as


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V. Sasyuk, G. Beskin, S. Karp ov, S. Bondar, A. Perkov, E. Ivanov, E. Katkova and A. Shearer

switching between the filters and polaroid in 0.2-0.3 seconds, is facilitated by a set of servo-motors. A separate computer is used to collect data and control the operation of each channel; a separate computer controls the entire system. The developed software allows collecting and reducing data in real time, as well as controlling individual channels and the monitoring system as a whole (Beskin et al., 2010). In the monitoring mode (all channels are pointed at different regions of the sky) the area of the systems field of view is about 900 square degrees. The limiting magnitude in the filter B is about 12 mag at 0.1 s. In the follow-up mode (all channels are pointed at the same sky region) threeband photometry and linear polarimetry of the detected optical transient with a magnitude of up to 10-11 mag at 0.1 seconds and 15-16 mag at 1000 seconds are carried out simultaneously. Both the classification of the optical transients detected in the monitoring regime and the switchover to the follow-up mode are executed in 0.2-0.5 seconds. MMT will use custom fork mounts based on a Skywatcher EQ6 head, each carrying two channels simultaneously. MMT will be installed at the Engelgardt observatory of the Kazan Federal University, Kazan, Russia in summer 2014. Acknowledgements. This work was supported by the Bologna University Progetti
Pluriennali 2003, by grants of CRDF (No. RP1-2394-MO-02), RFBR (No. 04-02-17555, 06-02-08313, 09-02-12053 and 12-02-00743), INTAS (04-78-7366), by the Presidium of the Russian Academy of Sciences Program and by the grant of European Union (FP7 grant agreement number 283783, GLORIA pro ject). The construction of MMT is being financed by the Kazan Federal University. S.K. has also been supported by a grant of the Dynasty foundation. G.B. thanks the Landau Network-Centro Volta and the Cariplo Foundation for a fellowship and the Brera Observatory for hospitality.

References
Beskin, G.M., Karpov, S.V., Bondar, S.F., Plokhotnichenko, V.L., Guarnieri, A., Bartolini, C., Greco, G., Piccioni, A.: 2010, Physics Uspekhi 53, 406 Beskin, G.M., Karpov, S.V., Plokhotnichenko, Bondar, S.F., A.Perkov, E.Ivanov, E.Katkova, V.Sasyuk, A.Shearer.: 2013, Physics Uspekhi 56, 836 Karpov, S., Beskin, G., Biryukov, A., Bondar, S., Hurley, K., Ivanov, E., Katkova, E., Pozanenko, A., Zolotukhin, I.: 2005, Il Nuovo Cimento C 28, 747 Karpov, S., Beskin, G., Bondar, S., Perkov, A., Greco, G., Guarnieri, A., Bartolini, C.: 2011, Astronomical Society of India Conference Series 7, 219 Karpov, S.V., Beskin, G., Bondar, S., Perkov, A., Ivanov, E., Guarnieri, A., Bartolini, C., Greco, G., Shearer, A., Sasyuk, V.: 2013, EAS Publ. S. 61, 465 Zolotukhin, I., Biryukov, A., Beskin, G., Karpov, S., Bondar, S., Ivanov, E., Katkova, E., Hurley, K., Pozanenko, A.: 2005, ASP Conference Series 347, 568