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Astron. Astrophys. 335, 991-994 (1998)

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2. Observations

The observations were made during 1996 June and 1997 June using NUI, Galway's TRIFFID camera. The TRIFFID system consists of a multianode microchannel array (MAMA) 2-dimensional photon-counting detector with a B extended S-20 photocathode (Timothy & Bybee 1985) and a fast data-collection system (Redfern et al. 1993). The position and time-of-arrival of each photon are recorded to a precision of 25µm and 1µs, respectively. TRIFFID's 1024[FORMULA]256-pixel array was mounted at the prime focus of the SAO 6-m Telescope (BTA), resulting in an equivalent spatial resolution of [FORMULA] pixel-1. Timing was achieved using a GPS receiver and an ovened 10-MHz crystal. Absolute timing was unavailable for the 1996 observations however, and times were recorded relative to the last reset of the data-collection system. The data-collection system was reset at the start of the observing run and again after the 1996 June 23 observations.

The observations were made with standard B and V filters and are summarised in Table 1. In all, a total of 19,456 seconds of B-band data and 8,173 seconds of V-band data were collected. Photometric standard stars were observed each night for calibration purposes.


Table 1. Summary of observations

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© European Southern Observatory (ESO) 1998

Online publication: June 26, 1998