Photometric camera

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The primary focus with the CCD camera for optical imaging. Credit: Miroslav Šlechta.

The photometric camera G2-1000BI (Moravian Instruments) with E2V CCD 47-10 chip is installed in the primary focus. The focal length of the main mirror is 9 m (focal ratio f/4.5), but the correcting lens changes the effective focal length in primary focus to 7 m (focal ratio to f/3.5). The automatic exchange of the instruments between spectroscopic (fibers) and photometric (primary focus camera) configuration can be done within 1 minute. The camera is equipped with five position rotating filter wheel with different filters and cooled up electronically (down to -40° C under ambient) by Peltier cell.

Camera and chip
ADC Resolution Pixel size Read. noise Efficiency Linearity Reading

16 bit


1056 x 1027


13 x 13 μm





(500-700 nm)

> 95 %


10 s


Camera and telescope
Effective focal length Field of view Angular resolution Test image
7 000 mm 6.3′ x 6.3′ 0.385 “/pixel
Photometric filters

The camera is equipped with five position rotating filter wheel with different filters. Complete list of available filters: Sloan u’, Sloan g’, Sloan r’, Sloan i’, Sloan z’, H-alpha, [O-III], [S-II], Bessel B, Bessel V, Bessel R, Bessel I. Narrow band filters have bandpass width 3 nm.

Currently installed filters (see the table).

Position 0 1 2 3 4
Filter O III i’ (SSDS) r’ (SSDS) g’ (SSDS) Hα
Camera and telescope performance (in good seeing conditions)
brightness  exposure  filter  measurement error      Χ
~ 12.5 mag     8 s      r'       ~ 0.002 mag      ~ 1,05
~ 15.2 mag     8 s      r'       ~ 0.006 mag      ~ 1,10
~ 16.2 mag    10 s      g'       ~ 0.020 mag      ~ 2,20
~ 18.3 mag    20 s      g'       ~ 0.030 mag      ~ 1,10
~ 23.3 mag     7 h      r'       ~ 0.160 mag      ~ 1,40

Magnitude (Sloan r) limit after 60s exposure in different air mass.