Description

BEARS

BEARS is a 5x5 channels SIS heterodyne receiver array for the Nobeyama 45 m telescope. BEARS was installed at the Nobeyama 45 m telescope in 1998. Details about BEARS are described in Sunada et al. (2000, SPIE 4015, 237) and Yamaguchi et al. (2000, SPIE 4015, 614).

Number of beams 5 x 5 (25 beams)
Beam separation 41.1" grid spacing
Frequency range 82 - 116GHz
IF frequency 2.0 - 2.6 GHz (600MHz band width)
Operation DSB mode

Spectrometers for BEARS ( MAC, alias AC45 )

Autocorrelators (MAC) can be used for observations with BEARS. You can select one of five modes. Details about MAC are described in Sorai et al. (2000, SPIE 4015, 86).

Spectrometer Band width Ch Resolution*
AutoCorrelators 512 MHz 1024 500 kHz
AutoCorrelators 32 MHz 1024 31.25 kHz
AutoCorrelators 16 MHz 1024 15.63 kHz
AutoCorrelators 8 MHz 1024 7.81 kHz
AutoCorrelators 4 MHz 1024 3.91 kHz

* Resolution depends on the window function of FFT, which you can select when you make the observation table. Frequency resolution of Autocorrelator depends on both the band width and the window function you selected. You can select from four window functions- none(x1.21), hanning(x2.00), hamming(x1.82), and brackman(x2.30). Frequency resolution are calculated by the next equation;
Frequency resolution = Bandwidth / 1024 x factor(window function).
For example, in the case of the 32 MHz bandwidth and the window function "none", the resulting resolution is 37.8 kHz.

Observing Modes

You can use three observing modes; position switching, frequency switching and on-the-fly.