Research on sunspot Oscillations – I. The Pulkovo CCD Spectroheliograph-Magnetograph

ISSN： 0038-0938

Source： Solar Physics, Vol.213, Iss.2, 2003-04, pp. : 291-299

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Abstract

The CCD spectroheliograph-magnetograph is a focal-plane ancillary instrument for the Pulkovo horizontal solar telescope ACU-5. The instrument is placed at an exit port of an isothermal high-resolution diffraction-grating spectrograph. A modified Leighton optical scheme for registration of sunspot magnetic fields is used. The instrument provides FITS-format digital video maps of radial velocities, magnetic fields, and spectroheliograms in any line of the spectral region 3900–11000 Å. The time to obtain one video map of size 91′′×154′′ is equal to 10.24 s. The angular resolution of the instrument is 0.8′′; spectral resolution is 0.01–0.03 Å. Since 1996 the Pulkovo CCD spectroheliograph-magnetograph has been used to obtain high spatial and temporal resolution observations of oscillations of radial velocities and magnetic fields in the photospheric layers of sunspots.