Measuring electron density in coronal active regions. II: A multichannel coronagraph with a photoelectric spectrograph and a reflex monitor at λ 5303Å

In order to study the electron density at the scale of the most encountered structures in coronal active regions a new multichannel coronagraph associated with a photoelectric spectrograph is now used at the Pic-du-Midi Observatory. In its quasi-routine mode this instrument, which is described in this paper, works with a 30 arcsec field aperture in a parallel manner with a K-polarimeter. On each observed region it obtains maps of intensities of the 3388, 10747, and 10798 A emission lines due to Fe XIII ion. Each measurement point is associated with a quasi-simultaneous image of the emission corona structures viewed in the light of the 5303 A line of Fe XIV. Three examples of observations are given and the capabilities are discussed. Measuring electron density in coronal active regions. II A multichannel photoelectric coronagraph with a photo-electric spectrograph and a reflex monitor at 5303 A.