HAWAII-2RG Infrared Camera for Solar Polarimetry

H2RG

The solar polarimetry is indispensable to determine solar magnetic fields governing a variety of phenomena in the solar atmosphere. From the viewpoint of space weather, the magnetic field in solar filaments, which occasionally erupt and result in a harmful effect to the Earth, is of particular interest. To obtain accurate magnetic field information of filaments, the realization of advanced solar polarimetry, employing a high-speed, large-format detector covering near-infrared wavelengths is required. However, so far, this has been difficult to be realized.

Thus, we started the development of a new infrared camera for advanced solar polarimetry, employing a HAWAII-2RG (H2RG) array by Teledyne, which has 2048x2048 pixels. Although it has been difficult to synchronize H2RGs under fast readout mode with external devices, such as a polarization modulator, we solved this problem by introducing a MACIE card and relevant assembly codes provided by Markury Scientific. This enables polarization measurements with high frame-rates, such as 29 frames per seconds, using a H2RG.

The figure to the upper right shows the camera installed in the Domeless Solar Telescope of the Hida Observatory of Kyoto University. We confirmed the high polarimetric performance of the camera with such experiments.

This work is supported by a Japanese Kakenhi grant 15H05814,“Project for Solar-Terrestrial Environment Prediction” and also by a NAOJ research grant.
References
Y. Hanaoka et al.: “A HAWAII-2RG infrared camera operated under fast readout mode for solar polarimetry”, Earth, Planets and Space 72, 181, 2020
(doi: 10.1186/s40623-020-01318-8).