Development of the multi-spectral auroral camera onboard the index satellite

To investigate the fine-scale auroral structures, high time and spatial resolution imaging observations of optical auroras will be made by a multi-spectral auroral camera (MAC) onboard the INDEX satellite which will be launched by an H2A rocket as a piggyback satellite into a polar orbit at an altitude of ∼700 km. Monochromatic auroral image data at emissions of N2 + first negative band (427.8 nm), OI (557.7 nm), and N 2 first positive band (670 nm) are obtained by MAC with the field-of-view (FOV) of 7.6° using three independent CCD cameras in combination with interference filters. MAC will operate in the nightside auroral region by two operation modes in the following. (1) Simultaneous measurement with particle sensors (ESA/ISA). In this mode, MAC observes an imaging area of ∼80×80 km (at a 100 km altitude) around a magnetic footprint with spatial and time resolutions of ∼1.2 km and 120 msec, respectively. (2) Auroral height distribution measurement. The attitude of INDEX satellite is changed to direct the FOV of MAC on the limb of the Earth. In this mode, MAC observes an imaging area of ∼270×270 km (at a 2000 km distance from the satellite) with spatial and time resolutions of ∼4 km and 1 sec, respectively. In this paper, the science mission, the instrumentation, and observation modes concerning on MAC will be presented.