Mission name: FORMOSAT-2

Instrument: Imager of Sprites and Upper Atmospheric Lightning (ISUAL)

PI/Provider name: Rue-Ron Hsu

Institute: Department of Physics, National Cheng Kung University, Taiwan

Contact info: rrhsu@mail.ncku.edu.tw

Data format: CDF

Data description (including how measurements were made):

The Imager of Sprite and Upper Atmospheric Lightning is the scientific nighttime 
payload onboard the Taiwanese FORMOSAT 2 satellite and provides the observation 
of TLEs within a +/-60 degree range of latitude. The satellite was launched by a 
Taurus launch vehicle on May 20, 2004, from Vandenberg Air Force Base in California. 
After monitoring the upper atmosphere for 12 consecutive years, FORMOSAT 2 was 
terminated on June 21, 2016, due to the failure of the attitude control gyros. 
The total duration of the mission is more than twice the original designed lifetime.

The ISUAL instruments include an intensified CCD (iCCD) imager, a six-channel 
spectrophotometer (SP), and an array photometer (AP). The instruments have different 
time resolutions and the size of the field of view to record the evolution of TLEs 
from space. So long as a flash is detected by the trigger detection hardware, the 
data capture mode is initiated and a preprogrammed sequence of data is recorded in 
the storage device. TLEs are identified manually with the Imager according to their 
morphology [Kuo et al., 2007; Chen et al., 2010; Chou et al., 2010] along with 
the apparent vertical motion shown in the AP.

Time resolution/cadence: 1 millisecond

Acknowledgment: We are grateful to National Space Organization(NSPO), Taiwan, for the FORMOSAT-2.

Related publications:  Rajesh, P. K., et al. (2009), First results of the limb 
imaging of 630.0 nm airglow using FORMOSAT-2/Imager of Sprites and Upper Atmospheric 
Lightnings, J. Geophys. Res., 114, A10302, doi:10.1029/2009JA014087.

Project websites with more information:
https://formosat.tw/nspo_esok/about_isual_en.php
https://formosat.tw/nspo_esok/about_isual_operating_en.php

An EXCEL spreadsheet with detailed format and parameter descriptions is available in the 'documents' directory: Formosat2_ISUAL_description.xlsx

updated 2021 May 12