Efficient Absolute Aspect Determination of a Balloon‐borne Far‐Infrared Telescope Using a Solid State Optical Photometer

The observational and operational efficiency of the Tata Institute of Fundamental Research 1 m balloon‐borne far‐infrared telescope has been improved by incorporating a multielement solid state optical photometer (SSOP) at the Cassegrain focus of the telescope. The SSOP is based on a one‐dimensional linear photodiode array (PDA). The on‐line and off‐line processing schemes of the PDA signals which have been developed lead to improvement in the determination of absolute telescope aspect (∼ 0.′8), which is very crucial for carrying out the observations as well as off‐line analysis. The SSOP and its performance during a recent balloon flight are presented here.