We present a low-cost Raspberry Pi-based star sensor StarberrySense using commercial-off-the-shelf components, developed and built for applications in small satellites and CubeSat-based missions. A star sensor is one of the essential instruments on board a satellite for attitude determination. However, most commercially available star sensors are expensive and too bulky for use in small satellite missions. StarberrySense is a configurable system—it can operate as an imaging camera, a centroiding camera, or a star sensor. We describe the algorithms implemented in the sensor, its assembly, and its calibration. This payload was selected by a recent announcement of an opportunity call for payloads to fly on the PS4-Orbital Platform by the Indian Space Research Organization.

Star sensors are an essential instrument used to determine the attitude of satellites by identifying the stars in the field of view. The high cost and large sizes of commercially available star sensors pose challenges for small satellite missions. We at the Indian Institute of Astrophysics have developed a low-cost star sensor, StarberrySense, based on the Raspberry Pi as the main controller and built from commercial off-the-shelf components. The StarberrySense was flown on the PS4 experimental orbital platform module of the Polar Satellite Launch Vehicle C-55 by the Indian Space Research Organization. This work describes the flight hardware, environmental tests in preparation for the flight, and in-orbit performance of our StarberrySense.

We present design, development and scientific objectives of a compact Far-Ultraviolet (FUV) imaging instrument (FISAT) intended for deployment on a CubeSat platform. The instrument employs a Ritchey-Chrétien optical configuration optimized for wide-field imaging in the 130–180 nm wavelength range, enabling high-sensitivity observations within the constraints of a small satellite mission. The primary science objective is to conduct a systematic survey of the ultraviolet sky, focusing on detecting and characterizing transient astrophysical phenomena. The complete optomechanical architecture of the payload is described, including optical design, structural configuration, and detector integration. The FISAT engineering model was assembled and characterized to withstand the payload requirements. Particular emphasis is placed on achieving a lightweight and compact system while ensuring mechanical robustness. Structural integrity is validated through comprehensive finite-element analysis. The results confirm that the instrument satisfies strength and stiffness requirements, with the fundamental natural frequency exceeding typical launch vehicle constraints and stresses remaining within allowable material limits. This work demonstrates the feasibility of conducting FUV transient surveys with CubeSat platforms, providing a cost-effective, scalable approach to time-domain ultraviolet astronomy. The instrument is scheduled to be launched in collaboration with InterCosmos by the end of 2026

Atmospheric dispersion causes light from celestial objects with different wavelengths to refract at varying angles as it passes through Earth’s atmosphere. This effect results in an elongated image at the focal plane of a telescope and diminishes fibre coupling efficiency into spectrographs. We propose an optical design that incorporates a Rotational Atmospheric Dispersion Corrector (RADC) to address the broad-band dispersion for the multi-object mode of the High-Resolution Optical Spectrograph (HROS) on the Thirty Meter Telescope (TMT). The RADC corrects the dispersion across the entire wavelength range (0.31–1 $~\mu \text{m}$), using Amici prisms optimized for over $90{{\ \rm per\ cent}}$ transmission efficiency and minimal angular deviation of the beam from the optical axis after dispersion correction. For enhanced accuracy, particularly in the blue region, we have, for the first time, implemented the Filippenko model in Zemax via a custom Dynamic-Link Library (DLL) file.