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The future of astronomy in the coming decades will be shaped by the upcoming three extremely large optical telescopes, the Thirty Meter Telescope (TMT), the Giant Magellan Telescope (GMT) and the European Large Telescope (ELT). The USA astronomy and astrophysics 2020 decadal survey and the Canadian long-range plan for astronomy have recently recommended these large observatories as a top priority for ground-based astronomy for the upcoming decade. India is a 10% partner in one of these large observatories, the TMT, which is jointly funded by the Department of Science and Technology (DST) and Department of Atomic Energy (DAE). Here, we highlight India’s contributions to the development of the telescope and science instruments. The size of back-end science instruments scale with telescope aperture, hence, science instruments for TMT will be the biggest ever built for any telescope. Designing and building them requires broad collaboration within India, across TMT partnership and industries. India contributes >30% of the work share towards the development of wide field optical spectrometer (WFOS). India is part of the development of other first-light instruments, the infrared imaging spectrograph (IRIS) and multi-object diffraction-limited high-resolution infrared spectrograph (MODHIS). Infrared guide star catalog is an important contribution from India to these adaptive optics (AO)-assisted instruments. India leads the development of high-resolution optical spectrograph (HROS), a major workhorse among the first decade instruments of TMT. India is also part of the instrument development team of other first-decade instruments. Concerted efforts have been made to contribute to some of the TMT precursor instruments that will help us to maximize the scientific productivity when TMT is operational, especially in the area of exoplanet science and observations that require AO. India-TMT is part of the science team for the Keck high-resolution infrared spectrograph for exoplanet characterization (HISPEC), a precursor instrument to TMT-MODHIS. In addition, Indian Institute of Astrophysics (IIA) is participating in the science and development of Santa Cruz array of lenslets for exoplanet spectroscopy (SCALES) project for Keck, which is a direct imaging spectrograph for exoplanet studies and a precursor to the TMT planetary system imager. [ABSTRACT FROM AUTHOR]

Abstract—The ultraviolet wavelength range (90–300 nm) is one of the most important parts of the electromagnetic spectrum for astrophysicists. The success of the GALEX and ASTROSAT/UVIT missions has given a new view on the ultraviolet sky with unprecedented detail of extended objects, such as planetary nebulae or supernova remnants. Direct images of the sky allow us to track the morphology of such objects, but provide very limited information about their physical conditions: temperature, density, and radiation fields. Spectroscopic observations make it possible to study local physical conditions, but usually only at one point in an extended nebula. Our proposed long-slit spectrograph (SING, Spectroscopic Investigation of Nebular Gas) will allow tracking emission lines across the entire spatially extended nebulae in the wavelength range of 140–270 nm, which is the key to understanding their dynamics and evolution. The spectrograph will operate onboard the Chinese space station. The article describes the scientific tasks for which this unique device is created, its main characteristics and preliminary design. [ABSTRACT FROM AUTHOR]

Though the ultraviolet (UV) domain plays a vital role in the studies of astronomical transient events, the UV time-domain sky remains largely unexplored. We have designed a wide-field UV imager that can be flown on a range of available platforms, such as high-altitude balloons, CubeSats, and larger space missions. The major scientific goals are the variability of astronomical sources, detection of transients such as supernovae, novae, tidal disruption events, and characterizing active galactic nuclei variability. The instrument has a 80 mm aperture with a circular field of view of 10.8 degrees, an angular resolution of ∼22 arcsec, and a 240 - 390 nm spectral observation window. The detector for the instrument is a Microchannel Plate (MCP)-based image intensifier with both photon counting and integration capabilities. An FPGA-based detector readout mechanism and real time data processing have been implemented. The imager is designed in such a way that its lightweight and compact nature are well fitted for the CubeSat dimensions. Here we present various design and developmental aspects of this UV wide-field transient explorer. [ABSTRACT FROM AUTHOR]

We present a design for a near-ultraviolet (NUV) imaging instrument which may be flown on a range of available platforms, including high-altitude balloons, nanosatellites, or space missions. Although all current UV space missions adopt a Ritchey-Chrétien telescope design, this requires aspheric optics, making the optical system complex, expensive and challenging for manufacturing and alignment. An all-spherical configuration is a cost-effective and simple solution. We have aimed for a small payload which may be launched by different platforms and we have designed a compact, light-weight payload which will withstand all launch loads. No other UV payloads have been previously reported with an all-spherical optical design for imaging in the NUV domain and a weight below 2 kg. Our main science goal is focused on bright UV sources not accessible by the more sensitive large space UV missions. Here we discuss various aspects of design and development of the complete instrument, the structural and finite-element analysis of the system performed to ensure that the payload withstands launch-load stresses and vibrations. We expect to fly this telescope-Lunar Ultraviolet Cosmic Imager (LUCI)-on a spacecraft to the Moon as part of the Indian entry into Google X-Prize competition. Observations from the Moon provide a unique opportunity to observe the sky from a stable platform far above the Earth's atmosphere. However, we will explore other opportunities as well, and will fly this telescope on a high-altitude balloon later this year. [ABSTRACT FROM AUTHOR]

We have developed a low-cost off-the-shelf component star sensor ( StarSense) for use in minisatellites and CubeSats to determine the attitude of a satellite in orbit. StarSense is an imaging camera with a limiting magnitude of 6.5, which extracts information from star patterns it records in the images. The star sensor implements a centroiding algorithm to find centroids of the stars in the image, a Geometric Voting algorithm for star pattern identification, and a QUEST algorithm for attitude quaternion calculation. Here, we describe the software package to evaluate the performance of these algorithms as a star sensor single operating system. We simulate the ideal case where sky background and instrument errors are omitted, and a more realistic case where noise and camera parameters are added to the simulated images. We evaluate such performance parameters of the algorithms as attitude accuracy, calculation time, required memory, star catalog size, sky coverage, etc., and estimate the errors introduced by each algorithm. This software package is written for use in MATLAB. The testing is parametrized for different hardware parameters, such as the focal length of the imaging setup, the field of view (FOV) of the camera, angle measurement accuracy, distortion effects, etc., and therefore, can be applied to evaluate the performance of such algorithms in any star sensor. For its hardware implementation on our StarSense, we are currently porting the codes in form of functions written in C. This is done keeping in view its easy implementation on any star sensor electronics hardware. [ABSTRACT FROM AUTHOR]

The Lunar Ultraviolet Cosmic Imager (LUCI) is a near-ultraviolet (NUV) telescope with all-spherical mirrors, designed and built to fly as a scientific payload on a lunar mission with Team Indus—the original Indian entry to the Google Lunar X-Prize. Observations from the Moon provide a unique opportunity of a stable platform with an unobstructed view of the space at all wavelengths due to the absence of atmosphere and ionosphere. LUCI is an 80 mm aperture telescope, with a field of view of 27.6 ′ × 20.4 ′ and a spatial resolution of 5 ″ , will scan the sky in the NUV (200–320 nm) domain to look for transient sources. We describe here the assembly, alignment, and calibration of the complete instrument. LUCI is now in storage in a class 1000 clean room and will be delivered to our flight partner in readiness for flight. [ABSTRACT FROM AUTHOR]