The Square Kilometre Array (SKA) observatory is a next-generation radio astronomy facility, which is just started its construction, after successful completion of the design and early prototyping phases. With more than 12 countries currently participating in the international consortium to build this facility, the SKA is expected to revolutionize radio astronomy, while driving the growth of many important new state of the art technologies. Once completed and fully operational by the turn of this decade, the SKA observatory will offer cutting edge science capabilities in an extremely broad range of topics in astrophysics. Indian scientists and engineers have played a significant role in the definition of the SKA concept and its science case as well as in the design of the instrument. India is now getting ready to join the construction phase of the SKA, and Indian astronomers are preparing to engage in front line science with the facility as and when it is ready. This paper describes the current status of this global project with a focus on India’s role in the collaboration.

Decades long monitoring of millisecond pulsars, which exhibit highly stable rotational periods in pulsar timing array experiments is on the threshold of discovering nanohertz stochastic gravitational wave background. This paper describes the Indian pulsar timing array (InPTA) experiment, which employs the upgraded Giant Metrewave Radio Telescope (uGMRT) for timing an ensemble of millisecond pulsars for thispurpose. We highlight InPTA’s observation strategies and analysis methods, which are relevant for a future PTA experiment with the more sensitive Square Kilometer Array (SKA) telescope. We show that the unique multi-sub-array multi-band wide-bandwidth frequency coverage of the InPTA, provides dispersion measureestimates with unprecedented precision for PTA pulsars, e.g., $\sim$$2 \times 10^{−5}$ pc cm$^{−3}$ for PSR J1909-3744. Configuring the SKA-low and SKA-mid as two and four sub-arrays, respectively, it is shown that comparable precision is achievable, using observation strategies similar to those pursued by the InPTA, for a larger sample of 62 pulsars, requiring about 26 and 7 h per epoch for the SKA-mid and the SKA-low telescopes, respectively. We also review the ongoing efforts to develop PTA-relevant general relativistic constructs that will be required to search for nanohertz gravitational waves from isolated super-massive black hole binary systems like blazar OJ 287. These efforts should be relevant to pursue persistent multi-messenger gravitational wave astronomy during the forthcoming era of the SKA telescope, the thirty meter telescope, and the next-generation eventhorizon telescope.

India has been a significant contributor to the SKA project from 2009, with a special emphasis on the Telescope Manager, the central control system for the SKA Observatory. This paper describes the details of the design and early prototyping phases of the Telescope Manager work package, including the accompanying life cycle activities. It also traces the history of India’s involvement in the work on the Telescope Manager in various phases of the project, describing the contribution starting with the concept design to the currentlyongoing construction phase, and looks at the road ahead. The details of the design and the outcomes of the prototyping and development contributed by India in each phase, are also included.

The Square Kilometre Array (SKA) Observatory is a next-generation radio astronomy facility that has recently entered into the construction phase, after successful completion of the design and prototyping phases during 2013–2021. Planned to be operational by the end of this decade, the SKA is expected to revolutionise astronomy by allowing cutting edge explorations in an extremely wide range of science areas, while driving the growth of many important new state-of-the-art technologies. There are more than 10 countries currentlyparticipating in the international consortium to build this facility, which will be co-located in Australia andSouth Africa with the global headquarters in the United Kingdom. Indian scientists and engineers have played a significant role since the beginning: from the definition of the SKA concept and its science case, to some important aspects of the design of the instrument and the prototyping activities. India is now getting ready to join the construction phase of the SKA with a well defined proposal for technical activities spanning a few different areas of work. Along with this, Indian astronomers are busy refining their science case for the SKA and preparing in different ways to be ready for front line science with the facility as and when it is commissioned. All these activities are coordinated by the SKA India consortium, which currently has a membership of more than 20 institutions across the country. In this paper, we describe the current status of the SKA project, and focus on India’s role—past contributions, ongoing activities and future plans.

Backed by advances in digital electronics, signal processing, computation and storage technologies, aperture arrays, which had strongly influenced the design of telescopes in the early years of radio astronomy, havemade a comeback. Amid all these developments, an international effort to design and build the world’s largest radio telescope, the Square Kilometre Array (SKA), is ongoing. With its vast collecting area of 1 km$^2$, the SKA is envisaged to provide unsurpassed sensitivity and leverage technological advances to implement a complex receiver to provide a large field of view through multiple beams on the sky. Many pathfinders and precursor aperture array telescopes for the SKA, operating in the frequency range of 10–300 MHz, have been constructed and operationalized to obtain valuable feedback on scientific, instrumental and functional aspects. This review article looks explicitly into the progression of digital-receiver architecture from the Murchison Widefield Array(precursor) to the SKA1-Low. It highlights the technological advances in analog-to-digital converters (ADCs), field-programmable gate arrays (FPGAs) and central processing unit–graphics processing unit (CPU–GPU) hybrid platforms around which complex digital signal processing systems implement efficient channelizers, beamformers and correlators. The article concludes with a preview of the design of a new generation signal processing platform based on radio frequency system-on-chip (RFSoC).