AstroSat is India’s first dedicated multi-wavelength space observatory launched by the Indian Space Research Organisation (ISRO) on 28 September 2015. After launch, the AstroSat Science Support Cell (ASSC) was set up as a joint venture of ISRO and the Inter-University Centre for Astronomy and Astrophysics (IUCAA) with the primary purpose of facilitating the use of AstroSat, both for making observing proposals and for utilising archival data. The ASSC organises meetings, workshops and webinars to train users in these activities, runs a help desk to address user queries, provides utility tools and disseminatesanalysis software through a consolidated web portal. It also maintains the AstroSat Proposal Processing System (APPS) which is deployed at ISSDC, a software platform central to the workflow management of AstroSat operations. This paper illustrates the various aspects of ASSC functionality.

The Cadmium–Zinc–Telluride (CZT) Imager on board AstroSat is a hard X-ray imaging spectrometer operating in the energy range of 20–100 keV. It also acts as an open hard X-ray monitor above 100 keV capable of detecting transient events like the Gamma-ray Bursts (GRBs). Additionally, the instrument has thesensitivity to measure hard X-ray polarization in the energy range of 100–400 keV for bright on-axis sources like Crab and Cygnus X-1 and bright GRBs. As hard X-ray instruments like CZTI are sensitive to cosmic rays in addition to X-rays, it is required to identify and remove particle induced or other noise events and select events for scientific analysis of the data. The present CZTI data analysis pipeline includes algorithms for such event selection, but they have certain limitations. They were primarily designed for the analysis of data from persistent X-ray sources where the source flux is much less than the background and thus are not best suited for sources like GRBs. Here, we re-examine the characteristics of noise events in CZTI and present a generalized event selectionmethod that caters to the analysis of data for all types of sources. The efficacy of the new method is reviewed by examining the Poissonian behavior of the selected events and the signal to noise ratio for GRBs.

The data pipeline at the Payload Operation Centre (POC) of the Scanning Sky Monitor (SSM) onboard AstroSat involves: (i) fetching the Level-0 data from the Indian Space Science Data Centre (ISSDC), (ii) Level-0 to Level-1 data processing followed by Level-2 data generation, and (iii) transfer of theLevel-1 and Level-2 data back to ISSDC for dissemination of the re-packaged Level-2 data products. The major tasks involved in the generation of Level-1 and Level-2 data products are: (a) quality checks; time, alignment corrections, (b) temporal-HK plots generation, and, (c) image processing; light curve generation.The typical turn around time for this fully automated pipeline is about 25 min for one orbit data. In this paper, details of all the stages of this data pipeline are discussed.

The Cadmium–Zinc–Telluride Imager (CZTI) is an imaging instrument onboard AstroSat. This instrument operates as a nearly open all-sky detector above 60 keV, making possible long integrations irrespective of the spacecraft pointing. We present a technique based on the AstroSat-CZTI data to explore the hard $\gamma$-ray characteristics of the c-ray pulsar population. We report highly significant ($\sim$30$\sigma$) detection of hard X-ray (60–380 keV) pulse profile of the Crab pulsar using $\sim$5000 ks of CZTI observations within 5 to 70$^{\circ}$ of Crab position in the sky, using a custom algorithm developed by us. Using Crab as our test source, we estimate the off-axis sensitivity of the instrument and establish AstroSat-CZTI as a prospective tool in investigating hard X-ray characteristics of c-ray pulsars as faint as 10 mCrab.

The Cadmium Zinc Telluride (CZT) Imager onboard AstroSat consists of pixelated CZT detectors, which are sensitive to hard X-rays above 20 keV. The individual pixels are triggered by ionising events occurring in them, and the detectors operate in a self-triggered mode, recording each event separatelywith information about its time of incidence, detector co-ordinates, and channel that scales with the amount of ionisation. The detectors are sensitive not only to photons from astrophysical sources of interest, but also prone to a number of other events like background X-rays, cosmic rays, and noise in detectors or theelectronics. In this work, a detailed analysis of the effect of cosmic rays on the detectors is made and it is found that cosmic rays can trigger multiple events which are closely packed in time (called ‘bunches’). Higher energy cosmic rays, however, can also generate delayed emissions, a signature previously seen in the PICsIT detector on-board INTEGRAL. An algorithm to automatically detect them based on their spatial clustering properties is presented. Residual noise events are examined using examples of Gamma Ray Bursts as target sources.

The Cadmium–Zinc–Telluride Imager on AstroSat has proven to be a very effective All-Sky monitor in the hard X-ray regime, detecting over three hundred GRBs and putting highly competitive upper limits on X-ray emissions from gravitational wave sources and fast radio bursts. We present the algorithmsused for searching for such transient sources in CZTI data, and for calculating upper limits in case of nondetections. We introduce CIFT: the CZTI Interface for Fast Transients, a framework used to streamline these processes. We present details of 87 new GRBs detected by this framework that were previously not detected in CZTI.

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.