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New dimensions of Indian hard X-ray Astronomy
Santosh Vadawale, PRL
In this talk I will discuss the new aspects of hard X-ray astronomy which have emerged from the additional capabilities of AstroSat-CZTI, namely - hard X-ray polarimetry and hard X-ray transient monitoring. I will begin with a brief introduction to the field, discuss recent advances made with CZTI, and then discribe two new missions being proposed to ISRO, which will carry forward the legacy of AstroSat-CZTI and enable India to make a mark on international level.

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NUnderstanding Black-holes in our Galaxy with LAXPC/AstroSat
J. S. Yadav, IITK
AstroSat, the first Indian Space science mission was successfully launched by ISRO on 28th Sept., 2015 in near-earth 650 km circular orbit. The Large Area X-ray Proportional Counter (LAXPC) instrument is one of the major science instruments onboard AstroSat. I will share some of the exciting moments during LAXPC instrument development along with a comparison with more recent science space missions like Chinese mission HXMT and NASA`s Nicer space mission (both launched in June 2017). I will describe how LAXPC/AstroSat data is helping us in
unraveling the mysteries of Blackhole systems in our Galaxy.

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How gravitational wave detectors measure sub-nuclear displacements?
Saikat Ghosh, IIT Kanpur

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Ultrafast table-top spectroscopy for Space Science
Debu Goswami, IIT Kanpur

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Rings around minor planets
Bharath, IIT Kanpur
The cronian rings ( the rings around Saturn ) were analysed extensively in the last century. Through Voyager and Cassini missions, today we know that there are rings around Jupiter, Uranus and Neptune also. The recent discovery of rings around the much smaller centaurs and asteroids surprised the scientific community. Doublets of optically thin rings have been observed around the small bodies Chariklo and Haumea and another pair is hypothesized to be around Chiron. Unlike the cronian case, these ringlets are subject to a more complex dynamical environment with large perturbing forces coming from the non-spherical central field and the moons of the minor planets and a stronger self-gravity. This lead to several new questions that are worth researching. We do kinetic theory, assuming the rings to be dilute particulate flows, to study the internal structure of such rings. We also conduct numerical experiments through N-body codes to analyse the possible origins of such rings. Our results show interesting and subtle features that may arise, given the sensitivity of the dynamics to the parameters in the problem.

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To Be Announced
Ishan Sharma, IIT Kanpur

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Satellites as Gravimeters
Balaji Devaraju, IIT Kanpur
Satellites are projectiles orbiting around the Earth predominantly under the influence of the Earth's gravity field. Their position is a consequence of the attraction of the Earth's gravity field and other gravitational and non-gravitational forces. Thus, by knowing the positions of the satellites and accounting for the non-gravitational forces acting on them the gravity field of the Earth can be recovered to remarkable accuracy. In this sense, all satellites can be viewed as gravimeters---instruments that measure the gravity field attraction. While we know that the average gravity value on Earth is about 9.81 meters per square second, the reality is that the gravity varies from place to place and also with time. The mass transport of Earth both in geological time-scales (mantle convection, glacial isostatic adjustment, etc.) and in human time-scales (atmospheric/ocean circulation and hydrologic variations) is manifest in the gravity field. Thus the gravity field captures information of the past as well as the present, allowing us to understand geophysical processes in a broadband of temporal scales. In the past couple of decades, satellite gravimetry has emerged as a reliable technique for studying climate change. In this talk I will discuss the evolution of satellite gravimetry, the techniques, its applications and the challenges that lie ahead of us in the future.

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Space Debris Mitigation
Akhil B. Krishna, IIT Kanpur
In this work, we are proposing a novel and safe way of disposing of space debris by utilizing Solar Radiation Pressure. A group of co-operative satellites are employed having large reflective surface capable of reflecting solar radiation, mimicking the design of 'Solar Sails'. As a result of the co-operative action of the satellites, a force field is created which dispose of the space debris either into a safe grave yard orbit or to a non-periodic orbit resulting in its mitigation by falling on to Earth's atmosphere. For validating the proposed idea, a numerical simulation is carried out, using realistic space debris trajectory information provided by the European Space Agency (ESA). As a case study a patch of space debris collection is chosen and the

concentration of solar radiation force resulted in their orbital decay and falling on to Earth's atmosphere. A preliminary design of satellites are considered and rigid body simulations are carried out employing attitude control by using actuators. The numerical simulations show promising results. The stability analysis of the proposed controllers are done using Nonlinear Control Theory.

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In-situ data analysis to study the solar wind plasma
Supratik Banerjee, IIT Kanpur
In this talk, I will give a very basic/ introductory presentation on how using in-situ data (both plasma and electromagnetic field data), the nature of solar wind plasma can be studied. It will also consist of a brief description of the spacecraft instruments used for collecting those data. Finally, I will give a schematic outline of the methodology of studying turbulent properties of the Solar wind using such data.

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Gaia DR2 Informed Distance Constraint to the North Polar Spur
Kaustav K. Das, IITK
The North Polar Spur (NPS) is one of the largest structures observed in the Milky Way in both the radio and soft x-rays. While several predictions have been made regarding the origin of the NPS, modeling the structure is difficult without precise distance constraints. Building on the work of Zucker et al. 20191, which determined accurate distances to local molecular clouds, we fit for distance and extinction to stars for sightlines along the southern terminus of the NPS and towards high latitudes ranging up to 53°, using optical and near-infrared photometry and Gaia DR2 astrometry. We model these per-star distance-extinction estimates as being caused by dust screens at unknown distances, which we fit for using a nested sampling algorithm. Based on our results, we conclude that the NPS is not associated with the Galactic Center or the Fermi bubbles as is commonly believed, rather it is associated with, especially at higher latitudes, with the Sco-Cen association. The robust distance constraints to the NPS obtained will be of paramount importance for modeling the evolution and origin of the structure.

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Where is the matter in our Universe and what is the matter with it ?
Sharvari Nadkarni-Ghosh, IIT Kanpur
The matter in our Universe is distributed over a large range of scales. The smallest gravitationally bound objects are planets which measure about a few thousand km (or nano light years), whereas one of the largest gravitationally bound structure is the recently discovered Saraswati supercluster which is about 4000 million light years across. Inspite of being so ubiquitous over such a huge range of scales, the matter that is `visible' to us i.e., which interacts electromagnetically, is only about one sixth of the total matter in the universe; the rest of the matter is dark. Even more alarming is the fact that the total matter content of the universe "dark + visible" is only about 30 % of the total energy budget of the Universe. In this talk, we will introduce some of these issues related to the large scale matter distribution of the universe and what discuss the clues we can use to unravel these mysteries.

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Dark Energy: One of the greatest puzzles of Modern Science
Suratna Das, IIT Kanpur
What is Dark Energy? What do we mean by "Dark"? What kind of "Energy" is it? We will try to address some of such questions regarding Dark Energy in this short talk.

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GMRT discovery of a large ring of atomic hydrogen gas around a red and dead galaxy
Omkar Bait, NCRA Pune
I will present the Giant Metrewave Radio Telescope (GMRT) discovery of an extremely large and off-centered ring of atomic hydrogen (HI) around a red and dead galaxy named AGC 203001. This ring is interesting because unlike several other known ring galaxies it does not have any bright optical counterpart. We confirmed this lack of optical emission with our very deep g, r, and i-band imaging using the Canada-France-Hawaii Telescope (CFHT), which reached a surface brightness level of ~28 mag/arcsec^2. Such large HI-dominated rings are extremely rare with only one another case known so far -- the Leo ring. Conventionally, the formation of such structures around galaxies is explained by a collision with another galaxy leading to an expanding density wave of gas and stars in the form of a ring. Such a collision leads to the compression of the gas in the ring which condenses to form new stars. On the contrary, in our deep optical observations, we do not detect any strong signs of active star formation in the HI ring. I will discuss some modifications in simulations of galaxy collisions and alternative scenarios for the formation of such rare HI-dominated rings around galaxies. I will then briefly discuss our ongoing upgraded-GMRT (uGMRT) program to target more such galaxies selected using the same criteria as AGC 203001.

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The staggering power of thunderstorms
B. Hari Haran, TIFR Mumbai
Thunderstorms are a spectacular manifestation of massive electrical discharges of thunderclouds, and have fascinated humans through millennia. There is a dark side of thunderstorms as thousands of lives are lost every year worldwide, making them a major cause of death by natural disasters. The GRAPES-3 muon telescope's measurements showed that huge voltages developed in supercharged thunderclouds by using muon imaging technique. The voltage produced by a thundercloud on 1 December 2014 in Ooty measured 1,300,000,000 Volts (1.3 GV) across its height, which is 10 times larger than the previous record voltage of 0.13 GV. This verifies the 90-year-old prediction of 1,000,000,000 Volts (1 GV) by C.T.R. Wilson. Such massive voltages are essential for the production of high-energy (100 MeV) gamma rays in the Terrestrial Gamma Ray Flashes (TGFs) emanating from thunderstorms, first discovered 25 years ago.

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Shocking Granular Flows
Sanjay Kumar, IIT Kanpur
When a supersonic aircraft zooms past us we hear a boom a little later and also when a lightning bolt jumps across the sky the thunderclap reaches us a couple of seconds later. These are some examples of fluid dynamical shock associated with high energies not easily obtained in laboratories. In granular flows shocks occur more readily and can be easily studied. We exploit these features to present some very novel and interesting experiments which demonstrate many of the unique rheological complexities of such flows.

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Very Long Baseline Interferometric Technique - Its Applications in Geodetic Studies
B. Nagarajan, IIT Kanpur
Very Long Baseline Interferometry Technique is an advanced Space Based geodetic technique that can measure a distance of thousands of kilometers between its antennas, with an accuracy of few millimeters by receiving radio signals from deep space as for as several billion light years away.

With such unprecedented precision and resolution made possible by VLBI, various tasks such as geodetic positioning, reference frames interconnections, Earth rotation monitoring, estimating the crustal movements, and mapping the extra-galactic radio sources, have attained accuracies of the levels never reached before. In this talk, various Earth Science Applications which were impossible few decades back to be taken up can now be achieved with ease, will be discussed.

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Space science - the everlasting excitement
Shri V. Koteswara Rao
The romance with space science is enticing, exciting and everlasting. The human quest for knowing the unknown, particularly about the universe, is insatiable and everlasting. There are many questions related to the origin of universe, origin of human race, future of living beings and so on and so forth. The answers are not so easy to come in a definite form, all the more explaining everything together. The answers are expected to come through step by step advanced research in space science, thus revealing the universe layer by layer. The subject of space science is vast and need many researchers and institutes to carry on the arduous task. Space research institutes and organisations world over have several projects and missions to explore 'Space'. Indian space research Organisation (ISRO) took up some key initiatives in this area and continues to do the same in future through some innovative projects. The initiatives are in broad areas of planetary exploration, solar studies, solar interaction on planets, Earth observation, exo-world, aeronomy and astronomy. The academic institutes, with eminent scientists, can play a major role in the research of space science, astronomy and astro-physics.