 Good morning. Good morning, everybody. My name is Anvesh Mazumdar. I'm the National Coordinator of Science Olympiates. And it's my great pleasure to welcome you all to the annual felicitation of the Olympiad Medalist of 2023. These are the Infosys Awards. These are the awards that are instituted by an endowment from the Infosys Foundation in 2002. So we'll have the formal award function starting from 12. But the tradition of this award ceremony is that we always have two lectures in the morning by eminent scientists who are like inspirations for all of us, especially for the young kids who have their careers ahead of them. So we have two speakers. And it's my great pleasure to invite and welcome our first speaker of the morning, Professor Dipankar Bhattacharya from the Ashoka University. Professor Bhattacharya is Sunanda and Santimaya Basu Chair, Professor in Astrophysics at Ashoka University. And prior to joining Ashoka, he was the Dean of Core Academic Programs at the Inter-University Center for Astronomy and Astrophysics, or IUCA, as it is normally called. So Dipankar received his bachelor's and master's degrees in physics from Jadavpur University Kolkata and his PhD from the Indian Institute of Science, Bengaluru. He carried out postdoctoral research at the University of Amsterdam and the University of California, Santa Barbara, and was a member of the faculty at the Raman Research Institute, Bengaluru, before moving to IUCA. Professor Bhattacharya's research interests cover both theoretical astrophysics and observational astronomy with particular emphasis on high-energy astrophysics, including compact stars, black holes, and cosmic explosions. And today, you will see a lot of that. He is closely associated with the Indian Space Astronomy Mission Astrosat and is the chair of its science working group. So it's our honor and great pleasure to welcome Professor Bhattacharya. I will request all of you to kindly put your mobile phones on silent mode. And Professor Bhattacharya will take questions at the end of the talk. Welcome Dipankar. Good morning. And thank you all science and Olympiad background, but over diverse disciplines. I thought I will give you a glimpse of astronomy that is being done today from space. Space astronomy makes a lot of news. I'm sure all of you have seen James Webb Space Telescope pictures all over the news. But I wanted to particularly highlight what India is doing and where India is poised to go in the years to come. And that is important for all of you who will be thinking of science as a career to enter into in the coming decades. Space programs always take a long time. So what we are planning today will go on until several decades to come. So let me get started. Can we have the lights off please? So before I get into space astronomy, let me just put it in context. Because not all of you have been thinking about what astronomy is, how it is being done today. So the basic tenets of the quest of astronomy are partly exploratory. We are all explorers. Find out what objects are out there. The part of the universe that you have been able to explore is a very, very tiny fraction. And there is a lot more to be discovered. So astronomy certainly is a voyage of discovery in that sense. But not just discovering new objects. Once we find objects, we want to know what decides their properties. Why do they look like they do? How they change with time? What forces, what physical laws govern them? And as a result, govern all of the universe, including us. And of course, a bit of cosmic archaeology, how did everything that we see around us come to be? And based on that, we try to make guesses as to what is going to happen to us in the future, what's going to happen to the universe in the future. To do this kind of work, to what extent we can do, is propelled mainly by technological progress. And here, space astronomy has had a vital role to play, and we'll continue to do so. In astronomy, as you know, unlike other physical laboratory exercise where I can bring a sample to my lab, subject it to experiments, and then find out about it, we can't do that in astronomy. Physical exploration of astronomical bodies will require going to that body. And this is possible today only up to some distance, only two within our solar system. As you know, the Voyager has gone close to many of the solar system bodies. And our own planetary explorers like Chandrayaan and Mangalyan is the farthest that India has sent probes to. So this is still restricted to nearby objects. Maybe in the future sometime, we will be able to journey far, far away and look at other objects. But that will still be limited compared to what is the investigation that we plan to do today. And so what we rely mostly on is not actually going there, but examine the multiple types of messengers, those objects, and us. That includes electromagnetic radiation in all bands. It includes particles like neutrinos. It includes gravitational waves. So that's a new band of astronomy which has been added to our arsenal about a few years ago. So we have to be here. We look at whatever signals come. And based on that, we try to understand what goes on in the sky, what goes on in these objects. Astronomy has been done by humans for a very long time from time immemorial. But most of that has been confined to what we can see with our naked eye. And what we can see with our naked eye is by definition called the visible or the optical band. But there is much more to electromagnetic radiation than just the optical band. The optical band, as this cartoon shows, is restricted only to a very small fraction of the electromagnetic spectrum. And all our multiple colors that we see in the sky are packed within that small band. But there are so many other bands. And astronomical objects radiate in all of these bands. And to be able to understand what goes on in much of the universe, we need to cover these other bands, observing all these other bands. But there is a problem. Visible band, as optical band, and the radio frequency band are the only regions where our atmosphere is transparent. So these are bands in which we can carry out astronomy by putting telescopes, putting instruments on the ground. Everywhere else, this vertical axis is the amount of fractional absorption is 100%. Everywhere else, you see the atmosphere practically absorbs everything. So we cannot carry out astronomy by placing a detector on the ground. We have to place the detector above the atmosphere. So to have a detector that stays for a long time above the atmosphere, the only way to do so is to put it on an orbit around the earth at sufficient altitude so that atmosphere is no longer a problem. And as a result, as you can see, huge chunks of electromagnetic band are only accessible from space. And this is why space technology and astronomy has almost become synonymous today. Even in the bands that we do receive on ground, there are some advantages of going to space. For example, in the optical band, images that we take are corrupted by twinkling. And this twinkling is an atmospheric phenomenon. So if you put a telescope above, even an optical telescope, above the atmosphere, then the twinkling will not be present, and you get much sharper images. And that is why Hubble Space Telescope was sent into orbit. In radio bands, often the imaging is done by putting radio telescopes very far away from each other and then making the signals interfere. That gives you a better resolution. If you have seen the imaging of the black hole from even horizon telescopes, those are made with telescopes spread across the entire globe and connected together by interferometry. So if you want even better resolution, then you need to put radio telescopes even further away than the size of the Earth can accommodate. So you can put them out into space and use them as parts of your interferometer. And this has also been done. So going to space is advantage at all web bands and is essential in most web bands. So not surprisingly, for a large part of the spectrum, astronomy has moved to space. There is a whole bunch of space also which is currently operating. And this is only a small selection, which are watching the universe at different web bands. So what are the main questions that most of these instruments are trying to address? So there are questions which are quite varied. To put them in context, I will just quickly recall for you a brief history of the evolution of our universe. We think that the universe was born in a big explosion called the Big Bang. Immediately after the Big Bang, the universe expanded extremely rapidly. And after a while, that rapid expansion slowed and it started expanding somewhat more slowly. The universe was dominated by a huge soup of radiation and just elementary particles to start with. And then slowly atoms formed. The radiation which was being scattered by electrons then could propagate freely. And it therefore decoupled from the matter at some point. That is called the surface of mass scattering. And we get the structure of the cosmic micro background radiation, which we see today, from that epoch. And after some more time, gravity of different pieces of matter brought them together and structures began to form. So they formed galaxies, stars within galaxies. And the matter started getting more and more concentrated. And here we are today. And this has taken about 13.7 billion years. Exactly when did the first stars form? Exactly when did the first galaxies form? This is definitely a question for astronomers. And this is one of the areas that people are actively trying to look into. What kind of fluctuations in the initial matter distribution eventually led to all the structure formation? That is also something people are trying to look into. And then there are puzzles in the expansion and in the gravity of the universe that we see today. We seem to have the gravity of the universe dominated by a form of matter, which we can't see. We call them dark matter. And recently, the universe has started expanding faster than it should. And this expansion appears to be powered by some un-understood energy, which we have given the name dark energy. Just by giving the name, it doesn't mean that you have understood it. You just called it something. So these are all areas, including dark matter and dark energy. These are subjects of intense investigation today. The understanding the history of the universe is not complete without understanding the history of stars. So a star, when it's born, it starts as gas cloud and then it forms by condensation. Then as it condenses, it becomes hotter. And then nuclear fusion starts. And heat generated by nuclear fusion keeps the gas hot enough to be in the hell against gravity. And that is the kind of stars that mostly we see. And stars can come today in various different masses from 1 tenth of the mass of the sun to about 100 times the mass of the sun. The more massive the star, the hotter it is at the surface. So the bluer it is. But also the more massive the star, the faster it consumes its nuclear fuel and it lasts that much shorter. So heavy stars are more luminous, hotter, and last very short time. As you get lower and lower mass stars, they live much longer. But they are cooler at the surface. Eventually, when all the nuclear fuel runs out, the center of the star collapses because there's nothing now to oppose gravity. And that collapse happens quickly. The energy released in that collapse throws out the envelope. The envelope could be ejected slowly depending on what the mass of the initial star was. If the central object condenses to form something called a white dwarf, then the envelope is ejected slowly and you get something called a planetary enabler. If it was more massive, then the collapse is more violent. The interior collapses to either a neutron star, very small star, and very massive one. So it's like the mass of the sun squeezed into 10 kilometer radius. This is like a giant nucleus. So either a neutron star or if it is even more massive, it goes into a black hole. Those collapses are accompanied by a violent explosion. It's called a supernova. And for some of these supernovae, you also have an associated jet-like emission which causes what's called a gamma ray burst. So the end state of evolution of stars is always some kind of ejection and a central collapse. You can get compact objects, white dwarf, neutron stars, black holes at the center, and explosive ejection of matter along with it. So to then pick a few major areas of activity in astronomy today are to find the earliest galaxies, see how first stars formed, map the complete history of star formation. James Webb Telescope has been launched to address some of these questions. Then accurately measure the history of expansion. As I said, dark matter, dark energy is involved in deciding the course of expansion of the universe. Measuring that well is an important task of astronomy. Understand structure formation, how all the galaxies and stars came to be. Study the compact stars in detail because they uncover some detail physics at small scales. And find planets around stars. Understand the origin of Earth and eventually of us. So having said this much, let me now come to the main focus of my talk, astronomy from space, the Indian program. The Indian program in astronomy started in 1975. Not many may know this. The very first satellite that India had launched called Aryabhata in 1975. Apart from other things, it also carried a payload which was designed to do x-ray astronomy. And it observed accruing compact objects. So these are compact objects like neutron stars, black holes, which pull matter from another nearby star. And this matter, when it falls onto this compact object, it becomes hot and emits x-rays. So spectra and intensity variations of these objects were observed by this very first Indian satellite. So Indian space program has, right from the beginning, elements of astronomy built into it. Then we have also been building instruments, space astronomy instruments, which have been flown not just on Indian missions, but even missions sent by other countries. So this is another experiment built in TFR, it's a cosmic experiment. It was flown and put on the space station in 1985. Space lab was the laboratory on which it was put. Then we had other standalone astronomy missions. This is a satellite called Stretched Rohini series satellite C. And Stretched Rohini satellite C2. These two carried a gamma-ray bus detector built at the Eurospace Center, which was then called ISRO Satellite Center. And I mentioned gamma-ray bus and black holes formed by collapse. You have a supernova, and along with that you have jet-like ejection which produces gamma rays. So these detectors were built to detect such gamma-ray flashes. And SROC detected eight candidate GRBs. This was in 1992. And in 1994, the follow-up experiment detected 53 of them. That experiment survived for seven years. We have also been building solar observation payloads. There was a solar observation payload, solar X-ray spectrometer, which was built in PRL. And it was sent aboard the second geostationary satellite made in India. Geostationary satellites were meant for communication, but it also had space for a little experiment to do solar X-rays on me. There was a much larger solar observatory, which was a solar telescope, which was built for X-rays. And it was sent aboard the Russian coronas photon mission in 2009. And this was one of the larger astronomy experiments, which was flown aboard the Indian remote sensing satellite P3 in 1996. So this was an interesting mission, where one of these experiments was the X-ray astronomy experiment, which had proportional counters to detect medium energy X-rays in their spectra, their time variation. And the other side had other payloads for Earth-observing payloads. So the satellite would spend half the time looking down and half the time looking up. So that is how this whole mission was carried out. And this instrument, which was built at TFR, was most of the time used to observe one very interesting black hole binary in the sky. It's called GRS-1915 plus 105. And it discovered something very, very interesting. It discovered some various special intensity variation patterns. And it also could see that a track matter, which is coming close to the black hole and then goes into the event horizon and disappears. So it could actually catch events like that. And this was one of the first time that was done. The success of this experiment gave rise to the idea of doing a much bigger mission for astronomy and dedicated to astronomy. So this actually became precursor to Astrosat, which Anmesh referred to. And that has been one of the mainstay of Indian space astronomy since it has been launched. So it was launched in 2015. It is still operating. It has been eight years in space. This is India's first dedicated space astronomy also. So this mission does not contain any other payload. It is astronomy and only astronomy. It carries many instruments. It carries large-area extraproportional counters. It carries ultraviolet imaging telescopes. It carries a soft x-ray imaging telescope. It carries a high-energy cadmium telluride image detector. It carries a scanning sky monitor. And all together, it makes a formidable unit of multi-wavelength astronomy. It weighs 1 and 1 half tons. And it is ideal for the study of stellar birth, death, and life beyond death, which means newly formed stars and end states of stellar evolution, like in compact stars. So it's been put in a low-earth equatorial 650-kilometer circular orbit. And it's a versatile observatory. Operation is based on community proposals. So it has observed a great variety of objects, from nearby stars to distant galaxies. And as I said, it's particularly suited for studying star formation and stellar end states, compact objects, accretion, explosive phenomena, et cetera. Till date, there have been about 400 referee publications and a similar number of telegrams notices of new discoveries. Over 30 PhD thesis have been awarded, and many more are yet to come. And even referee publications are going up at a very rapid rate. And all this is based on only about 25% to 30% of the data that has been so far collected. It takes time for data to get analyzed and science to be communicated out of that. So many more reports are expected to appear. There are 1,500-plus users of the mission spread over more than 40 countries. And what is interesting and gratifying is that about 50% of these users are now from India. When we started the concept planning of AstraZeneca mission, one could count the numbers of people interested in space astronomy in India or active in space astronomy in your two hands. Now it has really become a major enterprise in India. This gives an idea of where all AstraZeneca has been pointing over time, over these last eight years. It has observed some 3,000 different locations in the sky. Some of them are repeated, about 1,700 individual targets. One of the USPs of Astrosat is very high angular resolution in ultraviolet. So this, for example, would be the ultraviolet image of a galaxy preastrosat by the galaxy mission. And this is the astrosat image of the same galaxy. So you can tell you how far the image resolution has improved. And as a result, one could study that all these bright regions are regions of new star formation. And particularly, the study of star formation in galaxies has been very well addressed by the astrosat mission. Ultraviolet mapping of host stars and galaxies in various different locations. And also, faint UV glows around, let's say, this plant-trainable is a white dwarf star. Earlier, the image of the plant-trainable was only this big. And now, with astrosat, we see that there is a huge glow around here, which is of a very specific kind, this is molecular hydrogen, which is a resonance line of molecular hydrogen, which is creating this glow. And this was discovered by astrosat. There's a famous remnant of supernova called the Cygnus loop. There's an optical image. And here is the detail that you can see in ultraviolet using an astrosat. Astrosat isn't able to do. And simultaneously, you can also take spectrum in x-rays, and you can tell what elements are present, which are producing this emission. So the combined x-ray ultraviolet study is very, very useful. Astrosat has also been looking for sources where large amounts of star formation has been happening. And these are a type of galaxies called lanon-brake galaxies. And astrosat is in finding new galaxies of this kind in the universe by looking at a deep field. And this is a continuing endeavor. And once you find something bright in ultraviolet, then you can go and look at the Hubble images, and then you can identify these galaxies. Another area which astrosat has been extremely active in is detailed temporal and spectral studies of compact objects, which includes neutron stars, black holes, et cetera. So it's a mattering of random mattering with few results. Up on the left is the very famous crab pulsar observed at multiple different web bands using astrosat. Next to that is an x-ray spectrum where you see a sudden drop here. It is the signature of electrons in resonant orbits around magnetic fields. So it allows us to measure magnetic field in the region where this emission is coming from. Then this is a temporal variation of intensity of very specific kind from a black hole, JRS-1950. And this is also Fourier characterization of temporal variation of intensity from another black hole. And you can see this sharp peaks of quasi-periodic oscillation. And these are, as I said, only a few. Thousands of such investigations which have been carried out, and it's been extremely successful. Astrosat also proved to be a prolific detector of gamma rebusts. Till date, we have detected about 560 gamma rebusts. And not only that, for the brighter ones of them, astrosat has the capability to measure gamma ray polarization. This is one of the most difficult challenges in astronomy to be able to measure polarization at very high energies. And astrosat has the capability of doing that for very bright gamma rebusts and a few other very bright X-ray sources as well. So astrosat is a community observatory. So it works with users at the center. The users can make observing proposals, which, when they're accepted, get scheduled, data are downloaded and sent to respective payload operation centers for individual payloads, which are in these institutions. And then science data, science products, when they're produced, they're sent back to the show which then gets into an archive. And after a short time, this archive data is open to public. So anybody who is interested can download this data, work on it. This includes students. It includes all of you. So I would like to emphasize that there is a lot that can be done with available astrosat data as student projects, as work in classrooms, and various other means of engaging with the data are available. There is an astrosat science support cell which aids in some of these things. But there are also others who can help you if you are interested in using this data. I should say that as a teacher in Ashoka University, I have been using astrosat data for classroom projects for undergraduates. So it's not difficult to do. You need to learn a little bit. But once you are there, it is a very, very rewarding experience. So post-astrosat. Some of you would have followed the launch of Aditya Ilwan on 2nd of September. So Aditya Ilwan is supposed to be placed in Ilwan, which is first Lagrangian point. And it is on its way there. It's going to reach there in January. This is a solar observatory. And it's going to observe the sun, particularly the surface phenomena of the sun and the atmospheric phenomena like chromosphere, corona, and so on. And connect that to space weather. It's going to do multi-band imaging of the solar disk, have detailed study of sunspots and the physics in them. So it's currently in transit. And while on the way, instruments are being switched on one by one and tested. So one of the instruments, which is solar ultraviolet imaging telescope, was switched on a few days ago. And it captured images of the sun in 11 different filters. One of them I'm showing you here. So these are sunspots. And this is an ultraviolet image in one of the bands, magnesium band. And you can see these brightnesses. And when you look at images taken across multiple bands, you can actually find out the temperature distribution and the dynamics of material at these sunspots. This is just the first light on the way. It's not yet reached its final location. And we are expecting a lot from this measurement. Next one is the ExpoSat, X-ray polarization satellite. I mentioned the measuring polarization at high energy is a very difficult task. The first polarization measurement of an X-ray source was made nearly 50 years ago. And nothing has been done since. And this is a completely virgin area. In December 2021, NASA launched a satellite, which is called IXP, which measures polarization over a restricted band of 2 to 8 kiloelectron volts in X-rays. And our X-ray polarization satellite is going to be launched on 28 December, if everything goes right. So it's the next week, basically. That's the projected launch. It depends on a few other factors. But it is going to be launched soon. It's already ready for launch. So this will do extra polarimetry and spectroscopy of several selected targets. And this is going to be the first polarimeter in this particular band of 8 to 30 kiloelectron volts, even higher energy than what IXP is able to do. So these are missions which are already on the way. And then there are future missions in planning. One of them is Daksha, which is being spearheaded by IIT Bombay here. And in collaboration with various other institutions. This is a mission which is meant for detecting fast-wearing transients, like gamma-ray bursts, but particularly tuned to electromagnetic counterparts of gravitational wave sources. So if you have a gravitational wave burst that you detect, was there an X-ray flash or a gamma-ray flash connected with it? So this satellite is going to dedicate most of its time doing that. And in the process, it's also going to detect gamma-ray bursts, X-ray bursts, and various other kinds of sources. It's a high-energy transient monitor. There is a much larger ultraviolet mission, which is also in planning. So these are missions which have been given some startup money to come up with initial configurations. That is, Daksha insists this Indian mission to study the original evolution of the galaxies and stars by doing imaging and spectroscopy in ultraviolet. So this will carry forward the work that ultraviolet imaging telescope and astrocyte has been doing. This is a radio spectroscopy mission, which has also been studied now. So do radio spectroscopy from space to look at the first time that the stars started becoming available. And the stellar radiation was going to ionize hydrogen. And this is going to find the time at which hydrogen turned from neutral form to ionized form. That will give us a good measure of precisely when first stars began to form. Planets, many of you must be aware that lots of planets outside the solar system are being now found by space observatories. All these yellow dots are discovered by one mission, Kepler, NASA mission. So India has a plan in place to study the atmospheres of these exoplanets. It's called exo-worlds. So this is in study phase. And so this will also be, hopefully, the reality in some time. And there are mission ideas which they have not fully fructified as yet in terms of mission plan. It includes a much larger extra-pollinumetric mission called expo. I talked about cosmic microwave background. The detailed study of cosmic microwave background can tell us a lot about cosmology. So far, people have measured the temperature distribution across the sky, measured the spectrum of the background radiation, and measured the temperature distribution across the sky, how they look like in the Fourier domain. One thing that is left to do is to measure polarization. And there is a mission which has been proposed. It's still in the study. It's called CMBVARA, which is to measure the polarization of the cosmic microwave background. It has additional information than what can be done. What can be found today from existing cosmic microwave background studies? It's also a few other missions which have been thought about. One is multi-leveling astronomy for compact objects, multi-payload mission specifically for compact objects, and then mid-infrared spectroscopy of star-forming regions to find newly-forming stars, which are mostly bright and infrared. So all of these are being studied. And at least some of these will become reality in the decades to come. And ISRO is very supportive of new mission ideas and really wants the space astronomy community in India to grow. So this is definitely a niche where one is looking for a lot of new talent, a lot of new young people to get into, because you need to stay with the project. And you will need to spend many years of your life if you want to get into this project and extract science. So I'll summarize saying that space astronomy platform plays a vital role in astronomical investigations of the present day. And Indian space astronomy program started small from the very first satellite and has been gradually built up over the past five decades and is now making a major impact. So users of space astronomy facilities in India have rapidly grown in number. And diverse new missions are coming up to enable a wide variety of astronomical research. And all missions have or will have open data available. And they can be used for not only research, but student projects and teaching and training. So welcome if you would like to join this venture. Thank you very much. Thank you, Professor Bhattacharya, for the wonderful lecture. Time for some questions. If you have questions. Yes? What is meant by the polarization things we're talking about of waves? Polarization of what? Like we were talking much about the polarizing of CMB and all of that. So what are the users of that? Like how do we? Right. So why would you like to study polarization of cosmic micro background? Now as you know, cosmic micro background is a thermal radiation, which is not expected to be polarized. It will be polarized if it undergoes scattering. So once you do see polarization, you can then infer about the scattering material that is present, which is otherwise not visible. And this includes gravitational waves. So cosmic micro background can scatter off gravitational waves and become polarized. So the invisible background of primordial gravitational waves at the moment cannot be discovered by any other wave other than to look at the polarization of cosmic micro background. So that's one of them. But there are other things like certain types of dark matter particles, for example, action-like particles. If photons scatter from them, they get polarized. So if dark matter consists of such particles, then cosmic micro background will be polarized. So you'll be able to see that same result. So there are various other predictions which can also be tested. And what is meant by the monopole and dipole of CMB? Oh, OK. That's just a nomenclature of the distribution. So if you take the temperature distribution of cosmic micro background in all directions in the sky, the average of that is the monopole. And then you subtract the average. What you'll see is one side of the sky is hotter. The other side is colder. So this axis, the axial dependence, is called the dipole. And this is caused by the fact that the Earth and the entire solar system is not stationary with respect to cosmic micro background. So moving in some direction and therefore temperature in front becomes higher due to Doppler shift and in the backward direction becomes cooler. If you subtract that away, then you find the small-scale fluctuations which are there all over the sky. And this is caused by the very early density fluctuations in matter. Thank you. Yeah, there's a question here. So which variables we study to study life other than Earth when you're doing all these? Yeah, so there are things called biosignatures which people are looking at. These are infrared spectroscopic signatures for specific molecules which you would expect in the atmospheres of bodies if life is in them. So that is one area which people are looking at. Not only that, that's to detect the presence of life. That's one area. The other thing that are being looked for is what are the places where life could possibly exist? So environments that are more conducive to host life. So that's also another area of investigation by looking at all these exoplanets, look at where the thermal and atmospheric conditions are reasonable for life to be present. So these are various areas where people are looking at. And of course, there is one whole branch which is called search for extraterrestrial intelligence. So that's intelligent life. That's even more difficult. So looking for signals coming from other civilizations. So thanks for this wonderful overview. And I think one of the nicest things is that most of the Indian things are putting out their data into the public domain, allowing anybody to use it. And in particular, as you said, students. Now, given that most of the students here are undergrads and will be undergrads very soon, how does one as a student access this data, work with people who can access this data? Is there a mechanism to sort of use this data to do citizen science projects where students are mainly involved? Because many of them are probably interested in working with real data from telescopes. Very fair question. And there is no one centralized mechanism. But what is being set up is support cells for each individual mission. So for example, astrocyte science support cell is in Ayukha. And anyone who is interested can contact astrocyte science support cell in Ayukha. And they can help you in getting data, as well as training you in how to use it. Aditya Alavan has its support cell established in Aries, Nainita. So they also have a similar mandate to bring data closer to people. So what I understand from ISRO's current approach to this is that for each mission, they are going to establish individual centers where people can approach. Thank you. Just a little bit of advertisement. So we have at HBCC the NIUS astronomy program, in which we do have mentors who are closely connected with missions like Aditya Alavan and astrocyte. And many student projects are going on with data from these missions. So if the students are interested, we have many NIUS chemistry students here today. But the Olympian students who are here, you will have the opportunity to join the NIUS program in coming years. Just a minute. We have a question from there and then here. Namaste, sir. My question is that, can we predict the time or the direction of the gamma ray burst, like when will they occur, or the direction from which they occur, or is there any method to do that? Or once they occur, we are able to capture it or such. I wish there was a way to predict it. No, it's completely unpredictable, because they're coming from objects which are far, far away. It could occur in any galaxy in the universe. So there is no way for us to even observe these precursors, because they're very, very faint. When the gamma ray burst occurs, it becomes so bright that it out shines the whole sky. That is the first time we will be seeing such a galaxy. Before that, there was no way to even see it. So no, so we cannot predict them. But we capture the bursts very, very quickly. So then it enables us to study the burst immediately. So how do we know whether it's a gamma ray burst? Like is there any energy range or intensity range for that? So it's called gamma ray burst because it's bright in gamma rays. Thank you, sir. Yeah, here. I enjoyed your lecture very much. I am Sampath Kumar from TIFR, retired. I'm not working in this field, but I'm very remotely connected with AstroSat program. They say that I was one of the persons strongly supported, brought to help the system to bring the conclusion to TIFR. It was a 12 years effort. I think young people here should know. It was an effort of 12 years to bring AstroSat to a conclusion, to a launch. And I'm extremely happy to see that it turned out to be great success and very highly productive, very interesting results are coming out of the program. I would strongly suggest that younger people who are here should take up the very challenging projects which are very, very, very, absolutely important in broad progress of science. Having said that, may I ask you one short question? There are five instruments in AstroSat. All the five instruments are working or now? It's very pleasing to see. They're all working. So this AstroSat is now beyond its designated mission life. It was five years mission. So now it's eight years are completed. So some degradation has happened. I see, OK. For lack of specific, one unit is no longer working. Two units are working, one with reduced efficiency. Ultraviolet imaging telescope lost communication with its near ultraviolet channel. Other two channels are working. Everything else is working. But it's very commendable that practically things almost all the instruments are working. Nice data. Thank you. Thank you. Thank you. Any more questions? Yeah, here. Is there some? Namaste, sir. Thank you so much. That lecture was very enjoyable. I had one question. Like you spoke about the AstroSat extending its mission life. Even the Voyager 1, I believe, is way past its mission life. So is there any way to remotely fix or work on the problems that occur on the instruments on a mission that is past its mission life or? These, some missions are designed for it. Some missions are not. AstroSat is not designed for in-space intervention on board. So we will have to just let it take its course, as you say. So it's something that you need to foresee before you launch the mission. Yeah, so we have some redundancies built in. But it can only take you so far. Unlike Hubble, for example, where you could send astronauts go and fix the mission on board, these missions are not like that. All right, sir. Thank you so much. Thank you. Any more questions? OK, if not, let's thank Professor Bhattacharya again. Thank you very much. Thank you for the lecture. Yeah, we'll now move to the second lecture of the day, by Professor Sangamitra Bandupaddha. And while she's getting set up, I would to introduce Professor Bandupaddha. I would like to invite my colleague, Professor Pritheejeet De, who is a national coordinator of the Mathematical Olympics. And he will introduce Professor Bandupaddha. Thank you. Shall we go?