The recent ring images of millimeter wave emission from the centres of M87 and our own galaxy, and even more so the non-emission from the centre of the ring, have captured attention well beyond the astronomical community. This talk will focus on the actual measurements, how they are processed into correlations, and how these lead to an image. All three steps face major challenges. These will be brought out both to appreciate the magnitude of the EHT achievement ,and its limits. The level will be technical - numbers and equations will not be avoided - but the target audience is meant to be wider than just astronomers. The astrophysical interpretation of the image - a black hole accreting and heating strongly magnetized plasma which gives out radiation which is bent or swallowed by the strong gravitational field- is another story.
Zoom link: https://icts-res-in.zoom.us/j/89635793348?pwd=RFBMV2NSMnhzampCRmdiYUFmZ2ZRQT09
Meeting ID: 896 3579 3348
Passcode: 112211