1. CHANDRA Manjil P. Saikia Department of Mathematical Sciences, School of Science and Technology, Tezpur University, India The Man and The Machine

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4. Chandra can observe X-rays from particles up to the last second before they fall into a black hole!!! Explanation: The last stable orbit for a Schwarzchild metric is 6GM/c^2 ~ 10^7 cm for a 10 solar mass black hole. The time to fall in from this point on is ~ 0.001-.01 seconds, depending Manjil P. Saikia4 Chandra can observe X-rays from particles up to the last second before they fall into a black hole!!!o a black hole!!! Explanation: The last stable orbit for a Schwarzchild metric is 6GM/c^2 ~ 10^7 cm for a 10 solar mass black hole. The time to fall in from this point on is ~ 0.001-.01 seconds, depending

5. The light from some of the quasars observed by Chandra will have been traveling through space for ten billion years. Explanation: If we take a Hubble constant of 60 km/sec-Mpc, then the Hubble time is approx 16 billion years, so for a quasar at z > 3, the look back time, depending on Omega, is greater than 10 billion years. Manjil P. Saikia5 The light from some of the quasars observed by Chandra will have been traveling through space for ten billion years.en billion years. Explanation: If we take a Hubble constant of 60 km/sec-Mpc, then the Hubble time is approx 16 billion years, so for a quasar at z > 3, the look back time, depending on Omega, is greater than 10 billion years.

6. The electrical power required to operate the Chandra spacecraft and instruments is 2 kilowatts, about the same power as a hair dryer. Explanation: A standard hair dryer uses 1600-1800 watts (slightly less than 2 kilowatts) on its high setting. Manjil P. Saikia6 The electrical power required to operate the Chandra spacecraft and instruments is 2 kilowatts, about the same power as a hair dryer. Explanation: A standard hair dryer uses 1600-1800 watts (slightly less than 2 kilowatts) on its high setting.

7. Chandra's resolving power is equivalent to the ability to read a stop sign at a distance of twelve miles. Explanation: The letters on a stop sign are 25 cm high. Assuming that we need a 5 x 5 pixel square, then the resolution element is 5 cm high, which would subtend an angle = 0.5 arcsec at a distance D = 5/2.5E-6 = 2 E6 cm = 20 km = 12 miles. Manjil P. Saikia7

8. If Colorado were as smooth as Chandra's mirrors, Pikes Peak would be less than one inch tall! Explanation: Numbers: Assume optics size = 84 cm Assume rms low frequency figure errors are < 100a = 1e-6 cm Assume size of Colorado= 600 km = 6 E7 cm Then the ratio of the (rms errors)/(optics size) < 1.2 e-8 Assuming that there will be one 3 sigma peak in 1000 trials (the approx. number of measurements of the figure), then the ratio is < 3.6e-8. Then the largest mountain (which is not Pikes Peak, but is not much taller than Pikes Peak) in Colorado would be < 2.2 cm < 1 inch. Manjil P. Saikia8

9. At 45 feet long, Chandra is the largest satellite the shuttle has ever launched. Explanation: For comparison, the Hubble Space Telescope was just over 43 feet long. Manjil P. Saikia9 At 45 feet long, Chandra is the largest satellite the shuttle has ever launched.as ever launched. Explanation: For comparison, the Hubble Space Telescope was just over 43 feet long.

10. During maneuvers from one target to the next, Chandra slews more slowly than the minute hand on a clock. Explanation: According the CXC Observatory Guide, it takes Chandra 31 minutes to slew 90 degrees. It takes the minute hand on a clock 15 minutes to slew 90 degrees. Manjil P. Saikia10 During maneuvers from one target to the next, Chandra slews more slowly than the minute hand on a clock. hand on a clock. Explanation: According the CXC Observatory Guide, it takes Chandra 31 minutes to slew 90 degrees. It takes the minute hand on a clock 15 minutes to slew 90 degrees.

11. Chandra can observe X-rays from clouds of gas so vast that it takes light five million years to go from one side to the other! Explanation: If we assume conservatively that a cluster extends out to a radius of 1 Mpc, then it has a diameter of 2 Mpc, or 6 million light years. Manjil P. Saikia11 Chandra can observe X-rays from clouds of gas so vast that it takes light five million years to go from one side to the other!ide to the other! Explanation: If we assume conservatively that a cluster extends out to a radius of 1 Mpc, then it has a diameter of 2 Mpc, or 6 million light years.

12. Chandra flies 200 times higher than Hubble - more than 1/3 of the way to the moon! Explanation: For the planned operational orbit of Chandra, the closest approach to Earth and the most distant point from Earth will be as follows: Altitude at Perigee (closest approach) = 10,000 km = 6,214 (statute) mile = 5,400 nautical mile Altitude at Apogee (most distant point from Earth) = 140,000 km = 86,992 (statute) mile = 75,594 nautical mile For reference, Mean radius of Earth = 6,371 km = 3,959 (statute) mile = 3,440 nautical mile Manjil P. Saikia12

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22. Partial Acknowledgements Chennai Mathematical Institute, India The Institute of Mathematical Sciences, India Dr. Purusottam Rath Dr. Sanoli Gun Dr. G. Fabbiano Department of Atomic Energy, Govt. of India Madhurrya Prakash Talukdar Astronomy Club, Tezpur University Manjil P. Saikia22