Andy thinks he has a brilliant idea, that he can use the Observatory for high re

Question

Andy thinks he has a brilliant idea, that he can use the Observatory for high resolution spectroscopy of Centauri A to search for planets during the daytime. Each resolution element of his spectrograph (which observes in V band) will have a bandwidth of 0.1 Angstroms, about 10% of sunlight is scattered by the atmosphere, there are 1011 square arcsec over the full sky and the sun has an apparent magnitude of -26.74. The telescope Andy wants to use has an aperture diameter of 40 cm and an overall throughput of 10%. Centauri has an apparent magnitude of 0.

To obtain a precise enough radial velocity, Andy needs a signal-to-noise of 1000. How long will he need to integrate to achieve this?

Explanation / Answer

The angles A and A' are small,they may be approximated by their tangents.From the right triangles Fab and F'cd, A = -y'/f1 A' = y'/f2 and the angular magnification M is M = A'/A = -y'/f2/y'/f1 = -f1/f2 (angular magnification for a telescope) The angular magnification M of a telescope is equal to the ratio of the focal length of the objective to that of the eyepiece.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---