AST460: Assignment 2 -------------------- (Sep 14 2016) 1. As we are starting to work with our radio telescope, it is time to become familiar with several coordinate systems astronomers use to specify positions of astronomical sources: the horizontal coordinate system (Azimuth and Elevation, azel), the equatorial system (RA, Dec), and the Galactic system (l,b). Use "An Introduction to Modern Astrophysics" by Carroll & Ostlie (this book is available in the Astronomy Library, 6515 Sterling Hall), to find definitions of these coordinate systems. Also, define: the Universal Time, the Local Siderial Time, and the Local Standard of Rest. 2. It is very frequently needed to convert coordinates of astronomical sources between different coordinate systems. We can do this by hand using spherical trigonometry, or by using an existing computer program. For example, NASA/IPAC Extragalactic Database (NED) provides a handy conversion tool: http://nedwww.ipac.caltech.edu/forms/calculator.html (a) The equatorial coordinates of the Andromeda galaxy are: RA=00h40m00.087s, Dec=+40d59m42.78s (B1950 epoch) Using NED's calculator, calculate equatorial J2000 and Galactic coordinates (l,b) for Andromeda. (b) Go to the main NED web page at http://nedwww.ipac.caltech.edu/ and search for Andromeda's entry using either the "near name" or the "near position" search tool. This should give you various information about Andromeda, including its coordinates, fluxes and images at various bands. Check your results. What is the Heliocentric Radial Velocity of Andromeda? Print an image of Andromeda using various data sets provided via NED and specify the wavelenght, telescope and angular resolution of this image. 3. Imagine you have an observing session with our Small Radio Telescope starting at LST~0 hours (LST= local siderial time) and lasting for about two hours. The sky is full of galaxies, all having different RA and Dec coordinates, and you want to pick a galaxy that's best visable during your observing session. What galaxies (in terms of coordinates) would be transiting at the time of your observations? A rough range will be fine. Briefly explain your reasoning. The assignment is due at the next class meeting.