AST460: Assignment 2
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(Sep 14 2012)

1. As are starting to work with the radio telescope, it is time to
become familiar with several coordinate systems astronomers use to
specify positions of astronomical sources.
Have a look at Section 1.3.3 in the SRT User Manual to see
how a source position can be given in three coordinate systems:
the horizontal 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
(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?


3. Imagine you have an observing session with the SRT 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.



The assignment is due at the next class meeting.