ASTR 3030/3031 Methods & Instrumentation in Astronomy

1. ASTR 3030/3031Methods & Instrumentation in Astronomy Instructor: Dr. J. Allyn Smith Office: SSC B-329 Office Hours: MRF 1230 – 1330; MW 1530-1630 or by appointment Class Meeting Time: Tuesday & Thursday 6:35 – 9:35pm; B310 SSC

2. Measuring Celestial Coordinates The Meridian Telescope Measure when an object crosses the meridian and you have its Right Ascension

3. Measuring Celestial Coordinates II Find the angle between the object and the North (or South) Celestial Pole and you have the compliment of its declination

4. Parallax Apparent shift in the object’s position due to motion of the observer. Quick Michael Richmond Description

5. Time Solar Time: Time kept by the Sun Sidereal Time: Time kept by the stars ===== Local Apparent Solar Time = the HA of the Sun as it appears on the sky + 12 hours Local Mean Solar Time = HA of fictitious mean Sun + 12 hours. Equation of Time = LAST – LMST Universal Time: = LMST at Greenwich Zone time = UTC + Longitude correction for the zone

6. Date Julian Date = number of elapsed UT days since 4713 BC Jan. 1.5 (12 hrs UT on January 1) J2000.0 = “Julian Epoch 2000.0” = 2000 Jan 1.5 UT = JD 2,451,545.0 Now, everyone can speak in a coordinated observation system.

7. Motion Proper Motion = motion of stars. - Epoch = time of observation (e.g. 2010.67) - Equator and Equinox = Equatorial coordinate system used to record an observation. (e.g. J2000.0) Two components: tangential velocity and radial velocity.

8. Motion Radial velocity:

9. Magnitudes The apparent magnitude (m) of a celestial body is a measure of its brightness as seen by an observer on Earth, normalized to the value it would have in the absence of the atmosphere. In astronomy, absolute magnitude (also known as absolute visual magnitude when measured in the standard V photometric band) measures a celestial object's intrinsic brightness. To derive absolute magnitude from the observed apparent magnitude of a celestial object its value is corrected from distance to its observer. The absolute magnitude then equals the apparent magnitude an object would have if it were at a standard luminosity distance (10 parsecs, or 1 AU, depending on object type) away from the observer, in the absence of astronomical extinction.

10. Magnitudes

11. Magnitudes This page was copied from Nick Strobel's Astronomy Notes. Go to his site at www.astronomynotes.com for the updated and corrected version.

12. 1st Lab Proper Motion of a Star: This exercise uses photographic data to calculate the proper motion of Barnard’s star. The images were taken in 1924 and 1951, roughly 27 years apart, so they provide a fair baseline for a nearby star. Though it’s a bit dated, the fundamental techniques are the same as used today … just modified for a computer to do the work. It’s important because it shows graphical analysis and if you want to program a computer to do this, you need to know the steps involved. Also, Barnard was a “local” astronomer, on staff at Dyer Observatory.