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EURO­ASIAN ASTRONOMICAL SOCIETY

R o u n d

Prac

XX XX International Astronomy Olympi ad
, , 15 ­ 23. X. 2015 Kazan, Tatarstan, Russia

G r o u p





language

English

Practical round. Problems to solve
6. The extinction in terrestrial atmosphere. Extinction is a term used in astronomy to describe light attenuation due to its absorption and scattering. A star was observed at different zenith distances during one night at the Engelgardt's Astronomical Observatory in the program of atmospheric extinction study at blue. Astronomers use parameter , air mass, as an extinction characteristic. This parameter corresponds to relative length of the ray's way in the atmosphere. That means = 1 for zenith, = 2/31/2 for z = 30є; = 2 for z = 60є and so on. The determination of the star's brightness was performed with the method of photon counting. The 3rd column includes number n ­ the quantity of photons which z n mb were detected during one second. A luminescent source was used 39.7 15135 for calibration the data of observations. It produces a stable flow of 45.6 13816 photons N = 9900 ± 100 per second, which is equal to magnitude m 49.5 13180 mb = 9.64 beyond the terrestrial atmosphere. 6.1. Draw the table (similar to that you see right) in your answer 53.0 12246 book. Calculate the air mass for given zenith distances in 1st 54.9 11800 column, and write the result into the 2nd column. 58.2 10089 6.2. Calculate relative magnitude of the star mb (blue), and write the result into the 4th column. Use the luminescent source as standard for the relative magnitudes. 6.3. Find functional relation between m b and with a help of graphical method. 6.4. Determine the magnitude of this star as it was observed in zenith.

Practical round. Problems to solve
7. Spectral observations. Astronomer performed spectral observations of a single star at the one and a half meter KFU telescope RTT-150 during a year. The spectrograms with marks of observation time are given to you for analysis (see separate sheet). The abscissa is wavelength, the ordinate is intensity in arbitrary units. Spectra are shifted by Yaxis for better visibility. The same spectrum with laboratory wavelengths is drawn by the bold line. It's recommended to measure at least two spectral lines for better accuracy. date (measur) Vr

7.1. Draw a table in form of the above example (columns 2, 3, 4 must be replicated as much, as many lines you measured). Calculate the radial velocity Vr of the star on each date, the results of measurements and write calculations into the table. 7.2. Plot the radial velocity curve, the graph of Vr vs time function. 7.3. Find equatorial coordinates of the star. 7.4. Indicate the accuracy of radial velocity in your measurements.
, , 2015 Kazan, Tatarstan, Russia