IAO 2010, Практически тур, Групи α и β — Задача 6. ZHR

1.

Observations were organized in Sudak, the local time (LT) used. Please, write in Table 1 the time of the beginning ($T_b$) and the end ($T_e$) of observations using Universal time (UT).

2.1.

The meteors that belong to the same shower (S) have one radiant. The name of the shower coincides with the name of the constellation where the radiant is situated.

Indicate the place on the map where the radiant is situated (for Perseids). List in Table 2 the numbers of meteors (No) that are showed on the map that belong to this stream (see the supplement).

2.2.

Determine and list in Table 2 the equatorial coordinates of the radiant ($\alpha,\delta$).

3.

Write in Table 2 the date of the maximum of the meteor shower Perseids (in DD.MM format). Estimate (roughly with an accuracy 1h) the beginning ($T_b$) and the end ($T_e$) of the shower visibility during the night of the maximum.

4.

The calculation of the hour number of meteors (ZHR) for the Perseid shower.

ZHR is a measure of the shower activity. It can be defined as a number of meteors that are seen by observer during one hour of observations with the favourable conditions and with a radiant situated in zenith. The corresponding formula is:

$K$ – coefficient of the luminosity function that is equal to 2.5,

$lm$ – limiting stellar magnitude (each observer determines this value individually taking the most faint star he or she can observe),

$N$ – observed number of meteors,

$F$ – coefficient correcting the cloudiness of the sky,

$T_{\rm eff}$ – effective time of observations in hours,

$h_r$ – the angular altitude of the radiant above the horizon.

4.1.

Calculate the mean value of the limiting stellar magnitude (lm) for each interval. Write your results in Table 3.

4.2.

Calculate effective time of observations ($T_{\rm eff}$) for each interval. Write your results in Table 3.

ZHR corresponds to the ideal sky condition. If there is a haze in the sky, some clouds or some extra light (Moon, artificial light, twilights), the visual number of meteors will be decreased, because faint meteors can not be observed.

4.3.

Calculate the correction for the cloudiness for each interval ($F$).

Where $k$ is percentage of the cloudiness, $t$ is corresponding time interval in minutes, and $t_{\rm total}$ is the total time of observation in a given interval.

Write your results in Table 3.

4.4.

Calculate zenith hour number (ZHR) of the meteors for Perseids shower for each interval. Write your results in Table 3.

Table 1 · Таблица 1

Table 2 · Таблица 2

Table 3 · Таблица 3

Observation log · Sheet 1

Observation log · Sheet 2

Observation log · Sheet 3

Observation log · Sheet 4

Gnomonic map

Supplementary star map