Measurement interval

N

Period (min) ± SE

17-23 February, 2009

10150

1448.31 ± 1.87

26 Sep-06 Oct, 2009

14396

1431.22 ± 10.51

04-25 June, 2010

31200

1435.54 ± 33.2

13-27 September, 2010

20160

1438.70 ± 3.31

10 May-05 Jun, 2011

36840

1444.03 ± 3.46

11-25 May, 2011

21600

1434.38 ± 2.88

13-21 June , 2013

12300

1449.50 ± 2.59

Mean

1440.24 ± 2.69