Effect of Intermittent Operation of Flare Patrols on Observed Flare Frequency.

Abstract

view Abstract Citations (1) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Effect of Intermittent Operation of Flare Patrols on Observed Flare Frequency. Acton, Loren Abstract It is not required that an observing station observe a solar flare throughout its entire lifetime in order to report the flare. For this reason it is necessary to consider the breaks in observing time as well as the actual observing time when calculating flare frequency. This consideration has been neglected in most earlier studies involving the occurrence frequency of solar flares. We used the following method, similar to that of Svestka (Bull. Astron. Inst. Czech. 7, 9-18, 1954), in calculating the "effective observing time" (E.O.T.) for flares of each importance for each observing station. E O T =A O T $Zt tB + t0N, where A.O.T. actual observing time; Bj number of breaks in observing of duration tj t0 N total number of breaks with duration t#t0 t0 mean lifetime of flares of a given importance. After analyzing some 300 flares, each reported by two or more observing stations, we adopted the mean flare lifetimes given in Table I. The percentage changes in observing times range from a low of 4% for 1-flares observed at Capetown to a high of 243 % for 3+ flares observed at the Dunsink Observatory. The mean value for importance 2 flares is about 60%. The application of these corrections yields significant changes in calculations involving the fre- TABLE I. Mean flare lifetime as a function of importance. Imp 1- 1 1+ 2- 2 2+ 3- 3 3+ to (min) to 20 35 50 60 65 70 75 80 quency of occurrence of solar flares. Two examples of such changes are: (1) The shape of the curve of flare frequency vs flare importance is changed, the percentage decrease in flares per hour being larger for the larger flares. (2) The disparity of reported flares per hour between different observing stations (Dodson and Hedeman, J. Ceophys. Research 65, 123, 1960) is considerably lessened when one considers the number of flares per "effective" observing hour rather than the number of flares per actual observing hour. % for 1-flares observed at Capetown to a high of 243 % for 3+ flares observed at the Dunsink Observatory. The mean value for importance 2 flares is about 60%. The application of these corrections yields significant changes in calculations involving the fre- TABLE I. Mean flare lifetime as a function of importance. Imp 1- 1 1+ 2- 2 2+ 3- 3 3+ to (min) to 20 35 50 60 65 70 75 80 quency of occurrence of solar flares. Two examples of such changes are: (1) The shape of the curve of flare frequency vs flare importance is changed, the percentage decrease in flares per hour being larger for the larger flares. (2) The disparity of reported flares per hour between different observing stations (Dodson and Hedeman, J. Ceophys. Research 65, 123, 1960) is considerably lessened when one considers the number of flares per "effective" observing hour rather than the number of flares per actual observing hour. % for 1-flares observed at Capetown to a high of 243 % for 3+ flares observed at the Dunsink Observatory. The mean value for importance 2 flares is about 60%. The application of these corrections yields significant changes in calculations involving the fre- TABLE I. Mean flare lifetime as a function of importance. Imp 1- 1 1+ 2- 2 2+ 3- 3 3+ to (min) to 20 35 50 60 65 70 75 80 quency of occurrence of solar flares. Two examples of such changes are: (1) The shape of the curve of flare frequency vs flare importance is changed, the percentage decrease in flares per hour being larger for the larger flares. (2) The disparity of reported flares per hour between different observing stations (Dodson and Hedeman, J. Ceophys. Research 65, 123, 1960) is considerably lessened when one considers the number of flares per "effective" observing hour rather than the number of flares per actual observing hour. Publication: The Astronomical Journal Pub Date: 1962 DOI: 10.1086/108623 Bibcode: 1962AJ.....67Q.109A full text sources ADS |