Comparison of relative sunspot numbers measured in Malaysia with international sunspot number calculated by SIDC-SILSO

Abstract

The accuracy of Langkawi National Observatory (LNO) relative sunspot number (RSN) data has been officially acknowledged when LNO has become one of the contributors to International Sunspot Number (ISN), RISN since June 2015. However, RSN from LNO (RLNO) can only be obtained if the weather is favourable and the instruments are working well. These disadvantages can be solved if there are other observers across Malaysia that can contribute data of RSN to LNO. This research aims to compare the RSN collected by an amateur observer at National Planetarium, RNP with RLNO and RISN. 11 days data between the month of November 2014 and January 2015 are analysed to see the differences between RNP to both RLNO and RISN. Results show that, the value of RNP is lower than RLNO and RISN. The highest percentage difference is between RNP and RISN which is due to the different method and instruments used in observing the sunspot. The correlation of relative sunspot number is high between RLNO and RISN proving the reliability of LNO as contributor to ISN. The observational index is also determined in this study based on the ratio of correction factor of RNP to RLNO.