Solar Radio Observation using Callisto Spectrometer at Sumedang West Java Indonesia: Current Status and Future Development Plan in Indonesia

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1 Ground-based Solar Observations in the Space Instrumentation Era ASP Conference Series, Vol. 504 Ivan Dorotovič, Catherine E. Fischer, and Manuela Temmer, eds. c 2016 Astronomical Society of the Pacific Solar Radio Observation using Callisto Spectrometer at Sumedang West Java Indonesia: Current Status and Future Development Plan in Indonesia T. Manik, 1 P. Sitompul, 1 M. Batubara, 1 T. Harjana, 1 C. Y. Yatini, 1 and C. Monstein 2 1 Space Science Center of Indonesian National Institute of Aeronautics and Space (LAPAN), Bandung, West Java, Indonesia;timbul.manik@lapan.go.id 2 Institute for Astronomy, ETH Zurich, Zurich, Switzerland; Abstract. Sumedang Observatory (6.91 S, 107,84 E) was established in 1975 and is one of the solar observation facilities of the Space Science Center of Indonesian National Institute of Aeronautics and Space (LAPAN), located around 40 km, east part of Bandung City, West Java, Indonesia. Several instrumentations for solar and space observation such as optical telescopes, radio solar spectrograph, flux gate magnetometer, etc. are operated there, together with an ionosphere sounding system (ionosonde) that was set up later. In July 2014, a standard Callisto (Compound Astronomical Low-cost Low-frequency Instrument for Spectroscopy and Transportable Observatory) spectrometer was installed at Sumedang Observatory for solar radio activity monitoring. Callisto has been developed in the framework of IHY2007 and ISWI, supported by UN and NASA. Callisto spectrometer has observation capability in the frequency range of MHz. The Callisto spectrometer receives signal by using a set of 21 elements log-periodic antenna, model CLP5130-1N, pointed to the Sun and equipped with a low noise pre-amplifier. With respect to the Radio Frequency Interferences (RFI) measurements, the Callisto spectrometer is operated individually in frequency ranges of MHz and MHz. Observation status and data flow are monitored in on-line from center office located in Bandung. The data was transferred to central database at FHNW (Fachhochschule Nordwestschweiz) server every 15 minutes to appear on e- Callisto network subsequently. A real time data transfer and data processing based on Python software also has been developed successfully to be used as an input for Space Weather Information and Forecasting Services (SWIFtS) provided by LAPAN. On 5th November 2014, Callisto spectrometer at Sumedang observed the first clear solar radio event, a solar radio burst type II corresponding to a coronal mass ejection (CME), indicated by a strong X-ray event of M7.9 that was informed on by Space Weather Prediction Center (SWPC) NOAA. Thereafter, Callisto spectrometer at Sumedang also observed several solar radio bursts in various types. This paper describes the system configuration of Callisto spectrometer installed at Sumedang, RFI measurement and chosen observation strategy, real time data transfer and processing, as well as several samples of present results of solar radio burst monitoring at Sumedang, and future development plan of Callisto spectrometer in Indonesia which will be able to cover 14 hours of day solar observation. Keywords: Callisto spectrometer, solar radio observation, SWIFtS. 331

2 332 Manik et al. 1. Introduction Space weather refers to the variable conditions on the Sun, throughout space, and in the Earth s magnetic field and upper atmosphere that can influence the performance of space-borne and ground-based technological systems and endanger human life or health as quoted on Williamson & Samuel (2010). Space weather is mainly caused by the Sun because of the variability on various time scales in 1) mass emission, i.e. solar wind, Coronal Mass Ejections (CMEs), and in its Solar Energetic Particles (SEPs) which affect magnetosphere, and in 2) photon emission, i.e. irradiance and flares which affect Earth s climate and Earth s ionosphere resulting several communication problems as reported by Gopalswamy (2009). The components of the Sun that influence space weather are flares and CMEs. Solar radio bursts are believed to be the precursors of the CME. The influence of the CME may reach Earth in a period of hours to days after the occurrence of the radio burst. Solar radio burst are also associated with shock waves that propagate from the Sun, with type II bursts usually observed at frequencies below 400 MHz as reported by Monstein & Baludansky (2013). Solar radio bursts can be divided into five basic types i.e. I, II, III, IV, and V. Each of these types occurs through a different mechanism, namely thermal, plasma radiation and synchrotron radiation as reported by Kesumaningrum et al. (2010) and Zucca et al. (2012). Callisto is a smart radio frequency-based spectrometer, dedicated for solar radio astronomy and radio interference observations. Callisto installed at Sumedang Observatory, Space Science Center of Indonesian National Institute of Aeronautics and Space (LAPAN), and is used for solar radio activity monitoring. Callisto has been installed in 66 locations and the user from more than 120 countries, and connected in a global e-callisto network as reported by Monstein (2015). This paper presents the system configuration of Callisto spectrometer installed at Sumedang, the RFI measurement, the real time data transfer and processing, several samples of present result of solar radio burst monitoring, and development plan of Callisto spectrometer in Indonesia. 2. Callisto and RFI at Sumedang Station According to Suratno (2014), since established on 1975, observation in Sumedang Station was developed gradually. Several observations are conducted daily for solar and space observations. LAPAN operates various optical telescopes, radio solar spectrograph, flux gate magnetometer, ionosonde, GRBR, SID VLF receiver, and Callisto, so simultaneous observation is possible. Sumedang Station is located ± 54 km in the east part of Bandung City, West Java Indonesia. Geographical coordinate is 6.91 S, E, the altitude is 900 m a.s.l. The local time is UT+07 hours. Callisto is working at frequencies between MHz with a frequency resolution of 62.5 KHz and radiometric bandwidth of 300 KHz at -3 db. The dynamic range is 50 db with a noise figure<10 db. Sensitivity measurement of Callisto is 25.4 mv per db. Data is stored in a FITS (Flexible Image Transport System) file which contains of the frequency to time data in binary format. Callisto can take measurements up to 800 samples per second with maximum 400 channels but usually 200 frequencies per sweep.

3 Solar Radio Observation using Callisto Spectrometer in Indonesia 333 Data is transferred via the RS-232 to the PC as reported on Benz et al. (2005) and Benz et al. (2009). System software used is Callisto-V117 developed by ETH Zurich that is compatible with Windows XP and Windows 7, 8 and 10. A block diagram of the Callisto system configuration is shown in Figure 1. Figure 1. Block diagram of Callisto system configuration (Top:) and Radio Frequency Interference (RFI) (Bottom:) at Sumedang Station. The Callisto system consists of an antenna and 50 Ω dummy load, pre-amplifier/lna (Low Now Amplifier), Low Noise Cable, Callisto spectrometer, and a PC with software as shown in Figure 1 top. The antenna is a commercially available log periodic antenna CLP5130-1N. The antenna gain is db and antenna VSWR is less than 2:1. The antenna consists of 21 aluminum antenna elements with maximum 2 meters length, 3 meters width and can be used in the amateur band on frequency range of MHz. Type N cable connectors are used. RFI measurements obtained at Sumedang station as shown in Figure 1 bottom, were referred to determine the appropriate operating frequency for Callisto. The operating frequency was determined by selecting the frequency with minimum RFI and neglecting high level RFI. Frequency of FM radio ( MHz) and DVB-T ( MHz) were not included in the configuration of frequency file.

4 334 Manik et al. 3. Solar Radio Burst Observation On 5 th November, 2014, Callisto Sumedang detected and received a clear type II solar radio burst from 09:40 UT to 09:50 UT, as reported by Monstein (2014), and by Manik & Sitompul (2015) as shown on Figure 2. The dark background denotes the undisturbed background noise, shades of light colors refer to strong and very strong solar activity. The left figure shows a type II burst which has been declared as the first successful result of solar radio burst observation using Callisto in Indonesia, and the rest shows type III bursts. The solar radio burst signal was also received at several stations on the e-callisto network. Figure 2. Solar radio burst observation at Sumedang, left, type II burst occurred on 15 th November 2014, 09:40 UT to 09:50 UT, and the rest are type III bursts occurred on 15 th May 2015 at 05:24 UT, and on 15 th September 2015 at 02:22 UT respectively. 4. Real-time Data Processing The scheme of data transfer from Callisto s instrument to the data center was introduced by Manik et al. (2015). Originally, data has been sent only to FHNW Switzerland and recently also sent to local server for real-time processing purpose. From this local data server (known as LAPAN RDSA - Space Science Data Repository) data was sent to PC for further real-time processing as shown in Figure 3. Spectogram of the frequency radio-waves intensity has been generated by using Gaussian Filter and image enhancement, and the numpy pyton modules has been used as a scripting which is run automaticaly by task-scheduler. The image of spectogram produced in this process will be displayed in SWIFtS web-server (Space Weather Information and Forecast Services) in order to real-time support of the SWIFtS activity. Samples of result are also shown on Figure 4. Three type III bursts with background subtraction. Vertical axis is Frequency (MHz), and color bar indicates solar signal strength in db. 5. Future plan of CALLISTO in Indonesia The next Callisto instrument in Indonesia is planned to be set up in eastern part of Indonesia, at Mount Timau, Kupang, East Timor (9.59 S, E, altitude 1532 m a.s.l.), where Indonesian National Observatory is planned to be established. Then some simultaneous observation can be conducted with space observation such as fluxgate magnetometer and other solar radio instrumentations. A preliminary RFI measurement

5 Solar Radio Observation using Callisto Spectrometer in Indonesia 335 Figure 3. On-line data transfer and processing system. Figure 4. Some results of local data processing, shows three types III bursts occurred on 15 th May 2015 (Left), 15 th June 2015 (Center) and 15 th September 2015 (Right) has been conducted at Mount Timau on 2013 by Hidayat as reported on Hidayat et al. (2014), as shown on Figure 5. The RFI measurement promised a good solar radio observation can be conducted in future observatory, a promised clear radio environment. 6. Conclusion Callisto installed in Sumedang Indonesia for solar radio observation and has successfully detected solar radio bursts on 5 th November 2014, then observed several radio

6 336 Manik et al. Figure 5. RFI measurement at Mount Timau on May bursts thereafter. Callisto Sumedang also connected to e-callisto network to contribute observation from equatorial region along the day. The data transfer and processing system has been developed to support SWIFtS (Space Weather Information and Forecasting System) at LAPAN. Future plan is to setup a new Callisto instrument at location of Indonesian National Observatory at Mount Timau, Kupang East Timor Indonesia which shown a clear radio environment based on preliminary RFI measurement. Acknowledgments. Authors would like to thanks to the staffs of Sumedang station for operation and maintenance of the Callisto spectrometer, also to the IT staffs of Space Science Center for help on maintaining data transfer. This work is a part of 2015 research program of Space Science Center of LAPAN. References Benz, A. O., Monstein, C., & Meyer, H. 2005, Solar Physics, 226, 143 Benz, A. O., Monstein, C., Meyer, H., Manoharan, P. K., Ramesh, R., Altyntsev, A., Lara, A., Paez, J., & Cho, K. S. 2009, Earth Moon Planet, 104, 277 Gopalswamy, N. 2009, Coronal Mass Ejections and Space Weather (Tokyo: Terrapub) Hidayat, T., Munir, A., Dermawan, B., Jaelani, A. T., Leon, S., Nugroho, D. H., & et al. 2014, Exp Astron, 37, 85 Kesumaningrum, R., Sungging Mumpuni, E., Sulistiani, S., Muhamad, J., & Maryam, S. 2010, Final Report of Intensive to Accelerate Diffusion and Application of Science and Technology Program 2010 of LAPAN, 1 Manik, T., & Sitompul, P. 2015, in Proceeding of SNSAA 2014, edited by Jiyo, & S. Kaloka, vol. x of LAPAN, 195

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