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Timau National Observatory will be the new Indonesia’s astronomical observatory in East Nusa Tenggara, planned for 2020. Besides the main 3.8-m optical telescope, it will host two 0.5-m “off-the-shelf” f/3.8 and f/8.0 telescopes, equipped with two CCD cameras and two filter wheels. The system will be controlled with a robotic system for autonomous operation. In this paper, we present the system description and current development progress, as well as the future plan for the facility, including its two potential scientific studies: near-Earth objects and exoplanetary transits.

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τ Ceti, a G8-V class star, has similar physical properties with our sun, even though most values are smaller and not as active as the sun. It has also been widely reviewed that this metal-poor population II star has terrestrial planetary systems, some of which are in the Habitable Zone. This paper aims to build the interior structure of τ Ceti through modeling experiments with Modules for Experiments in Stellar Astrophysics (MESA) program. The work began with the determination of several fundamental parameters obtained from previous observations of both interferometry and spectroscopy on several references, and also from basic calculations which are then used as input to build the model in MESA. Structural modeling has been carried out in accordance with current star conditions, which is in the main sequence phase. Finally, the result various physical parameters so-called stellar interior structure such as mass, luminosity, pressure, temperature, radius, and age, as well as zonal division of nuclear core (R < 0.23 R⊙,), radiative (0.23 < R⊙ < 0.54), and convective zone (0.54 < R⊙ < 0.775) were obtained.

Wind shear has been believed as the main mechanism behind the occurrence of E-sporadic layer in 90-120 km altitude. The occurrence of this layer is related to gravity wave, tidal wave, and global-scale atmospheric wave (planetary wave) with different periodicity. Meteor showers that happen annually may also influence the occurrence probability of E-sporadic layer, while Solar and geomagnetic activity contribute less significantly. In this article, E-Sporadic data obtained in Balai Pengamatan Atmosfer dan Antariksa Sumedang, Jawa Barat in 2015 was studied. The main purpose of the study is to understand the characteristics and occurrence pattern of E-sporadic layer in low-latitude region. Conclusions can be deduced from the conducted analyses. Percentage of occurrence of E-sporadic layer (P) is relatively high during May-July and December-January period. The occurrence of E-sporadic layer with critical frequency higher than 2 MHz can be as high as 97%. The observed diurnal variation is the increase of P before midday followed by a significant decrease at 12:00 local time. The value of P rises again and peaks at around 16:00 local time and then declines as the photoionization rate diminishes through time. During May-July, E-sporadic layer with frequency above 6 MHz also occurred in night time. Further examinations are required to analyse the relation between E-sporadic occurrence during those time windows and the activity of high-flux meteor shower. Besides, diurnal and seasonal variations concluded in this study are expected to become rerference for space weather forecast which is demanded by stakeholders. AbstrakGesekan angin (wind shear) telah lama dipercaya sebagai mekanisme penyebab kemunculan lapisan E-Sporadis pada ketinggian 90-120 km. Kemunculan lapisan ini berkaitan dengan gelombang gravitasi, gelombang pasang-surut, serta gelombang atmosfer skala global (planetary wave) dengan perulangan yang berbeda. Hujan meteor yang terjadi setiap tahun juga dapat mempengaruhi probabilitas kemunculan lapisan E-Sporadis, sementara aktivitas Matahari dan geomagnet tidak banyak memberikan pengaruh. Pada artikel kali ini, data E-Sporadis hasil pengamatan di Balai Pengamatan Atmosfer dan Antariksa Sumedang, Jawa Barat sepanjang tahun 2015 telah dipelajari. Tujuan utamanya adalah untuk mengetahui karakteristik dan pola kemunculan lapisan E-Sporadis di daerah lintang rendah. Beberapa kesimpulan dapat dideduksi dari analisis yang dilakukan. Persentase kemunculan lapisan E-Sporadis (P) cukup tinggi pada bulan Mei-Juli serta Desember-Januari. Persentase kemunculan lapisan E-Sporadis dengan frekuensi kritis lebih dari 2 MHz dapat mencapai 97%. Variasi diurnal yang teramati adalah peningkatan nilai P menjelang tengah hari yang diikuti penurunan sekitar pukul 12:00 waktu lokal. Nilai P kembali naik dan memuncak pada pukul 16:00 waktu lokal lalu menurun seiring berkurangnya laju ionisasi oleh radiasi Matahari. Pada bulan Mei-Juli, lapisan E-Sporadis dengan frekuensi lebih dari 6 MHz juga muncul pada malam hari. Pemeriksaan lebih lanjut perlu dilakukan untuk mengetahui kaitan antara kemunculan E-Sporadis pada rentang waktu tersebut dan aktivitas hujan meteor dengan fluks tinggi. Selain itu, variasi diurnal dan musiman yang diperoleh dalam studi ini dapat menjadi rujukan bagi proses ramalan cuaca antariksa yang diperlukan bagi sejumlah stakeholder.