Abstract.We observed the white-light corona during the total solar eclipse of 2016 March 9 from Corong Beach, East Borneo. The solar corona is nearly circular with exception on the southern part of the Sun. Coronal structures are clearly seen. Based on the data, we obtained the Ludendorff flattening index, Nikolsky geometric flattening index, and phases of solar activity (Φ and P) are 0.129, 1.32, -0.716, and 0.573 respectively. Relation between Ludendorff and Nikolsky index, sunspot number, and phases of solar activity were discussed. We also predicted the amplitude of solar cycle 25 to be 196 ± 52 (based on 13-month smoothed monthly data) and 130 ± 42 (based on monthly sunspot number data).

We report optical spectroscopic observations in 2017 at Bosscha Observatory on an interesting nova, ASASSN-17hx (Nova Sct 2017). The nova ASASSN-17hx was observed on July 26th, July 29th, July 31st, and August 14th. Based on the light curve, we propose that our spectroscopic observation of ASASSN-17hx was conducted during “iron curtain” phase. The observed spectra showed a strong Hα emission line and multiple emission lines of Fe II multiplets, which is typical for a Fe II type nova. However, since ASASSN-17hx was classified as a He/N type only few days after its outburst, it is suggested that the nova is actually a hybrid type nova. We will discuss the characteristic of ASASSN-17hx by analysing its expansion velocity, electron density, and evolution of the emission lines.

We present the spectroscopic observation of β Lyrae, an interacting eclipsing binary, with orbital rotation period of 12.9 days, with one component known as the B-emission (Be) star. The primary star is a B6-B8II of 3 M⊙ and the secondary is a 13 M⊙ B0.5V star. The secondary star is embedded in the accretion disk produced by the infalling matter from the primary star, and this disk is estimated as the source of the emission lines. The observations were conducted at Bosscha Observatory, Lembang, Indonesia from May to August 2018, using 10” Meade LX-200R Telescope (D = 254 f/D = 9.84), equipped with a Littrow High Resolution Spectrograph (LHIRES) III, grating of 1200 grooves/mm yielding in the resolution of R∼5900, and CCD SBIG ST-402 XME camera with backfocus at 17.5 mm. Seeing during observation was estimated to be 2 arc seconds. During this period, we have obtained 15 spectra in various wavelength coverage, 4 spectra covering around λλ = 5779 – 6046 ÅÅ (typical S/N = 0.02), 1 spectrum covering around λλ = 6430.257 – 6694.434 ÅÅ (typical S/N = 0.06), and 10 spectra covering around λλ = 6487 – 6752 ÅÅ (typical S/N = 0.06). The observed spectra show Hα-emission profiles with V/R variation, He I 6678 Å with P-Cygni profiles, and He I 5876 Å with P-Cygni profiles. These variations are due to the fact that β Lyrae is a binary star system, and also it is suspected that another possible mechanism might be involved.

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We report low and intermediate resolution spectra of the recurrent nova RS Oph taken at two observatories. A low resolution spectrum (R ≈ 1000) was taken at ITERA Astronomical Observatory (IAO) in Lampung by using 25 cm (f/8) RC Astrograph telescope equipped with a LISA Pack Spectrograph eight days after the outburst. Twenty intermediate spectra (R ≈ 5000) were taken on several consecutive nights using LHIRES III spectrograph attached to a 25 cm (f/10) Meade LX-200R telescope at Bosscha Observatory, Lembang. We identified significant change in the strength of atomic lines from low resolution spectrum compared to previous observations. A clear and distinct Balmer emission decrement can be seen from the spectrum. Our intermediate resolution spectroscopy revealed a variability of P-Cygni profile on a broad Hα line. The P-Cygni profile evolved and disappeared at recent observations. It is thought that there was a new shell formed after the outburst and later combined with the previous shell in the next days. From the broad Hα profile, we measured and found decreasement in expansion velocity during our observation. We estimated vexp = 2907.97 ± 64.14 km/s and vexp = 997.12 ± 8.18 km/s on 1.6440 and 22.729 days after the outburst, respectively.