Mohd Zambri Zainuddin

The Application of Sky Quality Meter at Twilight for Islamic Prayer Time

Abstract —The aim of this study is to detect elusive light that indicate the prayer time (Isha’). Therefore, we focused on optical sky brightness at dusk from May 2007 through April 2008 intermittently. The measurements of twilight sky brightness were covered at one (1) site covering; West coast of Peninsular Malaysia. The measurements were done by applying Sky Quality Meter (SQM) which covered between 400-700 nm in accordance of human eyes and SQM range. Results showed that there are clear indications of light changes when Sun at certain degree below horizon that visible by plateau form in twilight sky brightness dependences versus solar zenith angle. It is clarified that the yearly averages of solar depression by observation are best correlated within the range of 17.3o – 19.5o for Isha’. Index Terms —Twilight; prayer time; sky quality meter. I. I NTRODUCTION Early studies done by astronomers such as Ibn Muadh, al-Biruni, al-Qayini, Ibn Yunus etc.[1], [2]. Ibn al-Shatir adopted various value for each prayer times such as 17

The Solar Chromosphere Spectrum Observation during Annular Solar Eclipse 2010

The solar chromosphere spectrum observations usually perform during total solar eclipses. However, total solar eclipse only happened once a year in average and the observation outside eclipses condition suffer from strong stray light from the Sun and daytime astronomical seeing which difficult to be controlled precisely. The idea of the observation during annular solar eclipse was based on the fact that: 1) The brightness of the solar chromopshere is as bright as the full moon, 2) The Moon is visible during daytime under excellent weather condition, and 3) The sky brightness observed during annular phase of an annular solar eclipse is 3 times dimmer than that of on the day without eclipses. The objective of the observation is to see how much information can be reveal, compare to those observed during total solar eclipses. Observation had been conducted on the annular solar eclipse occurred on 15th January 2010 at Bagan, Myanmar, under excellent weather condition. A spectrograph was built based on the desi...

Acquirement of the observatory code of Langkawi National Observatory

Observatory code was assigned by The International Astronomical Union (IAU) Minor Planet Center (MPC) for a permanent observatory that intended to do astrometric CCD-observing program of minor planet or comets in solar system. The purpose of acquiring an observatory code is to document specific details about a particular observation site and the types of instruments used within the observatory. In addition, many astronomical centers and stations worldwide will know there is an active observatory at the particular location and international cooperation program in astronomy observation is possible. The Langkawi National Observatory has initiated an observation program to monitor minor planet, specifically those Near Earth Objects (NEOs) that may bring potentially hazardous to the Earth. In order to fulfil the requirement that stated by MPC for undertaking astrometric CCD-observing program, an observatory code was required. The instruments and methods that applied to obtain the observatory code will be discu...

H-α profile of M-type red giant stars by using astronomical spectroscopy technique

The technique of spectroscopy in astronomy is a research or a method which uses spectrum lines emitted by a body that emit electromagnetic ray. These lines will be used to determine the characteristics of any celestial body and one of the most dominant lines is H-α line. The research has been using 20RC Carbon Truss Ritchey-Chretien telescope, SBIG Self Guided Spectrograph (SGS) with high resolution camera Couple-Charged Device CCD ST-7E. Since H-α line is to be found at 6562.817 A, neon lamp is being used as calibration because of the obvious lines of this element is in the higher range of visible wavelength, from 5800 to 7500 A. The software: TheSky and CCDSoft are being used for collecting and analyzing observed data while IRAF which being installed on LINUX interface are used to process the collected data. The data were processed to measure the full width half maximum (FHWM) and equivalent width (EW) for H-α line for each star. Seven M-type red giants that have been chosen are HD 80493, HD 148478, HD ...

Solar spectrum observation with intermediate resolution spectrograph

The observations have been conducted with the slit of the spectrograph placed at the center of the solar disk and also tangent to the solar limb. The recorded spectral range covered from 3600 A to 8500 A with average dispersion of 1.5 A/pixel. The observed photospheric spectrum shows the typical Fraunhofer lines such as CaII K (λ3933.68 A), Hβ (λ4861.34 A), NaI D1 (λ5895.92 A) and Hα (λ6562.8 A). Several emission lines from the solar chromosphere were recorded when observed on the solar limb. Lines identification of these emission lines with its corresponding wavelengths and elements were made. The surface temperature determined from the photospheric spectral is approximately 6052.43 ± 78.87° Kelvin.

Spectral line profiles of Alpha Orionis

A study of spectral line profile of Hα was conducted on Alpha Orionis based on data taken from Elodie archive data. In this paper we analyse the Hα absorption line profiles and study the correlation between wind component and the changes in pattern of Hα absorption lines of Alpha Orionis. The physical reasons of this phenomenon are discussed.

The Pleiades Using Astronomical Spectroscopic Technique within the Range of H‐α Region

The Pleiades is an open star cluster located in the constellation of Taurus, which mainly consists of hot and luminous B‐type stars. Observations were conducted over five‐day period in December 2009 at Langkawi National Observatory, Malaysia by using 20‐inch telescope diameter of Ritchey‐Chretien reflector telescope, together with SBIG Self Guided Spectrograph and SBIG ST‐7 CCD camera. The spectra of seven main members of the cluster, namely Alcyone; Atlas; Celaeno; Electra; Maia; Merope and Taygeta; and of Alcyone B; a smaller component of Alcyone quadruple system, were obtained in the optical range of approximately 6300 A to 7100 A. This range was picked due to the vicinity of Balmer H‐α spectral line at 6562.852 A. Alcyone, Electra and Merope were found to have H‐α emissions possibly caused by the presence of equatorial circumstellar disks or envelopes made up of ejected matter. Electra and Merope in particular exhibited peculiar asymmetric double emission peaks, which could be evidence of one‐armed de...

Evolutionary study of the Be star 28 Tau

We present an evolutionary study of 28 Tau, a Be star, in connection with its rapid rotation. The photometric data during the absence of its envelope in 1921 have been used to determine the effective temperature and luminosity of the star at the main sequence of the HR diagram. From an evolutionary model, we found that the mass and radius of the star are about 3.2 M ⊙ and 3.2 R ⊙ respectively. The equatorial rotation velocity of the star, ν e found to be close to its critical velocity, ν cr where ν e /ν cr ≃ 0.87.

Astronomical Limiting Magnitude at Langkawi Observatory

Astronomical limiting magnitude is an indicator for astronomer to conduct astronomical measurement at a particular site. It gives an idea to astronomer of that site what magnitude of celestial object can be measured. Langkawi National Observatory (LNO) is situated at Bukit Malut with latitude 6°18’ 25” North and longitude 99°46’ 52” East in Langkawi Island. Sky brightness measurement has been performed at this site using the standard astronomical technique. The value of the limiting magnitude measured is V = 18.6±1.0 magnitude. This will indicate that astronomical measurement at Langkawi observatory can only be done for celestial objects having magnitude less than V = 18.6 magnitudes.

Fried Parameter Analysis of Astronomical Photometry

The physical relationship between atmospheric turbulence and astronomical seeing has been reviewed in detail by Roddier [2] and Coulman [3]. When a plane wave of light with uniform amplitude propagates through a refractive non‐uniform medium such as the atmosphere it exhibits amplitude and phase fluctuations. These effects will degrade astronomical image quality and limit the resolution of the point source (star). The measurement of Fried parameter of the Eagle Nebulae has been done at An‐Najm Observatory, University of Malaya, using direct imaging technique. The image was captured by a Celestron CGE‐14 telescope and a STL‐1001E CCD camera (Clear filter) with Normal guided and Active‐optical element guided techniques. Statistically, the Fried parameter measured for the Eagle Nebulae using Normal ‐guided technique was 0.18±0.13 mm. Use of Active‐optical element has improved and increased the Fried parameter of the Eagle Nebulae by up to 11%.