Identifying light pollution sources at two major observatories in Malaysia

A spectral observation and analysis were conducted in order to identify the main contributor of sky brightness at two of Malaysia’s most active observatories. The light pollution observations were carried out under moonless clear night sky with a 90 mm refractor telescope and SBIG’s Self Guiding Spectrograph. We found that the main contributor to Balai Cerap Teluk Kemang (BCTK) sky brightness is High Pressure Sodium (HPS) street lighting due to its number and density used within 5 km radius of the observatory. HPS spectral lines dominate the spectrum between 556 - 640 nm, agrees with the orange hue visible to the naked eye. The intensity due to HPS lighting is so high that there was no trace of the concerned white LED spotlight less than 1 km away. However, some traces of elements from Mercury Vapor (MV) lamps at 3.6 km distance managed to reach the observatory in the green spectrum. The finding concludes that the nearby LED spotlight does not affect the night sky brightness over BCTK. Meanwhile, Langkawi National Observatory (LNO) sky profile was also observed during heavy fishing season as comparison. The sky spectra for LNO was similar to BCTK in the reds except for a very distinct peak in green region corresponding highly with green MV (532 - 547 nm) with peaks at 536 nm and 546 nm, matches the lamps used for squid fishing around the island. The intensity of the green MV light matches the intensity of HPS light sources, during the observation period of peak squid season in January. This made LNO a far less favorable condition for astronomical observing site compared to BCTK. We also found that LNO sky has brightened 3.767 times compared to finding of 2013

A new crescent moon visibility criteria using circular regression model: a case study of Teluk Kemang, Malaysia

Many astronomers have studied lunar crescent visibility throughout history. Its importance is unquestionable, especially in determining the local Islamic calendar and the dates of important Islamic events. Different criteria have been used to predict the possible visibility of the crescent moon during the sighting process. However, so far, the visibility models used are based on linear statistical theory, whereas the useful variables in this study are in the circular unit. Hence, in this paper, we propose new visibility tests using the circular regression model, which will split the data into three visibility categories; visible to the unaided eye, may need optical aid and not visible. We formulate the procedure to separate the categories using the residuals of the fitted circular regression model. We apply the model on 254 observations collected at Baitul Hilal Teluk Kemang Malaysia, starting from March 2000 to date. We show that the visibility test developed based on elongation of the moon (dependent variable) and altitude of the moon (independent variable) gives the smallest misclassification rate. From the statistical analysis, we propose the elongation of the moon 7.28°, altitude of the moon of 3.33° and arc of vision of 3.74 at sunset as the new crescent visibility criteria. The new criteria have a significant impact on improving the chance of observing the crescent moon and in producing a more accurate Islamic calendar in Malaysia

Analysis data of the 22 years of observations on the young crescent moon at Telok Kemang observatory in relation to the Imkanur Rukyah criteria 1995

The main challenge in the young crescent moon (YCM) observation is the ability to detect the appearance of the YCM, which has varying contrast due to the phenomenon of twilight. The advancement of technology in digital imaging helps the faint and thin image of the YCM to be detected and taken during observation. The techniques used in the observations of the YCM were naked eyes, telescope, and telescope with cameras. A digital imaging technique is also being used in the observations to assist in detecting and recording the image of the YCM more effectively. This paper presents the analysis of the YCM observation data recorded at Telok Kemang Observatory from 2000 to the present. A total of 275 observation sessions were conducted during this study, with 87 positive sightings successfully recorded. The studies found that the smallest elongation and the minimum altitude at sunset of the YCM successfully recorded were 6.81° and 5.40°, respectively. The moon was recorded at an altitude of 3.37°, while the sky is still bright with the sun at an altitude of –2.64° using the digital imaging technique. Based on the records, the YCM which has the minimum criteria of Imkanur Rukyah, i.e., altitude of 2° and elongation of 3° at sunset was never detected or recorded during the 22 years of observations. Therefore, this work suggests the need to change the visibility of Imkanur Rukyah criteria used since 1995 to a more potentially observable criterion. In other aspects, the lengthy observation activities have contributed to the development of a database system for JAKIM that other researchers can access

The characteristics of be star in delta scorpii system / Nazhatulshima Ahmad

Mechanisms of the disk formation in Be stars may differ from one Be star to another, which may result in the variations in the circumstellar disk’s spectral characters. The mechanism of disk formation is still under debate for the case of binary stars in which a mass transfer could not happened. -Scorpii, the target star in this study, is one of the bright Be binary stars that has been classified as a Be star since 1990s when the star shows a weak Balmer emission line. This thesis mainly presents the spectral characteristics in optical region from the year of 2007 to 2011 in order to study the Be characteristics of this type of star. Over 350 spectra of data have been used for this work. The circumstellar regions of H, H, H, and HeI λ6678 and photospheric region which are represented by HeI λ4388, HeII λ4686, MgII λ4481 and HeI λ4921 have been used in the investigation of the Be disk of -Scorpii. We found that the size of the Be disk of the star particularly, H, was varies with V/R ratio that larger disc size correspond to smaller V/R ratio. The long term V/R variation of -Sco in H line shows that the rotation of the circumstellar disk around the primary is following the one-armed oscillation disk model in a prograde direction. All the circumstellar lines used in this study were found correlated mostly in the same manner: their strength were found decreasing from 2007 to the end of 2010 but increased in 2011 as this star approaches the periastron; the lines were shifted toward the longer wavelength for V>R and vice-versa except during the periastron where the disc is rotating faster. The H and H lines were used in the investigation during the recent periastron and we found that the strength of both lines was largely increased. The high eccentricity of this binary leads the close encounter or periastron that could be significant for the mechanisms of the disk formation. In the second part of this work which studies the evolutionary status of this star, we found that this binary which had the orbital period of 10.817 years was iv unable to perform a mass transfer. Our evolutionary model generated using EV stellar evolution code showed that the star is rotating at ~0.5 of critical velocity, cr, lower than the rotation which was suggested for the Be phenomenon to happen i.e 0.7cr. Even with the slower rotation, the relative intensity of the H emission line still shows about double increment during the 2011 periastron passage compared to the last periastron passage in 2000. It shows that the close encounter of the 8 M companion has a high influence on the appearance and survival of the Be phenomenon of -Sco

Analysis of geomagnetic Ap index on worldwide earthquake occurrence using the principal component analysis and hierarchical cluster analysis

Geoeffective solar events, especially the coronal mass ejection (CME) and the high-speed solar wind (HSSW) will induce geomagnetic storm upon its arrival to Earth. The solar events could trigger an earthquake occurred during the arrival. In this study, the focus is on the proxy of the geoeffective solar events, which is the geomagnetic Ap index and the data of shallow worldwide earthquakes. The main objective was to investigate the impact of geomagnetic storms on the occurrences of earthquakes from 1994 to 2017 from a statistical perspective. The geomagnetic Ap index data was obtained from the Helmholtz-Centre Postdam - GFZ German Research Centre for Geosciences and the shallow worldwide earthquake data were from the United States Geological Survey (USGS) earthquake catalogue. The Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) were used to analyse the data. Two groups were obtained from the PCA biplot: Group 1 - before the event (Day-4 to Day-1) and Group 2 - after the event group (Day 0 to Day+4). A two-cluster solution was obtained from the HCA, which shows that days before and after geostorm are divided into two main clusters. The statistical results show that earthquakes activity might have different behaviour before and after the geostorm occurred. In conclusion, the results emphasize that there are differences between days before and after the geostorm occurrence, hence, the solar influence upon earthquake occurrences cannot be neglected entirely

Enhancing Moon Crescent Visibility Using Contrast-Limited Adaptive Histogram Equalization and Bilateral Filtering Techniques

Image enhancement is becoming increasingly im portant with the advancement of space exploration techniques and the technological development of more durable and sci entifically sound observatories equipped with more powerful telescopes. The enhancement of images helps astronomers an alyze the results and act toward determining the dates of religious festivals. This work describes a technique known as contrast-limited adaptive histogram equalization (CLAHE) with grayscale contrast enhancement and bilateral filtering. We apply CLAHE on the L component of the CIE-Lab color space to adjust lightness contrast. Subsequently, grayscale contrast enhancement is performed to increase the visibility of the moon crescent. Noise caused by grayscale contrast en hancement is reduced using bilateral filtering. Two quantitative measures are selected (PSNR and MSE) to show the visual improvement achieved by the proposed algorithm

Enhancing Moon Crescent Visibility Using Contrast-Limited Adaptive Histogram Equalization and Bilateral Filtering Techniques, Journal of Telecommunications and Information Technology, 2022, nr 1,

Image enhancement is becoming increasingly im portant with the advancement of space exploration techniques and the technological development of more durable and sci entifically sound observatories equipped with more powerful telescopes. The enhancement of images helps astronomers an alyze the results and act toward determining the dates of religious festivals. This work describes a technique known as contrast-limited adaptive histogram equalization (CLAHE) with grayscale contrast enhancement and bilateral filtering. We apply CLAHE on the L component of the CIE-Lab color space to adjust lightness contrast. Subsequently, grayscale contrast enhancement is performed to increase the visibility of the moon crescent. Noise caused by grayscale contrast en hancement is reduced using bilateral filtering. Two quantita tive measures are selected (PSNR and MSE) to show the visual improvement achieved by the proposed algorithm

The astronomical seeing measurements at Langkawi National Observatory

We present seeing measurements of Langkawi National Observatory during the period from 2014 May 6 to 2015 March 26. The measurements were carried out with Differential Image Motion Monitor (DIMM) of STV and Alcor system. The median seeing was measured to be best at 0.8 arcseconds in May 2014 with STV system and 0.5 arcseconds in December 2015 with Alcor system