The receiver is a signal receiving device in a radio telescope system. As an important parameter to characterize the receiver performance, noise temperature is very practical to calibrate accurately. The traditional receiver noise temperature calibration method is the cold and ambient load method. Through the establishment of K-band ambient receiver, and its amplitude calibration test platform of the cold and ambient load method, chopper wheel method, and ambient and hot load method, comparison and analysis of the above three methods were carried out. The test and calculation results show that the test accuracy of the cold and ambient load method is about 1.3&#x0025;, that of the chopper wheel method (nonlow elevation) is about 3&#x0025;, and that of the ambient and hot load method is about 9&#x0025;. The test accuracy of the ambient and hot load method is slightly lower than that of the above two methods. The analysis is mainly due to the uncertainty of the hot load temperature and the small temperature difference between the two loads, which leads to the deterioration of the overall accuracy. But the advantage is that the method can perform real-time calibration in the process of observation, and it is easier to implement than the traditional cold and ambient load method. The results of noise temperature measurement are compared with those of theoretical calculation, the error is basically within 10&#x0025;, and it can satisfy the demand of the noise temperature test. In the future, we expect that on the basis of increasing the hot load temperature, further experiments were carried out on the thermostatic treatment of hot load and the accuracy of temperature acquisition, and finally we hope that this method can better meet the testing requirements of receiver noise temperature and radio source amplitude calibration.

Kai Wang

Maozheng Chen

Jun Ma

Xuefeng Duan

Yang Wang

Liang Cao

Hao Yan

Binbin Xiang

Analysis and Research on the Centimeter Band Receiver Amplitude Calibration Method

Advances in Astronomy is pleased to announce the appointment of Prof Josep Trigo Rodr&#x00ED;guez as its new Chief Editor. In this Editorial, Prof Trigo introduces himself, describes some of the journal&#x2019;s journey and current status, and shares his vision and aspirations for its future.

Josep M. Trigo-Rodr&#xed;guez

Introducing Our New Chief Editor

Feng Wang

Wenda Cao

Denis Bastieri

Junhui Fan

Chenzhou Cui

Astronomical Massive Data Processing Technology

Sky brightness measuring and monitoring are required to mitigate the negative effect of light pollution as a byproduct of modern civilization. Good handling of a pile of sky brightness data includes evaluation and classification of the data according to its quality and characteristics such that further analysis and inference can be conducted properly. This study aims to develop a classification model based on Random Forest algorithm and to evaluate its performance. Using sky brightness data from 1250 nights with minute temporal resolution acquired at eight different stations in Indonesia, datasets consisting of 15 features were created to train and test the model. Those features were extracted from the observation time, the global statistics of nightly sky brightness, or the light curve characteristics. Among those features, 10 are considered to be the most important for the classification task. The model was trained to classify the data into six classes (1: peculiar data, 2: overcast, 3: cloudy, 4: clear, 5: moonlit-cloudy, and 6: moonlit-clear) and then tested to achieve high accuracy (92&#x0025;) and scores (F-score&#x2009;&#x3d;&#x2009;84&#x0025; and G-mean&#x2009;&#x3d;&#x2009;84&#x0025;). Some misclassifications exist, but the classification results are considerably good as indicated by posterior distributions of the sky brightness as a function of classes. Data classified as class-4 have sharp distribution with typical full width at half maximum of 1.5&#x2009;mag/arcsec2, while distributions of class-2 and -3 are left skewed with the latter having lighter tail. Due to the moonlight, distributions of class-5 and -6 data are more smeared or have larger spread. These results demonstrate that the established classification model is reasonably good and consistent.

Rhorom Priyatikanto

Lidia Mayangsari

Rudi A. Prihandoko

Agustinus G. Admiranto

Classification of Continuous Sky Brightness Data Using Random Forest

When the Large Hadron Collider resumes operations in 2021, several experiments will directly measure the motion of antihydrogen in free fall for the first time. Our current understanding of the universe is not yet fully prepared for the possibility that antimatter has negative gravitational mass. This paper proposes a model of cosmology, where the state of high energy density of the big bang is created by the collapse of an antineutrino star that has exceeded its Chandrasekhar limit. To allow the first neutrino stars and antineutrino stars to form naturally from an initial quantum vacuum state, it helps to assume that antimatter has negative gravitational mass. This assumption may also be helpful to identify dark energy. The degenerate remnant of an antineutrino star can today have an average mass density that is similar to the dark energy density of the &#x39b;CDM model. When in hydrostatic equilibrium, this antineutrino star remnant can emit isothermal cosmic microwave background radiation and accelerate matter radially. This model and the &#x39b;CDM model are in similar quantitative agreement with supernova distance measurements. Therefore, this model is useful as a purely academic exercise and as preparation for possible future discoveries.

Tom F. Neiser

Fermi Degenerate Antineutrino Star Model of Dark Energy

X. Huang

I. Usoskin

L. Y. Zhang

H. N. Wang

Big Data Processing and Modeling in Solar Physics

To investigate the periodic behaviour and relationship of sunspot numbers with cosmic ray intensity and solar wind speed, we present analysis from daily data generated from 1995 January to 2018 December. Cross-correlation and wavelet transform tools were employed to carry out the investigation. The analyses confirmed that the cosmic ray intensity correlates negatively with the sunspot numbers, exhibiting an asynchronous phase relationship with a strong negative correlation. The trend in cosmic ray intensity indicates that it undergoes the 11-year modulation that mainly depends on the solar activity in the heliosphere. On the other hand, the solar wind speed neither shows a clear phase relationship nor correlates with the sunspot numbers but shows a wide range of periodicities that could possibly be connected to the pattern of coronal hole configuration. A number of short and midterm variations were also observed from the wavelet analysis, i.e., 64&#x2013;128 and 128&#x2013;256 days for the cosmic ray intensity, 4&#x2013;8, 32&#x2013;64, 128&#x2013;256, and 256&#x2013;512 days for the solar wind speed, and 16&#x2013;32, 32&#x2013;64, 128&#x2013;256, and 256&#x2013;512 days for the sunspot numbers.

Jacob Oloketuyi

Yu Liu

Amobichukwu Chukwudi Amanambu

Mingyu Zhao

Responses and Periodic Variations of Cosmic Ray Intensity and Solar Wind Speed to Sunspot Numbers

About this journal

Advances in Astronomy publishes in all areas of astronomy, astrophysics, and cosmology, and accepts observational and theoretical investigations into celestial objects and the wider universe.

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Chief Editor, Professor Trigo-Rodríguez (ICE, IEEC-CSIC), has a background in the formation of primitive solar system minor bodies, the study of their fragments in space and the analysis of their surviving rocks that arrived on the Earth.

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Advances in Astronomy - Table of contents 2020

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Advances in Astronomy publishes in all areas of astronomy, astrophysics, and cosmology, and accepts observational and theoretical investigations into celestial objects and the wider universe.

Advances in Astronomy