Astronomy Science and Technology Research Laboratory

Guangzhou, China

Astronomy Science and Technology Research Laboratory

Guangzhou, China

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Fan J.H.,Guangzhou University | Fan J.H.,Astronomy Science and Technology Research Laboratory | Kurtanidze O.,Abastumani Observatory | Kurtanidze O.,Kazan Federal University | And 6 more authors.
Astrophysical Journal, Supplement Series | Year: 2014

Variability is one of the most observable characteristics of active galactic nuclei, and it is important when considering the emission mechanism. In this paper, we report optical photometry monitoring of two nearby brightest quasars, PHL 1811 and 3C 273, using the ST-6 camera attached to the Newtonian focus and the Ap6E CCD camera attached to the primary focus of the 70 cm meniscus telescope at the Abastumani Observatory, Georgia. PHL 1811 was monitored during the period from 2002 September to 2012 December, while 3C 273 was monitored during the period from 1998 February to 2008 May. During our monitoring period, the two sources did not show any significant intra-day variability. The largest detected variations are ΔR = 0.112 ± 0.010 mag. for PHL 1811, ΔB = 0.595 ± 0.099 mag, ΔV = 0.369 ± 0.028 mag, ΔR = 0.495 ± 0.076 mag, and ΔI = 0.355 ± 0.009 mag for 3C 273. When the periodicity analysis methods are adopted for the observations of the sources, a period of p = 5.80 ± 1.12 yr is obtained for PHL 1811 in the R light curve in the present work, and periods of p = 21.10 ± 0.14, 10.00 ± 0.14, 7.30 ± 0.09, 13.20 ± 0.09, 2.10 ± 0.06, and 0.68 ± 0.05 yr are obtained for 3C 273 based on the data in the present work combined with historical works. © 2014. The American Astronomical Society. All rights reserved..


Yang J.,University of Science and Arts of Iran | Yang J.,Guangzhou University | Fan J.,Guangzhou University | Fan J.,Astronomy Science and Technology Research Laboratory | And 2 more authors.
Science China: Physics, Mechanics and Astronomy | Year: 2012

In this paper, a sample including 68 blazars (18 BL Lacs and 50 FSRQs) with known Doppler factors and superluminal velocity from our previous papers is presented. Both the Lorentz factors (Γ) and viewing angles (θ) are estimated for the 68 sources. The relationship between BL Lacs and FSRQs is also revisited using the two variables of Γ and θ. The Lorenz factors are in the range of 2.33 to 64.07. The viewing angles are in the range of 0.04 to 24.56. The averaged value of the viewing angle for BL Lacs is slightly larger than that for FSRQs, while the averaged value of the Lorentz factor for BL Lacs is smaller than that for FSRQs. © Science China Press and Springer-Verlag Berlin Heidelberg 2012.


Fan J.-H.,Guangzhou University | Fan J.-H.,Astronomy Science and Technology Research Laboratory | Yang J.-H.,University of Science and Arts of Iran | Liu Y.,Guangzhou University | And 3 more authors.
Research in Astronomy and Astrophysics | Year: 2013

Observations suggest that γ-ray loud blazars are strongly beamed. The Fermi mission has detected many of blazars, which provide us with a good opportunity to investigate the emission mechanism and the beaming effect in the γ-ray region. We compiled the X-ray observations for 138 Fermi blazars (54 flat spectrum radio quasars, 36 low-peaked BL Lacertae objects, and 48 high-peaked BL Lacertae objects) and calculated their Doppler factors, δγ. It is interesting that the calculated Doppler factors, δγ, are strongly correlated with the γ-ray luminosity. © 2013 National Astronomical Observatories of Chinese Academy of Sciences and IOP Publishing Ltd.


Fan J.-H.,Guangzhou University | Fan J.-H.,Astronomy Science and Technology Research Laboratory | Yang J.-H.,Guangzhou University | Yang J.-H.,University of Science and Arts of Iran | And 4 more authors.
Research in Astronomy and Astrophysics | Year: 2011

Active galactic nuclei (AGNs) have two major classes, namely radio loud AGNs and radio quiet AGNs. A small subset of the radio-loud AGNs is called blazars, which display extreme observational properties, such as rapid variability, high luminosity, high and variable polarization, and superluminal motion. All of those observational properties are probably due to a relativistic beaming effect with the jet pointing close to the line of sight. Observations suggest that the orientation can be expressed by a core-dominance parameter, R. The R, to some extent, is associated with the beaming effect. Blazars are believed to be unified with Fanaroff & Riley type I/II (FRI/II) radio galaxies. In this work, we collected relevant observations from the literature for a sample of 1223 AGNs including 77 BL Lacertae objects, 495 quasars, 460 galaxies, 119 FRs and 72 unidentified sources, and calculated the core-dominance parameters and spectral indexes, discussed the relationship between the two parameters, and gave some discussions. Our analysis suggests that the core-dominance parameters in BL Lacertae objects are larger than those in quasars and galaxies, and the radio spectral indexes in BL Lacertae objects are lower than those in quasars and galaxies. We also found that the core-dominance parameter-spectral index correlation exists for a large sample presented in this work, which may come from a relativistic beaming effect. © 2011 National Astronomical Observatories of Chinese Academy of Sciences and IOP Publishing Ltd.


Yuan Y.,Guangzhou University | Yuan Y.,Astronomy Science and Technology Research Laboratory | Yuan Y.,Hefei University of Technology
Science China: Physics, Mechanics and Astronomy | Year: 2012

Based on the new data from the database of the University of Michigan Radio Astronomy Observatory (UMRAO), we analyze the spectral index and optical variability of OJ287 and 3C279. The main results show that 1) the time delay among three radio bands (4.8, 8, and 14.5 GHz) shows: τ 8-14.5 = 31 d, τ 4-8.8 = 41 d for OJ287, but no time delay lying in 3C279; 2) strong correlation lies in the polarization and flux density at 8 GHz for OJ287 and at 8, 14.5 GHz for 3C279; 3) the logarithmic brightness temperature log(T B) = 14.1 K for OJ287 is 14.1 K, log(T B) = 15.1 K for 3C279. © 2012 Science China Press and Springer-Verlag Berlin Heidelberg.


Yuan Y.-H.,Hefei University of Technology | Yuan Y.-H.,Guangzhou University | Fan J.-H.,Hefei University of Technology | Fan J.-H.,Astronomy Science and Technology Research Laboratory
International Journal of Modern Physics D | Year: 2010

In this work, we used the preliminary data of University of Michigan Radio Astronomy Observatory (UMRAO) for the spectral index calculation for two blazars, 3C 273 (1226+023) and 3C 446 (2223-052), and found that the spectral indices are variable. Therefore, we used three methods (Jurkevich method (J), the discrete correlation analysis (D), and the Periodogram method (P)) to investigate the period in the spectral index variation curves. The results show that 3C 273 has a quasi-period of 8.8 ± 1.3 yr, and 3C 446 has a period of 5.8 ± 1.2 yr. © 2010 World Scientific Publishing Company.


Fan J.H.,Guangzhou University | Fan J.H.,Astronomy Science and Technology Research Laboratory
Journal of Astrophysics and Astronomy | Year: 2014

In this paper, we describe what we have done with regard to astronomy training for physics students. More and more students are interested in astronomy, they spend their summer holidays and spare time in observations and studying the observation data. Some students are familiar with using the telescope for observations, dealing with absorption line features achieved from the observations. Astronomy was selected as the key subject in Guangzhou city and Guangdong province, the laboratory for astronomy science and technology was selected as the key laboratory of Guangzhou city and that for the education department of Guangdong Province. We also provide a master degree programme for astronomy. © 2014, Indian Academy of Sciences.


Lin C.,Guangzhou University | Fan J.-H.,Astronomy Science and Technology Research Laboratory
Research in Astronomy and Astrophysics | Year: 2016

BL Lacertae objects (BL Lacs) are the dominant population of TeV emitting blazars. In this work, we investigate whether there are any special observational properties associated with TeV sources. To do so, we will compare the observational properties of TeV detected BL Lacs (TeV BLs) with non-TeV detected BL Lac objects (non-TeV BLs). From the 3rd Fermi/LAT source catalog (3FGL), we can obtain 662 BL Lacs, out of which 47 are TeV BLs and 615 are non-TeV BLs. Their multi-wavelength flux densities (F R, F O, F X and F γ), photon spectral indexes (αX ph and αph γ), and effective spectral indexes (αRO and αOX) are compiled from the available literature. Then the luminosities (log vL R, log vL O, log vL X, log vL γ) are calculated. From comparisons, we find that TeV BLs are different from low synchrotron peaked BLs and intermediate synchrotron peaked BLs, but TeV BLs show similar properties to high synchrotron peaked (HSP) BLs. Therefore, we concentrated on a comparison between TeV HSP BLs and non-TeV HSP BLs. Analysis results suggest that TeV HSP BLs and non-TeV HSP BLs exhibit some differences in their αRO and αγ ph, but their other properties are quite similar. © 2016 National Astronomical Observatories, Chinese Academy of Sciences and IOP Publishing Ltd.


Fan J.H.,Guangzhou University | Fan J.H.,Astronomy Science and Technology Research Laboratory | Liu Y.,Guangzhou University | Liu Y.,Astronomy Science and Technology Research Laboratory | And 4 more authors.
Journal of Astrophysics and Astronomy | Year: 2011

Variability is one of the characteristics of blazars. The rapid variability is superposed on the long term variation. In this work, the variability on different time scales, such as intra-day (IDV), short-term (STV) and long-term (LTV) variations are presented for some sources. We also presented our own observations of some selected objects, for which the historical data were compiled for periodicity analysis using several methods. The parameters of the binary black hole system OJ 287 are determined. © 2011 Indian Academy of Sciences.


Yuan Y.H.,Guangzhou University | Yuan Y.H.,Astronomy Science and Technology Research Laboratory | Fan J.H.,Guangzhou University | Fan J.H.,Astronomy Science and Technology Research Laboratory | Pan H.J.,Chinese Academy of Sciences
Astronomical Journal | Year: 2015

Using the 1.56 m telescope at Shanghai Observatory, China, we present the photometric results of 1ES 1959+650, which cover from 2006 June 11 to 2014 July 31. The maximum variabilities are DmV max = 1.74 ±0.02 ± mag in the V band, ΔmR max = 0.97 ±0.02 ± mag in the R band, and ΔmI max = 1.15 ±0.03 ± mag in the I band. During the monitoring period, we obtain intraday variabilities on 2009 September 2 (JD 2455077) and 2009 September 3 (JD 2455078). On 2009 September 2, the intraday variabilities are ΔmV = 0.36 ±0.08 mag within 1.56 hr, ΔmR= 0.21 ±0.04 mag within 23 minutes, and ΔmI = 0.53 ±0.03mag within 45 minutes. On 2009 September 3, the intraday variabilities are ΔmV = 0.40 ±0.10 mag within 27 minutes, ΔmR = 0.48 ±0.04 mag within 3.24 hr, and ΔmI = 0.68 ±0.06 mag within 3.72 hr. The two intraday variabilities occur in 24 hr, which may occur in the same variable phase. Other results show that (1) no quasi-periodicity is found in the longterm light curve and (2) the correlations between the brightness and the spectrum show obvious anti-correlation, a = -(0.18 ±0.02)FV + (2.33 ±0.12), with the correlation coefficient r = -0.74 and the chance probability p >0.01%. © 2015. The American Astronomical Society. All rights reserved.

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