10 research outputs found
The observed radio/gamma-ray emission correlation for blazars with the Fermi-LAT and the RATAN-600 data
We study the correlation between gamma-ray and radio band radiation for 123
blazars, using the Fermi-LAT first source catalog (1FGL) and the RATAN-600 data
obtained at the same period of time (within a few months). We found an apparent
positive correlation for BL Lac and flat-spectrum radio quasar (FSRQ) sources
from our sample through testing the value of the Pearson product-moment
correlation coefficient. The BL Lac objects show higher values of the
correlation coefficient than FSRQs at all frequencies, except 21.7 GHz, and at
all bands, except GeV, typically at high confidence level (> 99%). At
higher gamma-ray energies the correlation weakens and even becomes negative for
BL Lacs and FSRQs. For BL Lac blazars, the correlation of the fluxes appeared
to be more sensitive to the considered gamma-ray energy band, than to the
frequency, while for FSRQ sources the correlation changed notably both with the
considered radio frequency and gamma-ray energy band. We used a data
randomization method to quantify the significance of the computed correlation
coefficients. We find that the statistical significance of the correlations we
obtained between the flux densities at all frequencies and the photon flux in
all gamma-ray bands below 3 GeV is high for BL Lacs (chance probability ). The correlation coefficient is high and significant for
the GeV band and low and insignificant for the GeV band for
both types of blazars for all considered frequencies.Comment: 14 pages, 5 tables, 8 figures, accepted to MNRA
Statistics of the Planck CMB Signal in direction of gamma-ray bursts from the BATSE and BeppoSAX catalogs
The observed radio/gamma-ray emission correlation for blazars with the Fermi-LAT and the RATAN-600 data
Astrometric results of observations at Russian observatories of mutual occultations and eclipses of Jupiter's Galilean satellites in 2009
International audienceIn 2009, in five Russian observatories photometric observations of Jupiter's Galilean satellites during their mutual occultations and eclipses were carried out. Based on these observations, an original method was used to ascertain astrometric results such as the difference between the coordinates of pairs of satellites. Fifty-three phenomena were successfully observed. A total of 94 light curves of satellites were measured. The error in the coordinates of satellites due to random errors in photometry, calculated on all data obtained, was 0.041" in right ascension and 0.046" in declination. The discrepancies between the theory and observations in these coordinates was found to be 0.060" and 0.057", respectively. The results were uploaded to the common database for all observations of natural satellites of planets at the Natural Satellites Data Center (NSDC), which is available online at http://www.sai.msu.ru/neb/nss/index.htm . For the first time in the practice of photometric observations of satellites in epochs of mutual occultations and eclipses a new method of observation was tested, which eliminates from astrometric results the major systematic errors caused by an inaccurate account of the background level. The tests were conducted in the Terskol Observatory and the observatory of the Crimean laboratory of the Sternberg State Astronomical Institute of the Moscow State University. The application of the new method showed that the elimination of the background level at these observatories was carried out correctly