1,720,977 research outputs found
Digitizing the Markarian Survey: first tests of scientific importance
No full textWe present technical details of the digitization of the First Byurakan Survey plates with an EPSON 1680 Pro scanner, a joint venture of the Rome University and the Byurakan Observatory. The astronomical coordinate system is applied to each plate by a semi-automatic procedure, the transparency converted to intensity and all the spectra in each plate automatically extracted by IRAF procedures. A first check of the photometric accuracy achieved is presented
The TACOR educational telescope and the Italian RemoteLab Project-Learning tools for the International Year of Astronomy 2009
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The TACOR educational telescope and the Italian RemoteLab Project - Learning tools for the International Year of Astronomy 2009
No full textThe Department of Physics of La Sapienza University has installed a didactic remote controlled telescope (TACOR) which, in collaboration with the Department of Physics of University Roma Tre, is currently used by mid-level and high-school classes. TACOR operates in the framework of the National RemoteLab Project which is supported by Italian Ministry of Public Education. During the forthcoming IYA2009, TACOR and RemoteLab will be powerful online tools for an interdisciplinary teaching and public communication of astronomy
OPTICAL FOLLOW-UP OF BL LAC CANDIDATES IN THE 2QZ SAMPLE
No full textWe investigate the nature of the BL Lac candidates in the northern part
of the 2BL sample (Londish et al. 2002, MNRAS, 334, 941) searching for optical variability
by means of RC band photometry with the Asiago 1.8 and Loiano 1.5 m telescopes during years 2002, 2003 and 2004. We also made aperture photometry of the candidates on the plates available
on the web from the Palomar and UK Schmidt telescopes. No significant variability was detected for the majority of the objects without detected radio and/or X-ray emissions,
while clear variability was found for the few sources of the sample with
strong radio and/or X-ray emission, which is a constant feature of the “classical” BL Lacs.
Some considerations on the nature of the 2BL sources are made, taking into account their most recent data available in proper motions catalogues (SuperCOSMOS, USNO-B1) and in the Sloan Digital Sky Survey
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
long term variability of S5 0716+714 from the Asiago archive plates
No full textWe present the historic light curve of the BL Lac object S5 0716+714, spanning the time interval from 1953 to 2003, built using Asiago archive plates and our recent CCD observations. The source shows an evident long term variability, over which short term variations are superposed. We can model the source behaviour with an average monotonic brightness increase, since about 1975. This behaviour might be due to a precessing motion of the jet, as already suggested in the literature for other BL Lac objects. We remark the importance of preserving and digitizing the astronomical plate archives which are fundamental facilities to perform long term variability studies
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