Ján Svoreň

A procedure of selection of meteors from major streams for determination of mean orbits

A procedure of selection of meteoroids from major streams is suggested and applied to the IAU Lund photographic database modified by a check for internal consistency among orbital elements (3411 orbits). Limits for choice of stream members were defined by break points on the plots of the cumulative numberNC vs. the Southworth-HawkinsD discriminant. For the break points were considered the points from which the dependenceNC vs.D changes to a quasi-linear one, and with the increasingD, NC changes only moderately. Except for the Taurids which desire a separate analysis, theNC vs.D diagrams are presented for the following major meteoroid streams: Quadrantids, Lyrids,η Aquarids,α Capricornids, N and Sδ Aquarids, Perseids, Orionids, Leonids and Geminids. The mean orbits, velocities and radiants of the streams are derived and compared with the osculating orbits of their parent bodies. The limitingDB was found to be a function of the number of the stream membersNCB. Omitting the exceptionally concentrated Geminids, the relation is in the formDB = 0.058 *ln(NCB) − 0.04.

A search for streams and associations in meteor databases. Method of Indices

Abstract A new method of searching for minor meteor streams and associations is presented and discussed. The procedure, based only on mathematical statistics, enables a parallel separation of major and minor streams or associations. The approach utilizes a division of the ranges of examined parameters into equidistant intervals. The method is tested on the IAU Meteor Data Center Lund catalogue of precise photographic orbits representing the most extensive set of photographic meteor orbits. Besides the five orbital elements incorporated in the Southworth–Hawkins D-criterion, we have also included in the procedure the coordinates of the radiant which belong to the most accurately known parameters and the geocentric velocity as a significant parameter characteristic for physically related orbits. The basic idea of the procedure is a division of the observed ranges of parameters into a number of equidistant intervals and assignment of indices to a meteor according to the intervals pertinent to its parameters. The meteors with equal indices are regarded as mutually related. Since various parameters listed in the catalogue contain various relative errors, it is necessary to use several intervals in the division of each parameter to obtain a good fit with the real orbital distribution. The relative ratios, approximated by small integers, corresponding to the reciprocal values of the relative errors, were applied as the basic numbers for the division of the parameters. To test the quality of this method, the first step presented in this paper is aimed at wider intervals providing a less detailed classification (a smaller branching). In this step all the major streams (except of the northern branch of δ-Aquarids) were identified, confirming the efficiency of the procedure. After combining the related groups, 16 streams were identified. The search program also identifies widely spread Taurids. There are separated orbits pertinent to some minor streams such as the o-Draconids, κ-Cygnids, October Draconids, Pegasids and December Monocerotids. Rather surprisingly, even at this strict level, a pair of meteors in orbits similar to the Lyrids with the maximum on April 8 (Arter and Williams, 1995. Earth, Moon, Planets 68, 141–153) are identified. In the next steps the search will be concentrated on the separation of minor streams and eventually some so far unknown associations.

On separation of major meteoroid streams from the sporadic background

The paper deals with a search for chosen photographic meteoroid streams compiled from the IAU Meteor Data Center Lund catalogue from which less than 2% of the orbits had to be removed due to internal inconsistency among the orbit parameters. Additional 35 orbits were removed due to extremely high hyperbolic velocities. The final set consists of 3411 orbits. Members of the Quadrantids, Lyrids, Perseids and Geminids were searched for, firstly, by a stream-search procedure utilizing the Southworth-HawkinsD-criterion. This choice, as a rule, represents the most abundant filament of the stream. Secondly, rate distribution histograms ofD were divided into region of shower meteors and region of sporadic background meteors. The searched database with a relatively low abundance of sporadic meteors in the analyzed periods simplified this choice, and followingly, fitting the obtained values by means of power and exponential functions, the limitingDs for particular showers were derived. The derivedDs appears as the optimum value, as for higherD, the number of sporadic meteors included in the stream sample increases more rapidly than the number of additional shower meteors, and for smallerD, the number of shower meteors decreases quicker than the number of omitted sporadic meteors. The following counts of shower meteorsN and limitingDs were found: Quadrantids (39, 0.22), Lyrids (11, 0.15), Perseids (595, 0.53) and Geminids (224, 0.32). Efficiency of the procedure was tested comparing the number of sporadic meteors in the region of radiant area and the neighbouring regions of the same size.

Colour variations of Comet C/2013 UQ4 (Catalina)

We report observations of color in the inner coma of Comet C/2013 UQ4 (Catalina) with the broadband B and R filters. We find significant temporal variations of the color slope, ranging from -12.67

Comet C/2011 J2 (LINEAR): Photometry and stellar transit

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Applicability of meteor radiant determination methods depending on orbit type

8.16 \% per 0.1~

Discovery of a new branch of the Taurid meteoroid stream as a real source of potentially hazardous bodies

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Determination of the period of activity of meteoroid streams

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BRIGHTNESS OF LONG-PERIOD COMETS OBSERVED AT LARGE HELIOCENTRIC DISTANCES-I. THE COMPUTER CATALOGUE FOR 1861-1941

35.09 \pm 11.7

Narrow-Band Photometry of Comet C/1995 O1 (Hale-Bopp)

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