1 The IAU Meteor Data Center Database of Photographic Orbits

Databases of meteor orbits are, for meteor research, main source for getting basic information and knowledge about the structure and distribution of the whole meteoroid population in our surroundings. The IAU Meteor Data Center, which was thanks to efforts of Dr. B. A. Lindblad established at the General Assembly in 1982, became a platform for official realization of the photographic meteor database summarizing the most precise information on meteoroid orbits (Lindblad 1987, 1991, 1995, 1999, 2001; Lindblad and Steel 1994).

The last version of the photographic database containing basic orbital and geophysical parameters of 4,581 meteors was issued in 2003 (Lindblad et al. 2003). Still since that time new additional photographic orbits have been published, or some meteors published earlier have not been included in the catalogue yet, an upgraded version 2013 have been prepared.

To the new version of the IAU MDC database of photographic orbits an additional 292 orbits from 4 sources (compiled to 6 catalogues) have been added, thus the new 2013 version of the database summarizes the orbital and geophysical parameters of 4,873 meteors compiled in 41 catalogues from 18 sources altogether. The orbits are referred to the equinox 2000.0. The list of all catalogues is given in Table 1. The newly added catalogues are marked with a bullet in front of their identification code.

Table 1 The statistics on the catalogues included in the new, version 2013, IAU MDC Database of photographic meteor orbits
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The first set of new orbits was announced in our earlier paper (Neslušan et al. 2012). As B2 was labelled the catalogue of 75 orbits gained within an observational campaign of the Leonids in 1998 by the Dutch Meteor Society (Betlem et al. 1999). The European Network (EN) managed by the Astronomical Institute of the Academy of Sciences of the Czech Republic in Ondřejov provided 98 orbits which are in the catalogue labelled as E3 (Ceplecha and Spurný 1990; Borovička and Spurný 1992; Spurný 1994, 1995, 2003a, b, 2004, 2010; Spurný and Borovička 1997a, b, 1998; Spurný and Ceplecha 1992; Spurný et al. 1991, 2004).

The first upgrade also contains 32 orbits determined from the observations conducted by the Spanish Meteor and Cometary Society (SOMYCE) (Trigo and Artéz 1996; Trigo 1997) and the Spanish Photographic Meteor Network (SPMN) (Trigo-Rodríguez and Castellano-Roig 2000; Trigo-Rodríguez et al. 2000a, b, 2004, 2005), which were published in the period 1996–2005. The collected partial catalogue of the Spanish data is labelled as R1. Finally, the first set also includes 6 orbits obtained by the Tokyo Meteor Network (Shiba et al. 1989; Shiba and Ohtsuka 1992; Ohtsuka and Tomioka 1993; Shimoda et al. 1994, 1995; Tomita et al. 1998). This partial catalogue is labelled as T3 in the IAU MDC.

Meanwhile, we have compiled another two catalogues, which are labelled as B3 and E4. The first are 47 published orbits of the 1999 Leonid meteor storm (Betlem et al. 2000) and the second are 34 orbits of Leonid fireballs (Shrbený and Spurný 2009).

2 Comment on a Checking of Data Consistency

Before being included to the IAU MDC database, the consistency of the mutually depending quantities was checked. Specifically, the date of meteor detection has to agree with the solar longitude and longitude of the ascending node, orbital elements can be calculated from the geophysical parameters and vice versa, and additional orbital elements as well as geophysical parameters can be calculated from the appropriate basic set (e.g. the aphelion distance, semi-major axis and reciprocal semi-major axis can be calculated from the perihelion distance and eccentricity).

The re-calculation of the orbital elements from the radiant coordinates and geocentric velocity in the time of detection was done in a standard way. Namely, the heliocentric radius-vector of the meteor in the detection time can be identified with the well-known radius-vector of the Earth in this time. The radiant coordinates and geocentric velocity define the geocentric velocity vector of meteor. Subtracting the Earth’s velocity vector from the latter, we obtain the heliocentric velocity vector of meteor. Using the well-known relations for the Keplerian orbit, we can use the radius and velocity vectors of meteor in the time of its fall to calculate its orbital elements. The actual position and velocity vectors of the Earth were taken from the JPL ephemeris (DE406). (In analogous calculations concerning the former, 2003 version, these data were calculated by using the formulas published by Bretagnon (1982).)

The corrections made in the catalogues already published in the 2003 version of the database were described by Lindblad et al. (2003, Sects. 2 and 3). We note, we regarded the meteors as possibly having erroneous data if the original-author and recalculated values of the perihelion distance, eccentricity, right ascension, declination, angular orbital elements, geocentric and heliocentric velocities, and date of fall was larger than 0.01AU, 0.05, 2o, 2o, 2o, 1.5 km s−1, and 0.01 day, respectively. In this investigation, we did not make a more sophisticated checking as, e.g., that suggested by Jopek et al. (2003). This checking is useful, especially, if one intends to improve the original values. However, we intended only to correct the obvious errors.

In the newly added catalogues, the data occurred to be more perfect. We checked if the re-calculated value of given parameter considerably exceeds the published uncertainty interval (for parameters published with their determination error) or if the difference between the original and re-calculated values exceeds 1 % (for parameters published without the determination error). It is worth noting that a lot of very small differences between the corresponding values calculated by the original authors and recalculated values occurred in the new catalogues. Many of these differences lie slightly outside the interval delineated by the published errors. The differences could appear due to rounding of the input values, using a different method of calculation of the Earth’s position and velocity, as well as, maybe, making some approximations by the authors in the processing. The original values published by the authors were retained in these cases.

3 Data Formats of the 2013 Database Version

In the last decades, many of the parameters characterizing meteors are published together with their determination errors. Due to this fact and circumstance that various authors publish their data with a different precision, the fixed-structure format, which was used in the 2003 version, has become obsolete. In version 2013, for storing the data we introduce a new format, which is independent on computer language, accepts any precision, as well as data with or without determination errors.

The record of a meteor must begin with its identification code, while other parameters are optional in sense that not the entire set of parameters established by the IAU MDC (currently including 31 parameters with a possibility of extension of the list in the future; Table 2) must be presented for each meteor. The record is terminated by the line containing three spaces and character “&”. Individual parameters are introduced by their three-character codes (listed in the second column of Table 2). The proper value of a parameter together with the determination error (if given) is presented in the next line. Hence, the record of each parameter occupies two successive lines of the entire record of meteor. The code alone, in the first line, is followed by two binary values. If the first value is 1, the value of the parameter is given. Otherwise the next line is empty. (This can either be a way of omitting a parameter or the value of that parameter does not exist.) If also the second binary value is 1, then the determination error is known and follows the proper value of the parameter, in the second line.

Table 2 The list of parameters included in the new 2013 version of the IAU MDC database
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Since the record in the new format is not very transparent and thus appropriate for a visual work with the data, basic parameters of each meteor are simultaneously given also in the so-called “single-line” format. In this format, the basic parameters of a meteor are written in single line with a fixed precision, without the determination errors. The basic parameters are marked by asterisks in Table 2. The IAU MDC will attempt to publish the complete set of basic parameters of every meteor also in the future and would welcome if the original authors also publish these parameters or those alternative parameters, from which the basic parameters can be calculated.

It is assumed that some users have programs that read the data in the old format and so the data are also given in the old format of the version 2003. Detailed description of the formats can be found in the documentation to the database. An example of the new full format of the current version as well as the single-line format is given in “Appendix”.

4 Access to the Data

The new 2013 version of the database can be freely downloaded from the IAU MDC web site:

http://www.astro.sk/IAUMDC/Ph2013/

The data on the web site are listed in the newly established format for the version 2013 as well as in the single-line format providing the reduced and unified set of parameters on each meteor in a single line of the datafile. The data in each format can be downloaded as a single compressed ZIP file or each catalogue can be downloaded separately as a plain file. The data in the original format of the 2003 version are also available, but only as the single, compressed, ZIP file.

We remind that a more detailed description of the data sources, listed parameters, formats, and made corrections are in the documentation which is also included in the ZIP archives or can be downloaded separately as the PDF file.

We will appreciate all users of the IAU MDC Photographic Meteor Orbits Database if they refer the database by citeing Porubčan et al. (2011) and this paper.