The documentation to the sample of
IAU MDC radio-meteor data

CONTENT
Description of the data and radar

2

IAU MDC format - version 20182

Format of data files readable with OS-Windows word editors

5

Reduced data: meteor in a single line5

1

Description of the data and radar

The Meteor Data Center (MDC) of the International Astronomical Union (IAU) provides a sample ofthe data on the meteors detected from four points by the radars at the Hissar Astronomical Observatory(HisAO) of the Institute of Astrophysics of the Academy of Sciences of the Republic of Tajikistan.
Specifically, the sample consists of 8916 radio-meteor records. The observations were performed inperiod December 1968 to October 1969 and in December 1969.
For measurements of radiants and meteor velocities, the bearing-time radio method was used. A
special set of radar equipment MIR-2 (an abbreviation for ”meteor pulse radar, second generation”) was
created in 1964−68. Its structure, principles of operation, and detailed characteristics were described by
Chebotarev et al. (Chebotarev R.P., Sidorin V.N., Polushkin G.A. et al.: The complex of equipment forradar studies meteors in Dushanbe. Bulletin of the Institute of Astrophysics, Academy of Sciences ofTadjukistan SSR, 1970, No. 55, p. 25-28.) and Chebotarev and Issamutdinov (Chebotarev R.P., Isamutdinov Sh.O. Multibeam Meteor Radar Indicator. Bulletin of the Institute of Astrophysics, Academy of
Sciences of Tadjikistan SSR, 1970, No. 55, p. 34-39.). The main characteristics of the radar were asfollows:• the transmitter frequency ν = 37.4 MHz;• the transmitter wavelength λ = 8 m;
• the transmitter output power per pulse 65 kW;• the bandwidth of the primary and remote receivers 600 kHz;• the threshold sensitivity of the receivers (at Uc/Uw = I) 8 · 10−14 W or 2.5 µV;• sensitivity in the measurement of radiants and velocities varied from 17 to 34 µV;• the bandwidth of the signals retransmission from the removed points 2 MHz, at the frequencies
about 100 MHz.
Antennas in the radiant and velocity measurement mode were half-wave vibrators located at a heightof λ/3 above the ground, having a maximum power gain of about 5.3 at an elevation angle of about 45oin the east and west directions.
The limiting magnitude of meteors in the measurement of radiant positions and velocities was +5m .

2IAU MDC format - version 2018

FILE: HISSAR.d18
The current version of the IAU MDC database is given in the standard format, which was establishedwith the ”version 2013” of the IAU MDC photographic database. Since the radio-meteor data require
another characteristics, the original set of provided parameters is enlarged. It currently consists of 34
parameters, in maximum, about each meteor. The list of all parameters is given in Table 1.
Basically, a unique identification code is assigned to each meteor. In the radio-meter data, theidentification code is introduced by two letters, rH (radio-Hissar), followed by five-digit integer numberof meteor.
Each parameter is given in two lines of the datafile. In the first line, the code of the parameter (listedin the 2nd column of Table 1) and two binary values are written. If the first value is ”1” and the secondvalue is ”0”, then only the value of the parameter, without the determination error, is presented in thesecond line. If both values are ”1”, then the second line contains the value of the parameter together withthe determination error. (The place for the parameter can be reserved with its code, binary values both
equal to ”0”, and blank second line. Such a record is identical to the omission of the parameter.) The
number of decimal digits of the value of any parameter and its determination error is arbitrary, usuallydepending on the precision of its determination. (We speak here about the number of valid decimal digits.
Because of the automatic, computer writing, there can occur a lot of redundant 0s or 9s beyond the valid
decimal digits. These should be ignored, of course.)

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The record about a given meteor begins with the meteor identification code and is terminated withthe line containing 3 spaces and character &. It is not necessary to list all 34 parameters in a particular
record. Only the identification code is mandatory. The order of parameters within each record is optional,
except for the code, which always begins the record.
Table 1: The list of parameters in the current, 2018 version, of IAU MDC database. No.P. is the serial
number of the parameter in the list and C.P. is the code of the parameter. The positional parameters
are referred to the equinox 2000.0.
No.P. C.P.
explanation
1 #IC: IAU MDC identification code
2 ANo: number/code assigned to the meteor by author
3 Yr :
year of the detection
4 Mn :
month of the detection
5 Day:
day and fraction of day of the detection (UT)6 LS :
solar longitude corresponding to the date of the detection [deg]7 mv :
magnitude of maximum photographic brightness of meteor
8 HB :
height of beginning of meteor trail [km]9 HM : height of maximum brightness [km]10 HE :
height of end of meteor trail [km]11 RA :
right ascension of geocentric radiant [deg]12 DEC: declination of geocentric radiant [deg]13 Vi :
extra-atmospheric velocity [km s−1 ]14 Vg :
geocentric velocity [km s−1 ]15 Vh :
heliocentric velocity [km s−1 ]16 cZ :
cosine of the angular distance of geocentric radiant from the zenith
17 Qm : quality code
18 q :
perihelion distance [AU]19 e :
numerical eccentricity of orbit
20 1/a:reciprocal semi-major axis [AU−1 ]21 a :semi-major axis [AU]22 Q :
aphelion distance [AU]23 i :
inclination of orbit to the ecliptic [deg]24 arg:argument of perihelion [deg]25 nod:longitude of ascending node [deg]26 pi :
longitude of perihelion [deg]27 Sh :
shower number
28 Mas:pre-atmospheric photometric mass [g]29 lgM:
decadic logarithm of the mass
30 cor:correction mark (type of correction if any)
31 crh:extreme-hyperbolicity mark32 mr :
magnitude (stellar) of radio meteor
33 Hrf:the height of the central point of the meteor trail [km]34 LpA: decadic logarithm of linear electron density of the central point ofmeteor trail, pα ; the unit of the density is [electron cm−1 ]The prevailing majority of parameters and their determination errors, if given, are double-precision(REAL*8) numerical values, which can be read into an array (or the errors into another, independentarray). Unfortunately, the old photographic data contained some non-numerical marks, which impliedan establishment of five exceptions:(1) Meteor number/code given by the original author (ANo) sometimes contains a character, therefore

3this parameters is given as the text, 7-character variable.
(2) Quality of meteor data (Qm) was given as a single or two-character code. In the IAU MDC data,
this paramater is given as 2-character variable. (Our reading subroutine returns only the first characterand the second position is always a space.)(3) Shower number is, sometimes, not a numerical, but a composite (numeral and character) variable.
In the IAU MDC, this parameter is, therefore, given as the 2-character variable.
(4) A tiny fraction of photographic meteors was corrected in the IAU MDC and the character of thiscorrection was given as a single-character variable. (A more detailed description of these corrections isgiven in the documentation to the photographic catalogs.)(5) A small part of photographic meteors (video and radio meteors have not been analyzed in thisrespect, yet) has an extremely hyperbolic (beyond the Gaussian tail) eccentricity. (This phenomenon wasdescribed in the paper by Lindblad B.A., Neslušan L., Porubčan V., Svoreň J.: 2003, Earth, Moon, andPlanets 93, 249-260.) The mark indicating the extreme hyperbolicity is the single character ”h” in theIAU MDC data.

3Format of data files readable with OS-Windows word editors

FILE: HISSAR.xlsx
Since there are the researchers prefering the environment of the OS Windows and corresponding word
editors, the large set of the parameters in the IAU MDC catalogues is also provided in the form of theExcel sheet. In the case of radio-meteor data, the sheet consists of 23 parameters:#IC, Yr, Mn, Day, Hrf, mr, RA, DEC, Vi, Vg, Vh, cZ, q, e, 1/a, a, Q, i, arg, nod, pi, LpA, lgM.
The codes are explained in Table 1. Number of lines is equal to the number of meteors in the catalogue.

4

Reduced data: meteor in a single line

FILE: HISSAR.1l (alternatively: HISSAR by date.1l)
The single-line format provides the reduced and unified set of parameters on each meteor in a single
line of the datafile (the file is written as a common, plain text). This format is provided to enable aneasy visual reading of the data.
The reduced set consists of 11 parameters listed in Table 2. (This set is the same as in 2013 version.)In the files with the 1-line data, the parameters are arranged in successive columns in the same order asin Table 2. The IAU MDC attempts to achieve that all these parameters are provided for each meteor
included into the center’s data.

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Table 2: The reduced (compulsory) set of the parameters in the IAU MDC database. h.c. is the code ofparameter in the headings of single-line file (table).
h.c parameterunit
IC identification codeyr mn day date of meteor fall in the form year-month-day;time of the fall is given as the fraction of day[UT]
q perihelion distance[AU]
e numerical eccentricity[1]
i inclination to the ecliptic[deg]
arg argument of perihelion[deg]
nod longitude of ascending node[deg]
RA right ascension of geocentric radiant[deg]
DEC declination of geocentric radiant[deg]
Vg geocentric velocity[km s−1 ]Vh heliocentric velocity[km s−1 ]5