Manual

Lists of Meteor Showers

• Established A meteor shower with a well-defined parameters, reliable activity predictions, and sufficient observations to establish its identity as a distinct meteor shower. It met the criteria for an established classification. Established shower was given an official name approved by the IAU F1 Commission.
• Working List Meteor showers that are currently being studied and observed, but have not yet met the criteria for an established classification. From 2022 onwards, instead of traditional names only preliminary designations are given to them.
• Removed Meteor showers or their individual solutions that were previously recognized by the IAU but are no longer considered reliable due to e.g. missing required information or other factors. These meteor showers have been removed from the main lists of meteor showers (but not MDC itself!). This is not because they have been permanently eliminated, but rather because our current understanding suggests they're no longer active or suitable for prediction purposes. The IAU has officially recognized it through publication in peer-reviewed journals. Note: the counter of the Removed class shows number of fully moved meteor showers to this list, i.e. solutions of existing showers are excluded here.

Content of the Table(s) of the Meteor Showers

• The header of each table contains: IAU number^*, three letter IAU code^*, [meteor shower] Name^*, and Provisional Name^*
  (^*when applicable; for more see the nomenclature rules)
• AdNo - additional number of the solution of the shower
• Activity - the observed activity of the stream

Averaged geocentric elements:
• λ_☉ - averaged value of the ecliptic longitude of the Sun in deg (in the downloaded database it is under the column name: LoS)
• λ_☉[beg-end] - averaged value of the ecliptic longitude of the Sun at the beginning and the end of stream activity in deg (in the downloaded database they are under the column names: LoSb and LoSe, respectively)
• Ra - averaged value of Right Ascension of the shower radiant (in deg)
• De - averaged value of Declination of the shower radiant
• ΔRa - radiant drift in Right Ascension; degrees RA per day (in the downloaded database it is under the column name: dRa)
• ΔDe - radiant drift in Declination; degrees DE per day (in the downloaded database it is under the column name: dDe)
• Vg - geocentric speed: before or after acceleration by Earth's gravity (in km/s)

Averaged additional elements (optional at the submission):
• LoR - averaged value of ecliptic longitude of the shower radiant (in deg)
• SLoR - averaged value of ecliptic sun-centered ecliptic longitude of the shower radiant (in deg)
• LaR - averaged value of ecliptic latitude of the shower radiant (in deg)
• Theta - averaged elongation of the shower anti-radiant from the Earth apex motion (Öpik variable; in deg)
• Phi - averaged angle between the plane containing the directions of the anti-radiant and the apex of the Earth orbital velocity, and the plane perpendicular to the ecliptic containing the apex of Earth motion (Öpik variable; in deg)

Averaged heliocentric orbital elements:
• a - semi-major axis (in au)
• q - perihelion distance (in au)
• e - eccentricity
• Peri - argument of perihelion (in deg)
• Node - longitude of ascending node (in deg)
• Inc - inclination of the orbital plane (in deg)


• N - number of meteoroid orbits used for determining the average orbit; when the Look up Table is available N is active and the file can be downloaded through it
• References - source of the solution; as soon as available the link to ADS paper
• Parent body - parent body of the meteoroid stream; listed whenever known, together with references

Moreover, in the downloaded database additional flags are present:
• T - observation technique: C-CCD, P-photo, R-radar, T-TV, V-visual
• B - if the epoch is B1950 (R - data transformed to J2000)
• I - if the Vinf is given (R - Vinf transformed to VG)
• A - averaging method: M - median values, A - arythmetic mean, L - by method of least squares, O - other method
• Origin of the stream: P - parent body ejection; C - collision; O - other origin
• Assessment of Reliability: 1 - yes; 0 if not; or space if not known

Tools: Advanced search

The tool allows to search through the whole meteor showers database using filter options based on the geocentric or heliocentric parameters. The result of the search can be displayed in three forms: Short, Standard, and Full. Moreover, the search tool displays the results for each mean solution of a given shower.

Short display option: the search result, next to the name of the shower, shows results (columns) only for the filtering parameters. Standard display option presents the geocentric and heliocentric parameters (columns) only. While in the case of the Full display option, the remaining parameters (ecliptic and Öpik variables) are also displayed.

Tools: Active Showers

The tool shows the current active showers for a given date. The list of the active showers is presented in the form of a table. Additionally, after user provides a localisation, the result is in the form of a graph, with the active showers over that localisation.

Tools: (Dis)similarity Check

The tool roughly compares a new set of meteor shower parameters (a new solution) to all solutions in the database. It may be used to eliminate the possibility of submitting a duplicate shower.

Initially, the criterion must be selected in the input form. Subsequently, the threshold value is set as well. The threshold determines (dis)similarity of two sets of parameters defining a meteor shower/meteoroid stream. More, about the criterion and threshold values, can be found in listed below references. Depending on the selected criterion, additional parameters needed for the analysis become available. The form accepts geocentric or orbital parameters accordingly. Once all necessary information has been entered, users can submit their form to run the analysis.

References:

• Drummond, J. D. 1980, Southwest Regional Conference for Astronomy and Astrophysics, 5, 83
• Jopek, T. J. 1993, Icarus, 106, 603
• Southworth, R. B., & Hawkins, G. S. 1963, Smithson. Contrib. Astrophys., 7, 261
• Valsecchi, G. B., Jopek, T. J., Froeschle, Cl., 1999, MNRAS, 304, 743
• Kholshevnikov, K.V et al., 2016, 462, 2275

Input example: Using Drummond (1979) criterion and threshold value of Dc = 0.04 for the mean orbital elements of {q: 0.586, e: 0.770, peri: 268.4, node: 127.9, inc: 7.5}, the tool will find the similarity predominantly with alpha-Capricornids. Presently in MDC this shower has 11 solutions. Two of them are excluded due to a lack of orbital elements values. For two others the pre-calculation was applied; as for them, their solutions were lacking the value of eccentricity. For this example, the orbital similarity of the user's input parameters was found with 9 solutions of alpha-Capricornids. Thus, we can state that the user's mean orbit is not a new meteor shower but a new solution for the alpha-Capricornids. If user hovers the mouse over the shower name, information (reference) for which MDC's solution the found similarity corresponds to will appear.

Results table lists all mean solutions for which the comparison with the user input gives a value of D below the threshold value (Dc). Mean solutions in MDC have not always provided a full set of parameters that a given D criterion requires. Therefore, in such cases the missing value is pre-calculated to be used in the tool; e.g., for Southworth and Hawkins, the eccentricity (e) and the perihelion distance (q) are required. Thus, if a mean solution does not have either of them but a semimajor axis (a), then the missing e or q will be pre-calculated accordingly, and vice versa.

Whenever the full pair of (q, e) or (a, e) or (a, q) is missing, such a mean solution is excluded from the association search. Similarly, if the mean solution does not have the full set of angular parameters then such a mean is also rejected in the run.

Depending on which parameter had to be pre-calculated, the found similarity is flagged accordingly if the perihelion distance () or eccentricity () or semimajor axis () had to be calculated. If user hovers the mouse over the flag, the description will appear as well.

Tools: Internal Consistency

The tool performs the checks of internal consistency between the mean geocentric parameters and the mean orbital elements of a shower.

To use this tool, in the input form, users must first select whether they want to calculate geocentric parameters from orbital elements or vice versa. After making their selection, the required parameters for analysis will become available. Once all data has been entered, users can submit their form and the analysis will begin.

Results table displays a table with the output parameters obtained from the analysis, which users can compare. If the "Geocentric from Heliocentric" selection was made, the result includes information on which radiant calculation method was used: Q, B, W, A, H, P (their description can be found in Neslušan, L. et al., 1998 ).