"Thank you so much for visiting our class on Friday! The kids loved it...they thought it was pretty cool to meet a "real" Astronomer! Thanks again, Janine"
TABLE OF METEOR SHOWERS 2003
By Robert L. Hawkes
The more prominent nighttime showers visible from the Northern Hemisphere are included in the following table, with the most visually impressive ones given in italic type. Explanations of the entries in the various columns are given following the table. Follow links in the table to descriptions of the individual showers.
The column labelled Max lists the date and Time the hour (Universal Time) of the 2003 intersection of Earth with the densest region of the stream. These maxima are based on the solar longitude values ( λ ) for each shower given in the third column (epoch 2000). Many streams have a complex rate profile; for example, the Eta Aquarid and Orionid showers have earlier peaks for faint meteors than for bright meteors. Most showers show activity over a number of days, as shown in the next column, D (defined as the duration in days of 1/4 peak activity or more). Some showers (e.g. the Quadrantids) are highly concentrated with strong displays lasting only a few hours, while others are spread over weeks (e.g. the Taurid complex). Concentrated showers are more likely to be of recent formation. There are no records of the Quadrantid shower before the 19th century, while several showers have been observed for hundreds or thousands of years (e.g. the Perseids). Some showers (such as the Leonids) have meteoroids concentrated in a small region of the orbit and hence have much higher peak rates in certain years.
The column labelled ZHR gives the predicted zenithal hourly rate.
The higher the radiant is in the sky, the more direct the projection of the stream cross section on the sky area above the observer, and the apparent activity will be higher. The column labeled R indicates when the radiant is above the horizon for an observer at 43°N latitude; for example, >23 means that the shower can be observed after 11 p.m. local time. A √ means that the radiant is above the horizon throughout night hours. The number of meteors observed varies strongly with limiting magnitude; therefore, effective meteor observations must be made in the absence of significant moonlight. In the column labeled Moon the percentage of illumination of the Moon at the date of shower maximum is given. The rise and set times of the Moon must also be taken into account, however.
The relative number of bright and faint meteors is given by the population index, r, which is defined as the ratio of the number of meteors of magnitude M + 1 to the number of magnitude M. The number of meteors that can be observed is a strong function of limiting sensitivity. For example, for a limiting magnitude of +3.5, a shower with a ZHR of 60 and a population index r = 2.8 would have the number of observable meteors per hour reduced by a factor of (2.8)3 to a rate of only 2.7 meteors per hour.
The next two columns give the right ascension (RA) and declination (Dec) of the shower radiant. A typical meteor shower is active over several days, and the apparent radiant moves somewhat during this period. The tables published by the IMO give the daily motion of the radiant, which must be taken into account if one is observing meteor showers on dates significantly removed from the maximum of the shower. Meteors can only be observed when the radiant is above the local horizon (or nearly so). Finally, the geocentric speed v of the meteors in each shower is given in kilometres per second in the final column.
Excerpted from the Observer's Handbook 2003 © The Royal Astronomical Society of Canada, 2002. Used with permission of The Royal Astronomical Society of Canada. The Observer's Handbook can be ordered at http://www.rasc.ca/publications.htm.