During this period the moon reaches its new phase on Wednesday May 28th. At this time the moon will lie near the sun and will be invisible at night. This weekend the waning crescent moon will rise a couple of hours before dawn and will be a minor inconvenience while in the sky. Simply face away from the moon to avoid any lunar interference. The phase is thin enough that moon glow will be limited to the area surrounding the moon. The estimated total hourly meteor rates for evening observers this week is near 3 for observers situated at mid-northern latitudes and 4 for observers viewing from the southern tropics (latitude 25 S.). For morning observers the estimated total hourly rates should be near 8 for observers situated at mid-northern latitudes and 13 for observers viewing from the southern tropics. The actual rates will also depend on factors such as personal light and motion perception, local weather conditions, alertness and experience in watching meteor activity. Note that the hourly rates listed below are estimates as viewed from dark sky sites away from urban light sources. Observers viewing from urban areas will see less activity as only the brightest meteors will be visible from such locations.
The radiant (the area of the sky where meteors appear to shoot from) positions and rates listed below are exact for Saturday night/Sunday morning May 24/25. These positions do not change greatly day to day so the listed coordinates may be used during this entire period. Most star atlases (available at science stores and planetariums) will provide maps with grid lines of the celestial coordinates so that you may find out exactly where these positions are located in the sky. A planisphere or computer planetarium program is also useful in showing the sky at any time of night on any date of the year. Activity from each radiant is best seen when it is positioned highest in the sky, either due north or south along the meridian, depending on your latitude. It must be remembered that meteor activity is rarely seen at the radiant position. Rather they shoot outwards from the radiant so it is best to center your field of view so that the radiant lies at the edge and not the center. Viewing there will allow you to easily trace the path of each meteor back to the radiant (if it is a shower member) or in another direction if it is a sporadic. Meteor activity is not seen from radiants that are located below the horizon. The positions below are listed in a west to east manner in order of right ascension (celestial longitude). The positions listed first are located further west therefore are accessible earlier in the night while those listed further down the list rise later in the night.
These sources of meteoric activity are expected to be active this week:
The Camelopardalids (CAM) are particles from comet P/209 Linear and are predicted to peak near 7:00 Universal Time on May 24th. This timing favors North America. The radiant lies in a high northern position of 08:08 (122) +79, which places it in an obscure area of eastern Camelopardalis. This position also lies roughly 10 degrees from the 2nd magnitude North Star, also known as Polaris. This area of the sky is best placed as soon as it becomes dark during the evening hours. As the night progresses the radiant will slowly lose altitude as it circles to the left (west) of Polaris. At the time of maximum activity (3am EDT, 2am CDT, 1 am MDT, 12am PDT Saturday morning) activity could be quite high with several shower members appearing each minute. Since this is a new encounter with these particles, there is also the chance that little activity will occur. Stream models indicate that the Earth will intercept several streams of particles produced by comet P/209 Linear during the past two centuries. While a good show may fail to materialize, this appears to be the most favorable opportunity to view a meteor outburst for many years to come. The circumstances could scarcely be better as it occurs during the weekend and the waning crescent moon will hardy be a factor. I encourage everyone interested in celestial fireworks to take advantage of this opportunity and try and view this possible display. If an outburst occurs, it could be a most memorable sight as these particles are predicted to be larger than normal and may produce bright and colorful meteors. Unfortunately this display is limited to North America due to the timing and the high northern declination (celestial latitude) of the radiant. Even observers in high North American latitudes will have to deal with twilight all night long as the sun never sets far enough below the horizon to allow it to become totally dark. Observers in the eastern hemisphere will be in daylight at the time of predicted maximum and the sun will obscure any possible display. Lastly, observers in the southern hemisphere will see very little of this possible display as the radiant is invisible from most of the southern hemisphere. Little activity is expected to be seen away from the time of maximum activity.
The center of the large Anthelion (ANT) radiant is currently located at 17:04 (256) -23. This position lies in southeastern Ophiuchus, 7 degrees south of the 2nd magnitude star known as Sabik (Eta Ophiuchi). These meteors may be seen all night long but the radiant is best placed near 0200 local daylight time (LDT) when it lies on the meridian and is positioned highest in the sky. Due to the large radiant area, meteors from this source may also appear to radiant from the constellation of Serpens Cauda, Libra, Scorpius, northern Lupus, and western Sagittarius as well as Ophiuchus. Rates at this time should be near 2 per hour as seen from the northern hemisphere and 3 per hour as seen from south of the equator. With an entry velocity of 30 km/sec., the average Anthelion meteor would be of slow velocity.
The last of the Eta Aquariids (ETA) are expect to be visible this week. The radiant is currently located at 23:20 (350) +05 which is located in western Pisces near the fourth magnitude star known as Gamma Piscium. The best time to view this activity is during the hour before the start of morning twilight, when the radiant lies highest in a dark sky. Rates are expected to be near 1 per hour for observers in the northern hemisphere and 2 for observers south of the equator. With an entry velocity of 68 kilometers per second, a majority of these meteors will appear to move swiftly.
As seen from the mid-northern hemisphere (45N) one would expect to see approximately 5 sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near 2 per hour. As seen from the tropical southern latitudes (25S), morning rates would be near 8 per hour as seen from rural observing sites and 3 per hour during the evening hours. Locations between these two extremes would see activity between the listed figures.
The table below presents a list of radiants that are expected to be active this week. Rates and positions are exact for Saturday night/Sunday morning except where noted in the shower descriptions.
|SHOWER||DATE OF MAXIMUM ACTIVITY||CELESTIAL POSITION||ENTRY VELOCITY||CULMINATION||HOURLY RATE||CLASS|
|RA (RA in Deg.) DEC||Km/Sec||Local Daylight Time||North-South|
|Camelopardalids (CAM)||May 24||08:08 (122) +79||19||18:00||? – <1||III|
|Anthelions (ANT)||–||17:04 (256) -23||29||02:00||2 – 3||II|
|Eta Aquariids (ETA)||May 07||23:20 (350) +05||68||09:00||1 – 2||I|