During this period, the moon reaches its new phase on Thursday July 28th. At that time the moon is located near the sun and is invisible at night. This weekend the waning crescent moon will rise during the early morning hours but will not interfere with meteor watching as long as you keep it out of your field of view. This week and the first week of August will be the best time to view meteor activity this summer as the moonlight will be limited to the late morning hours and the early evening hours. The estimated total hourly rates for evening observers this week should be near 4 as seen from mid-northern latitudes (45N) and 4 as seen from tropical southern locations (25S) For morning observers, the estimated total hourly rates should be near 17 as seen from mid-northern latitudes (45N) and 18 as seen from tropical southern locations (25S). 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 brighter 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 July 23/24. 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. I have also included charts of the sky that display the radiant positions for evening, midnight, and morning. The center of each chart is the sky directly overhead at the appropriate hour. These charts are oriented for facing south but can be used for any direction by rotating the charts to the desired direction. 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 sporadic. Meteor activity is not seen from radiants that are located far 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 July gamma Draconids (GDR) were first noticed by Japanese observers of SonotoCo and the IMO’s network team of Sirko Molau and Juergen Rendtel in 2009. This stream is active from July 25-31 with maximum activity occurring on July 28. The radiant is currently located at 18:24 (276) +51, which places it in southeastern Draco, 4 degrees east of the 2nd magnitude star known as Eltanin (gamma Draconis). The radiant also lies 13 degrees due north of the brilliant zero magnitude star Vega (alpha Lyrae). These meteors are not well seen from the Southern Hemisphere as the radiant does not rise very high in their northern sky. Observers concentrating on this activity should face high in the northern sky as soon as it becomes dark to best view these meteors. With an entry velocity of 27 km/sec., the average July gamma Draconid meteor would be of medium-slow velocity. In 2016, this stream produced a strong outburst that lasted approximately 1 hour. Nothing unusual has occurred since 2016. Some researchers feel these meteors are related to the kappa Cygnids, which are active in August. Normal rates for this shower is less than 1 shower member per hour no matter your location.
The alpha Capricornids (CAP) are active from July 7 through August 15, peaking on July 30th. The radiant is currently located at 20:08 (302) -11. This position lies in northwestern Capricornus, 3 degrees northwest of the naked eye double star known as (alpha Capricornii). Current rates are expected to be near 2 per hour as seen from the Northern Hemisphere and 3 per hour as seen from south of the equator. Observers concentrating on this activity should face half-way up in the southern sky near 01:00 Local Standard Time (LST) to best view these meteors. With an entry velocity of 23 km/sec., the average meteor from this source would be of slow velocity.
The large Anthelion (ANT) radiant is currently centered at 20:56 (314) -15. This position lies in north-central Capricornus, 2 degrees northwest of the 4th magnitude star known as Dorsum (theta Capricorni). Rates at this time should be near 2 per hour as seen from the Northern Hemisphere and 3 as seen from south of the equator. Observers concentrating on this activity should face high in the half-way up in the southern sky near 02:00 LST to best view these meteors. With an entry velocity of 30 km/sec., the average Anthelion meteor would be of slow velocity.
The Southern delta Aquariids (SDA) are active from a radiant located at 22:16 (334) -17. This area of the sky is located in southwestern Aquarius, 1 degree southeast of the 4th magnitude star known as iota Aquarii A. This location is also 5 degrees southeast of the first magnitude planet Saturn. Hourly rates at this time should be near 1 as seen from the Northern Hemisphere and near 2 as seen from south of the equator. Observers concentrating on this activity should face half-way up in the southern sky during the last dark hour prior to dawn to best view these meteors. With an entry velocity of 41 km/sec., the average meteor from this source would be of medium velocity.
The Perseids (PER) are active from a radiant located at 01:20 (020) +53. This position lies on the Perseus/Cassiopeia border, 3 degrees south of the 4th magnitude star known as theta Cassiopeiae. Maximum is not until August 13th so current rates are expected to only 2 per hour as seen from the Northern Hemisphere and 1 per hour from the tropical Southern Hemisphere. Observers concentrating on this activity should face high in the northeastern sky during the last dark hour prior to dawn to best view these meteors. Observers in the northern hemisphere are better situated to view this activity as the radiant rises much higher in the sky before dawn compared to southern latitudes. With an entry velocity of 59 km/sec., the average meteor from this source would be of swift velocity.
As seen from the mid-northern hemisphere (45N) one would expect to see approximately 10 sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near 3 per hour. As seen from the tropical southern latitudes (25S), morning rates would be near 9 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 list below offers the information from above in tabular form. 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 Summer Time||North-South|
|July gamma Draconids (GDR)||Jul 25||18:24 (276) +51||27||22:00||<1 – <1||II|
|alpha Capricornids (CAP)||Jul 30||20:10 (303) -11||23||01:00||2 – 3||II|
|Anthelion (ANT)||–||20:56 (314) -15||30||02:00||2 – 3||II|
|Southern delta Aquariids (SDA)||Jul 30||22:16 (334) -17||41||04:00||1 – 2||I|
|Perseids (PER)||Aug 13||01:20 (020) +53||59||06:00||2 – 1||I|