δ Aquarids (SDA): 12 Ιουλ ως Αυγ. Μέγιστο: 28-30 Ιουλ. 2010

[Bi2L]

http://www.popastro.com/sections/meteor/meteor-jul2010.htm

 

 

July 2010

 

The midsummer overnight twilight persists for most of the month, but by mid to late July, the nights are showing signs of growing darker again across much of Britain, except for the more northerly parts of Scotland, which must wait until August for an end to the light nights. Twilight and exams often deter watchers from observing till late July, by when many school and college long summer vacations are underway of course. This year, July's full Moon lands very close to the late month near-ecliptic shower peaks, but this does herald a perfectly moonless Perseid maximum in August. During July though, just some low, early Perseid activity is likely to be seen, for much of the second half.

 

Shower of the Month: The δ Aquarids (SDA)

 

July-August brings some of the stronger near-ecliptic meteor showers during the year, the strongest of which is the δ Aquarids. This was previously called the "Southern δ Aquarids", hence its abbreviation to "SDA". Its former Northern branch, which visual observers often struggled to identify, has now been subsumed into the Antihelion Source (see below). The maximum SDA Zenithal Hourly Rates (ZHRs) are about 15-20, usually achieved for a day or two around July 28-30. Regrettably, the SDA radiant's southerly Declination (its radiant drift is shown on the accompanying chart) means observed meteor numbers are always much lower than the ZHRs from Britain, though rare SDA meteors can be very bright at times. Like the α Capricornids and Antihelion Source, the SDA radiant is above the horizon throughout the short summer nights. Unfortunately, full Moon on July 26th will make any kind of useful coverage of the shower's best almost impossible from the UK this summer. Lower activity of these medium-speed meteors is usually seen from July 12 into August.

 

 

 

ακόμα:

http://meteorshowersonline.com/showers/delta_aquarids.html