α-Ηνιοχοΐδες: 25 Αυγ. ως 8 Σεπ. Μέγιστο: 01 Σεπ. 2009

[Bi2L]

πηγη imo.net

Aurigid Showers

 

 

α-Aurigids (AUR)

 

http://www.imo.net/calendar/2009#julsep

Active: August 25-September 8

Maximum: September 1 01h UT (λo = 158°6)

ZHR = 7

Radiant: α = 84° δ = +42°

Radiant drift: see Table 6

v∞ = 66 km/s; r = 2.6

TFC: α = 052° δ = +60°; α = 043° δ = +39° and

α = 023° δ = +41° (β > 10° S)

 

Along with the September Perseids (SPE), these essentially northern hemisphere showers appear to be part of a series of poorly-observed sources with radiants around Aries, Perseus, Cassiopeia and Auriga, active from late August into October. IMO investigations using data collected since 1986 have suggested there are at least three showers which repeat annually, of which the AUR are the marginally stronger. Telescopic data to examine all the radiants in this region of sky - and possibly observe the telescopic β-Cassiopeids simultaneously - would be especially valuable, but still-imaging, video records and visual plotting would be welcomed too.

 

The AUR have produced short, unexpected outbursts at times, with EZHRs of ~ 30-40 recorded in 1935, 1986 and 1994, although they have not been monitored regularly until very recently, so other events may have been missed. Only three watchers in total covered the 1986 and 1994 outbursts, for instance! While badly moonlit, the first predicted outburst happened roughly as expected in 2007, producing short-lived EZHRs of ~ 130 for western North America, with many bright meteors. Radio data suggested there was a 'tail' to that event where more faint meteors continued for maybe an hour after the strongest peak, but visual observers could not confirm this, pobably due to the moonlit sky. Both Aurigid radiants reach useful elevations after 23h-0h local time, and this year conditions are reasonably good for the AUR peak, with the waxing gibbous Moon setting between midnight and 2h on August 31-September 1. No predictions for stronger activity had been made when this text was written, however.

 

The DAU name has recently been adopted for the weaker segment of what may be a single shower, as its radiant and activity follow along directly from those of the September Perseids. At present, the showers should be treated as distinct in your observations. The DAU seem to give a weak and very ill-defined maximum between roughly λo = 181°-191° (2009 September 24 to October 4). September 29 is simply the approximate middle of this peak interval, with a waxing gibbous Moon this year that will set before local midnight north of the equator. The later part of this possible maximum spell will see increasing moonlight problems as full Moon approaches on October 4.

 

 

 

 

πηγη popastro.com

http://www.popastro.com/sections/meteor/meteor-aug2009.htm

As August draws to a close, some α Aurigids (AUR) may be spotted, as they probably begin around August 25, lasting into early September. Their activity is from one of a number of known or suspected radiants around Auriga, Cassiopeia, Perseus, Aries and Triangulum during the early autumn, and is probably the annually strongest. The whole series of showers is currently undergoing detailed investigation, after recent IMO video data revealed a number of significant anomalies to the previously-detected sources here, including the September Perseids (SPE) and δ Aurigids (DAU), neither of which is believed active before early September (all three radiants are shown on the accompanying sky map). At least five different near-Auriga showers have been suggested in late August to mid October by the video results, and it is possible none of the radiant positions currently assumed are correct. The α Aurigid maximum seems to fall around August 31 to September 1, producing ZHRs of ~7. The peak is most likely on the latter date this year, with a waxing gibbous Moon setting between 01h and 02h UT for the UK, quite good news, as the radiant area is usefully-observable only after 23h UT. Unexpected α Aurigid outbursts occurred in 1935, 1986 and 1994, which produced ZHRs of ~30-40, though none of these was widely-seen, while the first predicted outburst was seen in moonlit skies in 2007, yielding estimated ZHRs of ~130 briefly. α Aurigid meteors are swift, like the Perseids, but not usually so bright, though the 2007 event was rich in fireballs.

 

 

 

 

 

 

πηγη meteorshowersonline.com

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

Observing

 

This shower's duration seems to persist from August 25 to September 6. Maximum occurs from α=85°, δ=+41° on September 1 (λ=158°). The annual maximum ZHR may be as high as 9, but outbursts of over 30 occurred in 1935 and 1986.

 

History

 

The Alpha Aurigids were discovered by C. Hoffmeister and A. Teichgraeber (Sonneberg, Germany) on the night of August 31/September 1, 1935 (λ=158°). The maximum hourly rate was reported as 30, while the radiant was determined as α=84.2°, δ=+42.0°. The meteors possessed an average magnitude of 2.62, while 74% of those brighter than magnitude 3.5 left trains. V. Guth immediately noted the similarity between this radiant and the predicted radiant of α=90.2°, δ=+39.3° for comet Kiess (1911 II).

 

In his 1948 book, Meteorströme, Hoffmeister noted that the link with comet Kiess made the circumstances of the 1935 observations curious. He pointed out that the comet's orbit was nearly parabolic, making the shower's sudden appearance 24 years after its perihelion passage difficult to explain. Hoffmeister examined his own annual observations made near the end of August and in early September, and noted probable detections of this shower in 1911, 1929, and 1930. In the former year, 5 of the 55 meteors he had plotted on September 2 (λ=159.2°) converged at α=84°, δ=+43°. During 1929, he found radiants of α=85 deg, δ=+38 deg on September 1 (λ=158.1°), α=87°, δ=+38° on September 3 (λ=159.8°), and α=89°, δ=+39° on September 4 (λ=161.0°). In 1930, one radiant was found at α=82°, δ=+38° on August 31 (λ=156.4°). Hoffmeister concluded that, although activity seems to have been present since the comet's perihelion passage, there is no evidence that the Alpha Aurigids are a permanent shower. He added that the strong 1935 shower was probably due to an isolated meteor group in the comet's orbit. Hoffmeister's conclusion seemed well founded, as additional observations failed to appear in the records of American, European, or Russian observers in the four decades following 1935, however, three significant observations have been made in recent years.

 

During 1979 and 1980 members of the Western Australia Meteor Section (WAMS) succeeded in observing the Alpha Aurigids. In the former year, observations were made over the period of August 25-September 2. Maximum activity came on September 2, when the ZHR reached 8.52+/-1.87 from a radiant of α=87 deg, δ=+42 deg. In 1980, observations were made during August 31-September 6. Maximum came on the 6th, when the ZHR reached 9.11+/-0.96, from α=82°, δ=+38°.

 

The latest detection of this shower came on September 1, 1986, when I. Tepliczky (Hungary) observed 24 meteors from RA=94°, DECL=+36.4° between 00:47 and 02:11 (UT). Around 01:25 (λ=158.34°), the ZHR reached 39.6+/-8.1. The meteors ranged in brightness from magnitude -4 to +4, with an average of +0.5.

Minor Activity

Recommended experience level: Expert

 

α-Aurigids (AUR) 2009