(meteorobs) Size of radiants.

[Mikhail Maslov]

Sorry, George, forgot to replace your address with 'meteorobs'.

"Using an IBM 360/65 computer at the University of Liverpool,
telescopic observations of the Quadrantids were examined. The computer
revealed a normal radiant diameter of 8 degrees, which contracts to
less than a degree at the time of maximum."
http://www.maa.agleia.de/Comet/meteors/showers/quadrantids.html,
abs.4,

Orionids are composed with very old material, it has broad and
filamentary structure, as well as eta-Aquarids. "The radiant
diameter was consistently about 5 deg across, and McIntosh's
orbital calculations showed excellent agreement with the
orbit of Halley's Comet."
http://www.maa.agleia.de/Comet/meteors/showers/eta_aquaridhistory.html,
abs. 6.

About ecliptic showers. Many of them have northern and southern
branches, developed from a single stream due to secular perturbations.
See the Taurid example:
"For the period of 1951-1953, the Jodrell Bank survey obtained four
radiant determinations. In 1951, 57 echoes detected on November 7,
revealed a 4 degree-diameter radiant of RA=61 deg, DEC=+25 deg, while
the maximum hourly rate reached 25. Two radiants were detected in
1952. The first was a 3 degree-diameter radiant located at RA=52 deg,
DEC=+24 deg on November 5, while the second was a 6 degree-diameter
radiant located at RA=59 deg, DEC=+17 deg on November 10. The maximum
hourly rates attained 7 and 14, respectively. In 1953, a 3
degree-diameter radiant was detected at RA=58 deg, DEC=+25 deg on
November 9. The maximum hourly rate reached 8. The additional survey
years of 1954-1958 closely reflected the results obtained during
1950-1953."
http://www.maa.agleia.de/Comet/meteors/showers/taurids.html, abs.12,

"Sekanina said the most notable difference in the orbital elements was
in the longitude of perihelion, which varied from the photographic
orbits by nearly 10 deg. He concluded that the separation between the
photographic and radio data "may suggest a difference in the mean age
between the two groups of meteors.""
http://www.maa.agleia.de/Comet/meteors/showers/taurids.html, abs.14,

etc., for other shower similar figired could be given. So a question
still remains: can photografic radiants be much smaller than visual,
radio- and telescopic ones?

Best regards, Mikhail


Mikhail>>>Size of radiant varies for different showers. Diffused  showers, 
Gac> mainly
Gac> ecliptic ones, have large radiants, up to 10° or 15°. These  are such
Gac> showers as Virginids, Taurids etc. On other hand, compact, not  perturbed
Gac> showers have very tight radiants, about 3° in diameter. Very  good
Gac> example are Lyrids. Also, showers can change their radiant size  through the
Gac> period of activity.,,


Gac> Here are some shower radiant sizes determined  photographically:


Gac> Quadrantids - 1.13 deg
Gac> Lyrids - 0.25 deg
Gac> S. delta Aquarids - 1.41 deg
Gac> Perseids - 1.26 deg
Gac> Orionids - 0.84 deg
Gac> S. Taurids - 2.20 deg
Gac> N. Taurids - 1.94 deg
Gac> Leonids - 0.32 deg
Gac> Geminids - 0.49 deg


Gac> George  Zay