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Re: (meteorobs) Call for Observations for delta Cancrids



I've got the orbital elements on IMO's Visual Handbook in 1995:

>>>
Omega = 296.4 degrees (longitude of ascending node)
omega = 282.6 degrees (argument of perihelion)
inclination = 0.3 degrees
excentricity = 0.800
perihelion distance q = 0.448 AU
half major axis a = 2.273 AU
period = 3.4 years
<<<
(Many thanks for Marc Gyssens's data supply.)

For a comparison, the YB5's are:
>>>
Omega = 109.4571317 degrees (longitude of ascending node)
omega = 114.0351649 degrees (argument of perihelion)
inclination = 5.423753 degrees
eccentricity = 0.862053727
perihelion distance q = 0.324702744 AU
semi-major axis a = 2.353834849 AU
period = 3.6 years
<<<
(All but the "period" of the asteroid's data were from JPL-NASA; "period"
is calculated by myself.)


I think the two ones are similar in any way, but the "omega"s. On the
other hand, the inclination-values are also similar, so may meteoroid
streams travelled through the ecliptic in a long time, and "add" about
180 degrees in "omega" and "Omega"? I don't know of that.

However, this is a group of equations to describe the movement(paths) of
meteoroids (or asteroids, comets, planets). For a meteor shower,
mathematically, if we know the exact coordinate of a radiant, and the
exact geocentric velocity of the shower, we can know a single (only)
orbit of that body by solving the equations. DCA and YB5 have similar
radiants and velocities, so the similar orbits are in expectancy.


All best wishes and Clear skies!
Huan Meng  <meteorobs_menhu@hotmail.com>


----- Original Message -----
> I don't know if someone paid attention to the recent-discovered
asteroid
> 2001 YB5, which
> is also a "PHA". This asteroid is quite near to us recently (about 2.33
> times more than the Earth-Moon distance at the nearest point).
>
> I got through the webpage of NASA, and got the orbital elements at
> http://neo.jpl.nasadot gov/cgi-bin/db?name=2001+YB5. Then I used
Neslusan's
> program to calculate some information of a possible radiant by the
> orbital elements. The result is:
>
> >>>
>              EQUINOX: 2000.0;       DATA FOR YEAR: 2002
> --------------------------------------------------------------------
> METH.  ALPHA  DELTA    VG      VH        L     DATE-MAX.    D-DISC.
>  -Q    122.6   15.6   30.15   38.04    289.5   JAN.  9.9     .018
>  -B    122.6   15.7   30.42   38.22    289.5   JAN.  9.9     .017
>  -W    123.8   15.5   30.46   37.78    289.5   JAN.  9.9     .038
>  -A    121.2   16.0   30.44   37.78    286.9   JAN.  7.5     .005
>  -H    121.2   16.1   30.44   37.78    287.0   JAN.  7.5     .004
>  -P    121.2   15.8   30.45   37.78    287.0   JAN.  7.5     .007
>  Q+    127.8   28.1   20.91   39.74    109.5   JULY 12.0     .413
>  B+    127.7   27.7   22.24   40.70    109.5   JULY 12.0     .407
>  W+     97.5   27.4   30.02   36.99    109.5   JULY 12.0     .757
>  A+    152.4   15.9   30.49   37.18    161.4   SEP.  4.1     .084
>  H+    151.6   14.4   30.42   37.18    161.1   SEP.  3.8     .074
>  P+    152.4   18.3   30.58   37.18    160.8   SEP.  3.5     .119
> --------------------------------------------------------------------
> FIRST/SECOND (-/+) SET OF DATA CONCERNS THE PRE-/POST-PERIHELION ARC
> THE BEST METHOD - PRE-PERIHELION ARC:  H     (D =  .004)
>                 - POST-PERIHELION ARC: H     (D =  .074)
> <<<
>
> Then I checked if there is some known shower has similar parameters. As
> the result, I surprisingly found the "delta-Cancrids" is very suitable
> for this calculated information. In IMO's 2002 calendar, it was written
> as:
>
> >>>
> Active       : January 1-24;
> Maximum      : January 17 (lambda = 297);
> ZHR          = 4;
> Radiant      : alpha = 130, delta = +20;
> Radiant drift: see Table 6;
> V            = 28 km/s;
> r            = 3.0
> <<<
>
> And in IMO's shower list, it was written as:
> >>>
> Shw Name                 Activity      Max  Sollong Alpha Delta dAlpha
> dDelta    V    r
> -----------------------------------------------------------------------
--
> -----------------------
> DCA Delta-Cancrids       01/01 - 24/01 17/01 297.00 130.0  20.0
> 0.90  -0.20 30.0 3.00
> <<<
>
> We can easily find the coordinates of the radiant, the velocities and
the
> active periods are all in very good agreement! As far as I know, people
> haven't known who is delta-Cancrids' parent body. Now, I think the
> Asteroid 2001 YB5 is very probable.
>
> PS: all above is my own opinion, I would like to discuss it with anyone
> interested in this problem.
>
>
> Further more, we are preparing observations for the DCA shower in
China.
> For monitoring DCA, a group of observers, including Dr. Jin Zhu and
Yuwei
> Fan who met Lew Gramer and our Dutch colleagues at Xinglong in
November,
> will to go to a station to the north of Beijing. The group will do
> observations in both January 7th and January 17th and compare them.
> (January 7th is the maximum date calculated; and January 17th is the
> traditional maximum night.)
>
> Also, we would like to ask more observers to keep an eye out for this
> meteor shower. Visual plotting, video and photographic observations can
> all be used to determine the coordinate of the radiant. Radiant
position
> may be used to derive the evolution of the asteroid. Is it a corpse of
an
> old comet? Or how did it produce the meteoroid stream? Or even is it
the
> parent of DCA?
>
> So far, we have just got both spectrum data and photometry data of this
> asteroid. More meteor observations may help to know more information on
> the asteroid.
>
>
> All best wishes and Clear skies!
> Huan Meng  <meteorobs_menhu@hotmail.com>
>
>
>
>
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