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(meteorobs) IRAS-Araki-Alcockids...



Greetings all,

Have been out of touch most of the winter, but now have a new place of 
abode and a functioning computer...  Wanted to comment for the sake of the 
newbies on the list about this possible shower that Marco Langbroek 
mentioned in his email of May 6th.

This shower that Marco talks about comes from the comet 
IRAS-Araki-Alcock.  To many of you, this sounds like just another obscure 
comet probably seen only in telescopes at the time, if you knew where to 
look...

However, this was a phenomenal comet, really unusual - and really easily 
visible with the naked eye.  It was independently discovered about May 3, 
1983 by 3 observers - IRAS, the Infrared Astronomical Satellite, Japanese 
amateur Genichi Araki, and British observer George Alcock.  And get this - 
Alcock found it with a pair of 15x80 binoculars, while observing <indoors> 
through a closed window!!

As far as close approaches go, this comet is high on the list, at number 3, 
with a distance of only .0312 AU on May 11.5, 1983.  This is close!

This comet was <big> in apparent diameter.  In John Bortle's article in Sky 
and Telescope in August 1983, the width of the comet on May 11-12th was 
said to be about 3 1/2 degrees!!  This is something that would barely fit 
into the head of Draco in the sky!!  It reached about brightness 1.7 
according to reports.  And - it was hoofing it across the sky.

I was living in Richmond Hill, Ontario (Canada) at the time, and this thing 
was just flying across the sky from night to night.  I have never seen a 
comet change so much in position from night to night.  It looked like a 
huge fuzzy snowball.  It was big and round and nebulous.  It was easy to 
see with the unaided eye - I showed all the neighbours, even from the less 
than great skies of essentially a suburb of Canada's largest city.

It trucked across Draco and Ursa Minor and near the pointer stars of the 
Big Dipper.  It made for great photos, even with simple equipment such as 
camera and tripod.  Must dig out my comet archives one of these days...

Anyway, just wanted to provide a bit of background for the meteor activity 
from this comet that Marco mentioned...  It was one cool comet!

By the way, following is a summary of my observations last night, hoping to 
see a couple meteors from this old friend.  None seen, but maybe next time...

- Cathy Hall
   south of Ottawa, Canada

NAMN Visual Observing Form:
--------------------------------------------------------------------
DATE:  May 9/10 2001  BEGIN: 3.40 UT  END: 5.41UT
OBSERVER: Cathy Hall (HALCA)
LOCATION: Long: 75 30'  7.5" West; Lat: 45 14' 18.3" North
City & State: Metcalfe, Ontario, Canada
Elevation: 315 feet
RECORDING METHOD: Tape Recorder
---------------------------------------------------------------------
OBSERVED SHOWERS:
ETA  340.2 -0.4  (RA 22h 40.8m Dec -0.4) 66 km/sec
SAG 239.2 -20.8 (RA 15h 57m -20.8) 30 km/sec
and any possible Iras-Araki-Alcockids (as per Marco Langbroek's email of 
May 6/01):
"IAA" 288 +44 (RA 19h 12m +44)  44km/sec
-----------------------------------------------------------------------
OBSERVING PERIODS:
0 = None seen; / = shower not watched.
(UT)
PERIOD   FIELD         TEFF F     LM   ETA SAG "IAA"SPO
3.40-4.40 18h00m+65  1.00  1.05  5.50   0     0     0     0
4.40-5.41 18h00m+65  1.02  1.05  5.10   0     0     0     2

Total Meteors:  2
Total TEFF: 2.02 hours
-----------------------------------------------------------------------
MAGNITUDE DISTRIBUTIONS:
SHOWER  +4 +5  TOTAL MEAN
ETA           0    0     0       n/a
SAG          0    0     0       n/a
"IAA"         0    0     0       n/a
SPO          1    1     2       4.50
-----------------------------------------------------------------------
SKY OBSCURED:
5 % FROM: 3.40 UT to 5.41 UT
-----------------------------------------------------------------------
DEAD TIME: .07 min
BREAKS: none
-----------------------------------------------------------------------
LIMITING MAGNITUDE:
         STAR STAR
TIME AREA COUNT LM
3.40   16       6          5.7
4.00   16       6          5.7
4.30   16       5          5.1
5.00   16       5          5.1
5.41   16       5          5.1
MEAN LIMITING MAGNITUDE: 5.34
------------------------------------------------------------------------
METEOR DATA:
(UT)              SPEED
# TIME MAG (1-5)  CLR TRAIN SHR DCV/LEN
------------------------------------------------------------------------
1.  5.15  4.5   3      W               SPO  0/2
2.  5.39  4.5   3      W               SPO  15/2

SPEED (VELOCITY) SCALE:
0 = Stationary
1 = Very Slow
2 = Slow
3 = Medium
4 = Fast
5 = Very Fast
-----------------------------------------------------------------------
REMARKS:
- recording time/meteor: 2 sec
- DCV is distance of meteor from centre of view
- LEN is length of meteor in degrees
- temperature cool, about 10C, slight north breeze
- sky mushy and moist after some rain earlier in day
- almost full moon, but was partially blocked by some trees
- very few meteors seen, but nice airplane at mag -4 at 3.40 UT
- 4.08 UT - light spike seen, but no evidence of aurora, must have been the 
searchlight at the raceway casino
- evening ended dewy and damp

- Satellites visible:
- 4.06 UT - satellite at mag 3 across Draco and Vega, confirmed as Lacrosse 4
- 4.50 UT - brief blink near star nu Draco, about mag 4, but I may have 
just blinked
- 5.32 UT - satellite at mag 4 across Draco and above Deneb
- Note: satellites checked after observing session using
www.heavens-above.com to determine their identity, if listed on the site

<end>


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