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(meteorobs) IMO-NEWS Re: small outburst on September 8/9 1996?


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From: Juergen Rendtel <jrendtel@aipdot de>
Subject: Re: small outburst on September 7/8 1996? (corr. to 8/9)
To: pegasoft@cc.ruudot nl (Casper ter Kuile)
Date: Thu, 7 Nov 96 9:12:04 MET

Hi everyone,

Some days ago the note about
> A Possible Small Meteor Outburst on September 7/8 1996
> ------------------------------------------------------
(later corrected to Sep 8/9) was posted.
 
> Dutch observer Koen Miskotte (Ermelo, 52 deg. 18' N, 5 deg. 37' E) observed
> something which might have been the descending slope of a small meteor
> outburst on September 7/8 1996. In only 47 minutes effective observing time
> with a limiting magnitude near +6.3, he observed 13 meteors, of which 8
> came from a sharp radiant at RA 4h10m, dec. +47 (1950.0), close to mu
> Persei. The meteors had a Perseid-like velocity and were clustered in the
> early part of the observational interval.

... (part deleted) 

> We are very interested to learn if anyone can CONFIRM the event, either
> from visual or radio observers. Due to the high velocity of the meteors and
> relatively low numbers, the event might not be suitable for radio detection
> however.
I checked my log book only now, and I add my results for the respective 
period below. Rainer Arlt already pointed out, that the given radiant position
and date fits well with the delta-Aurigid radiant as given in the Visual
Handbook. This information bases on three sources (in chronological order):
Hoffmeister's (1948) September-Perseids,
Drummond's paper in Icarus (1984?) on photographic delta-Aurigids,
a number of own observations coinciding with Hoffmeister's findings.
When we wrote the handbook, we analysed all available data and found the 
time of the rate maximum to be Sep 9, while Drummond gives Oct 8 as the
reference date for the photographic set of orbital data.

> Below the observational data. The observations have been reduced with a
> population index of 2.5 and gamma =1.4 in radiant altitude dilution.
> Miskotte has a Cp of 1.2.
> 
> 
> -Marco Langbroek and Koen Miskotte
> Observational team 'Delphinus'
> Dutch Meteor Society (DMS), the Netherlands
> 
> 
> 
> 
> Observational data. Observer Koen Miskotte, Ermelo, the Netherlands (52
> deg. 18' N, 5 deg. 37' E). Date: September 7/8, 1996
                                            (8/9 according to a lalter mail)
> 
> UT                Teff  Lm    Nstream     Nspo  Hrad        ZHR
> 
> 23:35-23:48       0.20  6.3   4           0     44 deg.     33.3 +- 16.7
> 23:48-00:00       0.20  6.3   2           1     46 deg.     15.9 +- 11.2
> 00:00-00:25       0.38  6.2   2           4     49 deg.     8.6 +- 6.1
> 
> 
> mag         +1    +2    +3    +4    +5
> mu Per      1     0     4     2     1
> spo         0     0     2     2     1

Observational data. Observer Juergen Rendtel, Potsdam, Germany
(52.4 deg N, 13.0 deg E)                           1996 Sep 8/9

UT         Teff  Lm   N(DAU) Hrad     ZHR   Nspo      (assumed values r=3.0
2203-2339  1.53  6.26   3    43 deg   3.7    12        gamma=1.0,
2339-0115  1.51  6.23   6    57       6.3    12        C_p=1.0)

I also checked the intervals listed from Koen's observation as well as
the neighbouring intervals of my observational record (Sep 8/9):
   UT      N(DAU)
2303-2315    0    
2315-2335    2
2335-2348    1
2348-0000    1
0000-0025    1
0025-0040    2
0040-0100    1
Perhaps the 4 shower meteors seen by Koen in the interval 23:35-23:48 UT 
are nothing else than a fluctuation as usual in meteor appearances. 
I also find an interval (0022-0033 UT) with 3 meteors of the DAU.
However, it seems sure that this night brought the `highest' rates
of DAU. On 1996 Sep 5/6 (2035-2330 UT) my average ZHR was 3.0, 
and on 1996 Sep 9/10 (2355-0213 UT) I found ZHR 2.6 as an average.

Obviously, early September deserves more attention than it usually gets.

Juergen Rendtel

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