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Re: (meteorobs) call for observing report + newly updated Leonid circular
Observation of the Leonids 99 on Nov. 18, 1999 (Eastern Part of Saudi
Arabia)
Observers: Dr. Ali Mohammad Al-Shukri et al. (Group of 12)
Physics Department, KFUPM Box # 378, Dhahran 31261, Saudi Arabia
(The sky was divided into four sections and each subgroup counted number of
meteors radiated from Leo in that section, then the numbers added for the
total)
Location: Dhahran, Saudi Arabia
Lat. 26deg 19m 30s N - Lon. 50deg 09m 30s E
Session # 1 (light pollution, clear sky) – Group of 12
Date : 17 – Nov – 1999
Start: 2255 UT - End : 2355 UT
Lm=4.0
Total Leo meteors observed : 45
Session # 2 (some light pollution, clear sky) - Group of 10
Date : 18 – Nov – 1999
Start: 0000 UT - End : 0105 UT
Lm=4.5
Total Leo meteors observed : 382
Session # 3 (little light pollution, clear sky) - Group of 12
Date : 18 – Nov – 1999
Start: 0110 UT - End : 0230 UT
Lm=5.0
Total Leo meteors observed : 1116 ( No fireballs or bolides)
Total Teff : 03 h : 25 m
Colors: white, Bluish white, yellowish white, off white
-------------------------------------------------------
Magnitude Distribution
-5 -4 -3 -2 -1 0 1
2 3 4 5
----------------------------------------------------------------------------
-----------------------------
Session #1 1 2 4 5 5 6 6
6 6 4 0
Session #2 3 5 10 12 20 77 75 80
60 40 0
Session #3 7 25 60 90 99 141 138 130 145
126 155
Some of my friends from Western part of Saudi Arabia (long. < 39 deg E)
claim
that the rate between 2:00 UT and 3:00 UT was beween 10 and 30 meteors
per minute.
Al-Shukri (alshukri@kfupmdot edu.sa)
___________________________________
[ Dr. Ali Mohammad Al-Shukri ]
[ Physics Department, KFUPM Box # 378 ]
[ Dhahran 31261, Saudi Arabia ]
[ email: alshukri@kfupmdot edu.sa ]
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-----Original Message-----
From: Marc.Gyssens <gyssens@charlie.luc.acdot be>
To: 100427.3075@compuserve.com <100427.3075@compuserve.com>; gbal@unimt.mt
<gbal@unimt.mt>; imo-news@egroups.com <imo-news@egroups.com>;
meteorobs@jovian.com <meteorobs@jovian.com>
Date: Saturday, November 20, 1999 09:32 ã
Subject: (meteorobs) call for observing report + newly updated Leonid
circular
>
>CALL FOR LEONID OBSERVATIONS !
>==============================
>
>We found it necessary to produce one more update of the IMO Leonid
>Shower Circular. Reading it gives you a taste of what a proper global
>data analysis may yield in terms of confirming features of existing
>models and revealing new features which will allow meteor astronomers
>to refine these models for the upcoming storm years!
>
>Making such a global analysis will be the next endeavor of the IMO, as
>the rough techniques used for rapid information dissemination have now
>been stretched to their limits. A preliminary such analysis is planned
>to go in the December issue of WGN and should therefore be completed
>in less than 2 (!) weeks!
>
>Therefore it is important the IMO Visual Commission receives the full
>reports of observers as soon as possible! Send your observations to
>Rainer Arlt at visual@imodot net or in any other way you are accustomed
>to. When preparing your reports, mind the following two issues:
>
>1) Report in narrow time intervals! It is in particular recommended -
> to the extent possible - to report 1-minute intervals (or shorter!)
> for the full hour between 1h30m and 2h30m UT. There are reasons to
> suspect minor peaks in this interval besides the two reported on in
> the Circular. These minor peaks will be smoothed out if you report
> in wider intervals - with 5-minute intervals, they disappear! Only
> if you report in narrower intervals will we be able to see which of
> these minor peaks are real and which are merely statistical
> fluctuations. Also for the remainder of the activity, report in
> narrow intervals, the length of which must be chosen depending on
> the number of meteors seen! Ideally, none of these interval should
> contain more than 10 meteors!
>
>2) It goes without saying that magnitude distributions - which were
> not required in the "express reports" - must be included! Without
> these magnitude distributions, it is not possible to compute the
> population index - a measure for the ratio between fainter and
> brighter meteors - and its variation throughout the Leonid
> activity. This information is vital to compute a correct ZHR
> profile!
>
>3) Mention the center of your field of view! Also notice that the
> cloud/obstruction correction factor refers to the field of view
> ONLY! Clouds outside the field of view must NOT be accounted for!
>
>Many of the above recommendations can also be found in Rainer Arlt's
>article "Hints for Visual 1999 Leonid Observations" which was sent
>out via the IMO News and MeteorObs mailing lists and which is printed
>in the October issue of WGN.
>
>We already thank those observers who have not awaited this message to
>send in their complete data; the others we thank in advance for their
>prompt cooperation!
>
>Kind regards,
>
>Rainer Arlt
>Marc Gyssens
>
>
>UPDATED SHOWER CIRCULAR
>=======================
>
>We added some data at the beginning and the end of last circular's
>activity profile. It is interesting to see that the 1h53m UT secondary
>peak may correspond to the 1-revolution old dust trail (although Asher
>and McNaught did not expect activity from this trail, they quote
>exactly this time as nodal crossing time for the 1-revolution old
>trail). Also, there is evidence for enhanced activity on November 18
>between 15h and 20h UT (in the order of magnitude of 100+), which in
>turn corresponds to a prediction by Emel'yanenko based on an older
>dust trail. These two features only give a taste of what is still to
>come once a global analysis is underway!
>
>
> -------------------------------------
>
> I M O S h o w e r C i r c u l a r
>
> -------------------------------------
>
>
> LEONID Activity 1999
> ====================
> *** 2nd UPDATE ***
> ====================
>
>ZHRs pertaining to the pre- and post-peak activity of the Leonids have
>been added. Additional comparisons with other observational reports
>have been made. Some cautious interpretations are suggested.
>
>Visual observations of the 1999 Leonids revealed a distinctive peak
>with a ZHR above 5000 on November 18, 2h04m +/-5m UT (solar longitude
>235.286 +/- 0.004, eq. 2000.0).
>
>It seems that the peak time of 2h08m UT predicted by Asher/McNaught is
>confirmed within a margin of at most a few minutes, although the
>observed activity is significantly higher. It is reasonable to
>conclude that the peak activity has been caused by the 3-revolutions
>old dust trail of 55P/Tempel-Tuttle.
>
>All observers who were able to view the peak under good sky conditions
>reported an abundance of faint meteors and a relative absence of
>fireballs. If this impression is real, taking it into account may
>result in ZHR values somewhat higher than those quoted below.
>
>Ten minutes before the abovementioned peak time, at 1h53m +/- 5m UT
>(solar longitude 235.278 +/- 0.004, eq. 2000.0), the ZHR profile shows
>a secondary peak with of ZHR of about 3500. This secondary peak does
>not only occur in the combined ZHR profile below, but also in the ZHR
>profile of several individual observers, and is therefore probably
>real.
>
>Asher and McNaught mentioned 1h53m UT as the nodal crossing time for
>the 1-revolution old trail, but did not expect activity from it.
>
>ZHR levels were above 1000 from roughly 1h20m UT to 2h45m UT (solar
>longitude 235.26-235.31, eq. 2000).
>
>Apart from the secondary peak mentioned above, the ZHR profile around
>the peak time looks remarkably smooth, even at the level of 5-minute
>intervals. However, observers in the French Provence report that, at
>the level of 1-minute intervals, additional minor peaks are visible
>between 1h30m UT and 2h30m UT. Whether these are significant will be
>one of the issues in a forthcoming detailed first global analysis.
>
>Some observers noticed a drop in the population index (i.e., a larger
>fraction of brighter meteors) after the peak.
>
>Reports from Mohammad Odeh (Jordanian Astronomical Society),
>Casper ter Kuile (Dutch Meteor Society, observing near
>Valencia, Spain), Mark Kidger (Canary Islands), and Ilan Manulis and
>Alex Mikishev (Israel) are very consistent with the picture sketched
>above.
>
>In addition, radio data from K. Maegawa (Toyokawa Meteor Observatory,
>Aichi, Japan) reported by Kazuhiro Suzuki and the backscatter
>radar data from Ondrejov Observatory (Czech Republic) reported by
>Petr Pridal and Rosta Stork yield a peak time between 2h00m UT
>and 2h10m UT.
>
>When the Americans took over from the Europeans on November 18 UT,
>activity stayed stable with a ZHR of 56 +/- 2 between 0500 UT and
>1400 UT (solar longitude 235.409-235.787, eq. 2000.0). The ZHR during
>the interval between 1400 UT and 1500 UT, however, doubles in the
>observations of Hawaiian-based Jim Bedient. Kun Zhou reports ZHRs
>above 100 for the interval between 1625 UT and 1936 UT (solar
>longitude 235.889-236.023, eq. 2000.0).
>
>Masaaki Takanashi of the Nippon Meteor Society reports ZHRs above 100
>between 1500 UT and 2000 UT (solar longitude 235.829-236.040); in the
>first half of this period even up to around 300. Rates drop sharply
>towards the end of the Japanese observing window.
>
>ZHRs during the West-European observing window of November 18/19 were
>consistently around 25. This is consistent with very low activity
>registered by the Ondrejov radar that night, as reported by Pridal and
>Stork.
>
>Although the available data are not yet conclusive, it seems that
>there are consistent indications for enhanced activity with ZHRs
>around or above 100 between November 18, 1500 UT and 2000 UT (solar
>longitude 235.829-236.040, eq. 2000.0).
>
>It is interesting to note that Emel'yanenko predicted a small secondary
>peak on November 18.7 UT due to an older duster trail.
>
>Emel'yanenko also expects significant Leonid activity on November
>19.7-19.8 UT (solar longitude 236.960, eq. 2000.0). Whether or not
>this activity materializes, and whether any other peaks in the
>observed activity profile exist, can only be revealed by a detailed
>global analysis of data, which is forthcoming.
>
>The following observers (with their observing sites, not their
>nationality or country of residence) have contributed data immediately
>after the event, from which the ZHR profile given below
>has been derived:
>
>Rainer Arlt (Spain), Jim Bedient (Hawaii), Felix Betonvil (Canary
>Islands), C.L. Chan (China), Mark Davis (USA), Asdai Diaz (Cuba),
>Yuwei Fan (China), Fei Gao (China), Lew Gramer (USA), Rafael Haag
>(Brazil), Wayne T. Hally (USA), Dave Hostetter (USA), Andre Knoefel
>(Spain), Detlef Koschny (Spain), Wen Kou (China), Alastair McBeath
>(UK), Alfredo Pereira (Portugal), Josep Ma. Trigo-Rodriguez (Spain),
>Helena Valero-Rodriguez (Spain), James Smith (Canada), Renke Song
>(China), Wanfang Song (China), Jan Verbert (France), Catarina Vitorino
>(Portugal), Jean-Marc Wislez (France), Mariusz Wisniewski (Poland),
>Dan Xia (China), Kim S. Youmans (USA), Dongyan Zha (China), Jinghui
>Zhang (China), Yan Zhang (China), Kun Zhou (China), Jin Zhu (China).
>
>(For groups of observers, only the name of the contributing
>observers have been mentioned.)
>
>Date Period (UT) Time (UT) Sol. Long. ZHR +/-
>-----------------------------------------------------------
>Nov 17 0057-0545 0339 234.344 14 2
>Nov 17 0600-1000 0800 234.527 16 2
>Nov 17 1600-2010 1805 234.951 30 5
>Nov 17 1900-2200 2030 235.052 53 14
>Nov 17 2300-2400 2330 235.178 82 6
>Nov 18 0000-0050 0026 235.217 210 60
>Nov 18 0030-0100 0048 235.233 370 80
>Nov 18 0050-0130 0110 235.248 560 90
>Nov 18 0115-0145 0132 235.263 1160 180
>Nov 18 0139-0155 0148 235.275 2360 600
>Nov 18 0145-0200 0153 235.278 3430 750
>Nov 18 0154-0205 0158 235.282 2820 550
>Nov 18 0159-0209 0204 235.286 5400 880
>Nov 18 0200-0215 0209 235.289 3540 580
>Nov 18 0212-0233 0222 235.298 2110 580
>Nov 18 0223-0247 0238 235.310 1140 280
>Nov 18 0244-0320 0257 235.323 690 150
>Nov 18 0315-0400 0340 235.353 240 60
>Nov 18 0347-0505 0423 235.383 153 59
>Nov 18 0500-0630 0537 235.435 57 11
>Nov 18 0609-0800 0656 235.490 62 11
>Nov 18 0711-0900 0756 235.532 51 9
>Nov 18 0812-0925 0847 235.568 57 4
>Nov 18 0901-1100 0958 235.618 59 9
>Nov 18 1100-1400 1254 235.741 56 4
>Nov 18 1400-1500 1430 235.808 90 12
>Nov 18 1625-1936 1825 235.973 106 13
>Nov 19 0018-0445 0306 236.338 23 2
>
>---
>Marc Gyssens, 1999 November 20, 18h UT
>wgn@imodot net
>---
>
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