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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@kfupm.edu.sa)



  ___________________________________
  [  Dr. Ali Mohammad Al-Shukri                     ]
  [  Physics Department, KFUPM Box # 378  ]
  [  Dhahran 31261, Saudi Arabia                  ]
  [  email: alshukri@kfupm.edu.sa                  ]
  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-----Original Message-----
From: Marc.Gyssens <gyssens@charlie.luc.ac.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 
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@imo.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@imo.net
>---
>
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