Sunny weather and hollidays last friday (Liberation Day here in the Netherlands) promised nice observing opportunities. We (Koen Miskotte, Casper ter Kuile and me) have been out in the field at our Biddinghuizen meteor observatory all night -below a table with my data. It is overcast now, but if weather improves, we will be out again coming night, and this time we will continue well into twilight to catch the odd eta Aquarid (they are rare here: at 51 degrees latitude north the radiant rises at the moment twilight starts -even deep in twilight, it stays below 10 degrees!).
Last weeks were energy consuming -lots of long days, and have been travelling to Israel (including the Leonid MAC Workshop) etc. That came down upon me this night - I inadvertently slept for an hour; took a small break and just fell asleep... Also, the nasty virus that caught about everybody at the institute is still operative in my body - woke up today and felt extremely bad, up to the point of vomitting....
But this night was good, especially since I haven't observed for a while last months due to circumstances. The sky at Biddinghuizen was dark albeit slightly hazy, most notably near the horizon. Limiting magnitude about +6.3 to +6.4 (zenith). Still haven't lost the touch: got a nice batch of meteors, 31 in 2.77 hours effective to be exact. Among them some eta Lyrids (meteors from 1983 comet IRAS-Araki-Alcock) that Koen and I both found surprisingly active. Also, some mu Virginids were recognizable, and I had one possible alpha Scorpiid and one possible late alpha Bootid. And... one possible eta Aquarid too!
That last one was a spectacular meteor. It appeared at 1:09:23 UT, which is about at the moment that the radiant of the stream pops up over the horizon... It had an exciting, extremely long trajectory of 90+ degrees (!): starting some degrees southeast of Altair (alpha Aql) and tracking an immense length of trail to beyond Arcturus (alpha Boo)! It took him some 2-3 seconds I estimate. Clearly, this was an Earth-grazing meteor, which lines up with the possibility of an eta Aquarid appearing just as the radiant rises. The direction of the trail is in agreement with this possible stream identity. The meteor wasn't that bright (+3) but it's long trajectory and it's appearance as a 'fuzzy ball' type of meteor made it very appealing.
Other nice meteors appeared at 0:13:43, a -1 sporadic from Hercules into Ophiuchus (also a quite long trail), and 1:27, a zero magnitude sporadic in Cygnus that concluded this night (I started at 21:25 UT (23:25 local time) and ended at 1:30 UT, having slept from 23:02 to 00:05 UT).
Below a table with my data.
- Marco Langbroek
(the Netherlands)
UT Teff Lm nLyr nAqr mVir aBoo aSco Spo 21:35-23:02 1.45 6.3 1 - 2 1 0 11 00:05-01:30 1.32 6.4 2 1 1 0 1 11 TOTAL 2.77 6.4 3 1 3 1 1 22 tot: 31 strm/mag -1 0 +1 +2 +3 +4 +5 +6Sporadics 1 1 1 2 5 7 4 1 <3.32> e Lyrids 0 0 2 0 0 1 0 0 m Virginids 0 0 0 1 0 1 1 0 e Aquarids 0 0 0 0 1 0 0 0 a Bootids 0 0 0 0 1 0 0 0 a Scorpiids 0 0 0 0 0 1 0 0
What a great night this was! We experienced a very dark night at Biddinghuizen, with Lm as deep as +6.8, and consequently saw multitudes of meteors. This really was 'harvesting by numbers'! We continued for over an hour into (deep) twilight to catch the odd eta Aquarid and were quite succesfull: Koen got 2, and I got 4 possible eta Aquarids with the radiant just above the horizon. Also, we got a very fine batch of eta Lyrids (possible IRAS-Araki-Alcock meteors), really surprising how well this stream showed up. Of course that was largely due to the very fine observing conditions. Sporadic rates were fine as well due to this, and sporadics and minor streams combined with the deep Lm thus made for an exciting 20 meteors/hour. Not bad for a May night! Below, a table with my data.
The Appel family (the owners of our observing ground) had come home from a short holliday, so we first spent some time having a social chat with them in their farmstead. It was some time ago we last had met them, so it was good to see and talk with them again for these are extremely kind people. Our converstations got that enjoyable that we lost control of time a bit and at a certain moment discovered that it already was past local midnight. So we said them goodbeye, left them a bottle of wine, and started observing. My session started at 22:25 UT (0:25 local time) and we ended at 2:20 UT with our sheets and plotting charts richly filled with meteors. All in all, I observed 64 meteors in 3.33h effective this night, including the one hour session into deep twilight. Yes, not bad at all for a night in May...! I thoroughly enjoyed it and so did Koen.
No really bright meteors this night: a couple of +2 meteors were the best ones. We had a long slow +3 possible alpha Bootid with a short wake at 23:15 UT, below Lyra. Eta Lyrids (IAA) appeared at raw rates of 5-6 hour, amazing. A nice milky way climbed higher and higher in the sky as the night proceeded. Low at the southwest horizon, we could see the remnants of the cirrus sheet from the thunderstorms over Belgium and the southern North Sea, but our skies were beautifully clear, and the temperatures were mild. At about 1:10 UT, both twilight set in and the eta Aquarid radiant rose. At 1:31 UT I had my first candidate, a long fast +2 trail from the Crb-Her border to below Arcturus. A second possible eta Aquarid appeared at 1:38, a faint +5 trailing from southern Lacerta to the Dra-Cep border. A third appeared at 1:51, a +3 going from the center of the Cygnus cross to the head of Draco. The last possible candidate appeared at 2:00 UT, a +3 trailing below Altair from Aql to Oph. At 2:20, the sky had become so bright that we quit. This was a very fine night!
Marco Langbroek
the Netherlands
Date: May 6-7, 2000 loc.: Biddinghuizen (Netherlands), 52d 28'N, 5d 38' E obs.: Marco Langbroek - LANMA UT Teff Lm nLyr mVir aBoo aSco nAqr Spo 22:25-23:30 0.97 6.8 6 0 1 1 - 13 23:30-00:40 0.82 6.8 5 1 0 0 - 10 00:40-01:20 0.58 6.8 0 1 0 0 0 14 01:20-02:20* 0.96 var 0 0 0 1 4 7 TOTAL 3.33 <6.8> 11 2 1 2 4 44 tot.: 64 * (strong) twilight strm/mag +2 +3 +4 +5 +6Sporadics 4 13 14 6 7 4.00 e Lyrids 2 3 2 3 1 3.82 m Virginids 0 1 1 0 0 a Bootids 0 1 0 0 0 a Scorpiids 0 1 1 0 0 n Aquarids 1 2 0 1 0 3.25
Below the data of Koen Miskotte of last two nights as well. He observed together with me at Biddinghuizen.
- Marco
Obs.: Koen Miskotte - MISKO loc.: Biddinghuizen (Netherlands), 52d 28'N, 5d 38' E Date: May 5-6, 2000 UT Teff Lm mVir Spo nLyr aSco nAqr 21:30-22:26 0.85 6.4 2 3 0 0 - 22:26-23:20 0.87 6.3 0 6 1 0 - 00:07-01:25 1.24 6.3 0 10 3 1 0 strm/mag -1 0 +1 +2 +3 +4 +5 Sporadics 1 0 0 4 5 5 4 n Lyrids 0 0 0 2 1 1 0 Date: May 6-7, 2000 UT Teff Lm nLyr aBoo Spo mVir nAqr 22:16-23:17 0.97 6.7 3 1 8 0 - 23:17-00:18 0.96 6.6 3 1 8 1 - 00:18-01:19 0.92 6.6 4 1 15 0 0 01:19-02:20 1.01 var 1 0 5 0 2 strm/mag +2 +3 +4 +5 +6 Sporadics 1 7 18 8 2 n Lyrids 0 1 5 5 0
*Date : 05/06-05-00
*Observer: Johannink, Carl (IMO-code: JOHCA)
*Place : Alte Piccardie (Germany)
*Coord. : 7o 04'E ; 52o32'N
*Center : R.A.=10h; Decl.=70 deg. at 22:30 UT
*Start : 22:25 UT
*End : 02:00 UT
*Teff : 3.42 hours
Time(UT): nAqr mVir aSco nLyr spor LM Notes
22:25-23:19 0 1 0 0 6 6.2 0.87 hour;plotting
23:19-00:19 0 0 1 2 9 6.1 0.95 hour;plotting
00:19-01:19 0 0 0 1 11 6.0 0.95 hour;plotting
01:19-02:00 1 0 0 1 7 6.0 0.65 hour;plotting
0 1 2 3 4 5 6 m n
nAqr. 0 0 1 0 0 0 0 2.00 1
mVir. 0 0 0 1 0 0 0 3.00 1
aSco. 0 0 1 0 0 0 0 2.00 1
nLyr. 0 0 2 2 0 0 0 2.50 4
Spor. 0 2 0 6 14 11 0 3.97 33
C.F. Johannink
Schiefestrasse 36
48599 Gronau
Germany
Phone: + 49 2562 22345
Email: cjohannink@netside.de
*Date : 06/07-05-00
*Observer: Johannink, Carl (IMO-code: JOHCA)
*Place : Lattrop (Netherlands)
*Coord. : 6o 58'E ; 52o26'N
*Center : R.A.=15h; Decl.=30 deg. at 23:00 UT
*Start : 22:45 UT
*End : 01:55 UT
*Teff : 3.07 hours
Time(UT): nLyr mVir aSco spor n LM Notes
22:45-23:45 3 1 0 3 7 6.1 0.97 hour;plotting
23:45-00:45 0 0 1 7 8 6.1 0.97 hour;plotting
00:45-01:55 1 0 0 9 10 6.0 1.13 hour;plotting
1 2 3 4 5 m n
nLyr. 0 0 0 3 1 4.25 4
mVir. 0 0 1 0 0 3.00 1
aSco. 0 0 0 1 0 4.00 1
Spor. 0 0 1 11 7 4.32 19
C.F. Johannink
Schiefestrasse 36
48599 Gronau
Germany
Phone: + 49 2562 22345
Email: cjohannink@netside.de
Observer (code) : ATL
Number of meteors : 49
Start (Date - UT) : 05-05-2000 22:15
End (Date - UT) : 06-05-2000 02:00
Duration of
observation (h) : 03:45
T mid. (UT) : 06-05-2000 00:07
Total time
of breaks (min) : 0
Number of notes : 4
Time per note (s) : 30
T eff. (h,--) : 3,72
Date Tm observer Lm Stream 0 1 2 3 4 5 6 N tot M mean
2000-05-05 0.12 ATL 6,0 spor 1 6 10 17 7 41 3,56
2000-05-05 0.12 ATL 6.0 mVir 2 1 3 3,00
2000-05-05 0.12 ATL 6,0 nLyr 5 5 5,00
2000-05-05 0.12 ATL 6,0 nAqr 1 1 3,00
Ton Schoenmaker
Observer: Ton Schoenmaker
Location: Roden, Netherlands (06 26' E, 53 08' N)
Frequency: 55.275 MHz
Transmitter: Spanish TV channel E3 (video); transmitters in
La Muela (30 kW),
Gamoniteiro (50 kW) and Aitana (60 kW); all stations within
100 Hz of nominal frequency; distance 1650 km
Antenna: 4-elements horizontal Yagi, geographical azimuth 195 degrees
(SSW), elevation 15 degrees
Receiver: Yupiteru MVT-9000 in FM mode; sensitivity 0.5 µV at 12 dB S/N
Observing: audio signal from ear-phone socket was rectified, digitized
and fed into a PC via the parallel computer port. HP VEE was
used to process the digitized signal and to store 15-minutes
counts of reflections stronger than 0.063 µV (-131 dBm).
Of each meteor stronger than the threshold also time,
maximum strength and signal duration at the threshold level
were registered.
Recently I completed the rebuilding of my observation station for
radio meteors. Instead of registering meteor reflections on a strip chart recorder,
the reflections are now automatically stored on disk in a PC. The rather dull and
time-consuming task of counting the reflections on a strip chart is no longer necessary
and the observations may also be reduced using different filtering for signal strength
and signal duration.
With this automatic setup an attempt was made to observe the ? Aquarids starting on
3 May 2000. The observations had to be stopped on 7 May because of electrical storms.
Figure 1 shows all reflections with a duration of at least 0.1 seconds and stronger
than -131 dBm. For Roden the radiant of the eta-Aquarids rises at 1h20m UTC, culmination
at 7h10m and setting at 13h05m. As the elevation of the radiant nearly coincides with
the daily variation of the sporadic meteors, it is difficult to determine whether the
small increase on 7 May is caused by the eta-Aquarids.
Figure 2 shows the reflections with a duration = 1 second. Although the hourly counts
are now reduced to about 15% of the original counts, on both 6 and 7 May the meteor
activity has increased around the time of culmination. Meteors reflections with a
duration = 1 second are expected to be overdense, so the activity will follow the
sine(elevation) rather than the observability function.
Ton Schoenmaker, Dutch Meteor Society
Meester Homanstraat 8, NL-9301 HP Roden, Netherlands
E-mail: schoenmaker@NFRA.nl
Call: PA0EFA
Hello everybody,
Finally I have time to report my Eta Aquarid observations.
This years campaign started in the morning of May 1. Together with six pupils from the
highschool where I teach, we went to a local hill known as 'Wela'. For them it was the
first time to observe meteors. They needed lots of instructions. Therefore I couldn't
do any serious observations.
At the beginning of the night there were no clouds. From
2 to 4 o'clock local time (6 to 8 o'clock UT) it became almost completely overcast.
We persisted and were rewarded at 4 o'clock local time when the clouds completely
disappeared again. We saw a lot of meteors, but no really bright ones. Only one
eta Aquarid was seen. Just before dawn we saw the rise of the very narrow lunar crescent.
Up to this day (May 17) there were only two other clear nights. The first night (May 7)
I overslept, the second night (May 8) I could observe during the two hours before
sunrise.
May 8 was another cloudless night. Again I went to the 'Wela'.
My other observing site (near the hill Yamanota) is in a valley. This has the advantage that
the observations are not hampered by light polution from nearby villages, but has the
disadvantage that the local horizon is relatively high. The Yamanota site can only be
reached by dirt roads, which are often in a (very) bad condition.
At the top of the Wela the local horizon remains low, but the observations are more hampered by light
polution and strong winds. There goes a very good asphalt road to the top of the hill,
which is not used at night (except by a loony astronomer...). Time will tell which site
I will use most in the future.
When I started my observations, the eta Aquarid radiant was already 20 degrees above
the horizon. In 1.72 hours effective time I could observe 32 meteors. Among them there
were 12 eta Aquarids, 2 possible eta Lyrids and 2 alfa Scorpionids. At the end of the
observations the eta Aquarid radiant was about 40 degrees above the horizon. Most
meteors were faint again. The brightest ones were a magnitude 0 and +1 eta Aquarid and
a magnitude 2 eta Lyrid.
----------------------------------------------------------------
Name: Erwin van Ballegoij (IMO-code: VANER)
Date: May 8 2000
Site: Wela, Aruba, Dutch Caribbean, 69d 58' W, 12d 29' N
Viewing direction: eastnortheast
Viewing height: 65d
period (UT) Teff Lm ETA etaLy alfaSc SPO total
07h45-08h30 0.75 5.9 5 2 2 6 15
08h30-09h30 0.97 5.8 7 0 0 10 17
total 12 2 2 16 32
-----------------------------------------------------------------
Erwin van Ballegoij
Tarabanaweg 9
Oranjestad - Aruba
tel: 00 297 821918
e-mail: ballegoy@setarnet.aw
The meteor shower of the eta-Aquarids is not easily observed from mid-northern latitudes where the majority of visual observers is located, because of the very late rising of the radiant before dawn, and fewer amateurs are observing from the southern hemisphere where dawn is much later, and the radiant climbs higher before the end of the meteor watch.
It is therefore even more challenging to produce a meaningful activity graph of the eta-Aquarids quickly after their maximum, and I am very grateful for the immediate submission of the reports by the following observers:
DAVMA Mark Davis (USA) JOHCA Carl Johannink (the Netherlands) LANMA Marco Langbroek (the Netherlands) LINMI Mike Linnolt (USA) MARAD Adam Marsh (Australia) MARPI Pierre Martin (Canada) MATMI Michael Matiazzo (Australia) MCLAL Alex M'clintock (Spain) MISKO Koen Miskotte (the Netherlands) MOSSC Scott Moser (USA) YOUKI Kim Youmans (USA)
The gradual increase of activity is nicely show in the below Table. The maximum time is, however, hard to fix because of a severe dip in the UT morning of May 6 when the ZHR fell below half-value of its neighbours. Maximum ZHRs appear to be at the lower end of previous years' typical values of 60-70 per hour.
-------------------------------------------- Date Time (UT) Sol. nETA nObs+- -------------------------------------------- Apr 29 1800 39.71 1 2 2.4 1.7 Apr 30 1640 40.63 2 1 20 11 May 01 1730 41.64 25 3 24 4.8 May 03 0050 42.90 23 4 36 6.1 May 04 0840 44.19 15 3 38 9.5 May 04 1750 44.56 14 4 50 13 May 05 1330 45.35 80 5 49 5.5 May 06 0530 46.00 12 5 24 6.8 May 06 1610 46.43 119 6 51 4.7 May 07 0530 46.96 19 4 25 5.7 --------------------------------------------
Solar longitudes refer to equinox J2000. Average times are given with
10-minute accuracy though often refer to many hours coverage. The average ZHR was
computed by
--
Rainer Arlt, 2000 May 08
Visual Commission - International Meteor Organization -- www.imo.net
rarlt@aip.de -- phone: +49-331-7499-533 -- fax: +49-331-7499-526
The large number of observing reports coming in after the first Shower Circular about the eta-Aquarids allowed an update of the activity graph. The shower appears to exhibit a period of about three days with ZHRs above 50. The data set does not allow to conclude about the fluctuations; yet the broad maximum and the maximum ZHR of ~60 are a clear result of this preliminary compilation based on the reports of the following observer:
ATAJU Jure Atanackov (Slovenia) BUCAN Andreas Buchmann (Switzerland) CERJA Jakub Cerny (Czech Republic) COOTI Tim Cooper (South Africa) DAVMA Mark Davis (USA) DIAAS Asdai Diaz Rodriguez (Cuba) HOLDA David Holman (USA) JOHCA Carl Johannink (the Netherlands) KONKH Khalil Konsul (Jordan) KOUWE Wen Kou (China) LANMA Marco Langbroek (the Netherlands) LINMI Mike Linnolt (USA) MARAD Adam Marsh (Australia) MARPI Pierre Martin (Canada) MATMI Michael Matiazzo (Australia) MCLAL Alex M'clintock (Spain) MISKO Koen Miskotte (the Netherlands) MOLSI Sirko Molau (Germany, from Jordan) MOSSC Scott Moser (USA) MOTER Erick Mota Perez (Cuba) NATSV Sven Nather (Germany, from Morocco) NITMI Mirko Nitschke (Germany, from Jordan) TELKH Khaled M. Tell (Jordan) YOUKI Kim Youmans (USA) -------------------------------------------- Date Time (UT) Sol. nETA nObs+- -------------------------------------------- Apr 29 1800 39.71 1 2 2.4 1.7 Apr 30 1740 40.67 18 4 18 4.1 Apr 01 2210 41.82 34 5 28 4.6 Apr 03 0050 42.90 33 4 36 6.1 Apr 04 0520 44.05 15 4 36 8.9 Apr 04 1820 44.58 17 5 54 13 Apr 05 0040 44.84 64 8 65 8.0 Apr 05 1330 45.35 86 6 48 5.2 Apr 06 0140 45.84 105 11 56 5.4 Apr 06 0840 46.13 35 7 35 5.9 Apr 06 1610 46.43 119 6 51 4.7 Apr 07 0630 47.01 61 8 38 4.8 Apr 08 0630 47.98 57 4 60 7.8 Apr 10 0210 49.73 23 4 24 5.0 Apr 11 0120 50.67 4 2 26 12 --------------------------------------------
Solar longitudes refer to equinox J2000. Average times are given with
10-minute accuracy though often refer to many hours coverage. The average ZHR was
computed by
--
Rainer Arlt, 2000 May 18
Visual Commission - International Meteor Organization -- www.imo.net
rarlt@aip.de -- phone: +49-331-7499-533 -- fax: +49-331-7499-526
At 11:38 07-05-2000 +0200, Jurre A. wrote:
Where is the Eta Lyrid radiant located and what is the speed of the meteors. I'd like to check my plots for any shower members...
(Message from Marco Langbroek, via Casper ter Kuile):
Hi Jurre,
The theoretical radiant position of Iras-Araki-Alcock meteors (eta Lyrids) is at RA 19h 15m, dec. +44, on the Lyra/Cygnus border, and indeed this is where Koen and I see our eta Lyrid meteors coming from for several years now. The maximum theoretically should be on May 8/9. Koen and I have observed activity from the radiant for a week or so around this date the past decade. It are mediumfast to fast meteors, theoretically they should have a speed of 44 km/s (comparable to Quadrantids, slightly slower than April Lyrids). Don't expect high numbers: we usually see say 1-2 streammembers per hour around the maximum at best. But last two nights and certainly last night Koen and I found them quite active, although that partly is due to the fact that this was the first time we observed them from our dark observing site Biddinghuizen instead of from our home locations.
Especially later during the night, the radiant is well located for observations (approaching zenith!). Observations this year are still possible for a few days untill the moon starts to interfere.
Very little actually is known about the stream. If I remember correctly, I believe the Japanese have been the first to observe them in the middle eighties.
You also wrote:
" And another thing. What is the orbital period of IRAS-Araki-Alcock, it appears that the meteoroid cloud (I presume there is no continuous stream as it is a long period comet) is quite 'long' as the comet passed perihelion in 1983"
I do not exactly remember the correct periodicity (anyone else knows?) of IRAS-Araki-Alcock, but if I remember correctly it was something like 44 000 years? Most likely the stream IS 'continuous' however! While this might seem counterintuitive to see meteors from long period comets like this, there are a number of other examples. The September Aurigids from comet 1911 Kiess, and the November alpha Monocerotids for example, are due to (very) long period comets as well (note: the alpha Monocerotids are sometimes still given a 10 year periodicity; however, our 1995 photographic and video orbits have shown that the stream has a period of tens of thousands of years [1]).
These streams are very interresting from another point too, and that is one of the reasons why Koen and I are targetting the eta Lyrid stream for several years now: like the alpha Monocerotids and Aurigids which are indeed known to do so, the eta Lyrids from Iras-Araki-Alcock are a possible candidate to produce the freak erratic "Far comet type" outbursts, such as the already mentioned other two streams do (the 1995 alpha Monocerotid example is well known, and in 1994 Bob Lunsford and George Zay for example catched an Aurigid outburst [2]). There is no way of predicting when the stream might produce such an event however as long as there are no previous chance records. They might happen as little as once-twice per 60 years.... The orbital geometry of the parent comet however is very favourable in principle, the orbit appraches that of earth up to about 0.003 AU! Reason to keep a watchfull eye on the stream around maximum each year...
- Marco Langbroek
Dutch Meteor Society
- P.Jenniskens, H. Betlem, M. de Lignie and M. Langbroek: Astrophysical Journal 479 (1997), 441-447.
- P. Jenniskens: Astronomy & Astrophysics 317 (1997), 953-961.
