Alfa Monocerotids 1995: results and publication
Groupphoto DMS Leonids Expedition 1995 Spain
On September 23, 1995 twenty DMS meteorobservers gather at the public observatory at Bussloo in advance of the DMS Leonids/alfa Monocerotids expedition to Spain. Note the photographic and video-equipment in front of the observers for three Dutch station and the Spanish station in Andalucia. (Photo by Kees Roos)

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Setting out to see a meteor outburst

In November of 1994, the first Leonid meteor outburst was reported by Dr. Peter Jenniskens (DMS and NASA/Ames Research Center), seen from Mountain View, California, and confirmed elsewhere. We set out to observe the anticipated outbursts of the Leonid in the following year, November 17, 1995. For that to happen, the Dutch Meteor Society mounted an observational expedition to the climatologically more favorable area around the city of Granada in Southeastern Spain, the nearest location with a fair chance of clear weather.

Moreover, Peter Jenniskens predicted the return of a spectacular outburst of the alpha-Monocerotid stream just days later. A brief display of meteors with rates peaking a 6 meteors per minute was expected to peak between 0h and 6h UT on November 22, 1995 (WGN June 1995; Astron. Astroph. 295 (1995), 206). The prediction was based on the hypothesis that a trail of dust in the orbit of long-period comets may tend to move around near the Earth's orbit by the combined influence of the major planets. On November 22, the planetary positions would be much the same as in 1935, when the shower was strong. This hypothesis differed from the assumption that a cloud of dust with a 10-year orbital period would be responsible for the alpha-Monocerotid outbursts. A likely scenario too, because alpha-Monocerotid outbursts were seen in 1925, 1935 and 1985. We were going to try and measure the orbital period of the alpha-Monocerotid meteors in order to distinguish among these theories.

Technical equipment used at station Alcudia, november 1995, DMS-Spain Five observers of team Alcudia-de-Gaudix pose with camera platforms and image intensified video cameras used to record the alpha-Monocerotid outburst from four locations in the province of Andalucia, Spain, in the night of November 22, 1995.
From left to right: Casper ter Kuile, Koen Miskotte, Marco Langbroek, Jos Nijland and Robert Haas


During the period of November 14 until November 23, 21 DMS Observers were going to establish three temporary meteor stations at the small villages of Almedinilla, Zaffaraya and Alcudia, about 80 kilometers distant of each other, in a geometric pattern favorable for multi-station photography and videography. Multi-camera photographic equipment capable to cover the whole sky above 5 degrees altitude were going to be employed on each site, as well as image intensified video equipment. In addition, spectrographic equipment would be employed in Almedinilla.

Goal of the expedition was to gather high precision photographic orbits from both streams as well as detailed visual observations of the outbursts. Similar activities are planned for future Leonid returns. Spanish observers of SMS was going to cooperate in the project and establish a fourth station, which would be supplied with photographic equipment by DMS. Peter Jenniskens planned a shadow Leonid campaign in the San Francisco area of California, which would allow covering a large part of the Leonid activity curve. Peter would then travel to Spain, where he would later establish a fifth station at Calar Alto observatory during the expected alpha-Monocerotids.


Spectacular alpha-Monocerotid outburst!

Following the prediction, a spectacular outburst of the alpha-Monocerotid stream has been observed by observers all over Europe on November 22, 1995.

alfa Monocerotid, Alcudia, Spain

A bright a-Monocerotid in Canis Major photographed by the DMS-team in Alcudia

The event started around 1:10 UT, on November 22, and was all but over by 1:50 UT. The peak rate occurred near 1:29 UT, when up to 5 meteors per minute were recorded. This translates to peak Zenith Hourly Rates of about 500, the highest ever observed by any of us. All stations saw the event. Three meteors were recorded multi-station by the photographic cameras and seven were recorded multi-station by the video cameras. A thin layer of cirrus clouds, and a typical lack of bright alpha-Monocerotids were responsible for the low harvest of meteors. From the results, we have calculated that the orbits of the particles were of long orbital period, consistent with the hypothesis that a trail of dust in the orbit of a long period comet is occasionally directed into the Earth's path.


References and Links


Radiant alfa-Monocerotids at position: RA=117.10, DEC=+0.83 (J2000)

Radiant alfa-Monocerotids


Visual Results

Activity curve of the a-Monocerotid outburst of November 21/22.

ZHR from visual observations alfa-Monocerotids


Combined magnitude/mass distribution. An unusual mass cut-off for higher masses is visible.

Radiant alfa-Monocerotids


A clear background (annual?) activity with a near-constant activity level (ZHR 5 ± 1) was present in the hours before and after the outburst. This curve is based on 62 streammembers observed by 5 observers during a total of 11.77h effective observing time outside the outburst period.

Radiant alfa-Monocerotids


All visual observations covering the period 01:00 - 02:00 UT, 22 November 1995

Observer Code Location No
Hans Betlem HBE Almedinilla (ES) 32
Marc de Lignie MLM Zafarraya (ES) 58
Ruud de Voogt RVV Almedinilla (ES) 19
Guus Docters van Leeuwen GDV Almedinilla (ES) 74
Engelien Geerdink EGS Almedinilla (ES) 82
Marco Langbroek MLV Calar Alto observatory (ES) 60
Koen Miskotte KMH Alcudia de Guadix (ES) 107
Fieke Mol FMR Almedinilla (ES) 56
Jos Nijland JNB Alcudia de Guadix (ES) 81
Iris Ooms IOV Almedinilla (ES) 84
Vera Pijl VPS Almedinilla (ES) 91
Alex Scholten ASE Eerbeek (NL) 26
Amold Tukkers ATL Lattrop (NL) 37
Olga van Mil OMV Almedinilla (ES) 83
Wendy van Mil WMS Almedinilla (ES) 72
Petrina van Tongeren PTV Almedinilla (ES) 42
Jaap van 't Leven JLB Zafarraya (ES) 50
Michiel van Vliet MVO Zafarraya (ES) 81
Annemarie Zoete AZL Almedinilla (ES) 46
Total 19 6 1181


Photographic Results

Orbital elements of four multistation photographed alfa Monocerotids

Code 95254 95260 95252 95255
Year 1995 1995 1995 1995
Month 11 11 11 11
Day 22.07 22.12 22.07 22.07
N 2 2 2 4
stream a-Mon a-Mon a-Mon a-Mon
Mv 0 -1 0 -2
q 0.50 0.48 0.51 0.50
tol q 0.02 0.01 0.01 0.01
Q -51.05 156.95 -32.64 -45.03
a -25.27 78.72 -16.07 -22.26
1/a -0.04 0.01 -0.06 -0.04
tol 1/a 0.09 0.04 -0.05 0.04
e 1.02 0.99 1.03 1.02
tol e 0.05 0.02 0.03 0.02
i 134.35 134.18 136.83 134.15
tol i 0.77 0.49 0.55 0.33
w 88.89 91.25 87.73 88.90
tol 3.08 1.36 1.88 1.52
W 59.33 59.43 59.32 59.33
p 148.21 156.95 147.06 148.23
tol 3.08 1.36 1.88 1.52
V g 63.2 62.6 63.9 63.2
V h 42.8 42.2 43.0 42.8
V inf 64.4 63.6 65.1 64.4
V 63.3 63.1 64.6 64.2
tol V 1.0 0.4 0.6 0.5
H beg 97.0 97.5 97.1 110.9
H end 85.0 84.1 85.2 81.3
RA Geo 117.14 117.20 117.85 117.08
Dec Geo 0.73 0.89 1.52 0.67
COSZR 0.66 0.80 0.66 0.68
Q max 49.39 53.79 28.70 85.10


LLTV Results

Orbital elements of 7 multistation LLTV observed alfa Monocerotids

Code 95664 95665 95667 95668 95675 95679 95681
Year 1995 1995 1995 1995 1995 1995 1995
Month 11 11 11 11 11 11 11
Day 22.0563 22.059 22.0618 22.0632 22.0674 22.0701 22.0729
N stations 2 2 2 2 2 2 2
Stream a-Mon a-Mon a-Mon a-Mon a-Mon a-Mon a-Mon
Mv 3 2 1 5 2 0 1
q (AU) 0.4803 0.4811 0.495 0.4743 0.4934 0.5087 0.4891
tol q 0.0119 0.0172 0.0115 0.023 0.0113 0.0115 0.0116
a (AU) 12.923 422.753 -36.2904 26.8892 -24.0179 214.485 251.592
1/a 0.07738 0.00237 -0.02756 0.03719 -0.04164 0.00466 0.00397
tol 1/a 0.05526 0.08957 0.05812 0.1184 0.05868 0.05767 0.05706
e 0.9628 0.9989 1.0136 0.9824 1.0205 0.9976 0.9981
tol e 0.0257 0.0431 0.0291 0.0553 0.0294 0.0293 0.0279
i 133.379 134.31 134.479 133.796 134.627 134.074 134.105
tol i 0.6532 0.8288 0.6324 1.0687 0.6098 0.6186 0.6503
omega 92.7096 91.5178 89.482 92.8136 89.4854 88.3462 90.6068
tol omega 2.1727 3.22 2.0784 4.3788 2.0501 2.1016 2.1149
Node 59.3156 59.3182 59.3213 59.3224 59.3269 59.3299 59.3327
tol Node 0 0 0 0 0 0 0
pi 152.025 150.836 148.803 152.136 148.812 147.676 149.94
tol pi 2.1727 3.2232 2.0784 4.3788 2.0501 2.1016 2.1148
V g 61.8906 62.6849 63.1065 62.2356 63.2308 62.9082 62.7192
V h 41.5641 42.3571 42.6693 41.9908 42.8154 42.3331 42.3403
V inf 63.132 63.906 64.318 63.456 64.43 64.11 63.914
V mean 62.947 63.724 64.138 63.272 64.251 63.93 63.733
tol v 0.6463 1.028 0.6581 1.3777 0.6591 0.6572 0.6542
H beg 114 112.4 113.6 101.1 114.9 119.6 116.3
H max
H end 88.9 89.1 89 89 87.2 94.1 89
RA 117.238 116.941 117.187 116.893 117.099 117.759 117.205
tol RA 0.129 0.17 0.147 0.118 0.201 0.171 0.108
DEC 0.9409 1.379 1.1529 1.3 1.264 0.6287 1.1019
tol DEC 0.271 0.247 0.261 0.276 0.223 0.246 0.28
RA Geo 117.269 116.951 117.188 116.89 117.078 117.736 117.163
DEC Geo 0.6097 1.0633 0.8406 0.9794 0.9573 0.3109 0.7895
Cos ZR 0.618 0.637 0.64 0.646 0.657 0.645 0.672
Q max 42.5 42.5 46 29.5 44.2 32.8 26.5



The Leonid outburst was observed too:

Rates went up to about ZHR = 35, about three times the normal rates. An abundance of bright meteors resulted in many photographic successes. The video cameras were less effective in capturing this outburst. The peak of the event was over Europe or western Asia, hence favorable for the observers in Spain. In California, the observers saw only the beginning and end of the enhanced rates.

The logo of the DMS Leonids and alfa Monocerotids expedition to southern Spain in november 1995.

Design and production: Robert Haas		 [Logo


Participants:

People that participated in the observing campaign were:
Dutch observers at Alcudia-de-Guadix were Robert Haas, Casper ter Kuile, Koen Miskotte, and Jos Nijland; in Almedinilla, Hans Betlem, Engelien Geerdink, Hans Klü, Guus Doctors van Leeuwen, Olga van Mil, Wendy van Mil, Ruud de Voogd, Annemarie Zoete; at Calar Alto Observatory, Charlie Hasselbach, Peter Jenniskens, and Marco Langbroek; observers at Zafarraya were Jaap van't Leven, Michiel van Vliet, Klaas Jobse and Marc de Lignie. Spanish observers at Chirivel were, among others, Luis Ramon Bellot and Francisco Reyes Andres. Additional visual observations were obtained by Alex Scholten in the Netherlands. We also thank Ilkka Yrjola, Peter Bus and Ton Schoenmaker for their efforts in obtaining radio meteor scatter data.


Acknowledgements:

The DMS expedition to Andalusia, Spain, has been made possible thanks to financial and material support by the Prins Bernhard Fund, the Kerkhoven-Bosscha fund of Leiden University (dept. of astronomy), the foundation Physica, Shell Netherlands bv, Honda power equipment, CANON, Delft Electronic Products, Kodak, Ilford and Op den Kelder Technologie Support, to all of whom we are greatly indebted.
Our special thanks go to Hans Betlem who organised the greater part of the DMS alfa-Monocerotids/Leonids expedition to Andalucia.



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DMS homepage		 back.gif This page was last modified on May 5, 1998 by
Casper ter Kuile and Hans Betlem

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