(meteorobs) ee by GUM - gamma Ursae Minorids in Sonotaco data

Mon Jul 18 10:24:48 EDT 2011

Hello all

We have found this stream in AKM video database - there is strong
maximum in 2006.

Results calculated using Radiant software are following:

Radiant RA: 226 deg

Radiant Dec: +70 deg

Geocentric Velocity: 30km/s

Peak activity: 18/19 01 2006

Radiant calculated from all observed meteors, resolution 6 deg/pixel,
tracings method

http://astro.ia.uz.zgora.pl/~pfn/Radiant_Gumi1.png

Radiant calculated from selected meteors, resolution 0.5 deg/pixel,
tracing method
http://astro.ia.uz.zgora.pl/~pfn/Radiant05deg.png

Above radiant is created from 12 meteor, angular speeds are slow and
moderate. Radiant is very small and compact - smaller than 2 degrees

>From radiant position and velocity we calculated mean oribt, then we
also found some meteor orbits using drummond criterion:

http://astro.ia.uz.zgora.pl/~pfn/gumi_orbit.png

Mean orbital elements calculated from above orbits are following:
a: 2.557 AU
e: 0.628
q: 0.951 AU
i: 45.8 deg
arg: 203.9 deg
node: 298 deg

Best greetings

Przemyslaw Zoladek
Polish Fireball Network

wisetdf at Safe-mail.net wrote:

> Brown et al (Icarus, 2010, 207, 66) listed amongst meteroid streams discovered with the Canadian Meteor Orbit Radar survey the gamma Ursae Minorids, or GUM in IAU MDC coding.  The shower and work were also noted in CBET 1938.
>
> CBET 2146 http://adsabs.harvard.edu/abs/2010CBET.2146....1J noted that a group of Finnish observers made an optical detection of an outburst from this shower in late January 2010
>
> Shower discovered and confirmed, not much to add really.
>
> I've been doing some D criterion work on the SonotaCo meteor orbits database and that too holds some visual members of this stream.  As it's already been confirmed well enough I don't intend to take them any further because there's not much point, but there's always a chance that observers might well be interested in the fact that it appears to churn out a few bright objects fairly regularly.
>
> Here's the orbit diagram for 8 objects :- http://oi52.tinypic.com/ilk5d1.jpg , outermost orbit (not fully shown) is that of Saturn.
>
> Taking this core and taking a median orbit from that core that was then used as a "seed" against which to check the complete SonotaCo dataset again with a slightly looser D criterion the test was redone, but no new ones turned up.
>
> Details from the SonotaCo dataset for the objects are given here :-
>
> RA	DEC	SOL	q	e	INCL	PERI	NODE	Vg	mag	LOCALTIME
> 225.163528	66.794395	299.2494	0.946105	0.598378	46.5340	206.2066	299.2496	28.19	0.80	_20070120_043221
> 226.343262	67.471405	300.2455	0.949760	0.589537	45.1152	205.0353	300.2457	27.36	-2.28	_20070121_040108
> 220.672211	68.806625	298.8301	0.946578	0.661844	47.1738	205.1962	298.8301	29.01	1.05	_20080120_004302
> 227.738358	65.581802	300.9672	0.955962	0.681967	49.5183	201.6191	300.9672	30.29	0.67	_20080122_030728
> 222.926620	69.501411	297.6231	0.948227	0.609727	44.5006	205.2369	297.6234	27.23	-0.15	_20090118_023436
> 221.209869	69.354401	297.6623	0.941233	0.633599	45.1455	207.3212	297.6626	27.81	1.15	_20090118_032958
> 229.766068	66.786743	299.7973	0.952824	0.650311	47.3588	203.1236	299.7976	28.97	0.10	_20090120_054949
> 220.525726	70.367599	300.4751	0.947293	0.594076	45.4315	205.8670	300.4754	27.59	0.65	_20090120_214839
>
> each line ends in the localtime, in case of word wrap.  Pasted from a tab delimited cut.
>
> Main descrepancy with CMOR elements for this shower are the eccentricity.  This might be connected with why the radiants are just that bit off from the CMOR one.  There are two each for 2007 and 2008 and four for 2009.  SonotaCo limiting magnitude is about 2.  So there does seem to be some proclivity for a handful of bright objects from this stream as noted in CBET 2146.
>
> Or maybe the differing mass distributions of the radio and optical meteors make a difference...
>
> ...except, the seed orbit was also tested against various meteor orbit databases I've found over the years as provided on the web.  The IAU photographic, MORP and Prairie and European Fireball Networks and the IAU radio meteor orbits' databases amongst them.  One photographic one from 1950 was found
>
> date METEORID	q	e	I	OMEGA	ASCNODE	VG	RAGEO	DECGEO
> 20.5138/1/50  01913 051W	0.955	0.670	48.3	202.2	299.9	29.56	238.2	67.5
>
> trouble is it's so long since I touched some of this data I've forgotten how to decode the bibliographic record, but I'm pretty sure "01913 051W" is a 1950s Harvard Photographic Meteor Patrol detection.
>
> One meteor isn't much though, could be coincidence.
>
> The Harvard Radio Meteor Patrol of the 60s faired better when the representative SonotaCo derived orbit was used as seed, though the irony is (and something as an obvious consequence), the eccentricity matches the SonotaCo orbits more than the CMOR ones.
>
> Whatever, here are those objects :-
>
> ID	STATION	NUMBER	YEAR	MONTH	DAY	APH	VINF	RA	DEC	q	A	ECC	INCL	ARGPER	ASCNODE	QCODE	LONGPER	ELONG	SERIES	SURVEY	MASS_UG
> HARVARD921	HARVARD	921	1962	1	16.640	3.60	28.4	201	73	0.896	2.246	0.601	41.7	220.5	295.9	4R	156.4	287.9	350	1	4.14
> HARVARD969	HARVARD	969	1962	1	18.806	4.06	29.3	222	71	0.936	2.496	0.625	44.0	208.9	298.1	4R	147.0	294.5	410	1	3.62
> HARVARD970	HARVARD	970	1962	1	18.807	3.26	25.9	232	74	0.951	2.104	0.548	38.3	204.7	298.1	4R	142.8	283.7	411	1	3.67
> HARVARD6830	HARVARD	6830	1963	1	16.728	4.20	30.3	226	70	0.945	2.574	0.633	46.4	205.8	295.7	BR	141.5	302.5	216	1	3.53
> HARVARD6840	HARVARD	6840	1963	1	16.751	3.75	30.3	224	69	0.943	2.345	0.598	46.8	207.5	295.7	BR	143.2	305.1	226	1	3.83
> HARVARD6871	HARVARD	6871	1963	1	17.752	3.91	29.1	240	69	0.968	2.438	0.603	44.5	196.7	296.7	BR	133.4	308.1	258	1	3.72
> HARVARD6908	HARVARD	6908	1963	1	17.972	4.42	30.2	232	70	0.958	2.691	0.644	46.0	201.4	297.0	BR	138.4	304.1	299	1	3.85
> HARVARD6917	HARVARD	6917	1963	1	18.942	3.37	28.5	209	71	0.909	2.138	0.575	42.6	217.9	298.0	BR	155.9	291.8	310	1	4.05
>
> MASS_UG is derived mass in micrograms as published by the surveys.
>
> These are mostly a day or few earlier than the CMOR mean date and most of the SonotaCo ones.
>
> And that's that basically.  Brown et al noted and delineated the shower, Finnish observers confirmed it and noted and discovered a visual counterpart in 2010, SonotaCo also found evidence for such in 2007, 2008 and 2009.  Archival data provided a potential visual one sixty years previously, but one meteor does not a shower make.  Archival radar data of around fifty years ago did present more firm results (D criterion was widened to 0.1 this time).
>
> Looks like a reasonable target for evey year, with some evidence from both SonotaCo and the Finnish team of at least some bright visual objects.
>
> Cheers
>
> John
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