Orionid Meteor Shower Peaked Oct 21 AND 23

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MeteorWayne

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One of the better annual meteor showers of the year, expecially for the last few years, is the Orionids, one of two showers that allow our atmosphere to sample the debris from Halley's Comet.

Activity has already begun at low levels. In the Northern hemisphere, the radiant doesn't rise until after 10 PM, so the dates I give below will be for the date of the early morning hours after midnight when the highest rates for each night are observed.... i.e after midnight.

The ZHR (Zenithal Hourly Rate) should be over 20 from the morning of the 19th to the morning of the 26th. Based on the last two years, the peak time should be close to dawn on the morning of the 21st for the US, with the west coast getting closer to the actual peak time. But of course, meteor showers are like a box o' chocolates; you never know what you will see unless you look.

The normal peak ZHR is only about 20, but 2007 saw a high of 70, and last year it was close to 40. Recent mathematical analysis of the orbits of the meteoroids indicates this may be one last year of enhanced rates.

For those who watchg from dark skies (not near a city) the hours right before dawn should allow you to see close to the ZHR count per hour.

The Orionids are cometary debris from Halley's comet inbound toward the sun. The eta Aquarids near May 5th sample the outbound leg. Because the comet (and the ejected meteoroids) are in a retrograde orbit (traveling around the sun in the opposite direction to the planets) we hit them close to head on, at high velocity. They impact the atmosphere at more than 67 km/sec, so they are swift and bright. They appear to come from the area of Orion's oustretched left arm (for those in the northern hemisphere). They can be seen from the southern himisphere as well.

In addition, there are 4 other active meteor showers with lower rates you can see during the night. The Northern and Southern Taurids produce slow meteors from radiants in Aries, the epsilon Geminids and Leo Minorids produce swift meteors from above Gemini, and below Leo respectively.

Of course, there are always sporadic meteors that can come from anywhere.

Once the IMO has their Orionid live report page up, I'll post a link.

Meteor Wayne
 
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MeteorWayne

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Re: Orionid Meteor Shower Peaks This Week

It finally stopped raining so I was out for 2.4 hours this morning. It was cold, right around freezing, and breezy...quite a shock since I haven't been out since the Perseids.

25 meteors in total (10.4/Hr), 11 were Orionids (4.6/Hr), 3 Southern Taurids, 4 from other minor showers, and 7 sporadics.

That's a pretty low rate for the Orionids this close to the peak. [edit- actually, I checked, and the rate is comparable to last year, although overall the Orionids were fainter than last year. Only 1 bright one (Mag -2), average mag +2.32] Perhaps this will just be a normal year. I haven't yet calculated my ZHR (need to get some sleep before all the math) but will probably come out around 12.

Satellite report: 3 very dim normal satellites, I haven't ID'd yet between 5:17 and 5:47 EDT. Also two flashing sats (most likely rocket bodies) One which had one very bright 1/2 second flash then was barely visible after that, and another with 2 flashes of 0 and +1 magnitude. [edit 2- I was able to identify the 3 normal sats, all CIS/russian. The first two were Okean-0 and it's rocket, in ~ 650 km orbit launched in 1999,and Cosmos 1378 ~ 545 km launched in 1982. The flashers I will be unable to identify]

Only 6 jets in the 2.4 hours, a low rate for here.

BTW, the peak for the US and Europe is Wed morning, for Australia it's the morning of the 22nd (that ol' International Date Line thing :)
 
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MeteorWayne

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Re: Orionid Meteor Shower Peaks This Week

I went out earlier this morning with the intention of having a longer session, but clouds put an end to that idea abruptly at 5 AM.

The morning turned out to be almost identical to the morning before, even the time turned out to be 2.4 hours. 26 meteors (10.8/Hr), 11 Orionids (4.6/Hr exactly the same), 5 from 3 other showers, and 10 sporadics.

It appears there may have been a brief spike a few hours earlier across Europe with a ZHR ~ 20, I saw no evidence of that on this side of the pond a few hours later.

http://www.imo.net/live/orionids2009/
 
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MeteorWayne

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Re: Orionid Meteor Shower Peaks This Week

Just a quick report before I crash. The Orionids were very good this morning. My overall count was 65 meteors in 2.7 hours (24.1/Hr). There were 46 Orionids (17.0/Hr), 5 from 4 other showers, and 14 Sporadics.

I have only had 6 nights in the last 4 years with higher meteor rates, 2 for the Perseids, 2 for the Orionids, and to frozen solid Quadrantid mornings.

It will be a while before I crunch the numbers, but I imagine my ZHR for the Oriods will be in the 35 to 40 range, not bad. It wasn't as clear as the last two mornings, but was a lot more comfortable with temps in the mid 40s F (~ 7C) vs the low 30's (1-2C) the previous two sessions.
 
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MeteorWayne

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Re: Orionid Meteor Shower Peaks This Week

Wonder why SDC took down the Orionid Front page article with 2 possible good mornings to go. Now the comment posters can't get to the replies I made to them (shockingly, some of the article comments were good, with good questions)

MW

Is it because the authour (RRB) doesn't know anything about the subject and assumed the predictions for this past morning were the only possible correct ones?

Hmmmmmm
 
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MeteorWayne

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Re: Orionid Meteor Shower Peaks This Week

It was cloudy last night so I've caught up on my number crunching, so here's a preliminary report on the first 3 nights.

Morning of Oct 19, my actual ORI rate 4.6/Hr, ZHR 9.4 +/- 2.8; closest IMO data ZHR 18 +/-3.
Morning of Oct 20, actual ORI rate 4.6/Hr, ZHR 11.2 +/- 3.4; closest IMO data ZHR 26 +/- 3.
Morning of Oct 21, actual ORI rate 17.0/Hr, ZHR 38.0 +/-5.6; closest IMO data ZHR 29 +/- 4.

Some notes on interpreting the above. When I am recording data, of course I am only one observer sampling a fairly small piece of the night sky. So I will have more variation that the worldwide collected data. Also, the time matches between my nightly observations and the current IMO calculated ZHR's is not exact.

My data is probably a little bit more accurate than most because of the effort I put in, and my level of experience. So far I have the 4th most hours, and 4th most Orionids in the data reported to the IMO in the world so far for the Orionids. I'm sure that will change as more observations are reported, or when I get another clear night. Could go up or down...probably down ;)

The IMO data in the "on the fly" calculations and graph have not been (and will not be) QC'd in that location. Full analysis will come out early next year and be published in the WGN journal. One part of the ZHR calculation is a pure estimate at this point, it's a magic number called "r" and represents the population index. This is, roughly, the ratio of bright to faint meteors in the shower. The more bright meteors, the higher the probability of observers detecting them.
The actual value at any given time is calculated from the full data set during the analysis process. The default value used in the "on-the-fly_ calcs and graph is 2.0. (that means there will be 2.0 times as many 2nd magnitude meteors as 1st magntude, 4.0 times as many 3rd magnitude meteors as 1st, 8.0 times as many 4th magnitude meteors, etc.). Over the last few years, duing the Orionid peak it has varied between 1.8 and 2.4.

Also, even the data sent in so far is quite preliminary, only 1217 Orionid meteors have been reported from 31 observers in 14 countries (see the link for the distribution). For example in 2008 3141 Orionids were reported, in 2007 4791.

As of the moment the currently calculated peak is around Solar Longitude 208.3, almost exactly as I expected based on the last few years. This is about 1700 UTC Oct 21 (about 1 PM in the afternoon here in NJ :) ). The peak ZHR so far is 49 +/- 6. However, there is limited data reported around the peak time, and very little after. In fact that peak time and ZHR is based on only 88 meteors from 3 observers...1 in Hawaii, one in Japan, and 1 in China, all scattered in time by a few hours. We also haven't even reached the time of the 2nd peak in 2006 which will be this upcoming morning. That time and ZHR will also change as more data rolls in.

Hope you enjoyed this peek into the meteor shower process.

And it really is too bad SDC took down the front page article so early, even before the peak time in 2006. That year there was a flat plateau around ZHR 50 for 2 full days.

Here's the current IMO (International Meteor Organization) page for the Orionids:

http://www.arm.ac.uk/~gba/imo/orionids2009/

By the time you look at it, almost any of the IMO info I listed above will probably have changed as more reports arrive and are assimilated.
 
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MeteorWayne

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Re: Orionid Meteor Shower Peaks This Week

Updated IMO ZHR's based on 2093 Orionids from 37 observers from 14 countries.

My ZHR....IMO ZHR (Interpolated from latest data)

10/19.... 9 +/- 3......17 +/-2
10/20....11 +/- 3......27 +/-3
10/21....38 +/-6.....26 +/-3

Current IMO data shows 2 peaks of ZHR 45

Sol Long.. UT Date Time .. ZHR
207.440.... 10/20 20:14 +/-2h....45 +/-5
208..317... 10//21 17:23 +/- 3h....45 +/-4

As I said, all this will change

I am currently 6th in hours, and 10th in number of Orionids.
 
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doublehelix

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Re: Orionid Meteor Shower Peaks This Week

MeteorWayne":byv0xtru said:
Is it because the authour (RRB) doesn't know anything about the subject and assumed the predictions for this past morning were the only possible correct ones?

Hmmmmmm

Whoa, brutal dude! :eek: :cool:

Here's the link to the article:

http://www.space.com/spacewatch/091020- ... hower.html

I like seeing meteor showers but it is just too darn difficult without a car to go somewhere to see them. I wish there was an option for most of us city-limited people...

-dh
 
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MeteorWayne

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Re: Orionid Meteor Shower Peaks This Week

Yeah, I was a bit irate at the time, though I wasn't wrong.

The fact is even most profesional astronomers, much less science writers understand meteors. It's a niche in astronomy, and if you are going to post accurate articles, you need to consult with experts.
 
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MeteorWayne

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Re: Orionid Meteor Shower Peaks This Week

Interesting development in the latest IMO data...there appears to be a later peak with ZHR > 40 very near the 2006 late peak time that I suggested earlier. That is why I was so irate about the Orionid article being taken down far too early.

Currently (and again, this will change with more data) there is ZHR 44 +/-4 around Sol Long 209.644 (2 AM UT Oct 23).

See????
 
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Wellington1114

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Re: Orionid Meteor Shower Peaks This Week

Wayne do you have any tips you could give me for watching showers? I went out on the 21st and saw a few but nowhere close to the ZHR for that day.
 
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MeteorWayne

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Re: Orionid Meteor Shower Peaks This Week

Not really. In most of the US, the ZHR rate is unattainable. First of all, there are few places in the US (certainly not in our area) wher the sky is dark enough to meet the standard conditions. Limiting magnitude 6.5 skies are available a few places in the western US....in PA and NJ, it will never be that dark, there's too much light pollution.
Second, unless the radiant is directly overhead (which almnost never happens) the observed rate will always be lower.

The best I can suggest is to watch for my updates here in SS&A. The Leonid peak rates in November are all during daylight for us, so that won't work out well; in addition, the Leonid peaks tend to be very faint meteors, which will be fainter than our background sky brightness; i.e. invisble. The best chance for us this year is the Geminids in December, which can produce rates near 100 per hour...if the weather cooperates and you can deal with the cold. The best rate I've seen in the last 4 years here in NJ for that shower has been only about 10 per hour, but the weather has been awful the last few years. 5 years ago under dark skies in California I saw rates of 120 per hour (2 per minute) but things have to work out well to see that.

Still, unless you watch, you will never see anything like that, so if the weather is good, it's worth the effort. I always say, wouldn't you hate to hear about it on the news the next day, when you could have seen it with your own eyes :)

Wayne
 
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MeteorWayne

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Re: Orionid Meteor Shower Peaks This Week

This is beginning to look more and more like 2006, except at about a 20% lower peak rate. So far there appear to be 4 peaks between Solar Longitude 206.7 (Oct 20 0300 UT) and SL 209.6 (Oct 23 0100 UT) a period of almost 3 full days.
They gave ZHR's right around 42, with some substantial dips in between, though some of the covereage is sparse. SO far the IMO online form has received reports of 2227 Orionids from 41 observers in 16 countries.
 
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MeteorWayne

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Re: Orionid Meteor Shower Peaks This Week

More support for why I was whining (or Wayneing) about the article being taken down too early from today's (10/24) SpaceWeather.com:

"ORIONIDS WON'T STOP: Amazingly, the Orionid meteor shower is still active. Three full days after the shower began, international observers are still counting as many as 40 meteors per hour during the dark hours before dawn"

BTW, that statement is inaccurate, since the Orionds begin around October 2nd, but why let any facts get in the way :)

http://www.spaceweather.com/
 
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MeteorWayne

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More preliminary Orionid data. Through the morning of Oct 31 3572 Orionids have been reported by 60 observers in 22 countries.

3 peaks are visible at the IMO link above. One on the 20th; ZHR ~ 38, one near the normal peak time on Oct 21 (SL 208.34) ZHR ~ 44, and a late peak similar to 2006 on the 23rd, with ZHR ~ 43 that lasted maybe 12 hours. I have been clouded out since the 26th, so only have 9 hours and 75 Orionids out of 130 total meteors.

The peak on the 23rd, which I suspected might occur, is why I was so mad SDC took down the article on the 22nd.

Current ZHR is only about 5, should continue to wind down to undectable levels over the next week.

Taurids are still active (at low rates as usual) and Leonids should start to show up in about a week.

MW
 
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