(meteorobs) HALWA at NJAA Oct 21

[meteoreye at comcast.net]

OK, here's the next (peak) morning. The IMO On-the-Fly ZHR graph based on worldwide data:

http://www.imo.net/live/orionids2008/

shows that the peak occurred toward the end of my observation period. I have not processed my observations far enough to calculate ZHR's yet. This is the raw data. The header describing the conditions of the obs are in the previous message, so I will cut to the chase.


UT Date October 21, 2008 (Observations 00:46-6:05 EDT)

Showers RA Dec
ORI 095  +16
NTA 039  +18
STA 041  +12
EGE 105  +27
LMI 159 +39
XGE 106 +11


UT Time     Teff    LM ORI NTA STA EGE LMI XGE SPO Tot Met/Hr Ori/Hr
0446-0601 1.25 +5.64  12    1      0      1      /       0       5      19    15.2    9.6
0601-0701 1.00 +5.38   9     1     0       0      /       2       3      15     15.0    9.0
0701-0803 1.00 +5.58  18    0      1      0      1      1      2       23    23.0    18.0
0803 0903  1.00 +5.42  11    1     0      1      0       0      3      16    16.0     11.0
0903-1005 1.00 +5.40   8      0     0      1      0      0       2      11    11.0      8.0
-------------------------------
0446-1005 5.25 +5.49  58     3     1     3      1      3       12     84    16.0     11.0

There were very thin cirrus reducing LM early. After 0718 it was very clear, although encroaching moon did reduce LM somewhat. LMIs only counted after 0646.

Two outstanding events. At 0521 UT two simultaneous Orionids occurred separated by only about 8 degrees. Most "simultaneous" meteors just overlap in time; in this case, they really did occur right next to each other at the same time in the sky. That seemed to shut off the Orionid pipeline for a while, as rates dropped right afterward.

The other was the -12 bolide I have referred to. So far there are 3 other reports of this that I know of. I estimated it at -12 (a terminal burst) it could have been brighter. That was at 0856 UT.

One fact that my preliminary analysis has shown is that there appears to be a distinct periodicity to the Orionid rates during ths morning. My highest rate was about 0755 UT, and peaks occurred for two periods ~ 56 minutes both earlier and later. The range was 50-61 minutes. The minima period ranged from 41-76 minutes. It will take some more time to finish the analysis of this phenomena; I'll add a follow up message later when I have finished. I have also not completed ZHR calcs. Once again, raw data here.

I didn't see much variation in the population index (ratio of bright to faint meteors) in the Orionids this morning. While there was some (perhaps higher r, i.e. fainter Orionids) ) during the first period, none of it was as distinct as the clear different regimes the previous morning.

My impression was that this year's ZHR was lower than the last two years. While 2006 and 2007 produced rates at least twice the long term average, this year seemed to be only about 60% higher than normal. Again, I have not completed that part of the analysis, so this is just an impression so far. I could be wrong due to the moon induced reduction in LM. More on that in a few days.

Highest 6 and 15 minute rates were at 0755 UT, 30 minute rate peaked at ~ 0748. Highest hourly rate was centerd at 0727.

Totals:

84 Total meteors (16.0/Hr) Average Magnitude +1.96 (rather bright)

58 ORI (11.0/Hr) Average Magnitude +1.76
3 NTA (0.6/Hr) Avg Mag +2.0
1 STA (0.2/Hr) Mag +4
3 EGE (0.6/Hr) Avg mag +1.5
1 LMI (0.2/Hr) Mag +1 (A very nice and distunctive meteor ~25 degrees long with a 1 second train)
3 XGE (0.6/Hr) Avg Mag +3.0
15 SPO (2.9/Hr) Avg Mag +2.57

More detailed report can be seen here:

http://umdb.urania.be/v2/obsview/view.php?id=4106


Wayne