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(meteorobs) My July Meteor Summary
Hi fellow list members,
Unlike some of the very experienced observers, it always takes me a while
to process my observations. Maybe in another 20 years I'll be as fast as
Bob :-) But for now, to maintain my quality standards it's usually a week
or so before I am done. So here is a summary of my July activity. My actual
reports are a little busy, since in addition to monitoring the current IMO
working list I also investigate a number of other radiants such as the
those of the DMS, ALPO, and some from Gary Kronk's extensive collection. I
also keep track of the seperate radiants that were combined to produce the
current IMO Sagittarids. For that reason, I generally don't post them to
the list. I will however include all 4 reports for July as .txt files in
another message, for those who are not interested in all the gory details,
you can just delete the whole message.
I managed to get out 4 times in July, recording 55 meteors in 8.26 hours
Teff.
The first was a pre midnight session which as expected produced the lowest
rates, and was also interrupted by observation of a Wallops Island sounding
rocket test, and ended abrubtly as the haze thickened, and the moon cleared
the horizon. In fact, I would not have even attmpted observing at the NJAA
on such a hazy night due to the local light pollution, but since I was at
my dark sky site, I gave it a try...and was rewarded with a 50 degree long
slow meteor traveling almost straight down toward the horizon. The
remaining 3 nights were under very good conditions for a July in New
Jersey. While LM's near 5.5 might seem really bad to many, when the summer
haze rolls in, that's difficult to achieve. The most frustrating night was
the 10/11...the peak night of the July Pegasids, when despite a promise of
clear skies, clouds dogged our efforts. During the 2 hours before it
cleared enough to begin recording data, we saw 3 or 4 JPE's between the 80%
overcast. Once we started, the rates were much lower. Such is life.
Below is a table showing the nightly observations. Here I'll comment on
the individual showers.
SPORADICS- As usual for early July (remember the moon wiped out most of the
Aquarids later in the month) the majority of the observed meteors were
sporadics, over 76%. The rate was lowest for the pre midnight session, and
reached a high of 6 an hour for the final one. Also included in the
Sporadic total are several non-IMO showers, the DMS's Cetids, alpha
Cygnids, and theta Ophiuchids. They are described separately below.
SAGITTARIDS- Only 6 SAG's were seen, but that led the pack for the annual
showers.
The highest rate observed was on the 7/8 when 1.1 per hour were recorded.
When you take into consideration the LM and radiant elevation, this results
in a ZHR in the range of 3 or 4, in line with expectations. Since I plot
all meteors, and have several years experience in judging the meteor speed
to radiant relationship, I also keep track of the old IMO showers that were
folded into the Sagittarids, The IMO theta Ophiuchids (TOP), and lambda
Sagittarids (LSA). I also track Kronk's sigma Capricornids, which Bob has
suggested as the continuation of the ecliptic source region. Of the 6
SAG's, 4 were judged to be TOP's, and 2 LSA's. Only one of the six can be
considered a SCP, but that shower was only active the last two nights.
JULY PEGASIDS (JPE)- as described above, we were clouded out of the peak
hours, when we finally got to observe, my observed rate was only 1.3 per
hour, or ZHR~2 to 3.
Kevin Kilkenny's may have seen an extra one, resulting in a rate of 2 an
hour, but since he was once again struck by the curse of the tape recorder,
all data including velocity estimates were lost, so this cannot be
confirmed. One intersting thing was that both of us did observe and plot
one meteor...comparing the two plots showed nearly identical angles and
path length, with a 2 or 3 degree transverse (sideways) displacement. this
is within the typical boundries of plotting accuracy.
ALPHA CAPRICORNIDS (CAP). The reliable CAP's made a typical appearence,
only 1 meteor observed on each of 3 nights, none were seen on the other
one. They stand out due to their slow speed.
NORTHERN DELTA AQUARIDS- Since I do plot, I also extend the radiant drift a
few days before the official start of a meteor shower, and a few days
afterward. This was the case for the one NDA recorded, which was 4 days
before the official start of the shower.
However, the plot and speed were an excellent match, so I feel pretty
confident about the call
DMS theta Ophiuchids (Oph)- this shower position has been revised by the
DMS, moving it many degrees away from the old position, which is tracked by
the IMO's TOP. While the TOP's fall into the SAG area, the Oph's are so far
away that they cannot be included as SAG's, so they were recorded as
Sporadics. Some evidence for a shower at this position was collected, since
3 meteors matched. The peak rate was 0.7 per hour, exactly the same as the
peak for the TOP's, even though they were at vastly different positions. So
it seems both showers do exist, at least as far as my limited observations
are concerned.
DMS alpha Cygnids- Another shower recorded as sporadics, the ACG's also
picked up 3 meteors with a peak rate of 0.7 per hour. So it seems we'll
watch again for this in the future.
Finally, the no shows---
No Early Perseids. My last session was 3 nights before the official start
of the Perseids on July 15. I watched for the Perseids during all 4
sessions, including both the extrapolations of both the IMO and DMS
positions (which are 7 or 8 degrees apart at that time) No meteors were
seen in 8.26 hours.
SOUTHERN DELTA AQUARIDS- None in 7.23 hours..only 2.86 of which were after
the official activity start date.
Pisces Austrinids- None in 4.43 hours, all before the official start date
Tau Aquarids, and Cetids (DMS) none observed in 3.83 and 1.10 hours
respectively.
July
Date 4/5 7/8 10/11 11/12 Total
Teff 1.03 2.80 1.57 2.86 8.26
F 1.00 1.00 1.03 1.00
LM 5.31 5.42 5.50 5.42
TotM 4 19 10 22 55
M/Hr 3.9 6.8 6.4 7.7 6.7
----------------------------------------------------Avg/Hr
SPO 3 15 6 18 42 5.1
SAG 0 3 1 2 6 0.7
TOP* 0 2 1 1 4 0.5 (Included in SAG Tot)
LSA* 0 1 0 1 2 0.2 (Included in SAG Tot)
SCP* x x 1 0 1 0.2 (Included in SAG Tot)
CAP 1 1 0 1 3 0.4
JPE 0 0 2 1 3 0.4
Oph* x 2 0 1 3 0.4 (Included in SPO
Total)
aCg* x 1 0 2 3 0.4 (Included in SPO Tot)
NDA x x 1 0 1 0.2
PER 0 0 0 0 0 --- IMO Position
Per 0 0 0 0 0 --- DMS Position
SDA x 0 0 0 0 ---
PAU x x 0 0 0 ---
tAq 0 0 x x 0 ---
Cet 0 x x x 0 ---
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