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Re: (meteorobs) Is any interesting activity expected in the heavens thisweek?
Hi John,
Below is a portion of the June issue of NAMN Notes which discusses activity
this month. The full text can be found at:
http://web.infoavedot net/~meteorobs
-Mark
<---- begin ---->
1. The Major Shower for June:
........This is the Sagittarids (SAG), which stretch from about April 15th
to July 15th, and just keep moving from constellation to constellation along
the ecliptic. And just how significant is this activity? Well, as far as
number of meteors seen per hour goes, the Zenithal Hourly Rate (ZHR) is only
about 5 meteors per hour, although this sometimes can be a bit higher. These
are medium velocity meteors, travelling at about 30 km per second.
The ecliptic radiant positions are as follows for this month:
June 10: 265 deg, ie. RA 17h 40m, Dec -23, lower Ophiuchus, up to left of
theta
June 15: 270 deg, ie. RA 18h 00m, Dec -23, near M20 in Sagittarius
June 20: 275 deg, ie. RA 18h 20m, Dec -23, up from teapot lid in Sagittarius
June 25: 280 deg, ie. RA 18h 40m, Dec -23, near M22 in Sagittarius
June 30: 284 deg, ie. RA 18h 56m, Dec -23, near nu Sagittarius
It is very useful to plot the meteors from this ecliptic activity, in order
to try to isolate some of the localized activity, the 'clumps' of debris as
it were, that the earth may encounter.
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2. June Lyrids - Deja Vu...
............. Some activity was seen by observers in the northern hemisphere
back in the 1960's and 1970's, and "evidence for its existence has been
virtually zero since" according to the IMO.
The IMO lists the date of possible maximum activity as June 16th, with
shower members visible from the 11th to the 21st. The radiant at maximum is
given as 278 degrees, ie. RA 18h 32m, Dec +35, which is a point forming an
equilateral triangle with alpha and beta Lyra. The meteors are average
velocity, at about 31 km per second. The IMO asks that all potential June
Lyrids be very carefully plotted, and states that "confirmation or denial of
activity from this source in 1999 would be very useful."
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3. Other June Showers...
There are other weak minor showers visible in June, but unless you plot the
paths of your meteors, it is unlikely that you will be able to differentiate
them from any random meteors seen. This is why it is a good idea to learn
and practice plotting your meteors on the special plotting maps available.
It is also interesting at the end of the night to see what you have plotted!
This is how new meteor showers are found.
Some of these very weak showers (not on the IMO working list) are as
follows, from the notes of ALPO, the Meteor Section of the Association of
Lunar and Planetary Observers. These are provided to show that there is a
lot of very minor meteor activity present at any given time - but at such
low rates that only plotting over hours or days will detect it!
The omega Scorpiids reach a maximum on June 1st, with a radiant at RA 15h
56m, Dec -20, just above the bright star Dschubba in the top of the 'J' of
Scorpius. These are slow meteors, at about 21 km per second.
The gamma Sagittarids have a maximum on June 6th, with a radiant at RA 18h
04m, Dec -26, about 5 degrees above the spout of the teapot, and are just
barely average velocity, at about 29 km per second. Both of these showers
can be seen until about the middle of the month.
The theta Ophiuchids reach a maximum on June 13th, but can be seen basically
all month, according to ALPO. The radiant at maximum is at RA 16h 36m,
Dec -15, just above and to the left of phi Ophiuchus - and not near theta at
all. These are just barely average velocity meteors, at about 27 km per
second.
In the last half of June, several other weak minor showers become active.
The tau Cetids, fast meteors at about 66 km per second, reach a maximum
level of activity on June 26th, at RA 01h 36m, Dec -12, about 5 degrees up
to the right of tau Cetus. The tau Aquarids, also fast, at 63 km per second,
have a maximum several days later, on June 28th, with a radiant at RA 22h
48m, Dec -12, just above tau Aquarius.
As noted above, these are extremely minor showers - with very low rates -
but are a challenge to those of you interested in carefully plotting what
you see!
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4. The Daylight Streams...
The Arietids are a daylight stream with a maximum on June 7th at 21h UT, and
a radiant at 44 deg, ie. RA 2h 56m, Dec +24, about halfway between the
Pleiades and the star Hamal in Aries. The zeta Perseids are also a daylight
stream, with a maximum on June 9th at 20h UT, and a radiant at 62 deg, ie.
RA 4h 8m, Dec +23, about 5 degrees to the left of the Pleiades.
In spite of being daylight streams, there have been some isolated reports of
nighttime visual sightings of these meteors - in the hours soon after sunset
and soon before sunrise. These are both strong showers, with rates of about
60 meteors per hour for the Arietids at maximum, and 40 per hour for the
zeta Perseids. If you see any unusual meteors coming up from the horizon,
plot them!
<---- end ---->
-----Original Message-----
I am hoping that there is some meteor activiy worth looking at while the
moon
is new. Apart from sitting for hours hoping for some nice sporadic
activity
does anyone have any suggestions? What is the story with this new NASA
SUNBURST(?) satellite? Is it easily observed without assistance, if so
where
and when? Thanks in advance for any input.
John
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