[Prev][Next][Index][Thread]

(meteorobs) GEMINIDS from California. (peak night Dec 13/14)



The weather reports seemed to improve as the peak night, Monday,
approached. The latest ones said it would be "clear" Monday night. Well,
obviously weathermen are not meteor observers, because there was some
cloud bands moving through, and worse of all, a subtle high level thin
cloud/haze layer, that reduced LM, and put a halo around the moon.

Given the less than optimum conditions over a wide area, and it being a
work night, I opted to travel to the nearest "dark site" to San
Francisco, called Mt. Tamalpais, north of the Golden Gate in Marin
county. It is not a particularly high mountain (< 3000' at the summit?)
and is only 20 miles from downtown SF. The sky glow is pretty bad to the
east, but the west is acceptable, since it overlooks the Pacific ocean.
It was quite blustery and cold (for Calif.!), with temps in the low 40's
and a gusty wind. The changing cloud conditions made it challenging to
keep up with the LM, but things settled down after 9pm.

Overall, it was a fair show, considering the lower LM's (5.7 +/-) than I
am used to on Mauna Kea or Haleakala in Hawaii. I saw one bright -4
fireball, however it did not leave much of a train. Hourly rates seem
pretty much as expected. Only unusual thing, I noticed a clustering of
brighter than average GEM's around 1000 UT.

So, in retrospect, a pretty good night!

Sincerely,
Mike Linnolt

REPORT FOLLOWS:
========================================================================

OBS: Mike Linnolt (LINMI)
DATE: Dec. 14, 1999
TIME: 0400 - 1102 UT (8pm - 3:02am PT Dec 13/14)
LOC: Mt. Tamalpais, Marin County, CA
ELEV: 500m
METHOD: Paper


Observing Periods Summary:
==========================

# Period(UT) FOV       Teff    F     LM    GEM   MON  XOR  HYD  SPO
  ---------- ---       ----    -     --    ---   ---  ---  ---  ---
1 0400-0500  00h +00   0.67    >2?   3-4?   4     0    0    0    0
2 0500-0600  02h +10   0.95    1.00  4.8   19     1    0    0    2
3 0630-0730  03h +10   0.90    1.00  5.7   30     0    1    0    5
4 0800-0900  03h +10   0.85    1.00  5.8   50     1    1    3    3
5 0930-1005  05h +10   0.50    1.10  5.4   25     0    0    2    2
6 1030-1102  06h +10   0.50    1.00  5.9   32     0    0    0    6

Periods Detail:
===============

Period #1:
----------

Mag->_-4___-3___-2___-1____0___+1___+2___+3___+4___+5
-------+----+----+----+----+----+----+----+----+----+
GEM:..................1.........1....2............... = 4
MON:................................................. = 0
XOR:................................................. = 0
HYD:................................................. = 0
SPO:................................................. = 0

DEAD TIME: 20 min
BREAKS: 0
LM: 3-4, approx.

Note: Period #1 had poor conditions. Moon up, variable high clouds
and low cloud bands moving through. LM changed drastically.

Period #2:
----------

Mag->_-4___-3___-2___-1____0___+1___+2___+3___+4___+5
-------+----+----+----+----+----+----+----+----+----+
GEM:............................2....8....6....3..... = 19
MON:............................1.................... = 1
XOR:................................................. = 0
HYD:................................................. = 0
SPO:......................................1....1..... = 2

DEAD TIME: 3 min
BREAKS: 0
LM: 4.8

Note: Moon still up, but much better sky conditions. Low clouds gone,
but still variable high clouds with halo around moon.

Period #3:
----------

Mag->_-4___-3___-2___-1____0___+1___+2___+3___+4___+5
-------+----+----+----+----+----+----+----+----+----+
GEM:.................................8....8...10....4 = 30
MON:................................................. = 0
XOR:................................................1 = 1
HYD:................................................. = 0
SPO:...........................................2....3 = 5

DEAD TIME: 6 min
BREAKS: 0
LM: 5.7

Note: Moon has set, much better sky conditions. No low clouds,
but still variable high thin clouds keep LM lower than expected.

Period #4:
----------

Mag->_-4___-3___-2___-1____0___+1___+2___+3___+4___+5
-------+----+----+----+----+----+----+----+----+----+
GEM:...1.........1..............4....5...18...15....6 = 50
MON:................................................1 = 1
XOR:...........................................1..... = 1
HYD:......................................2.........1 = 3
SPO:......................................1....2..... = 3

DEAD TIME: 9 min
BREAKS: 0
LM: 5.8

Note: Best sky conditions, so far. No low clouds, but still 
variable high thin clouds? Dead time higher due to time spent
handling photographic equipment.

Period #5:
----------

Mag->_-4___-3___-2___-1____0___+1___+2___+3___+4___+5
-------+----+----+----+----+----+----+----+----+----+
GEM:..................1....3....3....3....9....6..... = 25
MON:................................................. = 0
XOR:................................................. = 0
HYD:.................................1....1.......... = 2
SPO:...........................................1....1 = 2

DEAD TIME: 5 min
BREAKS: 0
LM: 5.4
F=1.10, estimated by 33% cloud cover for last 8 min of period.

Note: Sky conditions deteriorate somewhat. Apparently, more variable 
high thin clouds reduce LM. At 0200 local time, low clouds move in 
and start severe obscuration, had to stop the observation period short,
from the planned 1 hour to 35mins. Unusually large proportion of
brighter GEM occured around 1000UT.

Period #6:
----------

Mag->_-4___-3___-2___-1____0___+1___+2___+3___+4___+5
-------+----+----+----+----+----+----+----+----+----+
GEM:........1.........1.........5....8....8....9..... = 32
MON:................................................. = 0
XOR:................................................. = 0
HYD:................................................. = 0
SPO:.................................1....3....1....1 = 6

DEAD TIME: 2 min
BREAKS: 0
LM: 5.9

Note: Sky conditions improve to best of the night. Possible still 
variable high thin clouds, but least of the night.

END OF REPORT.
To UNSUBSCRIBE from the 'meteorobs' email list, use the Web form at:
http://www.tiacdot net/users/lewkaren/meteorobs/subscribe.html