(meteorobs) Unusual Fireball Time correction

[Roberto]

Hi Chris,
If the Moon is illuminated the half (last quarter or first quarter) the
inferior brightness and 4 times to the Full Moon, therefore it would have to
be of mag -11 approximately (4 times more faint is equivalent to 1.5 mag).
Roberto Haver

----- Original Message ----- 
From: "Chris Peterson" <clp at alumni.caltech.edu>
To: "Global Meteor Observing Forum" <meteorobs at meteorobs.org>
Sent: Monday, April 14, 2008 7:20 PM
Subject: Re: (meteorobs) Unusual Fireball Time correction


Hi George-

The terminology of Moon phases is confusing, and easily misinterpreted.
In normal usage, you have new Moon, first quarter Moon (half Moon,
waxing), second quarter Moon (full Moon), third quarter Moon (half Moon,
waning), and back to new Moon. We are currently just past the first
quarter Moon, so it is a bit larger than half, and waxing.

Phase is usually expressed as a value of 0-100%, which covers the range
of new Moon to second quarter Moon, and sometimes expressed as a phase
angle between the Earth, Moon, and Sun, and given in degrees, 0-180°.
This is sometimes called the astronomical phase, to distinguish it from
the more commonly used percentage phase.

The numbers you give are correct, but a quarter Moon isn't the same as a
half Moon.

Here's what I use for meteor calibration:

Phase Mag
0           (new)
5     -2.6
10    -4.9
15    -6.2  (crescent)
20    -7.2
25    -7.9  (quarter)
30    -8.5
35    -9.1
40    -9.5
45    -9.9
50    -10.2  (half, first quarter waxing, third quarter waning)
55    -10.6
60    -10.8
65    -11.1
70    -11.4
75    -11.6
80    -11.8
85    -12.0
90    -12.2
95    -12.4
100   -12.5  (full, or second quarter)

Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com


----- Original Message ----- 
From: <GeoZay at aol.com>
To: <meteorobs at meteorobs.org>
Sent: Monday, April 14, 2008 10:57 AM
Subject: Re: (meteorobs) Unusual Fireball Time correction

>>>For a half moon, figure mag -10.2. For the phase last night  (66%)
>>>figure
> mag -11.1.<<
> Chris, I was of the understanding that the magnitude of a quarter moon
> (same
> as a half moon I assume), is -8. Crescent moon -6 and a Full moon -12.
> George

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