A grazing occultation of magnitude 7.4 ZC2727 occurs about 7.28 pm NZST (8.28 pm NZDT) on the evening of Monday October 10. The lunar limb profile is quite interesting with the potential for multiple occultations to be seen from many sites. The graze point on the lunar limb occurs about 7.5 degrees into the dark limb measured from the southern cusp of the moon.

Graze Path through Plimmerton:

The graze "limit line" (line at which the star would just graze along the moon's limb if it were completely smooth) passes through southern Plimmerton - see below. However because the moon's limb is not smooth, the band over which the graze will be visible extends from about 5 km NORTH to 2 km SOUTH of this line, measured perpendicular to the line. (i.e. from Pukerua Bay ion the north to southern Mana).

Finding the star:

The diagram below shows the position and path of the star relative to the moon as would be seen by the naked eye. (In a telescope the view may appear inverted or back-to-front).

Graze Profile:

The graze profile below shows the expected shape of the southern limb of the moon. Because this is a southern limb graze, solid moon is at the top of the profile, and deep space at the bottom. The "0km" line shows the path the star would follow if an observer was situated on the line drawn on the map above. The scale on the sides of the profile shows distances in kilometres (measured perpendicularly) north or south of this "limit line". The region of interest for this graze extends from 5 km NORTH to 2 km SOUTH of the limit line.

Path Co-ordinates:

Grazing Occultation of    2727  A*      Magnitude   7.4 
Date   2005 October 10    (Monday)     Nominal site altitude  0m

E. Longit.   Latitude     U.T.    Sun  Moon   TanZ   PA    WA      CA
   o  '  "    o  '  "   h  m  s   Alt Alt Az          o     o      o
 173  0  0  -41 39 29   7 25 35    -8 68 300  0.41 168.8 173.88   6.99S
 173  7 30  -41 37 16   7 25 49    -9 68 300  0.41 168.8 173.85   7.02S
 173 15  0  -41 35  1   7 26  2    -9 68 300  0.41 168.8 173.81   7.06S
 173 22 30  -41 32 46   7 26 15    -9 68 299  0.41 168.7 173.78   7.10S
 173 30  0  -41 30 30   7 26 29    -9 68 299  0.41 168.7 173.74   7.13S
 173 37 30  -41 28 13   7 26 42    -9 67 298  0.42 168.7 173.70   7.17S
 173 45  0  -41 25 55   7 26 55    -9 67 298  0.42 168.6 173.67   7.21S
 173 52 30  -41 23 37   7 27  9    -9 67 298  0.42 168.6 173.63   7.24S
 174  0  0  -41 21 17   7 27 22   -10 67 297  0.42 168.6 173.60   7.28S
 174  7 30  -41 18 57   7 27 36   -10 67 297  0.42 168.5 173.56   7.31S
 174 15  0  -41 16 36   7 27 49   -10 67 297  0.43 168.5 173.52   7.35S
 174 22 30  -41 14 13   7 28  2   -10 67 296  0.43 168.5 173.49   7.39S
 174 30  0  -41 11 51   7 28 16   -10 67 296  0.43 168.4 173.45   7.42S
 174 37 30  -41  9 27   7 28 29   -10 67 296  0.43 168.4 173.42   7.46S
 174 45  0  -41  7  2   7 28 43   -10 67 295  0.43 168.3 173.38   7.49S
 174 52 30  -41  4 37   7 28 56   -11 66 295  0.44 168.3 173.34   7.53S
 175  0  0  -41  2 10   7 29 10   -11 66 295  0.44 168.3 173.31   7.56S
 175  7 30  -40 59 43   7 29 23   -11 66 294  0.44 168.2 173.27   7.60S
 175 15  0  -40 57 15   7 29 37   -11 66 294  0.44 168.2 173.24   7.64S
 175 22 30  -40 54 46   7 29 50   -11 66 294  0.45 168.2 173.20   7.67S
 175 30  0  -40 52 16   7 30  3   -11 66 293  0.45 168.1 173.17   7.71S
 175 37 30  -40 49 46   7 30 17   -11 66 293  0.45 168.1 173.13   7.74S
 175 45  0  -40 47 14   7 30 30   -12 66 293  0.45 168.1 173.10   7.78S
 175 52 30  -40 44 42   7 30 44   -12 66 292  0.45 168.0 173.06   7.81S
 176  0  0  -40 42  8   7 30 57   -12 65 292  0.46 168.0 173.03   7.85S

Path coordinates are referred to WGS84 (as used by GPS).

                Librations  Long -4.34   Lat +6.54
                            P +172.5     D +6.2
      Illumination of moon  44%+
        Elongation of Moon  83
    Vertical Profile Scale  1.94 km/arcsec at mean distance of moon
   Horizontal Scale Factor  1.47 deg/min

Limiting Magnitudes for various telescope apertures (in mm)
      CA\Tdia  50   100   150   200   250   300   350
     3.8      5.3   6.8   7.6   8.1   8.5   8.8   9.0
     5.8      5.9   7.4   8.2   8.8   9.2   9.5   9.7
     7.8      6.0   7.4   8.3   8.8   9.2   9.5   9.7
     9.8      6.0   7.4   8.3   8.8   9.2   9.5   9.8
    11.8      6.0   7.5   8.3   8.8   9.2   9.5   9.8

To particpate in this graze please contact Graham Blow as soon as possible.

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