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NLC 2009-07-21/22

BAA report

The report to the BAA Aurora Section gives an overview of the night, which times were cloudy, free of NLC, or with sightings of NLC.

Name of observer: Horst Meyerdierks
Location: Royal Observatory Edinburgh, 55.9N 3.2W
          unattended dSLR with limited field of view A ~325-35, h ~0-40
          images every 5 min
Date: 2009-07-21/22

  UT   forms  bright   height   azimuth   comments
               ness   top bot  left rght  e.g. weather
-----  -----  ------  --- ---  ---- ----  --------------------------------
21:15  X                                  cloud to h 15 and top right
21:30  IV         2    25       330   20  cloud to h 5
21:45  IV         3    35      <325  >35  cloud to h 5
22:00  III,IV     4   >40      <325  >35  cloud to h 5
22:15  II,III     5    35      <325  >35  cloud on horizon
22:30  II,III     5    20      <325   25  cloud on horizon
22:45  III        5                       cloud above and below
23:00  III        5    10   0   330   30  cloud below and in front
23:15  III        5    10   0         30  cloud below and in front
23:30  III        5    10   0         30  cloud on left below and in front
23:45  III        4    10   0             cloud on left below and in front
00:00  III        4    10   0             cloud on left, aeroplane trail
00:15  III        3    10   0         35  some cloud
00:30  III        3    10   0  <325  >35  some cloud
00:45  III        3    10   0             cloud above and some in front
01:00  NLC        3    10                 behind cloud
01:15  NLC        3                       behind cloud
01:30  III        3    10                 behind cloud
01:45  I          4                       behind cloud
02:00  I          4    15                 behind cloud
02:15  II,III     4    20                 cloud on left and below
02:30  NLC        3                       through cloud gap
02:45  NLC?       1                       through cloud gap
03:00  X                                  cloud
03:15  X                                  cloud

forms: I: veil
       II: bands
       III: waves
       IV: whirls
       NLC: other than or multiple of I-IV
       0: no NLC
       X: no decision possible (mist, cloud etc.)
brightness: 1: very weak
            2: clearly detected
            3: clearly visible
            4: very bright
            5: extremely bright

NLCnet report

The periods of positive sightings of NLC are reported to the NLC Observers' Home Page:

Name: Horst Meyerdierks
Country: Scotland
Location: Edinburgh
Date: 2009/07/21-22
Start: 21:30
End: 02:45
Forms: I,II,III,IV
Max elevation: >40
Max brightness: 5
Comments:
<a href="http://www.chiandh.me.uk/p/NLC_2009-07-21/22>Images</a>.

forms: I: veil
       II: bands
       III: waves
       IV: whirls
       O: other than or multiple of I-IV
brightness: 1: very weak
            2: clearly detected
            3: clearly visible
            4: very bright
            5: extremely bright

Images

Listed below are the images with positive sightings of NLC. These have been processed merely to adjust the brightness for underexposure. For some, there may also be an unsharp-masked version of the image.

  UT    exp    A    hSun  h15   h85  stretch  image      (masked)
----- ------ ----- ----- ----- -----  ----- ---------------------
21:30  0.250 320.6  -5.8   2.7 169.1  0-255 q08556.jpg
21:45  0.800 323.9  -7.1   0.6 160.8  0-255 q08559.jpg
22:00  2.000 327.3  -8.3  -0.6 137.2  0-255 q08562.jpg
22:15  2.000 330.6  -9.4  -1.5  65.9  0-200 q08567.jpg
22:30  4.000 334.1 -10.3  -2.1  28.3  0-255 q08575.jpg
22:45  4.000 337.5 -11.2  -2.7  17.3  0-255 q08588.jpg
23:00  8.000 341.1 -12.0  -3.2  12.4  0-255 q08602.jpg
23:15  8.000 344.6 -12.6  -3.5   9.7  0-255 q08617.jpg
23:30  8.000 348.2 -13.1  -3.8   8.1  0-255 q08632.jpg
23:45  8.000 351.8 -13.4  -4.1   7.1  0-255 q08647.jpg
00:00 15.000 355.4 -13.7  -4.2   6.5  0-255 q08661.jpg
00:15 15.000 359.0 -13.8  -4.3   6.3  0-255 q08676.jpg
00:30 25.000   2.6 -13.8  -4.2   6.3  0-255 q08690.jpg
00:45 25.000   6.2 -13.6  -4.1   6.7  0-255 q08705.jpg
01:00 25.000   9.8 -13.3  -4.0   7.4  0-255 q08720.jpg
01:15 15.000  13.4 -12.9  -3.7   8.7  0-255 q08736.jpg
01:30 15.000  17.0 -12.3  -3.4  10.7  0-255 q08751.jpg
01:45 15.000  20.5 -11.7  -3.0  14.1  0-255 q08766.jpg
02:00 15.000  24.0 -10.9  -2.5  20.6  0-255 q08779.jpg
02:15  8.000  27.5 -10.0  -1.9  37.8  0-255 q08790.jpg
02:30  3.200  30.9  -8.9  -1.1  98.8  0-255 q08798.jpg
02:45  1.300  34.2  -7.8  -0.2 150.5  0-255 q08802.jpg m08802.jpg

exp: Exposure time in seconds (200 ISO, f/3.5).
A: Azimuth of the Sun (degrees).
hSun: Altitude of the Sun (degrees, negative below horizon).
h15: Max. altitude of sunlight at 15 km height (degrees).
h85: Max. altitude of sunlight at 85 km height (degrees).
stretch: Contrast stretch (0-255 means no stretch).