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NLC 2010-05-23/24

The first tentative NLC reports have appeared on the NLC Observers' Home Page. My observations show some kind of thin cloud or ash low on the horizon. At times the play of light and dark strands looks a bit like NLC, but my reports are of "no NLC". I include here some images though.

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: Stichill Eastfield, 55.7N 2.4W
          unattended dSLR with limited field of view A ~310-20, h ~0-40
          images every 15 min
Date: 2010-05-23/24

  UT   forms  bright   height   azimuth   comments
               ness   top bot  left rght  e.g. weather
-----  -----  ------  --- ---  ---- ----  --------------------------------
21:00  0                                  cloud to h 5
21:15  0                                  cumulus to h 4, cirrus to h 7
21:30  0                                  cumulus to h 4, cirrus to h 8
21:45  0                                  cumulus to h 4, cirrus to h 8
22:00  0                                  cumulus to h 4, cirrus to h 8
22:15  0                                  cumulus to h 4, cirrus to h 8
22:30  0                                  cumulus to h 5, cirrus to h 7
22:45  0                                  cirrus to h 8
23:00  0                                  cirrus to h 7
23:15  X                                  cirrus to h 7, fake NLC
23:30  X                                  cirrus to h 7
23:45  X                                  cirrus to h 8
00:00  X                                  cirrus to h 8
00:15  X                                  cirrus to h 7, fake NLC
00:30  X                                  cirrus to h 7
00:45  X                                  cirrus to h 5
01:00  X                                  cirrus to h 7
01:15  0                                  cirrus to h 7
01:30  0                                  cirrus to h 7
01:45  0                                  cirrus to h 7, fake NLC
02:00  0                                  cirrus to h 10
02:15  0                                  cirrus to h 5
02:30  0                                  clear
02:45  0                                  cloud to h 5
03:00  0                                  cloud to h 8, birds, one near top

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 main periods of absence of NLC are reported to the NLC Observers' Home Page:

Name: Horst Meyerdierks
Country: Scotland
Location: Stichill
Date: 2010/05/23-24
Start: 21:00
End: 03:00
Comments: A "no NLC" result cannot be confirmed between 23:15 and 01:00,
  as low cirrus obstructs the altitudes where NLC might occur.

Images

Listed below are the images with sightings of fake 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)
----- ------ ----- ----- ----- -----  ----- ---------------------
17:30  0.000 274.7  22.0   0.0   0.0  0-255 q28303.jpg
23:15 30.000 347.7 -12.9  -3.7   8.7  0-150 q28333.jpg
00:15 30.000   2.0 -13.6  -4.2   6.6  0-80  q28357.jpg
01:45  8.000  23.4 -10.8  -2.5  21.3  0-100 q28390.jpg

exp: Exposure time in seconds (400 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).