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NLC 2011-07-27/28

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 15 min
Date: 2011-07-27/28

  UT   forms  bright   height   azimuth   comments
               ness   top bot  left rght  e.g. weather
-----  -----  ------  --- ---  ---- ----  --------------------------------
21:00  0                                  haze to h 5
21:15  0                                  haze to h 5
21:30  0                                  haze to h 5
21:45  0                                  haze to h 8
22:00  0                                  haze to h 8
22:15  0
22:30  0
22:45  0
23:00  0
23:15  0
23:30  0
23:45  0
00:00  0
00:15  0
00:30  0
00:45  0
01:00  0
01:15  I?
01:30  I           1    5       350   20
01:45  I           2    7       345  >30
02:00  I           2    8       340  >30
02:15  I           2   10      <335  >35
02:30  X                                  haze to h 8, cloud on left
02:45  X                                  widepsread cloud
03:00  0                                  cloud on left and right
03:15  X                                  widespread cloud
03:30  X                                  widespread 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: 2011/07/27-28
Start: 01:15
End: 02:15
Forms: I
Max elevation: 10
Max brightness: 2
Comments:
<a href="http://www.chiandh.me.uk/p/NLC_2011-07-27/28">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)
----- ------ ----- ----- ----- -----  ----- ---------------------
01:30 15.000  17.2 -13.5  -4.1   6.9  0-255 q17168.jpg m17168.jpg
01:45 15.000  20.7 -12.8  -3.7   8.9  0-255 q17174.jpg m17174.jpg
02:00 13.000  24.3 -12.0  -3.2  12.1  0-255 q17180.jpg
02:15  5.000  27.8 -11.1  -2.6  18.3  0-255 q17184.jpg m17184.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).