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NLC 2011-07-26/27

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: 2011-07-26/27

  UT   forms  bright   height   azimuth   comments
               ness   top bot  left rght  e.g. weather
-----  -----  ------  --- ---  ---- ----  --------------------------------
21:15  0
21:30  0
21:45  0
22:00  0
22:15  NLC         1    3        10   20
22:30  NLC         2    3         5   20
22:45  NLC         1    4         5   20  through haze
23:00  0
23:15  NLC         1    2         2   15  through cloud
23:30  NLC         2    3       355   20  through haze
23:45  NLC?        1    3       353   12  through haze
00:00  X                                  cloud on right to h 8
00:15  X                                  cloud to h 20
00:30  X                                  cloud to h 30
00:45  X                                  cloud to h 30
01:00  X                                  widespread cloud
01:15  X                                  widespread cloud
01:30  X                                  almost overcast
01:45  X                                  widespread cloud
02:00  X                                  cloud to h 20
02:15  X                                  cloud to h 15
02:30  X                                  cloud to h 15
02:45  0                                  cloud to h 15
03:00  0                                  cloud to h 10
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: 2011/07/26-27
Start: 22:15
End: 23:45
Forms: NLC
Max elevation: 4
Max brightness: 2
Comments:
Through haze. <a href="http://www.chiandh.me.uk/p/NLC_2011-07-26/27">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)
----- ------ ----- ----- ----- -----  ----- ---------------------
22:15  3.200 330.3 -10.3  -2.1  29.8  0-255 q16974.jpg m16974.jpg
22:30  6.000 333.8 -11.3  -2.7  16.9  0-255 q16979.jpg
22:45 13.000 337.3 -12.1  -3.3  11.6  0-255 q16985.jpg m16985.jpg
23:15 15.000 344.4 -13.5  -4.1   6.9  0-255 q16997.jpg m16997.jpg
23:30 15.000 348.0 -14.0  -4.4   5.7  0-255 q17003.jpg m17003.jpg
23:45 15.000 351.7 -14.4  -4.6   5.0  0-255 q17009.jpg m17009.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).