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NLC 2019-07-17/18

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 compact camera with limited field of view
          A ~325-35, h ~0-40; images every 15 min
Date: 2019-07-17/18

   UT     forms  bright   height   azimuth   comments
                  ness   top bot  left rght  e.g. weather
--------  -----  ------  --- ---  ---- ----  --------------------------------
21:30:05  X                                  overcast
21:45:06  X                                  overcast
22:00:08  X                                  almost overcast
22:15:10  X                                  almost overcast
22:30:19  X                                  widespread cloud
22:45:32  X                                  almost overcast
23:00:33  X                                  overcast
23:15:32  X                                  overcast
23:30:32  X                                  overcast
23:46:24  X                                  overcast
00:00:47  X                                  overcast
00:15:47  X                                  overcast
00:30:46  NLC?                               almost overcast
00:45:47  NLC                                through cloud
01:00:47  II,III     3                       through cloud
01:15:53  II,III     3                       through cloud
01:30:32  II,III     2                       through cloud
01:45:31  II,III     2    15                 cloud below and on right
02:00:19  II,III     2    21            >35  cloud below and on right
02:15:08  II,III     2    27            >35  cloud to h 5 or 10
02:30:06  III,IV     2    30            >35  cloud to h 5 or 10
02:45:06  III        1    21            >35  cloud to h 5 or 10
03:00:05  NLC        1    15                 cloud to h 5 or 10
03:15:04  0                                  cloud to h 5 or 10

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: 2019-07-17/18
Start: 00:30
End: 03:00
Forms: II,III,IV
Max elevation: 30
Max brightness: 3
Comments: at times through cloud
http://www.chiandh.eu/nlccam/20190717-18.html

forms: I: veil
       II: bands
       III: waves
       IV: whirls
       NLC: 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)
-------- ------ ----- ----- ----- -----  ----- -------------------
00:30:46 15.000   2.8 -12.9  -3.7   8.6  0-255 q9945.jpg
00:45:47 15.000   6.4 -12.7  -3.6   9.2  0-255 q9951.jpg
01:00:47 15.000  10.0 -12.4  -3.5  10.2  0-255 q9957.jpg
01:15:53 15.000  13.5 -12.0  -3.2  12.1  0-255 q9964.jpg
01:30:32  8.000  17.0 -11.5  -2.9  15.3  0-255 q9969.jpg
01:45:31  8.000  20.5 -10.8  -2.5  21.3  0-255 q9974.jpg
02:00:19  4.000  23.9 -10.0  -1.9  35.8  0-255 q9978.jpg
02:15:08  2.000  27.3  -9.1  -1.3  83.3  0-255 q9981.jpg
02:30:06  1.000  30.7  -8.1  -0.5 142.8  0-255 q9984.jpg
02:45:06  0.500  34.0  -7.0   0.7 161.7  0-255 q9986.jpg m9986.jpg
03:00:05  0.250  37.3  -5.8   2.7 169.3  0-255 q9988.jpg m9988.jpg

exp: Exposure time in seconds (200 ISO, f/2.8).
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).