chi and h site logo

NLC 2017-07-20/21

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: 2017-07-20/21

   UT     forms  bright   height   azimuth   comments
                  ness   top bot  left rght  e.g. weather
--------  -----  ------  --- ---  ---- ----  --------------------------------
21:15:01  X                                  patchy cloud
21:30:01  X                                  widespread cloud
21:45:07  X                                  almost overcast
22:00:08  X                                  almost overcast
22:15:10  X                                  almost overcast
22:30:32  X                                  patchy cloud to h 20
22:45:32  X                                  cloud to h 5, patches to h 15
23:00:52  IV          2    9       330       cloud to h 5
23:15:53  IV          2    8      <325   25  cloud to h 5
23:31:24  I,IV        2    8      <325   25  cloud to h 3
23:46:24  I,IV        2    6       330   25  cloud to h 3
00:01:24  II,IV       2    6       325   35  cloud to h 2
00:16:23  II,IV       3    7       325  >35  cloud to h 2
00:31:24  IV          3    8       325  >35  cloud to h 2, patches above h 25
00:46:24  IV          3    8       325   35  cloud patches above and on right, aircraft
01:01:23  IV          3    8       340       cloud patches on right
01:16:24  I           2    9       340       cloud patches on right
01:30:53  I           2   10       335  >35  cloud patches on right
01:45:53  I           2   13       340  >35  cloud on right to h 3
02:00:32  I           2   15       340  >35  almost clear
02:15:19  I           1   20       355   30  almost clear
02:30:09  X                                  widespread cloud patches
02:45:06  X                                  widespread cloud patches
03:00:05  X                                  widespread cloud
03:15:02  X                                  cloud to h 15

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: 2017/07/20-21
Start: 23:00
End: 02:15
Forms: I,II,IV
Max elevation: 3
Max brightness: 3
Comments: Through cloud.
http://www.chiandh.eu/nlccam/20170720-21.shtml

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)
-------- ------ ----- ----- ----- -----  ----- -------------------
23:00:52 15.000 341.3 -11.8  -3.1  13.2  0-255 q3448.jpg m3448.jpg
23:15:53 15.000 344.8 -12.4  -3.5  10.3  0-255 q3454.jpg
23:31:24 30.000 348.5 -12.9  -3.8   8.5  0-255 q3460.jpg
23:46:24 30.000 352.1 -13.3  -4.0   7.5  0-255 q3466.jpg
00:01:24 30.000 355.7 -13.5  -4.1   6.9  0-255 q3472.jpg
00:16:23 30.000 359.3 -13.6  -4.2   6.7  0-255 q3478.jpg
00:31:24 30.000   3.0 -13.6  -4.1   6.8  0-255 q3484.jpg
00:46:24 30.000   6.6 -13.4  -4.0   7.2  0-255 q3490.jpg
01:01:23 30.000  10.2 -13.1  -3.9   8.1  0-255 q3496.jpg
01:16:24 30.000  13.7 -12.7  -3.6   9.5  0-255 q3502.jpg
01:30:53 15.000  17.2 -12.1  -3.3  11.6  0-255 q3508.jpg
01:45:53 15.000  20.7 -11.4  -2.9  15.5  0-255 q3514.jpg
02:00:32  8.000  24.1 -10.7  -2.4  23.2  0-255 q3518.jpg m3518.jpg
02:15:19  4.000  27.5  -9.8  -1.7  44.9  0-255 q3521.jpg m3521.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).