NLC 2011-06-17/18

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 dSLR with limited field of view A ~325-35, h ~0-40
          images every 15 min
Date: 2011-06-17/18

  UT   forms  bright   height   azimuth   comments
               ness   top bot  left rght  e.g. weather
-----  -----  ------  --- ---  ---- ----  --------------------------------
21:45  0                                  cirrus to h 15
22:00  X                                  widespread cirrus
22:15  X                                  widespread cirrus
22:30  0                                  cirrus to h 20
22:45  X                                  cloud
23:00  X                                  overcast
23:15  X                                  overcast
23:30  X                                  almost overcast
23:45  X                                  widespread cloud
00:00  NLC             10                 through cloud
00:15  II,IV      4    13       330  >35  foreground cloud on horizon
00:30  II,IV      4    15      <330  >35  foreground cloud on horizon
00:45  II,III     3    20      <325  >35  foreground cloud below
01:00  II,IV      3    22                 foreground cloud below
01:15  IV         3    25                 foreground cloud below
01:30  II,IV      2    25                 foreground cloud below
01:45  IV         2    27                 foreground cloud below
02:00  X                                  cirrus
02:15  X                                  cirrus
02:30  X                                  cirrus
02:45  X                                  cirrus

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: 2011/06/17-18
Start: 00:00
End: 01:45
Forms: II,III,IV
Max elevation: 27
Max brightness: 4
Comments:
<a href="http://www.chiandh.me.uk/p/NLC_2011-06-17/18">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)
----- ------ ----- ----- ----- -----  ----- ---------------------
00:00  4.000 356.8 -10.6  -2.3  23.6  0-255 q14094.jpg
00:15  2.000   0.3 -10.7  -2.4  22.9  0-255 q14097.jpg
00:30  1.300   3.8 -10.6  -2.3  23.9  0-255 q14101.jpg
00:45  3.200   7.3 -10.4  -2.2  27.2  0-255 q14106.jpg
01:00  2.500  10.8 -10.1  -2.0  34.5  0-255 q14109.jpg
01:15  1.300  14.2  -9.6  -1.6  51.3  0-255 q14112.jpg
01:30  1.000  17.7  -9.0  -1.2  90.6  0-255 q14114.jpg
01:45  0.500  21.1  -8.3  -0.7 134.8  0-255 q14116.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).