chi and h site logo

NLC 2009-07-25/26

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 5 min
Date: 2009-07-25/26

  UT   forms  bright   height   azimuth   comments
               ness   top bot  left rght  e.g. weather
-----  -----  ------  --- ---  ---- ----  --------------------------------
21:15  0                                  cloud to h 10
21:30  0                                  cloud to h 5
21:45  0                                  some cloud on horizon
22:00  0                                  contrail
22:15  NLC?                               among cirrus
22:30  NLC        1    10      <325    5  among cirrus
22:45  NLC        2    10                 among cirrus
23:00  X                                  cirrus
23:15  X                                  cirrus
23:30  X                                  cirrus
23:45  X                                  cirrus
00:00  X                                  thin cloud
00:15  X                                  thin cloud
00:30  X                                  thin cloud
00:45  X                                  thin cloud
01:00  X                                  thin cloud
01:15  X                                  thin cloud
01:30  NLC        2    10                 amongst cirrus
01:45  NLC        3    10                 behind cloud
02:00  X                                  cloud h 5 to 10
02:15  X                                  cloud h 5 to 10
02:30  X                                  cloud h 5 to 10
02:45  I          3    15                 cloud h 5 to 10 and on left
03:00  X                                  cloud
03:15  X                                  cloud
03:30  X                                  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: 2009/07/25-26
Start: 22:15
End: 02:45
Forms: NLC
Max elevation: 15
Max brightness: 3
Comments:
<a href="http://www.chiandh.me.uk/p/NLC_2009-07-25/26>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 10.000 330.4 -10.2  -2.0  32.3  0-255 q09634.jpg m09634.jpg
22:30 20.000 333.8 -11.2  -2.7  17.8  0-255 q09645.jpg m09645.jpg
22:45 25.000 337.3 -12.0  -3.2  12.1  0-255 q09659.jpg
01:30 25.000  17.1 -13.2  -3.9   7.8  0-200 q09824.jpg
01:45 25.000  20.7 -12.5  -3.5  10.1  0-255 q09839.jpg
02:45  2.500  34.5  -8.6  -0.9 121.8  0-255 q09886.jpg

exp: Exposure time in seconds (200 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).