
NLC 2015-07-02/03
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: 2015-07-02/03 UT forms bright height azimuth comments ness top bot left rght e.g. weather -------- ----- ------ --- --- ---- ---- -------------------------------- 21:45:02 0 22:00:02 0 22:15:01 0 22:30:02 0 cirrus to h 10 22:45:02 0 cirrus to h 10 23:00:10 0 cirrus to h 10 23:15:18 0 cirrus, above h 10 as fake NLC 23:30:32 0 cirrus, above h 10 as fake NLC 23:45:32 0 cirrus, above h 10 as fake NLC 00:00:32 0 cirrus, above h 10 as fake NLC 00:15:33 0 cirrus, above h 10 as fake NLC 00:30:32 0 cirrus, above h 10 as fake NLC 00:45:20 0 cirrus, above h 10 as fake NLC 01:00:32 0 cirrus, above h 10 as fake NLC 01:15:19 0 cirrus, above h 10 as fake NLC 01:30:09 0 cirrus, above h 10 as fake NLC 01:45:02 0 cirrus to h 10 02:00:02 0 cirrus to h 10 02:15:01 0 cirrus to h 10 02:30:01 0 cirrus to h 10 02:45:01 0 cirrus to h 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 absence of NLC are reported to the NLC Observers' Home Page:
Name: Horst Meyerdierks Country: Scotland Location: Edinburgh Date: 2015/07/02-03 Start: 21:45 End: 02:45 Comments: Some cirrus.
Images
Listed below are the images illustrative of fake 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.
- #3569 illustrates "fake NLC", where cirrus at higher alitude above the horizon appears bright against the background sky. This is not NLC, as can be detected from its West-to-East movement (from consecutive images, and contrary to most real NLC), its mimicking the radial pattern of the dark cirrus below, and from it extending to higher altitude above the horizon than the sunlight limit at 85 km alitude above ground.
- #3579 illustrates "fake NLC", where cirrus at higher altitude above the horizon appears bright against the background sky. This is not NLC, as can be detected from its West-to-East movement (contrary to most real NLC), its grey rather than blue colour, it matching neither form I nor form IV, the gradation of colour from grey to white at higher altitude, and from it extending to higher altitude than possible for NLC.
UT exp A hSun h15 h85 stretch image (masked) -------- ------ ----- ----- ----- ----- ----- ------------------- 00:30:32 8.000 3.2 -11.0 -2.6 19.0 0-255 m3569.jpg 01:00:32 8.000 10.2 -10.5 -2.3 25.1 0-255 q3579.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).