2010. január 16., szombat
New halo in elliptical halo / Bottlinger family Part II
A video and two new images of the 09-10 January 2010 Display in Kangasala, Finland are now available for viewing (1 - 2 - 3). As you follow the first link please note that the video is displayed below the still image.
The video consists of 79 consecutive still images, each shot with a 6s exposure time. The camera shot a new frame automatically as the last one finished so the exposures lasted for 479 seconds (just under 8 minutes). Based on the EXIF data recorded by the camera the 79 frame sequence lasted for 585 seconds (so 106 seconds of the time were used by the camera's internal electronics and the operation of the shutter mechanism between frames). This time frame of 585 seconds is compressed into 20 seconds on the video.
The width of the halo changes abruptly between frames in the video. At one point (about three seconds into the video) the shift is particularly dramatic. Either the change is due to sudden changes in crystal orientations or the apex angle of the halo forming wedge in the crystals was changing (probably in steps, not in smooth continuity).
Part I of this post can be found here: (4)
Edit: new animated images are available (5 - 6). See comments for more information.