Last night while conducting an astronomy program, I saw a tangential arc. I was caught without a good camera and this cell phone photo failed to catch the full color of the 5-minute phenomenon. Also visible to my eye, but not well shown in this photo, was the 22-degree halo around the setting sun.
This is the second tangential arc I've seen. The last one was on Dec 2010 and was accompanied by a very faint circumzenithal arc:
I use this blog as a companion to my website www.brightstarstemeculavalley.org, where I call attention to local light pollution and share my enthusiasm for science and astronomy. I'm also a contributor to www.SkepticalScience.com.