Скачать или смотреть Determing the Edges of the Path of Totality on August 21, 2017 - David W. Dunham

The 231st Meeting of the American Astronomical Society (AAS) at the Gaylord Resort and Convention Center in National Harbor, Maryland.

January 9, 2018 3:10 PM - 3:20 PM

Author(s): David W Dunham1, Paul D Maley1, Jan Kok1, Fred Bruenjes1

Institution(s): 1. International Occultation Timing Association

The International Occultation Timing Association (IOTA) attempted a citizen-science project to determine the locations of the edges of the path of totality, similar to what was done visually in New York City during the 1925 eclipse. With ubiquitous smart phones, we asked observers to record the eclipse, preferably with clip-on 8x telephoto lenses. The limits are not sharp since the solar intensity drops off gradually at the path edges. We hoped to determine how accurately the path edges could be determined, and the width of their fuzziness. But it was not possible to find any astronomers who weren۪t also going to the center, who might otherwise help organize some path edge observations. In 1925, people were less concerned about the possibility of suffering eye damage from quick glimpses at the eclipse. In 2017, several were concerned about damage to their cell phones, although our tests showed this was not a problem for the two minutes desired. The only successes were at Minden, Nebraska where high school students set up 15 stations across the southern limit and recorded the eclipse with iPads, and near Wheatland, Wyoming, where Jan Kok set up 21 pre-pointed smart phones with 8x lenses that he was able to program, to record the eclipse during the critical two minutes. We found that the dynamic range of the smart phone recordings could not distinguish between the corona, and the Baily۪s beads around the contacts, so useful times of the duration of totality could not be determined. A few IOTA observers recorded Baily۪s beads telescopically at a few locations near the eclipse limits. An especially good color recording of Baily۪s beads was made by Fred Bruenjes from only 1.3 km inside the southern limit. We hope that similar recordings with accurate time stamping can be obtained at a few locations near both limits of future eclipses. Even better might be recordings of the flash spectrum near both limits, to measure the transition from absorption lines in the photosphere to emission lines of the chromosphere.

References:

   • Baily's Beads at DayStar, 2017 Total Solar...  

http://occultations.org/eclipse2017/