IOTA's Eclipse Edge Determination Experiment David W. Dunham International Occultation Timing Association (IOTA) Email dunham@starpower.net Cell phone 301-526-5590 5th 2017 Total Solar Eclipse Workshop Columbia, SC, April 1, 2017

Unique opportunity to deploy greater resources than usual

Outline and Goals Continue IOTA’s long term solar radius measurements from eclipses Emphasis on edge observations, the ultimate grazing occultation How accurately can the path edges and solar radius be measured? Citizen science with many observers, this time with smart phones Co-located use of previous techniques (visual, telescopic projected image, filtered telescopic video) to estimate realistic accuracies Standardization of scopes, cameras, and filters, IOTA for the 2012 May annular eclipse and IOTA/ES since 2008 Test color cameras and flash spectrum observations Re-reduce older observations with LRO lunar profile data (no longer limited to polar regions, so central timed recordings are useful) Desired Results: calibrate with Picard satellite & other solar radius data, and with methods used at previous central eclipses Occ’ns provide excuses to travel, or observe from home, between eclipses; IOTA encourages your participation, video cheap now

Enhancement of Edge Phenomena (Baily’s Beads, Chromosphere, Shadow Bands) near the edges of total solar eclipse paths By the late Tom Van Flandern, Meta Research

Grazing occultation analyzed with Watts profile data   Grazing occultation analyzed with Watts profile data From a grazing occultation of Antares observed from Bardoc, Western Australia, on 2009 February 17

Grazing occultation analyzed with Kaguya profile data   Grazing occultation analyzed with Kaguya profile data Same Antares graze as shown in the previous slide

  Solar Radius Determinations from Solar Eclipses Compared with SDS and SOHO Data The eclipse points with their formal solution error bars are plotted below. Four red dots are from the Solar Disk Sextant, from Sabatino Sofia. The gray curve is the “statistical thermal model correction” SOHO data from Fig. 13 of Kuhn, Bush, Emilio, and Scherrer, Ap. J., 613, p. 1249, 2004. Their “a priori thermal model correction” is about 0.2 below the statistical thermal model data. SOHO was not designed to measure the solar radius; the application of large thermal effect corrections may have systematic errors.

  The 1715 May 3 TSE Edmond Halley had the broadside to the left widely distributed across England, encouraging everyone to watch the eclipse and note where they were. It was the first Citizen Science experiment for a TSE. Thee observers reported “instantaneous” totality at locations near the actual limits, one at the north and two at the south. The observations were published in the Philosophical Transactions of the Royal Society. Paul Muller investigated the locations and measured coordinates from modern maps. North Limit South Limit 8

The 1925 Jan 24 TSE, S. Limit across N.Y.C.   The 1925 Jan 24 TSE, S. Limit across N.Y.C. Ernest Brown wanted to know where the southern limit was and encouraged residents of New York City to find it. Consolidated Gas Co. workers watched the eclipse from rooftops at block intervals along Riverside Drive, watching the Sun and looking for the shadow. Those north of 96th Street reported some totality, while those south of it said no totality occurred. 9

The 1983 June 11 TSE, Java, Indonesia   The 1983 June 11 TSE, Java, Indonesia Dr. John Parkinson organized 25 6th grade students on the north coast of central Java.  They divided into two teams, shown to the left, straddling the north (Batang) and the south edges (Bangil) of the eclipse path.  Their observations showed that the diameter of the Sun was 0.34 smaller than predicted. But the uncertainties were large, partly due to rushed training of some of the observers. The late Dr. Alan Fiala, seen near left, video recorded Baily’s Beads near the southern limit at Bangil for the first time during this eclipse. 10

Solar Radius Determinations from Solar Eclipses   Solar Radius Determinations from Solar Eclipses The radius correction, delta-R, is relative to the standard value at 1 A.U., 959.63 arc seconds. All have been reduced using David Herald’s WinOccult program and analyzed with the Solrad programs. The Delta-R values are from 2-parameter solutions using bead events within 30° of the poles to use the better accuracy of the lunar polar profile as explained in a previous slide. 11

  Accuracy of the Video Observations of the Total Solar Eclipse of February 26, 1998 The radius determinations were calculated in two stages, first a solution solving for corrections to the ecliptic longitude and latitude of the Moon’s center relative to the Sun’s center, and the solar radius. The longitude correction from this first solution was then fixed in a second solution that used only bead events within 30° of the poles and found corrections only to the latitude and radius. There were two video recordings made at each limit (N1, N2 and S1, S2) with observer’s initials in the table followed by the number of bead timings. The first line in the two tables includes all observers; the results for different combinations of single observers at each limit follow. The first line of the 2nd (2-parameter) table was used in the table in panel 9. Although the formal error for each result is rather small, the differences between results for different combinations of observers show that the true error is larger, about 0.15, apparently reflecting different levels of the Sun detected by different scope/filter/camera combinations. A similar analysis of the 1878 eclipse showed larger errors for visual observations.

Citizen Science Eclipse Edge Determination There are several cities and towns that straddle the 2017 TSE path edges. IOTA wants to mobilize people in those towns to observe the eclipse from many places, to say whether or not the eclipse happened, and if there is totality (last bead “completely” disappears, before another one reappears), time it as well as they can. In addition, we want observers to use smart phones, to video record the eclipse. We plan to work with the Megamovie project, to use their cell phone app and infrastructure to report and share observations. IOTA has some experience with this, with the cell phone app that was designed to report observations, including the observer’s location, for an occultation of Regulus by the asteroid Erigone in the northeastern USA in 2014. Unfortunately it was clouded out everywhere. For the 2017 eclipse, IOTA has much information for this project, concentrating on an effort at the southern limit in Minden, Nebraska, but applicable to other areas, at http://www.eclipsetours.com/eclipse-edge-2017/ The following are locations where the edges of the path of totality passes through the urban area proper: Northern Limit: Camden / Lugoff SC, Brevard SC, Warhammer TN, Oak Ridge TN, Bowling Green KY, Central City IN, St. Louis MO, Belleville MO, Moberley MO, Lincoln NE, and Canby OR. Southern Limit: Blue Ridge GA, Murfreesboro TN, St. James MO, Kansas City MO, Minden NE, Wheatland WY, Emmett ID and Redmond OR. Other towns are close enough to the path edge where similar experiments might be conducted, but it will be easiest at the ones listed above (they are listed from east to west along the path).

Volunteer observers invited to time the March 20, 2014 Occultation of Regulus http://occultations.org/regulus2014/ This was an example of an IOTA campaign to encourage public observation of a rare astronomical event using a cell phone app. Unfortunately, it was completely clouded out, but it gave us experi- ence that we plan to use for pro- moting observations near the edges of the 2017 total solar eclipse path. People were encouraged to observe using DSLR cameras, or visual timings using a new “Occultation 1.0” Android timing app (derived from an app that was developed for the transit of Venus in 2012; besides timing, it gets the observer’s position and automatically reports the observation).

St. Louis Schools in the northern graze zone of the 2017 August 21st Total Solar Eclipse Key to schools in the graze zone 1. Dewey IS-447 2. Compton Drew ILC-339 3. St. Louis University High School 4. Gateway STEM High-111 5. City Garden Montessori School 6. Mullanphy ILC-559 7. St. Margaret of Scotland 8. South City Preparatory Academy 9. Shenandoah-580 10. St. Frances Cabrini Academy 11. KIPP: Inspire 12. The Soulard School 13. Humbolt Academy of Higher Learning-496 3 4 5 6 7 9 8 13 11 12 10

Western Kansas City, MO Schools in the southern graze zone of the 2017 August 21st Total Solar Eclipse

IOTA Standardization Attempted for the May 2012 Annular Eclipse Equipment Specifications Telescope aperture: 75mm – 100mm Field of View – 15' - 20' Solar filter – Baader brand – in sheets Narrow band filters – Wratten #23, #56 Attempt to observe in Picard wavelengths Video camera: PC164C(EX-2), Watec 902H

0.5km 0.5km

Ted Swift, S. Limit of May 2012 Annular Eclipse 15 sec interval Unfortunately, clouds prevented observation near the northern limit.

Flash Spectrum Observations Recording the flash spectrum around 2nd and 3rd contacts promises good results, enabling measurement of the solar edge intensity profile in different wavelengths. Below: Flash Spectrum of 1980 Feb. 16th Total Solar Eclipse in Kenya

Many Occultations Between Solar Eclipses   Many Occultations Between Solar Eclipses Technology now allows observers to record transient astronomical phenomena more precisely and to fainter magnitudes than ever before. A new small, inexpensive, yet very sensitive camera (RunCam Night Eagle Astro) will allow you to participate in IOTA’s programs to accurately record occultations and eclipses, to measure the sizes and shapes of hundreds of asteroids, discover duplicity of both close double stars and asteroids with satellites, and measure the angular diameters of many stars. Occultations provide excuses for travel between eclipses, or you can just observe them from home, to further astronomical knowledge. A good example of the excitement of occultations is illustrated by this composite video of the 2017 Mar. 5th Aldebaran graze in Mississauga, ON https://vimeo.com/209854850 2011 July 19 occ’n of LQ Aquarii by Binary Asteroid (90) Antiope Near left: 10-in suitcase tele-scope deployed for an asteroidal occultation in the Australian Outback. 23

Three asteroidal occ’ns in central USA, Aug. 14 - 24   Three asteroidal occ’ns in central USA, Aug. 14 - 24 Occ’n of 5.9-mag. SAO 59794 = HIP 34358 by 930 Westphalia on Aug. 14 at 9:25 UT = 4:25 am CDT Occultation of 9.0-mag. SAO 164213 = TYC 5780-00308-1 by 834 Burnhamia on Aug. 23 at 3.9h UT = Aug. 22 at 10.9 pm CDT Below: Occultation video setup recording with an iView mini-PC Occultation of 10.4-mag. TYC 0741-01184-1 by 849 Ara on Aug. 24 at 10:49 UT = 5:49 am CDT 24