DEp.1.08 – Plans to Observe the 2017 Total Solar Eclipse from near the Path Edges

1. DEp.1.08 – Plans to Observe the 2017 Total Solar Eclipse from near the Path Edges David W. Dunham* and Richard Nugent, International Occultation Timing Association (IOTA); Konrad Guhl and Hans-Joachim Bode, IOTA/European Section * Email dunham@starpower.net Cell phone 301-526-5590 International Astronomical Union - General Assembly Honolulu, Hawaii, 2015 August 3 – 7 - Control ID 2258483 The August 21st, 2017 solar eclipse provides a good opportunity, to time the totality contacts, other Baily’s bead phenomena, and observe other dynamic edge phenomena, from locations near the edges of the path of totality. A good network of roads and generally favorable weather prospects means that more observers will likely be able to deploy more equipment than during most previous eclipses. The value of contact and Baily’s bead timings of total solar eclipses, for determining solar diameter and intensity variations, was described in an earlier presentation in Focus Meeting 13. This poster will concentrate on how observations of different types that have been used during past eclipses can be made by different observers,

2. to obtain better information about the accuracy of the different types of observations for determining the mean solar diameter, and the systematic differences between them. A problem has been that the few observers who have attempted recording Baily’s beads from path edge locations have wanted to use the latest technology, to try to record the observations better, rather than try to make the observations in the same ways that were used for many past eclipses. Several observers trying different techniques at the same location, and doing that at several locations at different places along the path, is needed. Past techniques that we would like to compare include direct visual observation (but keeping eye safety in mind); visual observation of telescopically project- ted images; direct filtered video telescopic observations; and recording the flash spectrum. There are several towns that straddle the path edges. IOTA would like to mobilize people in those towns to observe the eclipse from many places, to say whether or not the eclipse happened, and if it did, time it. A suitable cell phone app could be designed to report observations, including the observer’s location, as was attempted for an occultation of Regulus by the asteroid Erigone in the northeastern USA in 2014, but which unfortunately was clouded out everywhere.  Abstract - continued

3. Unique opportunity to deploy greater resources than usual

4. Primary goals for this eclipse • Continuation for IOTA’s long term solar radius measurement research • Standardization of video equipment • Standardization of solar filters • Co-located use of previous techniques (visual, telescopic projected image, filtered telescopic video) • 2nd use of narrow band filters (1st was for the May 20, 2012 annular eclipse) • Desired Results: calibrate with Picard satellite data and with methods used at previous central eclipses

5. IOTA Standardization Attempted for the May 2012 Annular EclipseEquipment 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

7. 0.5km 0.5km

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

9. January 24, 1925 Total Solar Eclipse – Boy Scouts and Con Ed workers found the southern limit by observing at one-block intervals across Manhattan. Similar efforts might be made at towns straddling the limits of the August 2017 TSE, a public outreach opportunity

10. 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).

11. Central eclipses before Aug. 2017 are either in remote, difficult to access regions, or in regions with quite poor weather prospects. IOTA plans to observe the Aug. 2017 eclipse from locations near the limits, for the best comparison with previous eclipse edge observations. But some IOTA observers will prefer to observe near the center, and with Kaguya and LRO profiles available, they can make useful observations for our purposes there. Some of them would likely be willing to run other non-IOTA experiments. Although capable, IOTA is too small to provide much help with a large campaign for the 2017 eclipse. Organizations such as the Astronomical League, with much greater access to those who live in or near the eclipse path, can help more.