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,
Abstract - continued
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 projectted 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.
Unique opportunity to deploy greater resources than usual
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
IOTA Standardization Attempted for
the May 2012 Annular Eclipse
Equipment Specifications
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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
Ted Swift, S. Limit of May 2012
15 sec interval
Annular Eclipse
Unfortunately, clouds prevented observation
near the northern limit.
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
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 experience that we plan to use for promoting 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).
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.