Observing the Eclipse from the Edge, and other IOTA Projects

1. Observing the Eclipse from the Edge, and other IOTA Projects David W. Dunham International Occultation Timing Association (IOTA) Email dunham@starpower.net Cell phone 301-526-5590 Riverside Telescope Makers Conference Camp Oakes, Calif. May 27, 2017

2. Unique opportunity to deploy greater resources than usual

3. 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

4. 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

5. Why Observations near the Path Edges were better than those near the Center • The Moon is very close to the ecliptic (hence its name) during a solar eclipse, so the latitude libration is near zero. • The longitude libration can have any value during an eclipse. • Consequently, the same lunar features cause bead events near the lunar poles, while different ones cause them near the center. • For observations near the eclipse path limits, this reduces the effect of the typical 0.2 error of the profile data from Watts’ charts (U. S. Naval Obs. Pub. #17, 1963) that were used for the profiles to the right. • Some of the polar profile has been refined by observations of lunar grazing occultations of stars observed by IOTA. • Central eclipse timings can be used now that the Lunar Reconnaissance Orbiter mapped the Moon accurately. Two Lunar Profiles from Watts superimposed, both lat. Libration 0 but with long. librations +1.0 and –5.0

6. Grazing Occultation Geometry

7. Starting in 1965, cable systems were developed for observing grazing occultations, first at USNO, then by 3 clubs in California (Riverside, Santa Barbara, and Mount Diablo Astronomical Society), and Milwaukee, Wisconsin This is a Riverside A.S. expedition near Adelanto in 1966; I’m wearing a white jacket. Observations were visual, with audio tones recorded at the central station.

8. Lunar Profile from Graze of delta Cancri – 1981 May 9-10 Alan Fiala, USNO, obtained the first video recording of multiple events during this graze, with 7 D’s and 7 R’s Circled dots are Watts’ predicted limb corrections

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

10. Grazing occultation analyzed with Kaguya profile data Same Antares graze as shown in the previous slide. Currently available LRO data are even better. Thus, timed recordings of Baily’s beads anywhere in the path of totality, including near the center, can be used for studies of the solar diameter.

11. 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.

12. 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 South Limit 12

13. 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. 13

14. 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. 14

15. 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. 15

17. 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.

18. 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). Citizen Science Eclipse Edge Determination

19. 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).

20. The northern graze zone of the 2017 August 21st Total Solar Eclipse over the western part of St. Louis The graze zone, where the largest drop in the central intensity is expected, is 300m outside to 700m inside the predicted limit line.

21. The southern graze zone of the 2017 August 21st Total Solar Eclipse over western Kansas City, MO

22. 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

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

24. 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

25. 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 In our opinion, the best place to Observe the eclipse is from the middle of the country, where we can observe the brightest “predictable” asteroidal occ’n of 2017 a week before, see upper left, then 2 good ones after the eclipse in n. Missouri. Columbia, MO is our base, but we’ll move to clearer areas, if necessary. Occultation of 10.4-mag. TYC 0741-01184-1 by 849 Ara on Aug. 24 at 10:49 UT = 5:49 am CDT 25

26. The Dunham’s Plans for 2017 August 21 • Joan - investigate effects of color on determining the bead events by simultaneously recording the eclipse in color and in B&W. • 2 telescopes + telephoto with 3 video cameras on an iOptron AZ Mount Pro • ZWO ASI120 on an 80mm apochromatic refractor, recording with SharpCap to a Win 10 laptop, data tagged with internal PC clock • RunCam Night Eagle Astro on a 115mm apochromatic refractor, recording with IOTA Video Capture to a Win 110 laptop, and tagging the data with a IOTA VTI. • QHY 5L-2II on a 500mm telephoto, recording with SharpCap to a Win 10 laptop, data tagged with internal PC clock • Also recording with a cellphone and a Nikon using a 500mm telephoto for the MegaMovie, neither on a driven mount. • David – A flash spectrum observation similar to Roger Venable’s, & video of a “legacy” projected image of the beads. • Location: Where it is clear and can be reached in 12 hours on the road from Columbia, MO, exact site to be picked about Aug 19.

27. 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. 27

28. RunCam Night Eagle AstroAn Inexpensive Entry-Level Camera for Recording Occultations RunCam Night Eagle Astro (top) compared RunCam Night Eagle Astro with metallic tape With the no-longer-available PC164C-EX2. added to block light leaks and relieve tension (bottom). on cables connections. The Night Eagle Astro is available from runcam.com for $65 without a fisheye lens (used by some on drones) and $80 with it (shown on the right; on the left, the M12 and other adapters needed to insert into a 1.25in eyepiece holder, are shown). The Night Eagle Astro has 3 levels of integration, up to 4 frames, making it able to reach stars more than a mag. fainter than the PC164C-EX2.

30. Occultation of the 6.0-mag. Close Double Star SAO 78349 by (9) Metis on 2001 September 7 • The star was known to be a close double, sep. about 0.08” with 6.5 and 6.9-mag. Components, from a photoelectric lunar occultation recording at McDonald Obs., Texas, on 1973 April 9 • Best asteroidal occultation of 2001 in the U.S.A. • Unfortunately, 1 night before the occultation of a 7th-mag. Star by Uranus’ satellite Titania in Europe & n. S. America • I made the first REMOTE recording of an asteroidal occultation during this event, in the Sacramento Valley of northern California • Kent Okasaki tried a remote observation of this event, but he tried to track with a 20cm SCT, and the tracking wasn’t accurate enough

31. Sky-plane plot of Metis occ’nfrom March 2002 S&T

32. Remote equipment at Orland, Calif.This used my image intensifier and a 50mm Nikon lens, but similar results (with a narrower, about 3°, field of view) are possible with the PC164C.

34. The Mighty MiniIntroduced to IOTA Aug 21st, 2008 Can record occultations of stars to mag. 9.5, even mag. 10.0 under good conditions 50mm objective, f/2 effective f/ratio (with Owl focal reducer)

35. “Paver Mount” for 80mm Orion Short-Tube Refractor, the “Mighty Midi” designed by Scotty Degenhardt, with the mount designed by John Broughton Remote stations for asteroidal occultations use 8cm Orion short-tube refractors on stationary pre-pointed “alt.-alt.” paver mounts like the ones shown above. On the right, Joan is using one to practice observing the Sun for the March 2016 Indonesian total solar eclipse. We call these systems “mighty midi’s” and can record stars to 11th mag., with at least ½ mag. gain with the new RunCam Night Eagle Astro with integra- tion. Mighty maxi’s are similar, larger, using 120mm short-tube refractors rather than 80mm ones; they can reach fainter than 12th magnitude.

38. The new (2016) design components All components, on our deck. The 2 PC164C-EX2 cameras shown were in carry-ons.

39. The new (2016) design assembled The altitude adjustment bars are attached; the scope is then ready to use. The upper wingnuts are tightened at the approximate event altitude; the lower ones are kept loose.

40. Record video to Computer In the past, we’ve recorded occultation videos with VCR’s, bulky “combo” units, and camcorders. Now it’s easiest to record them with a laptop computer. The view to the left is for a system suitable for remote-station deployments, using a $100 stick computer the size of a small matchbox. It needs to be connected tempor- arily with cables or dongles to a monitor and keyboard Labeled picture TBS for setting up, then just leaving the stick connected to its battery, and the StarTech video capture device that in turn connects to an IOTA-VTI and the camera on the telescope. At an observatory, or for an observer running one (attended) station, it’s simpler to just use a laptop. Then, you just need a laptop you already own, plus the StarTech video capture device (available for around $35) and free software (the StarTech driver and IOTA Video Capture), & IOTA-VTI or WWV for timing.

41. Sept. 11, 19:59 UT, occultation of 9.2-mag. star by Asterope Joan and I ran 11 stations along the Stuart Hwy from Wycliffe Well to Churchills Head (northern attended station), 3 120mm maxi’s, 6 80mm midi’s, a mini with an integrating camera, & the 10in. scope. The 3 southern stations had no occultation, station 4 camera battery was too low, and the 7 others were all positive, a record for us. The PPMX catalog showed a large north shift (see below) which is why we set up as far north as Churchills Head (good thing we did) & later work by S. Preson confirmed a north shift likely. failed Generated and posted by Brad Timerson Most stations didn’t have VTI’s so in 2016 Feb. we tested ZR’s

42. Sept. 11, 19:59 UT, occultation of 9.2-mag. star by Asterope With 7 chords recorded across the length of the asteroid, this was our most successful effort ever to observe an asteroidal occultation.

43. REGULUS! S U N R I S E

44. Path of the Regulus/Adorea occultation over New Ireland Kavieng  Predicted Central Line Predicted Southern Limit

45. During the 3s occultation, we recorded Regulus’ companion that was Discovered spectroscopically in 2005.  This was the first ever view of Regulus’ close companion, which was 12th magnitude, consistent with its being a white dwarf, as the discoverers had speculated. Adorea was only mag. 14, too faint to be recorded with our 10-in. scope. Note Regulus’ distant 8th-mag. visual companion above the star. The earlier clouds prevented pre-pointing 4 “mighty mini’s” that we had with us. During the trip, we also recorded an occultation by asteroid Lumen from the Glass House Mountains area of Queensland, attended the American Astronomical Society’s Division of Planetary Sciences conference in Pasadena, Calif., and visited our son in Ann Arbor, Michigan.

46. Occ’n by Centaur (95626) 2002 GZ32, 2017 May 20 observed from Europe • Occultation recorded (positive) • No occultation (negative)   On May 24, occ’n by Plutino 2003 FF128 observed from 2 stations in s.e. Australia

48. S. Calif. asteroidal occultations - 2

49. June 2/3, occultation of 15.6-mag. star by 2014 MU69, huge effort organized by SWRI near Mendoza, Argentina and north of Cape Town, South Africa using 22 16-in. Skywatcher GoTo Dobsonians (beautiful scope). We observed the target field at Steve’s place, Gamber, MD, with our 16in Skywatcher last 2 mornings.

50. IOTA Meeting Sept. 9-10, 2017 • You are invited to attend this meeting at the • Jack Davis Observatory in Carson City, Nevada • You don’t need to be a member to attend • Followed on Sept. 11 by planning for, and observing, an occultation of a 9.0-mag. star by (241) Germania at 11:15pm PDT