Aldebaran Graze Planning Meeting OSU, Stillwater, OK, July 28, 2019 David Dunham (may be given by someone else; see below) International Occultation Timing Association (IOTA)

View of Moon for the Aldebaran Graze, July 29, 2016 _ Aldebaran This is the view of the 23% sunlit waning crescent Moon as seen from Oklahoma, but the view will be virtually the same for other locations along the graze path across North America. The orange star will appear to approach the Moon from the sunlit side, passing very close to the northern cusp, where binoculars will probably be needed to see the star a few minutes before the graze. The star will become easier to see, even with the naked eye (where strong twilight or daylight doesn’t interfere), as it moves onto the dark side during the graze. The dark side of the Moon is faintly illuminated by “Earthshine”, and the darker “maria” (lava-filled “seas”) can be seen with binoculars.

Overview • Expedition Goals • Weather Forecasts • US 177 Sites • Alternate Sites • Site Schedule • What You Need to Do • Observing Strategy • Post-Graze Reporting

Expedition Goals Observe the whole profile. This has never been done before. It’s possible with this graze due to Aldebaran’s 0.020″ angular diameter, that projects to 46m on the ground (distance subtended at the Moon’s distance by the orange giant star, 67 light-years away, taking into account the angle of projection). So if we can video record the graze from stations spaced at 40m intervals across the graze zone, we should be able to do it – a just-ending disappearance at one station will be just starting at the next station north. 40m is perpendicular to the path; along a N-S road, the spacing is 46m. The diameter of Aldebaran is well-known from many past total occultations; we might resolve some disk features. Obtain a good color recording of the graze. I did that at the Antares graze in W. Australia in Feb. 2009, but strong wind shook the 2 telescopes with color cameras, giving an unstatisfactory result.

Weather Forecasts It’s clear this afternoon, but thunderstorms are increasing over western Nebraska and n.w. Kansas, and they are moving south-southeast towards us. The Canadian transparency forecast predicts these, and its animation shows how they will build further and move into Oklahoma and the Texas panhandle during the night.

WeatherBell Analytics (credit Brad Timerson, updated)

Canadian Weather Forecast for Astronomy Transparency

Canadian Weather Forecast for Astronomy Cloud cover - east

Canadian Weather Forecast for Astronomy Cloud cover - west

Canadian Weather Forecast for Astronomy Humidity

Skippy Sky - not updated www.skippysky.com.au

US National Weather Service Cloud cover, temperature, dew point

ECMWF forecast (credit Brad Timerson; updated)

US 177 Sites Beautiful site only 19 miles south of Stillwater. Graze will occur from 10:06.0 to 10:09.2 UT. Moon alt. 28°, az. 90°, Sun -16° Light traffic then, wide shoulders and fields extending to east Only one house & couple of Businesses in the zone Art Lucas has talked to the residents, they are ok with our presence.

US 177 Predicted Profile Used the one for Edmond, OK, about 35 km west

Alternate Sites Hobart, OK: 3h from Stillwater Carey, TX: 4h from Stillwater, near Childress, TX Abernathy, TX: 6h from Stillwater, n. of Lubbock

Hobart, OK

Hobart, OK

Hobart, OK (sites near airport) Update for Hobart Graze will occur from 10:06.0 to 10:09.2 UT. Moon alt. 28°, az. 90°, Sun -16° Light traffic then, wide shoulders and fields extending to east Only one house & couple of Businesses in the zone Art Lucas has talked to the residents, they are ok with our presence.

Carey, TX

Carey, TX (nw of Childress)

Carey, TX

Lubbock, TX

Lubbock, TX Sites n. (I-27) or n.w. (US64) of Lubbock

Abernathy, TX

My Site Schedule 5am + Observe the Graze 4am Add & turn on recorders at all remote stations 3am Finish pre-pointing?; 1 hr contingency 12am Start pre-pointing 10:30pm Site survey – pace stations, tape large # markers on telephone poles and/or fence 9pm Notify police, arrive in area, get motel 3pm Need to leave Stillwater if go to Lubbock But could use another hour to set up equipment; We’re currently planning to go to Childress, TX to join Ernie Iverson, and observe from the Carey sites, but if it looks worthwhile to go on to Lubbock when we arrive in Childress, we’ll do that.

What You Need to Do Video-record the graze, preferably with time insertion Pace distance from the number of your station, on fence or telephone pole, # of paces from the sign, East or west, and north or south

Observing Strategy Find clear-enough sky (can observe through thin-enough cirrus) More later

Post-Graze Reporting See “What you need to do” above; we’ll have a debrief Friday afternoon, for those who can make it back to Stillwater by then