The Annular Solar Eclipse of May 20, 2012

IOTA Research Planning for Bailey's Beads Recording at the Southern Limit - California Team

Narrative Page

Note - go to the bottom of the page for the fast-changing last minute plans!

Action Items:
* Find new sites now that cold front is moving in Sun afternoon.

Beads Video Examples
Apr 29, 1995 Annular (beads badly overexposed and contaminated by stray light - message: bring a dew shield!)
May 10, 1994 Annular by R. Wilds (overexposed vs our optimal exposure)
Jan 15, 2010 Annular by R. Nugent - Nugent suggests we try and insure our solar brightness matches this video. However, note the extended faintish light w/o beads during much of the earlier part of the video, with a representative moment screencapture here...click for a larger version Does this mean the image is too bright? Discuss at pre-eclipse meeting.

 

Derek Breit's Occult4 path of annularity (no elevation correction to this global map).

Richard Nugent's Eclipse page, with detailed filter information and planning. Also includes OCCULT4 bead animation for 1.5km track

Pre-Eclipse Meeting of the Willows Team (obsolete)
* Pre-eclipse meet up at 12:00 noon at Granzella's Restaurant in Williams
* (other suggestion, perhaps to be resuscitated if something goes wrong for Granzella's, is the Last Chance Bar and Grill in Willows)

 

Aptos to Williams is 178 miles using I-680 route, the fastest. About 3 hrs driving

Google Earth of Area: Williams to Willows

As of Friday eve, this it the cloud cover prediction for 5pm Sunday - clear skies over almost all of California, including the Willows area. Note clouds over Lake Tahoe, though - an otherwise beautiful location to watch the annular eclipse

 

Our group is setting up along "County Rd D", about 2 miles south of Willows and ~3 miles west of I-5. Elevations here are all 43 meters above sealevel, with only a tiny (~40m?) elevation correction southward to the path from what is shown here. The blue line is the OCCULT4 southern limit at sealevel.

Derek Breit's station shown on the red circle, at 1.34 km north of limit

2.0 km North of limit. Note latitude and use GPS to get there

1.5 km North

Southern limit sites, from R Nugent. #1 is 2.2km north, #2 is 1.45km north, and #3 is 0.9km north

 

Southern Limit Annularity Path Sites and Personnel

Site A: County Rd "D" ~4 miles south of Willows, 3 mi west of I-5
Site B: North of Rocklin
* equipment available for borrow during the eclipse:
-- Johnson V filter for the barrell which fits over the pc164c camera; equivalent to standard "green" filter - from Richard Nolthenius
-- miniDV recorder, from Ted Swift


Site C: at Lake of the Pines, north of Rocklin (Sandy Bumgarner)

Site D: Marysville (Andreas Tegtmeier)

Willows Stations (Note; we're now going to north of Rocklin, although Derek Breit may still be using one of these sites.)

Site
Track (km northeast (perpendicular to the limit) of the southern limit of annularity
Observers Equipment
Videocam color filter
   

 

A

Station #3 0.95 km north Richard Nolthenius 8" f/10 Meade eq mount, Walt Morgan mylar filter, 3.5" equiv diameter light gathering. PC164c w/ manual gain, Canon ZR45mc, Kiwi Red #23    
Chris Kitting + 2 student assistants 130mm Takahashi Green    
Becky Snow 8" f/10 Meade, eq, manual guiding, Thousand Oaks solar filter      
Allen Ginzburg (likely) DSLR, some photography only. No video timing gear, Arrival ~4:30pm --
A 1.45 km North Ted Swift 8" Meade eq, mylar filter. 3.87" equiv diam. PC164EX, Canon ZR45mc, Kiwi Red #23    
Walt Morgan    
A   Richard Nugent        
A 1.34 km north Derek Breit        
B ?? Sandy Bumgarner        
C 2.11 km north Lat     39°12'13.82"N
Long   121°32'39.05"W
Andreas Tegtmeier a Watec 120N with a "Russentonne" (objektiv Maksutov 10/1000) and Cuno-TimeInserter,
a green solarfilter with ND4 and a narrow band filter with 535nm
     
             

OCCULT4 Bead Simulations:
The bead animation settings panel in OCCULT4 which I used for 1.5km track on Rd D is...

Click on the links below to see the bead simulations for each track along Country Rd D. On Derek's eclipse map, set box to 146.73 to get the gray line on top of the southern limit at County Rd D. Some simulations are done at a variety of central angles, just to try and catch all beads. -1.50km continues to be the sweet spot

County Rd D Willows Bead Simulations
-2.20 km = track offset gray line 144.53 = lat 39.464691
-2.00 km = track offset gray line 144.73 = lat 39.46277
-2.00 km = at central angle 16deg
-1.80 km = track offset gray line 144.93 = lat 39.460771
-1.50 km
= track offset gray line 145.23 = lat 39.457733
-1.10 km = track offset gray line 145.63 = lat 39.453803
-1.00 km = track offset gray line 145.73 = lat 39.452794
-0.96 km = track offset gray line 145.76 = lat 39.452485
-0.96 km = at central angle 0 deg plotted
-0.96 km = at central angle 18 deg plotted
-0.96 km = at central angle 29 deg plotted
-0.90 km = track offset gray line 145.83 = lat 39.451802

 

Other useful links:
* Scotty's live annular eclipse from Area 51 (spooky!) and YouTube

Suggestions for Good Data Acquisition
* Be sure to have a well-shaded view of your monitor. My experiments showed it difficult to see the monitor (albeit with an uneclipsed sun). The annular sun will be only ~10% as bright, so this may be less of an issue at crunch time. I'd suggest a well-anchored black umbrella.
* Sitting out in the sun for ~5 hours in 90F temps will be tough! If you have disposable bucks, Outdoor World sells a 4-post shade about 8'x8' for about $50. I'll have one at my site at 0.95km north.
* Bring an inverter so you can run your camcorder or other equipment off a car battery in case it peters out. You can buy an inexpensive solid-state inverter for $25 or less at an auto parts store. I'm bringing two 12V gelcell batteries, but also a long 12v extension cord which can run from my driver's side cigarette lighter.
* While it's possible to shoot very short exposures of the low sun w/o damaging a typical digital camera, this is NOT true for a camcorder, which has continuous light on the sensor and will burn it out. Especially true if you use optical zoom!
* EVERYone should take a bathroom break at the end of our lunch meeting, whether they feel the need or not! We'll be 5 hours out in the sun at minimum. Emergency return to Willows for such purposes can be done, but let's try and minimize the need.

LATEST UPDATES on WEATHER!
* new predictions have a cold front moving uncomfortably close to our sites by eclipse time. For those based in the Bay Area, the optimum site now looks to be in the Rocklin/Auburn/Yuba City area. To maximize odds, we want to be as far SE as possible. However, we want to avoid late afternoon cumulus buildup over the Sierra (perhaps less of a danger as the sun is eclipsed, but still take note) and also the Sierra's difficult terrain for stationing people/scopes. Based on the latest weather map from SkippySky, I think Beale AFB looks best. I am looking in detail at sites and will post Google Earth images and predictions

6pm - my last webpost: You can see how the Skippy Weather forecast is changing. The cloud boundary is ratty and uncertain, but generally being south is always better. For completeness, if I were deadset on getting this eclipse regardless of any teams or any obligations (I teach all day Monday!), and no worries about gas costs, I'd drive to Bridgeport Reservoir's northern tip. Horizon looks OK, no weather front, but worries over cumulus in the afternoon would still be an issue (maybe they'd dissipate with the dimming sun?). Anyway, here's the Bridgeport map, with the red circle as the favored bead location including elevation correction,, in case anyone is interested. I'm still planning on meeting in Rocklin.

the forecast below is from Friday morning and is probably obsolete....
http://www.wrh.noaa.gov/total_forecast/getprod.php?prod=XXXAFDREV&wfo=REV

ECLIPSE VIEWING ON SUNDAY FOR EASTERN CA-WESTERN NV STILL LOOKS
BEST NORTH OF HIGHWAY 50 AND SOUTH OF SUSANVILLE-GERLACH,
INCLUDING THE TAHOE BASIN, RENO-CARSON VICINITY, AND PYRAMID LAKE.
IN THESE AREAS THE MID LEVEL MOISTURE HAS DECREASED COMPARED TO
YESTERDAY`S GUIDANCE, SO WHILE DAYTIME HEATING MAY GENERATE A FEW
FLAT CUMULUS, THESE CLOUDS WILL HAVE A SLIM CHANCE OF BLOCKING THE
ECLIPSE. FARTHER SOUTH IN MINERAL AND MONO COUNTIES, CUMULUS
COVERAGE WILL BE SOMEWHAT HIGHER BUT THESE AREAS SHOULD STILL HAVE
A DECENT SHOT OF SEEING THE ECLIPSE. FOR THE WEST CENTRAL NV
BASIN, SOME VIEWING UNCERTAINTY EXISTS AS MID LEVEL MOISTURE WILL
SPREAD NORTH DURING THE EVENING. THE LATEST GUIDANCE INDICATES
THAT SKIES SHOULD BE CLEAR ENOUGH DURING THE ANNULAR STAGE AROUND
630 PM, WITH POSSIBLE INCREASE IN CLOUD COVER AFTER THE SUN
EMERGES FROM ITS ANNULAR STAGE. NORTH OF SUSANVILLE TO THE OREGON
BORDER, THE VIEWING HAS MORE OF A POSSIBILITY OF BEING HINDERED AT
TIMES AS INSTABILITY IS HIGHER WITH MORE 500-400 MB MOISTURE. A
FEW DEEPER CUMULUS TOWERS ARE ALSO POSSIBLE ALTHOUGH FORCING
APPEARS LIMITED, SO WILL NOT INCLUDE MENTION OF THUNDER AT THIS
TIME.

Sat morn 8am SkippySky update for 5pm Sunday PDT. Cloud front is sharp. Sun will be in direction of cloud front, unfortunately, and only 18-20 degrees up, so we will need to be well SE of the cloud front for best odds. Retreat! To Yuba City/Auburn area. Detailed planning happening at this moment 9am Sat morning. Stay tuned...

Sat morn 10:45pm update, this time plotted for predicted time 8pm Sunday, after sunset. The cloud front appears to anchor at the Ca/NV/OR border and pivot around ccw, which favors sites SE. I'm still thinking that the Beale AFB site will likely work.

Sat eve 6pm forecast for 5m Sunday. Now we see the front leans south much further than the morning forecast.

Sat eve 6pm forecast now for 8pm Sunday. So the eclipse time is halfway between these last two panes. Clear skies build back into the Central Valley. It appears some high pressure ridging is increasing in the forecasts along the northern Central Valley around eclipse time. Or is it just that the simplified model cloud front of this morning is now taking on structure as simulations get more accurate and detailed?

 

From staring at these Skippy forecasts, I still have to say that being further south is better; clearly we're near the boundary of a cold front making clouds. It may be a nail-biter until the end.

Here's another weather site showing a bit less detailed cloud predictions - Weatherstreet.

Alternative Sites
B1. Silver Lake, CA (near Kirkwood Ski Area) on Hwy 88. Only if clouds really head farther SE than currently expected. Terrain difficult! Not favored.

B. Sites north of Rocklin. Settled - this is where our team will observe from. Meeting Site: 12noon at Taqueria Rincon Alteno, 4790 Rocklin Rd, phone (916) 630-1160, across the street from Sierra College (IOTA Annual Meeting site in 2011) in Rocklin. Here's a map to it.

B2. Waldo Junction/Beale AFB area:

Sun altitude = 18.24 deg here, from C2A. Sun azimuth = 281.47 degrees. Azimuth of eclipse southern limit path is 295.53 at Beale AFB, so D=295.53-281.47=14.056deg
so Tan(z)*sin(D) = Tan(90-18.44) * sin (14.056) = Tan(71.56) sin(14.056) = 2.999* 0.2429 = 0.7285. So 0.7285 km of path south shift perpendicular to the path, for every km of elevation.
Gray line on top of sealevel SoLimit at east boundary of Beale AFB for offset=147.47. Elevation at Waldo Junction is 260 ft, so path shift is .058km. So elev corrected south limit is at grayline=147.528. I like this countryside - grassland with little country roads which can expected to be vacant, gentle hills with little topography, the occasional big oak tree, near a river crossing.

Advantages: very quiet; trees available for shade during the long wait on a hot day. Traffic very unlikely. No fences, can set up as far from road as you can port your stuff. Unlikely to be bothered by anyone.
Disadvantages: might be a dirt road - hard to tell from Google Eath, be careful to set up upwind of any breeze, but again, traffic is very unlikely.

 

Waldo Jct site: station -0.9 km. Under tree on south side of road at red circle. Sun will be just left of the obvious tree at 281 az, but tree height estimated at 7 degrees.

Waldo Jct site: station -1.14km; turnout on road on east side. Relevant trees give local horizon of ~7 degrees or less, assuming 33' high

Waldo Jct site: Station -1.41km; west side of road. Trees at 5deg altitude on far side of mini-meadow

Waldo Jct site: Station -1.57km, on SW side of 3-way intersection.

Waldo Jct site: Station -2.00 km, on either side of road.

   

Waldo Junction Bead Simulations:



-0.90 km = track offset gray line 146.66 = long 121.30575, lat 39.100434
-1.14 km = track offset gray line 146.39 = long 121.3033, lat 39.104089
-1.41 km = track offset gray line 146.12 = long 121.303300, lat 39.106786
-1.57km = track offset gray line 145.96 = lat 39.108405
-2.00 km = track offset gray line 145.53 = long 121.308375, lat 39.114478


B3. Perimeter Rd. (about 8 miles further SE of Waldo Jct)
1200 ft elevation, so elev correction is 0.266 km SW of Derek's blue line for souther limit. True elev corrected southern limit at grayline=147.816 . Bead simulations essentially identical to Waldo Jct's above.

Advantages: paved road, a little higher elevation perhaps above grunge layer?
Disadvantages: residential, busier, narrower shoulders, likely interference from neighbors during our long stay.

 

 

Perimeter Rd, at 0.99km north. There's a power pole there, and set up on shoulder on the NW side of road. Long/lat on bottom of image. Long=

Perimeter Rd at 1.27 km North. Wide part of shoulder on sun side of road. Trees and slope permit observing.

Perimeter Rd, at 1.48km north. On the left side the fence line is a little recessed; unknown fence height. On right side, may need owner's permission?

Perimeter Rd, at 1.60km north. Looking towards the sun over a small canyon. shoulder looks wide enough for decent setup.

Perimeter Rd at 2.00 km north. North side of road has wide shoulder suitable for setup.