Grazing Occultation of Aldebaran – March, 2017

Grazing Occultation of Aldebaran,  March 4, 2017

 

moonview

Path across North America

n_america_map

A look at the Forecast Cloud coverage just before and after the graze.

 

 

 

Regional Maps

(click map to enlarge)

 

 

bc_id

mt

nd

mn_wi

mi_on_ny eny_ct_ri

The predicted lunar profile is shown for four locations along the graze path, based on NASA Lunar Reconnaissance Orbiter laser altimeter measurements as plotted with IOTA’s Occult 4 program. The smooth curve (dotted on the Moon’s dark side) shows the Moon’s average radius. A horizontal line shows the path of the star for an observer at the predicted northern limit, with  tick marks at 1-min. intervals relative to central graze. Other observers near the northern limit will see the star follow a similar horizontal path from left to right, but displaced north or south of the plotted horizontal line, depending on the observer’s distance from the predicted northern limit shown with the vertical scale in kilometers (on both sides). The gray bars on the left side shows the number of occultations of the star by different lunar features that is predicted for each observer, with the distance from the left edge proportional to the number of occultations. Observers will want to locate their observing sites at distances where the most occultations are predicted. In flat areas of the profile, more occultations than indicated are likely.

The top profile is for White Rock, BC, directly south of Vancouver. The graze zone is only a mile north of the US border and small telescopes are needed since the graze will occur on the sunlit limb. Near North Dakota Route 1, most of the graze will be on the Moon’s dark side, although the high mountains just after central graze will likely be sunlit. Along the path, the profile lines up best, for the most occultations of the star, at Oscoda, MI, on the west shore of Lake Huron, but the show will be nearly as good in the path across Michigan, Ontario, and into central New York. The last profile is for Narragansett, RI, the easternmost land in the graze zone; the Moon will be 13° above the western horizon there.

Animation of Graze Profile – MP4 file

 

Detailed Path Information

Use this information to determine the best times to observe based on your longitude.  Plan on observing the graze for 1.5 to 2 minutes before and after the central graze time shown in this table.  Table times are in UT and must be converted to Local Standard Time.

Google Maps for Specific Elevations

Pick the Google Map, from the list below, that most closely matches your site elevation above sea level.

Once you identify a place where you might observe, using either one of the static maps or a Google Map, find that place using Google Earth, setting the cursor on the location and, WITHOUT MOVING THE CURSOR, read the elevation given at the bottom following the latitude and longitude. If that elevation is within 100 feet of the elevation for the Google Map you used, you are done, but if not, find the Google Map for an elevation that is within 100 feet of that for the desired location, enter the appropriate offsets, and verify that the place is still between the dark gray lines on your new map. Hopefully, you won’t need another iteration to select a good site, or sites.

0 ft     100 ft (30m)    200 ft (61m)    300 ft (91m)    400 ft (122m)    500 ft (152m)    600 ft (183m)    700 ft (213m)    800 ft (244m)    900 ft (274m)    1000 ft (305m)

1100 ft (335m)    1200 ft (427m)    1300 ft (396m)    1400 ft (427m)    1600 ft (488m)    1700 ft (518m)    1800 ft (549m)    2000 ft (610m)    2200 ft (671m)    2400 ft (732m)

2600 ft (792m)    2800 ft (853m)    3000 ft (914m)    4500 ft (1372m)

Zones for specific areas are listed in the table below.

Use the offset values for the area where you plan to observe that are given in the last column of the table below

Read the cautions and notes at the bottom of the table.

Important Update:  The 2016 July and October graze observations showed a shift of 0.04″ south relative to the Occult 4 prediction, with an uncertainly of +/-0.02″. Since those grazes, like this upcoming graze in March, were/are northern limit grazes, it’s likely that a similar shift will occur for the March 4/5 graze. All of the prediction information (maps, profiles, offsets) were generated with Occult 4, so it will be useful to apply this correction. Since the vertical profile scale for the March 4/5 graze is 2.25 km/arc second, the shift will be 90 meters or 0.09 km to the south. You can just keep this in mind when using the static maps to select sites. For the interactive Google maps, you can modify the listed offsets by adding +0.09 to them, to take this into account, keeping in mind that the uncertainty is about 50 meters.

Region of Interest UT

Mar. 5

Local Time (Mar. 4) Static Maps Moon Alt Moon Az          Cusp Angle

 

Graze Profile Google Map

Elev., ft. (m)

Graze zone, km
Ucluelet, BC 3:31.6 7:31.6 pm PST Ucleulet, BC  53° 216° -2.0N Ucleulet, BC (0) -0.9 / -0.7
Ladysmith, BC 3:33.9 7:33.9 pm PST Ladysmith, BC  52° 219° -1.7N Ladysmith, BC 200 ft (61m) -1.1 / -0.6
Tsawassen, BC 3:34.9 7:34.9

pm PST

Tsawassen, BC  52° 220° -1.6N White Rock, BC (0) -1.0 / -0.5
White Rock, BC 3:35.2 7:35.2

pm PST

White Rock, BC  52° 221° -1.5N White Rock, BC (0) -1.0 / -0.5
Campbell Valley, BC 3:35.3 7:35.3

pm PST

Campbell Valley, BC  52° 221° -1.5N White Rock, BC (0) -1.0 / -0.5
Abbotsford, BC 3:35.8 7:35.8

pm PST

Abbotsford, BC  52° 222° -1.4N White Rock, BC (0) -1.0 / -0.5
Osoyoos, BC 3:39.4 7:39.4

pm PST

Osoyoos, BC  50° 227° -1.0N Osoyoos, BC 1000 ft (305m) -0.6 / -0.25
Porthill, ID 3:35.2 7:35.2

pm PST

Porthill, ID  48° 232° -0.5N Porthill, ID 1800 -0.65 / -0.45
Eureka, MT 3:44.8 8:44.8

pm MST

Eureka, MT  47° 234° -0.3N Eureka, MT 2600 -0.75 / -0.5
Babb, MT   (US 89) 3:47.1 8:47.1

pm MST

Babb, MT  52° 222° -0.0N Babb, MT 4500 -0.7 / -0.5
Route 1, ND 4:02.8 10:02.8

pm CST

Route 1, ND (s. of Cooperstown) 35° 256° +2.0N Route 1, ND 1400 -0.2 / 0.25
Gardner, ND 4:04.0 10:04.0

pm CST

Gardner, ND;

US75, MN 

34° 158° +2.2N Gardner, ND 900 -0.23 / -0.03
Moose Lake, MN (I-35) 4:07.7 10:07.7

pm CST

Moose Lake, MN 30° 262° +2.9N Moose Lake, MN 1000 -0.4 / 0.2
Amberg, WI (US 141) 4:11.5 10:11.5

pm CST

Amberg, WI 27° 267° +3.1N Amberg, WI 900 -0.05 / 0.55
Stephenson, MI (US 41) 4:11.7 10:11.7

pm CST

Stephenson, MI 26° 267° +3.1N Stephenson, MI 700 0.05 / 0.60
I-75, MI 4:13.7 11:13.7

pm EST

I-75, MI 24° 270° +3.4N I-75, MI 1300 0.15 / 0.55
Glennie, MI 4:14.4 11:14.4

pm EST

Glennie, MI 23° 271° +3.4N Glennie, MI 1000 0.34 / 0.52
Oscoda, MI 4:14.6 11:14.6 pm EST n.w. Oscoda, MI; Oscoda, MI;

Oscoda (detailed), MI

23° 271° +3.5N Oscoda, MI   [1] 600 0.34 / 0.51
Ripley, ON 4:15.7 11:15.7

pm EST

Ripley, ON [2] 21° 273° +3.6N Ripley, ON 700 ft (213) 0.29 / 0.46
w. Mississau-ga, ON 4:16.8 11:16.8

pm EST

Mississauga west, ON 20° 274° +3.7N Mississauga, ON 600 ft (183) 0.18 / 0.40
c. Mississau-ga, ON 4:16.8 11:16.8

pm EST

Mississauga centre, ON 20° 274° +3.7N Mississauga, ON 500 ft (152) 0.18 / 0.40
e. Mississau-ga, ON 4:16.9 11:16.9

pm EST

Mississauga east, ON 19° 275° +3.8N Mississauga, ON 300 ft (91) 0.18 / 0.40
Barker, NY 4:17.4 11:17.4

pm EST

Barker, NY 19° 276° +3.8N Barker, NY 300 0.15 / 0.45
Rochester, NY 4:17.9 11:17.9

pm EST

Rochester west and

Rochester south, NY

18° 276° +3.9N Rochester, NY 500 0.09 / 0.29
Phelps, NY   (I-90) 4:18.2 11:18.2

pm EST

Phelps, NY 17° 277° +3.9N Phelps, NY 600 0.10 / 0.50
I-81, NY 4:18.5 11:18.5

pm EST

I-81, NY 17° 277° +4.0N I-81, NY 1200 0.10 / 0.40
sw Oneonta,  NY (I-88) 4:19.1 11:19.1

pm EST

I-88, NY 16° 278° +4.0N Oneonta, NY 1100 0.15 / 0.43
Route 28, NY  (low) 4:19.1 11:19.1

pm EST

Route 28, NY (low) [3] 16° 278° +4.0N Oneonta, NY 1400 0.15 / 0.43
Route 28, NY  (high) 4:19.1 11:19.1

pm EST

Route 28, NY (high) 16° 278° +4.0N Oneonta, NY 1700 0.15 / 0.43
Hunter Mtn., NY 4:19.5 11:19.5

pm EST

Hunter Mountain, NY [4] 15° 279° +4.1N Hunter Mtn., NY 2400 0.03 / 0.72
Route 214, NY 4:19.5 11:19.5

pm EST

Route 214, NY 15° 279° +4.1N Hunter Mtn., NY 1700 0.03 / 0.47
Route 32, NY 4:19.6 11:19.6

pm EST

Route 32, NY 15° 279° +4.1N West Camp, NY 400 0.17 / 0.39
West Camp, NY (I-87) 4:19.6 11:19.6

pm EST

West Camp, NY 15° 279° +4.1N West Camp, NY 200 0.17 / 0.39
Clermont, NY (Route 9) 4:19.7 11:19.7

pm EST

Clermont, NY 15° 279° +4.1N Clermont, NY 200 0.07 / 0.36
n.w. Hartford, CT 4:20.1 11:20.1

pm EST

n.w. Hartford, CT 14° 280° +4.2N Hartford, CT 200 0.20 / 0.40
n.e. Hartford, CT 4:20.1 11:20.1

pm EST

n.e. Hartford, CT 14° 280° +4.2N Hartford, CT 100 0.20 / 0.40
East Hartford, CT 4:20.1 11:20.1

pm EST

East Hartford, CT 14° 280° +4.2N Hartford, CT 100 0.20 / 0.40
s. Manchester, CT 4:20.2 11:20.2

pm EST

Manchester south, CT 13° 280° +4.2N Manchester, CT 300 0.18 / 0.40
Lisbon, CT   (I-395) 4:20.4 11:20.4

pm EST

Lisbon, CT 13° 281° +4.2N Lisbon, CT 200 0.10 / 0.39
Wyoming, RI   (I-95) 4:20.5 11:20.5

pm EST

Wyoming, RI 13° 281° +4.2N Wyoming, RI 100 0.10 / 0.39
Narragansatt, RI 4:20.6 11:20.6

pm EST

Narragansatt, RI 13° 281° +4.2N Narragansatt, RI 100 0.10 / 0.39

Caution:  If actual observation site Elevation is more than 100 feet from the elevations shown, a revised Google Map should be used. For most of the static maps, we used the “Map” option, rather than “Satellite”, since most of the street names aren’t shown in the “Satellite” option. But the “Satellite” option is useful for seeing trees and other features that might hinder observation, especially at low altitude. Therefore, we recommend that you use the Google map for the specified elevation (above sea level) and the information above, to duplicate the static map for the area closest to where you plan to observe. Then switch to “Satellite” mode and zoom in, to see what’s in the area, and click on the “person” symbol in the lower right, to see the close street view of prospective sites, if that’s available for the road where you hope to observe. Note that in the “Google Map Elev.” column in the table, the elevations are given in feet, unless the value is enclosed in (), in which case, it is in meters (this is for sites in BC and ON, since topographic maps in Canada use meters rather than feet).

[Notes]:  1. Profile lines up best here, but almost as good across MI and ON to central NY.     2. Ripley is at the junction of Hwy. 6 and 7, on the east side of the map.       3. The separate maps for small areas show the importance of using the right Google Map (elevation) in hilly areas; you may need to iterate, checking the elevation above sea level frequently (Google Earth is a good source for elevations, with the coordinates and elevation of the cursor displayed at the bottom).   4. It’s interesting how the graze zone passes right over the upper slopes of the north side of the Hunter Mountain ski area. The elevation (2400 ft.) is approximately right for the center of the slope, where the northern edge of the graze zone passes, but the top, at 3200 ft., is much higher. Consequently, we’ve adjusted the southern edge of the graze zone, to approximately take this into account (the graze zone is broadened by this topography). The real situation is complicated by the rapidly changing elevations (which, of course, is why it’s good for skiing), and it would probably be very difficult trying to find a place to actually observe the graze, with the many trees and the 15° altitude above the horizon. If anyone actually wants to try to observe the graze in the area, we recommend using sites in the relatively flat valley, near NY route 214 about a mile east of Hunter Mountain, with a map and information for that given on the next line.

 

Did you observe this graze?  Do you have a video of the event?

Your observations are important!!

Please contact Brad Timerson for information on how to share your observation.