Best Grazing Occultations of the Coming Year

1. Best Grazing Occultations of the Coming Year David Dunham IOTA Meeting, Stillwater, Oklahoma 2016 July 30

2. Upcoming Aldebaran Grazes These are of the most interest, especially night-time grazes on the Moon’s dark limb. The one on July 29 was the best of the current 4-year series for North America; we won’t have one as good, or better, until the next series a Saros cycle (about 19 years) from now, actually starting in 2033; next good dark-limb event is in the s.e. USA on 2034 Sept. 5. The chances left in this series are: 2016 Oct. 19 UT (evening of 18th local time in West), with the northern limit about 500 miles north of that for July 29; thus, it passes over Los Angeles (right over downtown); Apple Valley, CA; Denver (s. & e. suburbs); and Minneapolis (far s.e. suburbs). It’s a good path with graze well on the dark side, but the Moon will be gibbous, 85% sunlit. 2017 March 5 UT (evening of 4th local time), with the northern limit passing near Seattle, Duluth, Toronto, and Hartford (Conn.). The Moon will be 46% sunlit, essentially first quarter, so it will be brighter than for the July 29th event. 2017 Aug. 16 UT (that am), will only be visible from St. Augustine, Florida essentially right at moonrise; very good atmospheric transparency will be needed to observe it. The Moon will be 36% sunlit with graze 5 deg. from the north cusp on the dark side. 2018 July 10 UT (that am), the southern limit starts at moonrise in n.e. Iowa, then crosses s. Wisc., n. Mich., and s. Ont., where twilight becomes strong. The graze will occur right at the thin southern cusp of the only 11% sunlit waning Moon.

3. The Aldebaran Graze, Oct. 19, 2016 2016 Oct. 19 UT (evening of 18th local time in West), with the northern limit about 500 miles north of that for July 29; thus, it passes over Los Angeles (right over downtown); Apple Valley, CA; Denver (s. & e. suburbs); and Minneapolis (far s.e. suburbs). It’s a good path with graze well on the dark side, but the Moon will be gibbous, 85% sunlit. So it won’t be a naked-eye event, but should be easy with binoculars or any small telescope. It is shown as the thick solid line #118 (label only on the upper right side) on the upper map on p. 178 of the RASC Observer’s Handbook for 2016. The event happens to occur during the American Astronomical Society’s Division of Planetary Sciences meeting in Pasadena, CA; I plan to attend that, and observe the graze, probably near Apple Valley. We will set up a web page for this event similar to the one for the July 29th graze.

4. View of Moon for the Aldebaran Graze, Oct. 19, 2016 Graze _ _ Aldebaran In the greater Los Angeles area, the grazing occultation will occur from10:25-10:29 pm PDT, for locations within the graze zone. The 85% sunlit waning Moon will be 19 above eastern horizon. The orange star will appear to approach the Moon from the sunlit side, passing very close to the north pole, where it may be difficult to see even with binoculars, a few minutes before the graze. The star will become easier to see as it moves onto the dark side during the graze. The view will be similar for other locations along the path in North America, but the graze will occur later for locations northeast of Los Angeles.

5. Profile for Aldebaran Graze for Los Angeles,California Oct. 19, 2016 The gray bars on the left show the num-ber of occultations of the star expected at that distance south of the pre-dicted northern limit line.

6. Path of Aldebaran Graze, Oct. 19, 2016California to Nebraska

7. Path of Aldebaran Graze, Oct. 19, 2016 , L.A. 10:25-10:29 pm PDT, Moon 85% waning, altitude 19 above eastern horizon, graze on dark side 12 from north cusp. The two black lines enclose the area where the graze will be seen, while the narrower area between the red lines is the “best” zone, with about twice as many occultations of the star. Path adjusted for height above sea level except where dashed in mountains. Approximate contours across the path show height in feet above sea level.

8. Path of Aldebaran Graze, Oct. 19, 2016Across Southern California

9. Path of Aldebaran Graze, Oct. 19, 2016Apple Valley, California Area

10. Path of Aldebaran Graze, Oct. 19, 2016Denver, Colorado Area

11. Path of Aldebaran Graze, Oct. 19, 2016Nebraska to Ontario

12. Path of Aldebaran Graze, Oct. 19, 2016Quebec and Labrador

13. Path of Aldebaran Graze, Oct. 19, 2016California to Nebraska

14. Aldebaran, 2017 March 4/5 2017 March 5 UT (evening of 4th local time), with the northern limit passing near Seattle, Duluth, Toronto, and Hartford (Conn.). The Moon will be 46% sunlit, essentially first quarter, so it will be brighter than for the July 29th event. The graze will occur at the northern cusp near Seattle, then will increase to 4 deg. on the dark side in Connecticut & s. R.I. Bitter cold weather could hamper observation along this rather far north winter path. The path is the thick solid line on this map for the 2017 RASC Handbookfrom Vancouver Island to Rhode Island

15. Aldebaran, 2017 August 16 2017 Aug. 16 UT (that am), will only be visible from St. Augustine, Florida essentially right at moonrise; very good atmospheric transparency will be needed to observe it. The Moon will be 36% sunlit with graze 5 deg. from the north cusp on the dark side. The path is the thick solid line on this map for the 2017 RASC Handbook going e. from St. Augustine Florida Note: This is 5 days before the Great American Eclipse

16. Regulus, 2017 October 15 2017 Oct. 15 UT (that am), at moonrise; very good The Moon will be 20% sunlit with graze a few deg. from the north cusp on the dark side. The path is the thick solid line on this map for the 2017 RASC Handbook From Oregon to Quebec

17. Aldebaran Graze, 2018 July 10 . 2018 July 10 UT (that am), the southern limit starts at moonrise in n.e. Iowa, then crosses s. Wisc., n. Mich., and s. Ont., where twilight becomes strong. The graze will occur right at the thin southern cusp of the only 11% sunlit waning Moon.

18. Aldebaran, 2017 August 16 2017 Aug. 16 UT (that am), will only be visible from St. Augustine, Florida essentially right at moonrise; very good atmospheric transparency will be needed to observe it. The Moon will be 36% sunlit with graze 5 deg. from the north cusp on the dark side. The path is the thick solid line on this map for the 2017 RASC Handbook Going e. from St. Augustine Florida Note: This is 5 days before the Great American Eclipse