Upcoming Grazing Occultations David Dunham IOTA Meeting, Carson City, Nevada 2017 September 10 Updated 2017 October 12

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. Other grazes from Sep. 11 to Oct. 26 are also shown; available at iota.jhuapl.edu/ GRAZEMAP.HTM and click on “North American grazes to mag. 7.0”

The Regulus Graze, Oct. 15, 2017   Sun  91 Sun- Alt -12 Alt 24 Rise  108 Alt 11 2017 Oct. 15 UT (morning local & UT), with the northern limit as shown above, across the northern USA and southeastern Canada. The predicted profile is given for the two longitudes shown.

Profile for Regulus Graze for Long. 108 W, near Billings, MT 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.

The Regulus Graze, n.w. USA, Oct. 15, 2017 2017 Oct. 15 UT (morning local & UT), with the northern limit as shown above, across the n.w. USA. The path passes over Billings, MT and Bismarck, ND

Profile for Regulus Graze for Long. 95 W, in north central Minnesota 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. The profile lines up best here, and the star altitude is higher.

The Regulus Graze, n.cen. USA, Oct. 15, 2017 2017 Oct. 15 UT (morning local & UT), with the northern limit as shown above, across the north central USA. The path passes over Bemiji and just south of Grand Portage, Minn., and over Isle Royale.

The Regulus Graze, Bemidji, MN, Oct. 15, 2017 2017 Oct. 15 UT at 10:01 to 10:05 UT (5:01-5:05 am CDT), with the northern limit as shown above, across Bemidji, Minnesota.

The Aldebaran Graze, Bemidji, MN, July 29, 1997 Remarkably, another 1st-mag. graze passed over Bemidji on 1997 July 29 UT at 10:00 UT (Sun alt. -9). Twin Cities amateurs went there, and worked with local people to successfully observe the graze. The event was a Meton cycle (19 years exactly) before last year’s Aldebaran graze seen s. of Stillwater, OK

The Regulus Graze, s.e. Canada, Oct. 15, 2017 2017 Oct. 15 UT (morning local & UT), with the northern limit as shown above, across southeastern Canada. The event is in bright twilight on the east end of the path shown. There are viable sites where the path crosses flat farm country in parts of Ontario and Quebec.

Aldebaran Graze, 2017 Dec. 30 .2018 Dec. 30 UT early evening, the southern limit passes over the Florida peninsula (so a total occultation is visible from most of the USA, in daylight in the West). The graze will occur among sunlit features at the southern cusp of the 93% sunlit waxing Moon. Sun alt. -10, Moon alt. 35 in east, around 6:25 pm EST.

.Lunar Profile for Florida. Aldebaran Graze, 2017 Dec. 30 .Lunar Profile for Florida.

The Last Aldebaran Graze (until 2033) 2018 July 10 UT, the s. 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. (Last of this series for us)  Alt. 12 Sun -8  Alt. 7 Sun -12  Alt. 5

2018 July 10 Aldebaran Graze Profile

2018 July 10 Aldebaran Graze Mackinaw City region & s.e. ON

Other Grazes in 2018 The 2017 February 18th graze of 3.9-mag.  Librae shows that you don’t need a 1st-mag. star to observe an interesting grazing occultation. A 6th or 7th-mag. star when the lunar profile lines up right can give an interesting show, that’s useful to resolve (discover, or cast into doubt a past claim) close double stars. The map below is just one of 6 that will appear in the RASC Observer’s Handbook for 2018, will be posted on IOTA’s graze site sometime in Dec. at http://iota.jhuapl.edu/GRAZEMAP.HTM, can be computed with Occult 4, and will be sent in the annual files to IOTA members.