Lunar Grazing Occultation Maps for North America for 2024 - New 2023 Dec. 23
by Eberhard Riedel and David Dunham
Observations of grazing occultations still valuable, as M. Soma discussed at IOTA meeting
A solar eclipse observed near the limits of central eclipse is the ultimate graze
We post here, the video of the Oct. 14th annular eclipse we recorded near the s. limit and a recent presentation about it
The best lunar grazing occultations of 2024 in North America are shown in a map and tables in this .pdf document. The map, tables, and text of the document are adapted from pages 171 to 174 of the 2024 RASC Observer's Handbook. But many additional good lunar grazing occultations that will be visible from North America in 2024 are shown in maps and tables with more detailed information given below. Below are links to maps and data for the brighter lunar grazing occultations in North America during 2024. There are 4 maps of populated parts of North America showing grazing occultations of stars brighter than mag. 7.0, that should be visible with small telescopes. In the maps, the lines are: - nighttime dark limb: solid lines - nighttime bright limb: dashed lines - daytime dark- and bright limb: dotted lines We use thick lines for all occulted bodies 1.5 mag. and brighter, and for major planets, regardless of their magnitude. Much information about observing occultations of all types is in "Chasing the Shadow: The IOTA Occultation Observer's Manual" available for free download here. ______________________________ Grazing occultations in North America during 2024 to mag. 7.0 Table Map, Jan. 1 - March 19 Map, March 20 - Aug. 31 Map, Sept. 1 - Oct. 15 Map, Oct. 16 - Dec. 31 Path data On the maps, time tick marks are on the north side of southern limits and on the south side of northern limits, that is, on the side of the limit that has a total occultation. The tick marks are at integral 10-minute intervals of U.T., with the U.T. at the western end of the path being given in the table. The Moon's shadow always moves from west to east across the map. The paths end in "A" when the altitude above the horizon equals the star's or planet's magnitude, and it ends in "S" if the Sun altitude equals the negative of the star's magnitude. The path ends in "B" if the graze goes onto the sunlit side of the Moon. ______________________________ Path data for grazing, properly partial, occultations of planets The above only include grazes of stars. There are six limit lines for grazes of planets given in the map and table on pages 1 and 2 of the .pdf document. The path data for the six grazes of planets that cross land on our North America map are given in separate files generated with the Occult4 program below. Since planets are not point sources like most stars, data for two paths are given, an inner limit where the planet is just completely covered only at the time of closest approach (the U.T. time given), and following it, an outer limit where the edge of the Moon just touches the limb of the planet at the time of closest approach. The inner and outer limit define the partial occultation zone, where the planet is partially but never completely covered during the graze; it is a few to several km wide, depending on the angular size of the planet and the distance to the Moon. The partial occultation has its longest duration at the inner limit, near which mobile observers will want to travel to observe the phenomenon. The inner limit, or edge of the partial occultation zone, is south of the outer edge for northern grazes and is north of the outer edge for southern grazes. Whether the graze is northern or southern can only be told by the N or S in the file name, or the same letters following the cusp angle (CA) given in the last column of the path data. April 7, Venus, northern graze June 27, Saturn, northern graze Since conditions for this event are good enough, the graze of Titan, the 8th-mag. brightest moon of Saturn, might also be seen: June 27, Titan, northern graze September 17, Saturn, northern graze September 17, Saturn, southern graze November 11, Saturn, northern graze December 18, Mars, southern graze Although observations of partial occultations of planets have no current scientific value, they are included since they can be interesting to watch, and recordings of them can have educational value. ______________________________ These maps, table, and path data were published previously in the RASC Observer's Handbook, for example, on pages 174-178 of the 2021 Handbook. But starting with 2022, only one map of the brighter grazes for the whole year are published, while these maps for many more grazes of stars of 7th mag. and brighter (but some fainter, to 9th mag., during total lunar eclipses) will be provided online, only at this Web site. During the gibbous phases, when glare is strong, especially near full moon, magnitude limits brighter than 7th are used. A page like this for North American grazes during 2022 is here and one for 2023 is here (but you will find there only the .pdf document that documents the brightest grazes; the more extensive maps and tables for many 2022 (and early in 2024, the 2023) grazes were\will be removed to make room for the 2024 material), and one for North American grazes during 2021 is here. Predictions of grazing occultations during 2024 within 200 miles of Blue Springs, Missouri during 2024 are here. Other information described below is on Bob Sandy's page of the main lunar IOTA Web site. These include predictions of total lunar occultations for 40 major North American cities, a list of all known successful grazing occultation expeditions, as published in Occultation Newsletter, that were conducted between 1974 and 1986. Reduction profiles (plots of the observations relative to Watts' charts of the edge of the Moon), most prepared by Bob Sandy, are also available for many of the larger graze expeditions. ___________________________________ GRAZE OBSERVATIONS STILL NEEDED, BUT TOO MANY NOW IGNORE THEM Dr. Mitsuru Soma described the continued importance of observations of grazing occultations of stars in his presentation at the 2023 IOTA meeting. In the YouTube video of his talk, he voiced concern over the large drop in observations of grazes in recent years as observers worldwide concentrate much more on asteroidal events. His last slide shows how, since 2021, only in Japan have a large number of grazes been observed, while in Poland 2 were recorded, and only 1 in each of 10 other countries. We do not need large expeditions like in the 1960s and 1970s when details of the lunar profile were poorly known. Now we can generate detailed profiles using Kaguya and LRO voluminous laser altimeter measurements so observers can be directed to the best distances from the predicted limit lines to obtain a maximum number of contacts. Although good astrometric information can be obtained by only one observer, recordings from 2 or 3 stations, spaced 100m or more apart, can give better results. Especially the brighter stars often have poor Gaia data that can be improved with lunar graze observations; as Dr. Soma explained, close double stars often cause the Gaia astro- metric errors that can be measured and quantified with graze data. ___________________________________ THE ULTIMATE GRAZE, THE 2023 OCT. 14TH ANNULAR ECLIPSE AT THE S. LIMIT - a preview of what might be done for the 2024 April 8th total solar eclipse Not shown on this page is a prediction for the ultimate grazing occultation, one of the Sun that will occur on April 8. Similarly, in our 2023 grazes page, we did not include predictions for the annular solar eclipse of October 14th. A good prediction site, which takes into account both the topography of the Moon and the Earth, is Xavier Jubiers zoomable Google map for the 2024 APRIL 8th TOTAL SOLAR ECLIPSE. We used his similar map for ASE_2023 that we used to select our observation site in Mentmore, NM, a few miles west of Gallup and a similar distance west of the Arizona border. The coordinates of our 127mm telescope were: Latitude 35.50030 deg. N, Long. 108.85797 deg. W (GPS, from IOTA-VTI), altitude 1966m (from Google Earth, within a meter of the IOTA-VTI value). You can see the multitude of Bailys beads during the central 3 min. in our video recording. Links to the full 7-minute video of our eclipse, and a couple of short videos of sunspot occultations, are on the 2023 graze page, but those videos will be removed in early 2024; they will be available upon request via a DropBox share after that, for those interested. David and Joan Dunham gave a presentation about their observations at a meeting of the East Valley Astronomy Club, held in Gilbert, Arizona and online on 2024 Nov. 17. A .pdf of their presentation was shown; there is also a .pdf of the narration for the presentation. At the end of the presentation, the prolonged visibility of Bailys beads and the chromosphere as seen from locations a km or so inside the path of a TOTAL SOLAR ECLIPSE was stessed, as shown in a great recording of the 2017 solar eclipse by Fred Bruenjes from his home about 2 km n. of the southern limit of totality. Please watch it; it may convince some to observe from locations just inside the path edges of the 2024 April 8th total solar eclipse. IOTA used to strongly encourage accurately timed video observations of solar eclipses from near the edges of the paths of totality or annularity, for measuring the solar diameter, but we came to realize the difficulty in deriving such information from such recordings, as noted in the presentation. Nevertheless, others are interested in obtaining such observations, mainly to improve predictions for future eclipse, and since this was the last annular eclipse visible from the USA until 2048, it was a last chance for us. Our success was payback for our failure at the 2012 annular eclipse, when we were misled by a hand-held GPS and ended up about 15 miles outside the zone of annularity. __________________________________ ONE OF THE BEST GRAZE VIDEOS, 2017 ALDEBARAN, 5 STATIONS SYNCHRONIZED On 2017 March 5 (4th local date), Andreas Gada led a team of observers to locations near a country club in Mississauga, Ontario, to record a grazing occultation of Aldebaran on the dark side of the crescent Moon. Video recordings of the event were obtained at five of the stations, and Andreas edited them to create this amazing synchronized composite video which clearly shows the multiple event grazing occultation phenomena and how they change with the geographic spacing of the observers. __________________________________ Total Lunar Occultation Predictions Predictions of the better total lunar occultations worldwide (mainly for stars and planets of 3rd mag. and brighter) for hundreds of cities are given in a large box, "Upcoming Bright Star Occultation Events", on the left side of IOTA's lunar occultations Web page at http://www.lunar-occultations.com/iota/iotandx.htm. Clicking on the star name takes you to a Web page for the event with a small-scale map of the occultation's region of visibility at the top (on this map, the northern and southern limits of the region are shown as white lines when the event occurs at night, dark blue lines when it is in dusk or dawn twilight, and dotted red lines when it occurs during daytime; the turqoise curves on the right and left side show where the occultation disappearance and reappearance occur at moonrise and moonset). Below the map is some general information, followed by the predictions for the disappearance, and that is followed by similar information for the reappearance. The cities are listed in alphabetical order by the two-letter country code, and by the city name for each country. For US cities, the state two-letter code is given after the city name, but the order is only by the city name, irrespective of in which state it is located. At the end, following the D and R information is a list of the longitudes and latitudes of all of the cities for which predictions are given. IOTA's lunar occulta- tions Web page is maintained by Rob Robinson, email address webmaster@lunar-occultations.com . ___________________________________ Dr. Eberhard Riedel IOTA-ES Public Relations Mobile +49 179 1253558 e-mail: E_Riedel@msn.com ___________________________________ Page set up by David and Joan Dunham on 2023 Dec. 23 Cell phone 301-526-5590 email dunham@starpower.net