The 2023 Dec. 11/12 occultation of Betelgeuse by (319) Leona - Updated 2023 Dec. 11, 22h UT

Another live-stream, and more for Florida observers with advice for a late campaign joiner; also, new weather maps (challenging)

Links for 3 planned live-streams are given, and correlation of Florida stations with the many European ones ia given

Expanded information on the Dec. 12th occultation of Betelgeuse by (319) Leona and info. about important online meeting held Nov. 11 added here

Also here, you can get the latest predicted Google Earth file with 40 fence lines but the 53 lines from Paris Observatory, link given, are the official ones

The overall path of the occultation is shown in this Occult world map that 
uses the latest prediction data (see below). It includes a diagram on the 
upper left showing the expected light curve of the event at the center.


For now, please use only At the moment, I can not 
access my work email,, so DO NOT USE THAT ADDRESS.
It should be fixed sometime later today (Dec. 11 our time),
perhaps a couple of hours before this occultation. You can also text me at 
+1-301-526-5590 if you need help. Since I am not trying the occultation, 
I can consult Web sites from my home to help those travelling.
_ _ _


Below is a message I wrote to a late-joining new observer, and his message:

Hi Juan,

For observing the occultation, a phone video or DSLR camera video through a wide-angle 
eyepiece of your Dob would be much better than a visual observation, so experiment with 
that during the hour or so of dark time before the event, to see what you can manage.

For selecting a site, it is best to use Carles Schnabels (Florida starting) Google map 
- this goes directly to the path in Florida, while the link on our Web page goes to Spain 
This map (also linked to in the FLORIDA section 2/3rds of the way down) shows the region 
around Miami from Schnabels map – no observers are currently on the black lines, so it would 
be best to select one of them to observe from; for example, line 21 (passing through Palmetto Bay, 
but of course sites west of there will be darker) is open and is a line not far from the central 
line not covered by others. But even a red line could be selected since most of them are occupied 
by European observers who may be clouded out – at this point, it seems to be a toss-up over who 
will have the thinnest clouds, Spain or Florida, both do not have real good forecasts, so 
observation in both regions are encouraged. Areas in Europe in the path east of Spain seem to have 
somewhat worse chances. In any case, observe at least one line interval (about 3.6 km) away from 
any other of the Florida observing site lines shown on the map.

Once you select a site, go to the Occult Watcher (OW) cloud link for the occultation. 
It includes another zoomable Google map that you can zoom in on, to the site you’ve selected; if you 
click on it, you will get a display like shown here giving the event time and local circumstances. 
It gives the occultation time as 01h 24m 56s of Dec. 12 UT; that’s just 4s before 8:25:00 pm EST 
tonight (Dec. 11 EST) and the time will be within a few seconds of that throughout the area shown 
on the map. It also shows that Betelgeuse will be 23 deg. high in the east while the Sun will be 
well below the horizon, more than an hour after the end of astronomical twilight, of course also 
true throughout s. Florida. For a first-mag. star, you do not need a real dark site, just avoid 
one with street lights blinding you from the east. Once you select a site, either submit the station 
with the form at the bottom of the map on OW cloud, or let me, Terry, and Estela know by e-mail 
where you plan to be. Of course, it is just a plan; do what you have to when you get to the area, 
to find a dark enough place hopefully with thin enough clouds to see the star.

Hope this helps, thanks for your effort, and good luck!

_ _ _

You wrote:


My name is Juan Olivares, I am an amateur astronomer from South Florida. My friend Kyle Ewing sent 
over the text website with info on tonight’s occultation, I wanted to see if you have any suggestions 
or recommendations for the event?

I have a 10-in. dob but sadly I have never gotten much into astrophotography, so my observation would 
nearly exclusively be visual and noted, perhaps aside a phone video or DSLR camera video/ photography. 
I do also have a brightness dimming mask as the article mentions. 

I could make my way to Homestead tonight, any recommendations or contacts in any stations in the area?? 
My closest other observing hubs would be Holiday park, the Markham park fox observatory, or a lookout 
point facing markham park on Atlantic blvd and I75, though that only has good visibility (dark skies) 
to the west, not east. All of these are within dimming zones, and all much further north than Miami, 
but totality is only about an hour away tops so I could make it down there. 

Also, I do not know if I missed it, but what will the time be for the event? I will be looking over the 
website for that information once again. 

I hope I am not too late to be a part of this! Just finished my last final exams so I am catching up on 
all news and emails, along with a backlog of S&T magazines. 

Either way, cheers and thank you for all the info!

Clear skies, 

Juan Olivares.
Sustainable Business MS Student, UM. 
Epsilon-Indi Factor Co-Author
_ _

I wrote last night:

Below, in the FLORIDA section about 2/3rds of the way down this long page, 
I show which chord lines in the European system, 
the 8 stations in Florida I know about are on; I know some have registered 
with Paris Observatory but maybe not all. Please let me know if you plan to observe 
in Florida, and where; if you have not decided, it is best to use the Google map by Schnabel
and select one of the black lines, as those are not covered by others. The lines
are counted starting with the northernmost one being 1 to the south, with the 
southernmost one being 53 and the central line being 27; count them to the one 
you have selected and let me (or Planoccult or IOTAoccultations) know so that 
others can be informed. You should select a station within 500 meters of the 
selected line. You are also encouraged to put your planned station on 
Occult Watcher, which I will also see. See the FLORIDA section for more.
_ _ _


I know of plans of four live streams for the occultation; if you know more, 
let me know. The three I know are:

Terry Redding in Florida but maybe not, if too busy trying to avoid clouds.
Virtual Telescope.
webcast by Gianluca Masi from southern Italy.
webcast by Tiago Ferreira from Algarve, Southern Portugal.

Possibly, the live streams of Gianluca Masi and Virtual Telescope may be the same. 

And Oliver Kloes provides more links (sorry, I do not have time to make them 
hot links from here:
Live with a telescope from the University of Cagliari and a special guest, 
Robert Panai, physicist of the university.

One more from Italy:

Two more links from Portugal:

All these links are added on my special web page with other updated information
but unfortunately that is not working now. Maybe a temporary server problem? I thought 
I accessed it alright a few hours ago.

The IOTA/ES page for the event has very comprehensive information about the event
but it has no weather maps like were on your page.
_ _ _


The latest prediction file is this Google Earth (GE) file based on the latest 
orbit, JPL#71, and the best position of the star computed from the UBSC catalog. 
NOTE THAT THE PATH REMAINS UNCERTAIN. The formal 1-sigma error in the path 
is less than 3 km, but with such a bright star (too bright for Gaia and 
poor for Hipparcos) relying largely on ground-based data, there could 
be significantly larger systematic errors. Also, we want to sample as 
much of Betelgeuse as possible with the observations, so we hope that 
observers will spread across most of the path of annularity, between the 
two blue lines (the edges of the annular zone) that you will see with this 
file on GE. The lines take into account elevations above sea level. The green 
line is the central line, heliotrope lines mark the narrow edges of the deepest 
annular eclipse, and the outer red lines mark the 1-sigma outer limits of 
annularity. There are also 40 parallel yellow lines, at 3.0-km intervals
on the sky plane, but about 3.6 km apart on the ground, 20 on each side 
of center. For the coordinated effort, observers will be asked to find 
sites within 500m of one of these lines. If you click on one of the 
black dots on the central line, you get the UT time at that point, and the 
local circumstances there. This GE file is close to the official lines, 
which are called chords (I do not like that, since chord is used to show 
an observed line across the asteroid on a sky-plane plot). The official 
lines are individually available on this Paris Observatory Nextcloud page.
The first file there, at the top, Betelgeuse_Leona_NIMAv4_HARPER17.kmz, gives 
the central line, the annularity inner and outer limits, and the 1-sigma lines. 
Files for the individual lines are then given, each called LeoBet_chord_xx.kmz
where xx ranges from 01 to 53, from north to south. My .kmz file given at 
the top is limited by Occult to 40 fence lines, so it covers most of these,
but not all; the northernmost of my fence lines is LeoBet_chord_07.kmz and 
the southernmost is LeoBet_chord_47.kmz. The central line is LeoBet_chord_27.kmz.
My Occult central line is 0.3 km north of LeoBet_chord_27.kmz just east of 
Spain and 0.7 km north of it in Florida, close enough for our predictions
considering the uncertainties involved and the spacing between lines, 
reflecting the difference between the calculations of Occult4 and Paris 
Observatory using basically the same orbit and stellar information; we 
would want closer agreement for a narrow near-Earth asteroid occultation.

The earlier JPL orbit #70 used the two well-observed Leona occultations in Sept.
Dave Herald writes about the brand new JPL-Horizons orbit solution #71: This solution
has incorporated the result of the single-chord occultation of a 15.7-mag. star 
observed last week by Paul Maley. As expected, it made little difference to the orbit 
solution. But more importantly, the orbit has incorporated the Gaia Focussed data release 
observations for this asteroid. Dave provided this Occult input file that uses JPL71 and, 
as before, the UBSC position for the star. Dave provided a GE for the entire path that 
agrees exactly with my GE file above, since they were both generated with his Occult 
input file. The path has moved 1.84km north compared to #70, with no significant change 
in the along-path position. The formal 1-sigma uncertainty of Leona on Dec 12 is now 
2.9 x 2.2 mas in PA 62 deg., with the corresponding uncertainty on the Earths surface 
in the across-path direction being about 3 km. Basic information about the new (Gaia)
Focussed Data Release includes 46 million astrometric positions of 157,000 asteroids.
The map using the above Google Earth file agrees with the plot of the lines on the 
official Web site for the occultation, but they decided to number the fence lines 
from north to south, with the northernmost one being 1. Then the central line is 11 
and the southernmost fence line is 21, with no need to specify north or south with 
the number, like we did with some past events where the fence lines were counted
from the center.

On Nov. 30, 4 observers at effectively co-located sites in central Europe recorded 
an occultation of a 13.1-mag. star by Leona. NTP was used for timing as they couldn't 
use 1PPS GPS, and there was a difference of 0.25s in their times for the 6.8s event. 
Dave Herald analyzed the observations and found that they fit the current shape model 
and the JPL #71 orbit well, with uncertainties large enough that the orbit could not 
be further improved by adding them, so the decision was made to not make any change 
to the prediction specified above using the JPL #71 orbit and the UBSC data for the 
star, as explained in Dave Herald's Dec. 4th message.

We have experience with only one similar event, an occultation of 3rd-mag. 
kappa Geminorum by the 4-km asteroid (109657) 2001 RQ10 that was observed 
across the USA on Nov. 2 UT. As for Dec. 12, 2001 RQ10 and kappa Gem had very 
close to the same angular size, 2.7mas. There was only one positive recorded,
from 3 km north of the predicted center with UBSC data (paths computed with 
Gaia and HIP data were about 20 km farther south). Analysis continues on the 
recordings made by observers who were 2 km north and south of the positive 
observation, made near Charlottesville, Virginia by Mike Skrutskie.
_ _ _


Information about sources for cloud cover forecasts that I use is given here.
General climate considerations with maps for N. America and Europe are
given in a section on CLOUD COVER PROSPECTS near the end of this page. 
Others have posted, especially to Planoccult, some other forecast sites 
which give more comprehensive cloud cover forecasts on color-coded maps 
such as as recommended by Jay Anderson; observers can use it 
to best decide during the last hours before the occultation.
I just use here, some maps from this Web site where yellow is clear 
sky and clouds are dark gray. This site uses N. American Central Standard Time
(CST; UT - 6h), so the maps below are for Dec. 12 at 1h UT = Dec. 11 at
7pm CST.  I do not have time now to distinguish 
low, medium, and high clouds (I just give total cover) but those 
can be found on the site, and also with
Below is from west to east, opposite the motion of the shadow.

Mexico, GFS

Florida, ECMWF 
Florida, GFS
Florida, Middle clouds, GFS
The above shows that there are only a few/low chance of
mid-level clouds over s.e. Florida, so the clouds will 
mostly be high and hopefully thin enough. The low cloud 
map shows low clouds just east of Miami, over the Bahamas,
so in the east, not where we want them for Betelgeuse.

s. Europe, GFS
s. Europe, ECMWF
s. Europe, Middle clouds, ECMWF
As can be seen above, there are no mid-level clouds for 
Iberia and n.w. Turkey, and only a few in s. Italy, so 
only high clouds, hopefully thin enough, affect those
areas. But there are low clouds expected along the 
s.w. coast of Italy in the path area.

Turkey and Armenia, ECMWF
The GFS map is better for n.w. Turkey.

central Asia, ECMWF
GFS is similar, as well as middle clouds, and low clouds 
is only slightly better. Azerbaijan looks pretty good but 
cloudy from Baku northward.

I do not plan to update these forecast maps, unless many ask 
me to do that. Most observers are now using their own sources, 
such as, and during the last several hours, consulting 
weather satellite loops will give the best information about 
where any clear areas might be by extrapolation.

Oliver Kloes special web page has new weather maps  
but unfortunately it is not working now. Maybe a temporary server problem? I thought 
I accessed it alright a few hours ago.

The IOTA/ES page for the event has very comprehensive information about the event
but it has no weather maps like were on your page.
_ _ _


Comprehensive information about the occultation, and recommended best ways 
to record it, including a place to register for the coordinated campaign, 
were given during a series of presentations, with extensive discussions, 
all in English, organized by workers at Paris Observatory. Links to the 
presentation files and the 2+hour recorded Zoom meeting are given below.

Documents (.pdf versions of the presentations) of the international meeting 
from November 11th are available at
Video of the recorded meeting can be viewed here.

Those who want to make the most useful scientific observations of the 
occultation need to view most of these presentations; I list them 
below with the start time of the presentation on the video in chronological 
order (there are hot links to go to these at the top of the page; click 
on "Show more" to see all of them; I give links to the presentation files
below so you do not need to download the rather large files from the 
ObsPM site in France given above:

Start Time: #_Presentor_Presentation

0m 0s:      0_Montarges_ScientificContext
22m 22s:    1_Desmars_Prediction - based on the earlier JPL70 orbit of Leona
42m 05s:    2_Midavaine_Leroy_Photometry - long useful discussion after 
1h 32m 06s: 3_Midavaine_Neveu_Buil_Spectrometry
1h 51m 20s: 4_Desmars_DataCollection
1h 54m 50s:   Neveu_ObserversCoordination (no .pdf for this; it is
               a demonstration of the registration, with discussion,
               including a spread sheet for the coordination
2h 00m 00s:   Q and A

For all wishing to participate to this program, if they have not already done so,
they should register at this registration link.

Be sure that Betelgeuse is not saturated before the occultation. But if you 
have a deep occultation, you should be able to record 6th or even 7th-mag. 
stars; there may be a few of those near enough to Betelgeuse to fit in your 
FOV. Some recommended using Bellatrix or other stars for comparison, but 
such bright stars are too far away from Betelgeuse for nearly all systems; 
even mighty minis have a FOV of only about 2.5 deg. So most will not be 
able to record another bright star in their FOV; they could, however, 
record Bellatrix, and/or Meissa and the fainter stars near it, before and 
after their Betelgeuse occultation recording, of course with the same 
cadence and camera settings.

Most observers will be recording for photometry, so they should pay attention
to the #2 talk. For useful observations for the campaign, observers need to 
use filters; different ones can be used, depending on the color band assigned 
(when you register, note which filters you have; different standard filters 
can be used, depending on what you have, as shown in the presentation). You may 
need to get help from others in your local astronomy club, to find useful
filters, since we rarely use filters when observing most occultations.

A few will be trying the more challenging spectroscopic observations; they 
should consult the #3 talk. 
_ _ _


This was not an open meeting, available to IOTA-ES members and several others 
organizing for the Leona/Betelgeuse occultation. Here is the Chat from the meeting, 
with some useful links provided. The meeting was NOT recorded. 

Carles Schnabel provides more useful information:

I have included the last NIMAv4_HARPER17 prediction with chords (fence lines) on My Maps:
These are the same as the ones at this Paris Observatory Nextcloud page
following the Gemini Pro-Am project.

So, we recommend that any observer or team that has not yet decided on their observation point 
should come at least 500 meters from one of the chords. Those chords that currently already have 
at least one announced station have been highlighted in red while the black lines have no 
registered observers. You can click on one of the chords listed on the left, to highlight it 
in white, to tell which one it is. The 53 lines, or chords, are counted from north to south;
the central line is chord 27. The map will be updated as the days and hours go by.

You may have followed some discussions about the best observing methodology for registering 
so a bright star. Jose Luis Ortiz (IAA) and Miguel Montarges (Paris Observatory) are giving 
following advices: it will be very convenient to record with telescopes and not only with 
small objectives. To avoid saturating the star, it is very convenient to use filters. 
In addition, it will surely be necessary to place a mask in the aperture with several holes 
(perhaps 3 or 4) to take advantage of the aperture, but at the same time to remove excess light 
without losing diameter (the problem is basically the scintillation of the star). There is also 
the option to defocus considerably or use narrowband filters (photometry on out-of-focus stars 
is somewhat problematic). Apart from the V, R or B photographic or photometric filters, 
professionals recommend SII, OIII and H-alpha. If you have any of these, it would be great to 
use them. otherwise, use any red, green, or blue filter, if you do not have the above filters.

[The following is a complication that I think is not necessary if the sky transparency is 
 uniform over intervals of several degrees and in time over a minute or two; in those cases,
 just record Betelgeuse for at least 60s before and 60s after the predicted time. With
 large transparency variations, especially rapid ones, even the steps below will do little 
 to help - hope you have stable conditions! - DWD]

Since operating in this way it will be impossible to have comparison stars, it is advisable to 
have another telescope next to or mounted in parallel with the main one and record a comparison 
star close to Betelgeuse with another camera. It would serve to detect possible high clouds or 
fluctuations that affect that part of the sky. But, of course, this would force you to use 
another fast camera. In any case, you could use the drift-scan technique with this other telescope. 
The fluctuations would thus be recorded in the trace of the comparison star, which the closer it is 
to Betelgeuse, the better.

You have to make some exposure test before recording. It's important not to saturate the star. 
Some light de-focusing can help, but the photometric analysis can have some problems. 
Therefore it is very recommended to use some filters: in order of importance: R, V, B, SIII, OIII, H-alpha.

To avoid problems of scintillation with small apertures, don't decrease a large aperture 
with a diaphragm! You can make with cardboard a mask with three or four holes using at the 
same time the maximum diameter of the objective. Claudio Costa has implemented this with 
a 20cm SCT as shown here and described here.
_ _ _


The meeting was held Sunday afternoon, Dec. 10, from 17h to 21h CET,
Meeting Point at Universidad Politécnica de Alicante
Sala ECISA del Edificio Politécnica IV (EPS4)
lat 38.382470, long -0.509959
Carles Schnabel,

Perhaps some of the observers in southeastern Spain might meet there 
again Monday, to consult the latest cloud forecasts to maybe change 
some plans before travelling to their observation sites.
_ _ _

FLORIDA (and Mexico)

The above is mainly set up for European observers. Most N. American observers 
will be going to southern Florida. The GE file at the top covers the whole 
path, including Florida and Mexico. Those planning to go to Florida should send an 
email to Terrence Redding at and to Estela Fernandez-Valenzuela, 
email who is leading a Univ. of Central Florida effort to cover the 
occultation and is collaborating with the European effort, especially the one in 
Iberia. Terry notes that he and some others from the Astronomical Society of the
Palm Beaches, are registered with Occult Watcher (OW) to observe from three locations 
in the Everglades. There are now 8 stations registered with OW in Florida.

I used the Google map by Carles Schnabel to plot the OW stations and see where 
they are relative to the lines/chords of the Paris Observatory.  The resulting Florida map 
shows the stations as dots with their OW descriptions; they are listed below with their 
corresponding chord numbers in the Paris Observatory system. The Florida map can also 
be used to help select sites since the black lines do not have any observers; their 
chord numbers are given so you can get the individual lines from the links above. The 
red lines are already covered by other observers, especially in Europe, where there 
may (or may not) be fewer clouds. As noted previously, all of the lines are numbered 
from north to south, but ignore the green lines on this particular map. The TR stations 
are Terrence Redding; his east station is just an alternative site in case it is too 
cloudy farther west. FSI are stations registered by Marin Ferrias, I believe as part of 
the Univ. of Central Florida effort. Below, the OW stations are listed from north to 
south relative to the path, with the final number being where they are relative to the 
chord numbers. Most are between lines (and most not within 500m of them) so I give the 
chord numbers to a tenth. Note that the interval between the lines is 3 km on the sky 
plane or about 3.6 km on the ground.

Florida stations that I know of (TR = Terrence Redding)
except for TR-east, TR sites are in the Everglades National Park:

mlaresm - 16.7 (near empty chord 17)
TRnorth(2) parking for Pa-Hay-Okee Lookout - 24.5
FSI-1 (Marin Ferrias) parking Pinelands Trailhead - 25.6
Kai Getrost - 25.7
TR-east - east end SW 344th St - 26.7
FSI-2 (Marin Ferrias) near Park Entrance - 27.0
TRcenter(1) parking Mahogany Hammock - 27.9
TRsouth(3) parking Nine Mile Pond Trail - 30.3

I think the place descriptions I give above are right, but I can not be sure, since 
OW moves the telescope symbol 1 to 2 km away from the location specified by the 
observer, for security.

I think there are more stations in Florida than are signed up on OW. During the Dec. 3rd 
IOTA/ES Zoom meeting, it was mentioned that 3 of the chords registered with Paris Observatory 
were in Florida, and I think their chord numbers were mentioned along with the names. 
I remember one of the observers was from St. Louis. Some of the above may be the other two. 
Unfortunately, I was informed that the Dec. 3rd meeting was not recorded; the chat from
it are given in a link beloe.

All of the Paris Observatory chords that are empty (from Schnabels map) are: 1-11, 14, 
15, 17, 18, 21, 29, 42-45, and 47-53. Of course most are near the northernmost and 
southernmost areas that are less likely to have any observable fadings.

Anyone hoping to observe from Mexico should contact Joel Castro at
but the cloud forecast is terrible with the event very low there.
_ _ _


One of the presentations during the Nov. 11th meeting (see above) discussed reporting.
There are different options, but best is probably to use the Lucky Star occultation portal.
Other options can be worked out by email to
More on this may be posted here after the event.
_ _ _


The latest (2023-4) issue of IOTAs Journal for Occultation Astronomy (JOA) is 
largely devoted to this occultation and has other useful information and tips 
for observers, including about spectroscopic observations. It is a free download 
from this IOTA-ES Web site.
_ _ _


The situation is not at all different to that of a total solar eclipse. For long term 
planning one has to rely on long term weather statistics, knowing that on the day of 
the event, these may well be totally useless. Below are two maps of cloud cover 
statistics that were derived a few months ago from weather satellites *at night* using 
data from the last 20 years. Note that the cloud cover statistics in daytime conditions 
are often different, and be especially aware of local foggy conditions.  
The first map is for south Europe and part of Asia, corresponding to statistics of cloud
coverage in the complete month of December for the last 20 years. 
The other map is a zoomed view of the Iberian Peninsula and specific for December 12th 
in the last 20 years. The maps include contour levels and the color scale is 
brownish-red for the less cloudy locations whereas it is blue for the poorest
locations. The lowest cloud coverage values are around 0.3 (30%). The
Leona shadow path is superimposed in the maps. The Iberian Peninsula
and Ibiza and other mediterranean regions enjoy the best statistics
and another advantage of the Iberian peninsula is the fact that it is
a large area and there is a big highway that quickly connects the
East-West locations. Even though Alicante and Murcia are probably the
most favored locations in Spain in terms of weather and Alicante has a
good airport it may make more sense to stay near Seville, Cordoba or
other more central locations and be mobile with a rented car or by any
other means. This is the advice I have been giving to those who asked
me. However, I strongly recommend not to focus completely on the
Iberian peninsula as a cloud front might come and ruin almost all
sites. So numerous observations in Italy, Greece and other countries
are encouraged too. But note that if you travel to an island or a
place where you have very low mobility, your chances of success are
smaller. I am trying to arrange logistics at Alicante University and
maybe at Seville University so that at least a rehearsal exercise and
some coordination can be carried out in their campuses.

Jay Anderson has provided the following for the expected cloud cover 
in Mexico and Florida:

Here is a map of average December nighttime cloud cover over the US part 
of the track based on 2000-2020 data; note that for it, blue good and 
orange is bad, the opposite of the color coding of the European maps. 
I can make up others to cover the eastern part of the track if you like. 
Numerical models do not go out to the date of the occultation, but some 
long-range ensembles go that far and provide a few hints. The GEFS 
(available on the College of DuPage site ( shows that 
the jet stream is well north of Florida on Dec 12, a position that enhances 
the possibility of good weather. Two week forecasts aren't particularly 
reliable, but the upper-level flow is slightly more predictable than the 
surface weather. This is at least an indication that 
Florida might be OK. Regular forecasts should be able to give good advice 
about 5 days out. Use the models available in, particularly the ECMWF. 
Watch them for a few days to see if the forecasts stabilize from day to day.
_ _ _

The earlier information below has been largely superseded by the above information.

European astronomers are organizing for the occultation of Betelgeuse by Leona 
on December 12; before then, observations of both objects are sought, especially 
light curve observations of the slow-rotating (319) Leona (period about 18 days) 
and of occultations of other stars by Leona, to get better information (the 
current data are very sparse) about the asteroid's size and shape. Astronomers 
at Paris Observatory and IOTA-ES have set up a special Web page
about the event, and the observations needed beforehand. The Web page is in French;
your browser probably has an option to translate it into your language, but if not, 
this .pdf version of it is machine-translated into English. It includes small maps 
and links to Lucky Star prediction pages for several occultations by Leona that 
will occur before (and a few after) December 12.

Also, David gave a presentation about the occultation and the work needed 
for it at the 2023 IOTA meeting last weekend; 
if you missed the meeting, or want to re-live parts of it, Ted Blank has posted 
YouTube recordings of all of the presentations. The IOTA meeting page
also has links set up for each of the presentations to get their PPT or PDF files.
The European Web site has more inforation than I gave, but in my presentation, I 
noted an occultation by Leona in the southeastern USA on Aug. 27 UT that's not in 
the European information; the Occult map for it is on slide 15 of my presentation. 
Unfortunately, the event could not be observed.

Before the IOTA meeting, we had a productive Round Table discussion by Zoom, 
organized by IOTA-ES (European Section) on June 4; much of the discussion was 
about the Dec. 12th occultation, and preparations for it. An article about the 
Round Table is on pages 18 and 19 of the 2023-3 issue of Journal for 
Occultation Astronomy (JOA), a free download from this IOTA-ES Web site. 
As noted in the JOA article, the Round Tables will be held every two months, with 
the next one scheduled to start on August 6 at 18:00 UT (= 14:00 EDT); the Zoom 
link will be sent to IOTA-ES and IOTA members a few days in advance.

Return to the special main-belt occultations page.

David and Joan Dunham, 2023 Nov. 28; updated 2023 Dec. 9 and 10, 16h UT; and 11, 7h and 22h UT.
cell phone:  301-526-5590