Occultation of SAO 164648 by Titan on 2022 July 9 - Updated 2022 July 17

by David Dunham

Read about this rare occultation in this .pdf document. 
It has much useful information, with maps and diagrams to 
illustrate the occultation, showing where it was visible and 
the view of Saturn, Titan, and SAO 164648. Some maps and finder 
charts are still in the .pdf document or below, but cloud cover 
forcasts, for example, have been removed. Removed material 
will be provided upon request. We will keep some of the basic 
prediction files for about a month.  The cloud cover forecast 
maps are removed; the infrared satellite image showing the 
actual cloud cover near the event time is here. And here is 
the last Occult Watcher list, with annotations about the basic 
first information that many observers reported.

Below are links to the interactive map for the event, and to 
plain text files with tables containing prediction information 
for hundreds of cities in the region of visibility of the 
occultation. The tables and diagrams were generated with IOTA's 
free Occult4 program.

Titan, the 8th-mag. largest moon of Saturn with a thick atmosphere, 
will occult a star of similar brightness on Saturday morning, July 9. 
The occultation will be visible from much of North America, south of 
the northern limit shown on the Occult map in the .pdf document; the 
southern limit crosses northwestern South America. Titan will be 
3 arc-minutes east of Saturn when the occultation occurs. The star to 
be occulted is 8.7-magnitude HIP 107569 = SAO 164648, a spectral type 
F05 star; the occultation will last up to 5.5 minutes, and will occur 
many minutes after 9h UT (5am EDT = 2am PDT).

This chart shows the star field that Saturn will be in, including 
the typical video FOV for an 8-in. SCT. For the observation, I 
recommend centering, then tracking, on a point halfway between the 
Titan/SAO 164648 merged image, and SAO 164647, a 7.5-mag. star 
10 arc-minutes to the north, marked "A" on the chart.
Here is a close-in view showing the inner satellites.

Predictions for the contact times (D = disappearance and R = reappearance) 
for many cities are here. The circumstances can be found 
in this list, including the altitudes 
of the star and Sun, in degrees, in the last two columns. The time
given is the time of central occultation, which for most locations
will be about 3 minutes after the disappearance, less for cities 
close to the northern limit. Both lists are in alphabetical 
order by country code and city name, so find the occultation for the 
sizeable city closest to you that is in that list. I suggest downloading 
the list to your computer, then editing it with any word processor, I 
recommend Notepad, so you can search for cities near you. Since they are 
ordered first by country code, the important ones of those to remember 
are BS for Bahamas, CA for Canada, CU for Cuba, MX for Mexico, and 
US for the USA. In the database used for these predictions, Puerto 
Rico has its own "country" code, PR. There are also predictions for 
countries in Central and South America, such as CO - Colombia; 
VE - Venezuela; GT - Guatemala; BR - Brazil; BZ - Belize; CR - Costa Rica; 
and PA - Panama. There are codes for other small countries and several 
islands in the Caribbean and Pacific. Within each country group, the 
lines are in alphabetical order by city name. The provinces of Canada 
are not distinguished or specified. The 2-letter postal codes of the 
States of the USA are given after the city name; the cities of the USA 
are all alphabetized by their names, NOT by their States.

Here is a separate version of the circumstances list, sorted by distance 
from the central line. That way, you can see the cities that are closest 
to the center, and to the limits.

This interactive Google Map shows the northern and southern limits (blue lines) 
and the central line (green). Specify +100 and -100 for offset values above 
the map and two dark gray lines will be plotted, defining the area where the 
central flash will most likely be seen.

REPORTING OBSERVATIONS

Lucky Star will also be collecting observations of the occultation through 
their occultation portal. You are also encouraged to report any observations 
briefly via Occult Watcher, and perhaps with some discussion to the 
IOTAoccultations email list. You could also report the observations to IOTA 
via reports at asteroidoccultation dot com using the IOTA report form that 
you can get from Occult Watcher, but IOTA doesn't have a mechanism for 
analyzing observations of occultations by objects with atmospheres, so we 
will defer to Lucky Star for that.

BASIC INFORMATION ON HOW TO RECORD OCCULTATIONS

For those less familiar with recording occultations, you can learn about 
the main techniques, equipment, and software currently used in a 
good primer by George Viscome. Some more detailed information can be 
found in the observing tab of IOTA's main Web site.
_ _ _ _ _ _

Visit IOTAs main page for occultations by distant objects to learn sbout 
other occultations by the TNOs and other strange objects that lurk in 
orbits beyond Jupiter.  

Page set up by David Dunham
Cell phone 301-526-5590
email dunham@starpower.net