If you can find Castor and Pollux, you can help create a detailed map of asteroid (363) Padua Sunday evening

On Sunday May 10th, at 10:16 pm MST, the approximately 85-km asteroid (363) Padua will occult the 5.7-magnitude star 14 Cancri for likely less than 4 seconds for all throughout the greater Phoenix and Tucson areas. The event, of the brightest star occulted by a sizeable asteroid in central and southern Arizona this year, can be seen with steadily-held binoculars, or with any telescope that can be pointed at the star, or with the telescope’s wider-field finder scope. We strongly encourage you to watch for this unique event, to see for yourself the bright star vanish from the sky for a few seconds. It would be great if you can additionally time the event with the stopwatch app of your cell phone, or use other timing methods described at https://occultationpages.com/events/temp/TimingOptions.pdf. It tells how cell phones or astronomical CCD cameras, which many of you have, can be used to time the occultation; DSLR cameras can also be used, as described at http://occultations.org/observing/educational-materials/equipment/dslr/dlsr-time-synch/ .

The detail of the asteroid resolved during an occultation depends strongly on the number of observers, as shown in the two asteroidal occultation sky plane views below. The Europeans took good advantage of their opportunity with the (87) Sylvia occultation, shown, last October. For the Padua occultation, we hope to do much better than our recent showing for Leopoldina (on the left side of the figure), for a star nearly 100 times brighter than the star occulted by Sylvia in Europe. We hope that you can spend a few minutes (very short observing time; just a little longer to set up) Sunday evening to look at 14 Cancri 6 deg. above and left of Pollux, to see and time the star wink out; every location gives a unique “cut” (chord) across the asteroid.
To help you observe this occultation, we have created a Web page with much information about it at http://www.occultationpages.com/events/20200511_363_Padua.html . There are a series of detailed star charts for both binoculars and telescopes, with labeled versions in .pdf files, and unlabeled versions in the “Star Charts page”. An example of one of the labeled charts is below.
A view of the star field recorded with a mighty mini system last Sunday evening can be found on the “Runcam-Mini” page. In a couple of days, we will add charts for pre-point opportunities for this event, but probably for most, just going directly to the target star and tracking it should work fine. 76 Geminorum, close to Pollux, provides a good pre-point opportunity 26 minutes before the occultation, and 3rd-mag. Mebsuta provides on an hour before that. But if your scope has a narrow field of view, you will need to use fainter stars near those bright stars, to pre-point your telescope accurately enough; the charts we will post later will allow you to do that.

We are interested in those who can record the occultation with an astronomical CCD (no other equipment, other than your computer, is needed for that, as described in the Web page about it with link in the attached timing options .pdf). If you can do that, please let me know where you plan to observe at dunham (at) starpower.net, so we can coordinate the overall coverage for the occultation; we don’t want mobile stations to duplicate your observation.

For others who don’t have cameras, I want to loan 5 or 6 of mine, providing everything from the camera that connects to any standard 1.25-inch eyepiece holder, to a USB plug to your laptop PC that can be used to record the occultation, with the free IOTA Video Capture software that you can download from IOTA’s Web site. If you have doubts about your telescope’s ability to find 14 Cancri, especially if the field of view is small, I can also provide a Runcam mighty mini (it has a field of view about 3.5 deg. by 2.5 deg.) along with the other equipment; all you would need to provide then is a laptop PC and some AA batteries. Clicking the “Runcam-Mini” box on the Padua occultation Web page, or directly at http://www.occultationpages.com/events/Runcam_Mini.html , gives pictures and detailed information about the equipment and how to use it. A similar effort was used successfully with a few observers for an occultation of a 12th-mag. star by Pluto in 2018, so the page for that is referenced, along with the few differences between the two efforts (of course, the small mighty mini optics could not be used for that much fainter event, so it was more about the camera and video recording using laptops). Please let me know at dunham (at) starpower.net, if you might be interested in borrowing the equipment; I will deliver it to your home either Thursday or Friday. Send me your phone number and address (and/or longitude and latitude). I’m most interested in those who might observe west of downtown Phoenix, or west of Chandler on the south side, as there are fewer known occultation observers in those areas, but let me know wherever you are in the “Valley of the Sun”, as observations anywhere in and near the path are important. Those to whom equipment is loaned, should use it Friday and/or Saturday evening, to do a short test recording of 14 Cancri, so we can communicate by phone, and possibly by Skype, to resolve any problems that might be encountered. And since we won’t be using the equipment for any large remote deployments at least through the summer, much of which we expect to spend in Maryland, you can keep the equipment, to try to observe lunar and other asteroidal occultations with your telescope; I will want to collect just a couple of the mini optics and tripods (but not the camera and other parts) before we leave Arizona. For each set of equipment, I will check to make sure that it works, then I’ll clean all surfaces thoroughly and put them in a box, and seal that, all while wearing a mask. Then I’ll coordinate by phone, to deliver the box to your front yard (or place of choice), where you can retrieve it after we do a distancing phone “handshake”.

On the main Padua occultation Web page, below all of the text, are three regional maps of the path, the first for the Sacramento, Calif. region, the second for the Phoenix and Tucson areas, and the last of the three for Monterrey, Mexico. The text above the maps describes the meaning of the colored lines. The narrow black lines on the Calif. and Arizona maps, generated with IOTA’s free Occult Watcher coordination software, are lines covered by observers who have used the system to declare that they plan to observe; we’re especially interested in filling the current gaps in the coverage that they provide. The map of the Monterrey area was generated with different (but similar) software that doesn’t include the observer lines; it also doesn’t show the light red 3-sigma lines, but does have two dark gray lines that have no meaning. If you live near one of the limits (blue lines), you might either have a very short occultation, or a clean miss; both are valuable for the overall coverage of the event.

Any observer, either in or very far from the path, could have a very short occultation that could mark the discovery of a satellite of Padua. The bright star makes it possible to obtain an unusually high signal-to-noise observation, providing more confidence, of any satellite event that might occur. This could happen up to about 300 miles from the predicted path (so observers throughout Arizona, as well as the very wide area between the two dark gray lines on the very bottom map on the page.

The Web site for Arizona occultations at http://iota.jhuapl.edu/AZoccs.htm has been updated through June with material provided by Wayne Thomas.

David Dunham