[Friends_of_SSASTROS] Notes From the Field

[Mike McCabe]

Notes From The Field,October 20th, 2023

Sometimes You JustGotta Do It!

The alarm went off at 2am. Now it should be known that I'mnot much of a wee-hours kind of observing guy. No, I'm more of the prime-timetype, happy to be out there right after supper, plying the skies in betweensatellite passes and incoming business flights. Those single-digit hours arefor the nocturnal folk, a camp that I'm decidedly not a member of.

But sometimes you have no choice. In this particular casethere would be some moonin’ hanky-panky going on at Jupiter, and I'm a big fanof Jovian observing. Normally I'd just wait until ol' Jup comes around in theevening and take my doses of King of the Planets at more convenient times, butsomething I'd just read convinced me that this would be a good time to chooseotherwise.

I was on SkyandTelescope.com during the day and was readinga Bob King article about the upcoming Orionids meteor shower, and along the wayhe stuck in a little piece about Jupiter. You can read his article here https://skyandtelescope.org/astronomy-news/orionid-meteors-fly-two-moons-shadow-jupiter/but I'll cut to the chase and share with you what he wrote that convinced me itwould be a good idea to interrupt my usual slumber, and it was this; On the night of October 19–20Jupiter-watchers will witness an eye-catching double shadow transit of Ganymedeand Io. This is a somewhat rare event during the current apparition because thereare no shadow transits in November and just two in December — on December 23rdand 30th. The first is unfavorable for North America, while the other isprimarily a twilight and early-evening event for the eastern half of thecountry. That's it till 2025!

What??? I LOVE Jupiter shadow transits and during everyevening apparition of the planet going back for as many years as I can rememberI could be found scouring the Jupiter's Moons tool on the S&T website fortransit predictions. No shadow transits? Whatever you be talking about, AstroBob??*

But far be it from me to question Bob. He's good at what hedoes and if he says we won't have any shadow transits from the end of 2023 allthe way to 2025, he's probably right. I set the alarm and hopped in the sackearly. Based on the forecasts I fully expected to climb out of the bed at 2am,walk to the window to confirm full cloud cover, and walk right back to the bed.Then a funny thing happened; the sky was perfectly clear at the time that ourprecious shadow transits would be happening!
It didn't take me but a couple of minutes to deploy the old4.5" Newt/Dob, and I didn't even bother with a low-power gaze. In went5mm's of eyepiece and we were off and running at 185x. Well glory be! Therethey were, the shadows of Io and Ganymede, sharp and bold as you please andlooking beautiful as all get out! Jupiter is transiting high this year and theseeing was reasonable up there. I played around with the power a little bit,went up to 200x and down to 150x, but the original 185x was the best on thisoccasion. Between slewing around to a few stars in Orion and whatnot andrepeatedly dropping back in on Jupiter, we watched the shadows march across theJovian disc for the better part of 45 minutes. It was a splendid session. Theair was still, the planes were parked for the night and it was as quiet andpeaceful as it gets. For a minute there I thought that maybe I should get out at these times more often…nah!
*Upon furtherinvestigation, it appears that Bob may have misspoken a bit in his article – a quickperusal of the S&T Jupiter’s Moons tool shows single-shadow transitshappening on a typically frequent basis going forward, so I think Bob must’vemeant to say that we will be sans double-shadowtransits after the end of the year and into 2025.
In the simulated view seen above, theplanet, moons and shadows appear exactly as they did in the eyepiece at 200x.At upper left is Callisto, Io is embedded in the southern equatorial belt,Ganymede is approaching the planet, and Europa is at a far ranging point in itsorbit around the boss of the planets.
I have toadmit that I’m looking forward to Jupiter’s upcoming opposition on November 2nd,after which the planet will start rising high enough to observe in the earlyevening and checking in on the moons and the comings and goings of the GreatRed Spot will be a prime-time activity once again. Planetary grab-n-go is oneof my favorite parts of this hobby, and Jupiter is a fantastic planetarytarget! 

Keep LookingUp! 

Sincerely,
Mike McCabe


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