Juno flyby over South Africa
Paul Kruger, Leslie Rose and myself set ourselves the task of trying to image Juno. We met on Marine Drive, just past Gordon's Bay, at the parking area just past the Steenbras River mouth. Mist from the sea and a bright Moon were going to make things tricky - but the scenery was a spectacle.
Scenic view from Marine Drive. The bright Moon dominates the view, with Venus below-left. Crux is at extreme left.
Leslie (left) and Paul (right)
Paul and I tried various combinations of ISO and shutter speeds, using 10-mm and 50-mm lenses. Leslie had his Sony piggybacked on an equatorial mount so he could take longer tracked exposures. Despite our best efforts, we found diddly. But it was a lot of fun.
Satellite guru Greg Roberts got some FORTY images of Juno!! And that was with equipment failure! Greg used a 135-mm lens at f/2.8 with an FLI 8300M CCD camera, and a 7-second exposure. He writes that he estimates it was around 9th magnitude, and that it was variable in brightness.
A report of Greg's observations are given on ESA's Rocket Science Blog (Juno flyby seen from South Africa).
Juno imaged by Greg Roberts, Cape Town
Labelled version of Greg's image.
Kos Coronaios took a series of 30-second frames, one of which (right) showed an interesting prospect. Via WhatsApp, Kos noted, however, "Need to check if it is Juno, just seems too bright and too high."
In Stellenbosch, Brett du Preez took a series of 15-second images. One frame, in more-or-less the correct part of the sky, showed an interesting feature.
Brett immediately phoned with the exciting news, and Leslie, Paul and I stood by the roadside listening to Brett's eager recounting on speaker-phone.
NASA's Juno spacecraft, en route to Jupiter, does an Earth flyby on Wednesday, October 09. It will be visible over South Africa around 21:00.
The accompanying diagram (I can't remember where on the webs I found this) shows its trajectory, from its launch in 2011 August, subsequent rendezvous with Earth on October 09, and onward to orbital insertion at Jupiter in 2016 July.
Dr Henry Throop, Senior Scientist at the Planetary Science Institute, has calculated that the Juno flyby will be visible from Southern Africa on the evening of the 9th of October. He has created a "Juno Flyby of Earth" page which includes details of observing this event from Pretoria and Cape Town.
He writes: "The best time to view it is immediately before it goes into shadow, which is around 21:19:34 SAST. From SA, it will be visible for a minute or so beforehand."
Chris Peat of heavens-above also has a special Juno page with additional viewing information.
Juno will brighten from about 8th magnitude (easy binocular target) at around 21:13 as it heads into shadow, disappearing suddenly. For Cape Town, Peat predicts this will be 3.9-mag at 21:19. Juno will move across Lupus to Circinus and disappear in Apus.
However, satellite guru Greg Roberts cautions that the predicted magnitudes are far too bright - see his discussion in the Comments section below.
Greg concludes: "Cape Town has by far the best seat - anything further east or north will only have less. But time visibility is going to be short so could easily be missed and almost a certainty there will be other satellites in the area to cause confusion."
So, caveat aspicientis, but carpe noctam!
The star chart below shows the path of Juno as seen from Cape Town on Wednesday, October 09. Right-click and save it for a printable version. The brighter part of the track is around 31°, so a modestly-wide-angle lens will suffice to photograph its path. Just dial up the ISO. A wide-angle photo of roughly this region of the sky can be used for comparison.
nothing more to see. please move along.