Interesting Io-B on 100820 at Nancay Hello Everybody ! I refer to: http://www.obs-nancay.fr/ql_routine_jupiter/B-W/2010/08/J100820.png This is not a "typical" Io-B arc, it looks like a fan to me ! RCP is stronger, which is typical. Generally the northern cyclotron masers (Io-A and Io-B) are RCP polarization. LCP shows ionospheric modulations. Near 0130 UT there is narrow band activity, stronger in LCP. I would love to see how the Paris Observatory PRES code fits this one. My ignorance is vast. Best regards, Victor