That's cool...you're a ham solar astronomer ?
I'm curious, why 19.5 Mc ?
Peter
I think the best answer is,,, that's where I was when the flare started!
I was looking at a wideband spectrum at the time... the VFO just happened to be at 19.500mhz.
Any HF/VHF frequency can be good.
But above 20mhz and into VHF, a preamplifier is usaually needed, ( there's no amplifier in the front end of this radio).
You want to be away from SW broadcast stations.... in a clear spot somewhere.
So, pretty much just a random thing.
I'm confident there would have been very little, if any, difference if this has been recorded +/- 2 mhz or so.