Advice please - 1420MHz radio telescope (21 cm hydrogen line)

I seem to have done it nicely with a 7-turn helix antenna and a low noise LNA from MiniCircuits. I used an ICOM R8500 receiver as a downconverter, followed by an SDR-14, and a *lot* of postprocessing in home-spun software. Much of the postprocessing effort was in RFI excision, and a few million spectra were effectively averaged. I even made a marginal detection last summer using an even cruder antenna- a "ground plane", but had to average something like 20 million spectra, and the results are not as nice. Having even a little gain in the antenna helps a lot, probably mostly because it helps exclude black body radiation from the terrain. I've been thinking about writing up a detailed article, but have trouble finding the time. BTW, at Arecibo, where I work, HI detection is trivial- just point the antenna anywhere at random and you see it strongly even with fairly short integration times.