RTL-SDR Spectrometer for a Small Radio Telescope
Marc Higginson-Rollins of the University of Kentucky has published an academic styled paper in conjuction with Dr. Alan E.E. Rogers of the MIT Haystack Observatory showing how they used an RTL-SDR to implement a Small Radio Telescope (SRT).
In the paper they discuss how they dealt with the frequency drifting and offset problems common in the RTL-SDR. They also show how they dealt with the center spur by correcting the bias that it introduced and how they filtered out RFI noise from a nearby radar station and electronics.
Using the RTL-SDR and SRT they were able to measure the spectra of several well known regions of neutral hydrogen emissions, and measure the galactic rotation curve shown below.
Another amateur astronomy project:
My 11 GHz solar intensity interferometer that uses an rtlsdr receiver w/gnuradio