VLBA RFI Bulletin 15:  IRIDIUM Downlink Blankets 1621-1627 MHz Region:

The IRIDIUM, 66 satellite Low Earth Orbit (LEO) constellation is now in
full-up operational testing.  Strong (20 dB over noise level) signals
are seen 24 hours per day, 7 days a week coming in the sidelobes of
VLA antenna #4, which is used for L-band monitoring.  Users of the VLA
and VLBA systems should write their observe files in such a way as to
avoid including the 1621.35 - 1626.5 MHz big LEO downlink band.

VLA and VLBA OH line observers need to use the narrowest bandwidth
possible which still meets the sensitivity and velocity requirements
of their study.  In addition, Tsys correction must be left "OFF", in
order to avoid corruption of the data by the strong, IRIDIUM downlink
signals.

OH line observers should check-out the additional set-up information
available on-line at: