1. Planning Spectral Observations
Surface Brightness
Masers - resolved often at <798Z1kpc
HI absorption - background Z106K
Resolution
Global?
Fill in e.g. MERLIN?
Check archives
NGC4261 van Langevelde et al.

2. MERLIN archive
/archive/
EVN archive
VL(B)A archives
via respective
web pages

3. Line frequency, width, VLSR,rad
RFI avoidance
Receivers, filters & No. IF's available
Correlator capacity NchNpolNBNIF/t<max
Resolution
HA coverage
Sensitivity
How long?
Calibrators observe more than once!
Delay
Bandpass - bright!
Fringe &/or phase
Polarisation leakage
Polarisation angle
Can be the same source(s)
Ask advice!