Subject
- north galactic pole1
- optical observation1
- photographic magnitude1
- plasmas1
- pre-main sequence stars1
- radio absorption1
- radio antennas1
- radio astrometry1
- radio interferometers1
- radio interferometry1
- radio observatories1
- radio spectra1
- radio spectrographs1
- radio spectrometers1
- radio telescopes1
- relativity1
- space astronomy1
- space observatories1
- space telescopes1
- stellar associations1
