The notebook where you record each observation: date, time in UT, place, instrument, magnification, seeing, transparency and what you saw. It shows your progress and helps you find good settings again. Well recorded observations can also be useful to amateur societies.
Related terms
- Sketching
Drawing what you see at the eyepiece, in pencil on white paper, under a red light. It forces you to look long and carefully: you notice far more detail. Galaxy and nebula sketches are often made in negative, then inverted.
- Universal Time (UT)
The time on the Greenwich meridian, used by astronomers worldwide to time events. UK winter time equals UT; summer time is UT + 1h (France: UT + 1h in winter, UT + 2h in summer). Always write UT in an observing log.
- Seeing
The restlessness of the atmosphere that makes images dance and boil; it is also what makes stars twinkle. It is measured in arcseconds (the size of a star in a photo) or on scales from 1 to 10 (Pickering) or I to V (Antoniadi). It limits high magnification far more often than the instrument does.
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