Grupo Astronómico de El HierroExplaining data panel
This panel is usefull to obtain direct information in order to a profitable observation.
We recomend to check it a few hours before starting the night watching. Those data are updated every two minutes and offered in the website.
Those related to weather are totally decisive since observation is difficult or even not possible if we do not contemplate that. Conditions may be different in relation to darkness. We could watch shinning objects even in not fully dark nights as it happens in some of the Moon phases. Finally if our aim is to take pictures of very weak objects, the atmospheric conditions are specially relevant and will mark the limitations of the observation
Weather
Those data are shown here as 3 coloured lights and the values may change according the data offered from the observatory weather station. Nevertheless the cloud evolution is not specifically referred to here and should be checked in the first place. The limits applied here are under experimentation and very likely they will be revised in future. As a starting point the colour values are as follows
| 
| 
| |
|---|---|---|---|
| Temperature | Above 5°C | Between 0°C and 5°C | Under 0°C |
| Rain | No rain | Rain | |
| Humidity | Under 80% | Between 80% and 90% | Over 90% |
| Average wind speed in 10 min | Under 6 m/s (aprox 20 km/h) | Between 6 m/s and 12 m/s | Over 12 m/s (aprox 40 km/h) |
Reading guide:
- All colours rating green it is a positive good moment to start observation.
- One red or two orange colours, calling the sesion off is advisable.
- One orange colour, you can try, but most chances are it will deteriorate.
- Cloud situation can be valued with the observatory web cam.
Darkness
At the bottom of the chart it is possible to check the sun and moon data which allow for quality of darkness through the night. Azimut is the position on the horizontal level measured from the South; Height shows vertical distance from the horizon.
For night watching the sun must be under the horizon, that is to say with negative height. Total darkness is ussualy regarded when it is 18° under the horizon.
The height of the Moon shows its visibility (again negative height means under the horizon) and how to place it in the sky, in case it is possible to watch it. The Moon light is very important as in very bright Moon (near full Moon) it is not possible to observe weak bodies. Nevertheless it is possible to watch them with less than 40% brightness. But above this and up to aprox 70%, only the Moon and the top shinning planets can be observed. Above 70% you can only assert star positions (Astrometry) and it is not possibly to watch directly or take pictures.
Stability
We don't have a manageable way to measure this. You can get an idea by clicking " Prevision seeing" in the file Weather in our web. We advise to be always cautious about that information.