bawn79 wrote:
tiompan wrote:
bawn79 wrote:
tiompan wrote:
UncleRob wrote:
Hi Rob , One problem that you might get with the site is working out the elevation .If you can do that then it looks like it will provide quite good accuracy .
Ive always wondered how elevation affects this, I know mountains etc may be in the way but generally you can observe this at the site.
Is that the main problem or is there something Im not thinking of?
The simplest way to show the effect of elevation is to imagine that you are attempting to observe an equinox sunrise i.e. due east , but if you there is a 30 m high wall between you and the sun then you will not see the sun until it has moved further west and subsequently higher on the horizon .The higher the wall the later the sunrise and more westerly the bearing . You only experience an equinox sunrise at approx 90 degrees if the horizon is relatively flat . The same problem applies to all astro events . Hope that helps and is not too convoluted .
No it makes perfect sense, so in reality observation is the best way to decide for sure.
Thanks again
Can't beat a bit of personal , on the spot observation . Except we do have trig to work it out , if , you know the distance you are from the wall and the height of the wall ,which we do in the case of sites to hill tps etc . It's worth mentioning the problem of refraction which makes the sun appear to be still above the horizon when it is actually below the horizon so in that case personal observation is not quite accurate .
