Wednesday, October 22, 2008

Limit of navigation

Further adventures in my pursuit of the 'limit of navigation' in the southern night sky.

Theoretically, from my back garden at 52 deg N, I should be able to see a star with declination 38 S when it is due South in the sky.

In practice of course, horizon haze, horizon obstructions (houses etc) and tossers with security lights mean that you may not be able to see that far down - in my experience you're doing well to see to within 5-8 degrees of the horizon, which puts the limit of navigation at 30 S - 33 S.

So last night I was pleased not only to see Fomalhaut easily visible at 29 1/2 S, but scanning with binoculars I found delta PsA below it at 32 1/2 S. I've seen that far before, at another site, in Sagittarius, but in fact at 32 deg 32 min South, this star just crosses the previous limit.

I also had a good look for gamma PsA (20 arcmin further south) but sadly it was hidden behind chimney pots.

In my world of binocular back-garden astronomy, spotting a 4th magnitude star less than 6 deg from the horizon is a real triumph.

Update Oct 23rd: Going out a little later last night, could easily see delta and gamma. Gamma takes me to 32 deg 52 S.

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