[APBeta] Odd behavior in the Observing Nights Script

[Paul Rodman]

On Jul 1, 2010, at 5:15 PM, David Crum wrote:

> Paul, ran into some interesting behavior in the Observing Nights Script.
> 
> I ran it for July and noticed that the output was bascially the
> same-Astronomical Twilight ending at 22:11 (acceptable for this time
> of year), but ending at 04:55 for the next 3 nights and increasing by
> 1 minute for almost the next 12 nights.  The moon rise at 00:40 on
> Saturday morning.
> 
> Unless I am looking at this the wrong way (very possible), lol.

Me too. At this time of the year (around the longest day/shortest night) the time of sunset/sunrise remains fairly constant, and then changes more and more rapidly as fall approaches. However, there do seem to be some anomalies, particularly if the specified latest-observing-time occurs before the start of the dark period (which it might do for higher latitude at midsummer). e.g. Here in Seattle (47 deg), astronomical twilight ends after midnight (making astronomy well nigh impossible during summer, and it rains for the rest of the year).

Paul R.