Isn’t it a problem if you want a horoscope? There is an hour of ambiguity.
“Isn’t it a problem if you want a horoscope?”
That fact someone wants a superstitious horoscope is the problem. The fact that a mere man-made timezone issue confuses a horoscope shows what a crock they are.
Horoscopes are calculated using GMT and latitude/longitude along with how far from the Prime Meridian your birthspot is, and whether you are east (add 4 minutes per degree off) or west (subtract 4 minutes per degree off) of the Prime. So, someone born at midnight local time in Atlanta may not have an 23:59, 00:00 or 00:01 horoscope, depending on how far off GMT they are.
But to play devil’s advocate, even if GMT wasn’t the standard used, an hour is negligible. Mercury moves 4 degrees in 24 hours, so about 1 degree every six hours. The moon moves 12 degrees in 24 hours, or 1/2 degree per hour. The rest of the planets just mosey along; Pluto moving something like one degree every 60 years. Angles between planets don’t have to be absolutely exact, ie., 88 is still counted as a 90 degree angle; 92 would also be looked at as 90 degrees. An hour on the cusp isn’t remarkable either since with cusp planets one has to consider the influence of adjoining cusp signs on that planet anyway. And, finally, a single degree wouldn’t affect sidereal time calculations for house horizon placement when doing a simple birth chart.