the sun - What constellation does sun occupy by location and date?

You can see for yourself for any date and location using the free Stellarium program (http://stellarium.org/).

The constellation that the Sun is in as seen from Earth does not depend noticeably on the precise location of the observer on Earth. It depends mostly on the time of year. Here are the approximate days of the year at which the Sun enters a new constellation:

• Aries: April 18


• Taurus: May 14


• Gemini: June 21


• Cancer: July 20


• Leo: August 10


• Virgo: September 16


• Libra: October 31


• Scorpius: November 23


• Ophiuchus: November 29


• Sagittarius: December 17


• Capricornus: January 19


• Aquarius: February 16


• Pisces: March 12

The "approximate" part is that the Sun may be up to one day earlier or later than the quoted dates, just like the start of the seasons may be one day earlier or later than the average. (Actually, it is the calendar that is early or late with respect to the phenomenon.) Also, because of the precession of the equinoxes, these dates shift by about 1 day every 70 years.

See http://aa.quae.nl/en/antwoorden/sterrenbeelden.html#6.