pytz.timezone shows weird results for Asia/Calcutta? [duplicate]

Question

Possible Duplicate:
Python datetime object show wrong timezone offset

import pytz, datetime

 pytz.timezone("Asia/Calcutta")

prints the following:

< DstTzInfo 'Asia/Calcutta' HMT+5:53:00 STD >

Why it is not 05:30 hrs? I am in timezone America/Los_Angeles.

Answer 1

Time zones change over the years. According to http://www.prokerala.com/travel/timezones/Asia/Kolkata?mode=history the original offset for that zone was 5.88888888889 hours, or 5 hours 53 minutes. pytz will use the proper offset and nomenclature once you assign the zone to an actual date.

>>> tz = pytz.timezone("Asia/Calcutta")
>>> tz
<DstTzInfo 'Asia/Calcutta' HMT+5:53:00 STD>
>>> tz.localize(datetime.datetime(1901, 7, 10, 12, 0))
datetime.datetime(1901, 7, 10, 12, 0, tzinfo=<DstTzInfo 'Asia/Calcutta' HMT+5:53:00 STD>)
>>> tz.localize(datetime.datetime(2012, 7, 10, 12, 0))
datetime.datetime(2012, 7, 10, 12, 0, tzinfo=<DstTzInfo 'Asia/Calcutta' IST+5:30:00 STD>)