diff --git a/COPYRIGHT b/COPYRIGHT
new file mode 100644
index 0000000..fea44e7
--- /dev/null
+++ b/COPYRIGHT
@@ -0,0 +1,22 @@
+Copyright (c) 2014, Chen Wei <weichen302@gmail.com>
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+2. Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
+ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/README.md b/README.md
index 046f109..85e9743 100644
--- a/README.md
+++ b/README.md
@@ -4,11 +4,12 @@ Google, Apple, and Microsoft used to provide Chinese Lunar Calender in iCalender
 format, but most links were died over years. It is become hard to find a usable
 Chinese Lunar Calendar for use with online and offline calendar apps.
 
-The Chinese Lunar Calender is mostly based on the motion of the Moon. It is said
-the motion of Moon is very hard to predict, especially on the long run. Luckily
-[Hong Kong Observatory] has published a convertion table for the period from
-1901 to 2100. It is the most trustworthy Lunar Calender I can find on the web so
-far.
+The Chinese Lunar Calender is mostly based on the motion of the Moon. It is
+said due to the complicate interaction, mostly from the Sun and the Earth, the
+motion of Moon is very hard to predict, especially on the long run.  Luckily
+[Hong Kong Observatory][HK_Obs] has published a convertion table for the period
+from 1901 to 2100. It is the most trustworthy Lunar Calender I can find on the
+web so far.
 
 
 ### License
@@ -16,12 +17,14 @@ far.
 This package is released under the terms and conditions of the BSD License, a
 copy of which is include in the file COPYRIGHT.
 
+*Hong Kong Observatory* has been very kind to provide and grant the permission
+of using their convertion table, which is only for Non-Commercial use.
 
 ### How to run
 
-run `lunar_ical`, it will fetch data from [Hong Kong Observatory][HK_Obs], save the data
-to a local sqlite database, then use that database to generate a ics file, which
-covers from the previous to the end of next year.
+run `lunar_ical`, it will fetch data from Hong Kong Observatory, save
+the data to a local sqlite database, then use that database to generate a ics
+file, which covers from the previous to the end of next year.
 
 Try the Chinese Lunar Calendar by add this [ics file][iCal] to your favorite
 calendar app.
@@ -38,16 +41,14 @@ The date must in ISO format.
 iCalendar是一种通用的日历交换格式，很多软件和设备，比如google calendar, apple
 calendar, thunderbird + lightning插件, iphone/ipad, 安卓都支持。
 
-以前订过iCalendar格式农历日历，但慢慢地它们都停止了更新。所幸[香港天文台][HK_Obs]上可以
-找到从1901年到2100年间两百年的农历-公历对照表，也就是这里用到的数据。
+以前订过iCalendar格式农历日历，但慢慢地它们都停止了更新。所幸香港天文台为公众提供了从1901年到2100年间两百年的农历-公历对照表，也就是这里用到的数据。
 
-下面是覆盖前年、今年以及明年三年的日历[ics文件][iCal]链接，把它加入到你最常用的软件
-就可以了。
+下面是覆盖前年、今年以及明年三年的日历[ics文件][iCal]链接，把它加入到你最常用的软件就可以了。
 
 [https://raw.github.com/infinet/lunar-calender/master/chinese_lunar_prev_year_next_year.ics][iCal]
 
 苹果设备上应该是:
- 设置 => 邮件、通讯录、日历 => 添加账户  => 日历 添加已订阅日历
+    设置 => 邮件、通讯录、日历 => 添加账户 => 其它 => 日历 添加已订阅日历
 
 如果在Mac的*iCal*里订阅到iCloud，这个日历还可以自动推送到所有使用那个iCloud
 账户的ios设备。
@@ -56,7 +57,7 @@ calendar, thunderbird + lightning插件, iphone/ipad, 安卓都支持。
 
 ### 生成更长时段农历
 
-如果你需要更长时段的农历，可以下载`lunar_ical.py`
+如果需要更长时段的农历，可以下载`lunar_ical.py`
 
 直接运行`./lunar_ical.py`会从香港天文台抓取1901到2100年间所有数据，然后生成上面
 那个前后三年时段的农历ics文件；
@@ -66,9 +67,14 @@ calendar, thunderbird + lightning插件, iphone/ipad, 安卓都支持。
     ./lunar_ical.py --start=2010-05-01 --end=2021-12-31
 
 
+### 版权
+
+本项目版权使用BSD协议，请参见所附COPYRIGHT文件。
+
+感谢[香港天文台][HK_Obs]为公众提供并授权本项目使用农历-公历对照数据，该部分数据仅限非商业用途。
 
 
 [Contact me](mailto: weichen302@gmail.com)
 
 [iCal]: https://raw.github.com/infinet/lunar-calender/master/chinese_lunar_prev_year_next_year.ics
-[HK_Obs]: http://gb.weather.gov.hk/gts/time/conversionc.htm
+[HK_Obs]: http://data.weather.gov.hk/gts/time/conversion1_text_c.htm
diff --git a/lunar_ical.py b/lunar_ical.py
index ee17bb0..391b683 100755
--- a/lunar_ical.py
+++ b/lunar_ical.py
@@ -1,7 +1,12 @@
 #!/usr/bin/env python
 # -*- coding: utf-8 -*-
 
-'''get lunar calendar from hk observatory '''
+'''get lunar calendar from hk observatory
+
+Hong Kong Observatory has been very kind to grant the permission for using the
+lunar calendar data from their website.
+
+'''
 
 __license__ = 'BSD'
 __copyright__ = '2014, Chen Wei <weichen302@gmail.com>'
@@ -24,7 +29,7 @@ APPDIR = os.path.abspath(os.path.dirname(__file__))
 DB_FILE = os.path.join(APPDIR, 'db', 'lunarcal.sqlite')
 RE_CAL = re.compile(u'(\d{4})年(\d{1,2})月(\d{1,2})日')
 PROXY = {'http': 'http://localhost:8001'}
-URL = 'http://gb.weather.gov.hk/gts/time/calendar/text/T%dc.txt'
+URL = 'http://data.weather.gov.hk/gts/time/calendar/text/T%dc.txt'
 OUTPUT = os.path.join(APPDIR, 'chinese_lunar_%s_%s.ics')
 
 ICAL_HEAD = ('BEGIN:VCALENDAR\n'