Weather Information for Astronomical Observation

Notes:

1. If your browser is not supported, you may not be able to use some special features and the response could be relatively slow. Presentation of the webpage may vary according to different browsers, computers and operating systems. For details, please refer to "Contact and Support".

2. All astronomical information is calculated for mean sea level at latitude 22°18'7.3", longitude 114°10'27.6", which is the location of the Hong Kong Observatory, based on astronomical data provided by the HM Nautical Almanac Office, United Kingdom and the United States Naval Observatory.

3. The starry sky keeps turning with time. "Monthly Star Map" shows the night sky at around eight o'clock of that particular month. For every two hours gone, the star map for the following month can be used.

4. The night sky brightness (NSB) is measured by the SQM-LE Night Sky Brightness monitors at the monitoring stations on the Hong Kong Night Sky Brightness Monitoring Network (NSN) and the Globe at Night - Sky Brightness Monitoring Network (GaN-MN); smaller value represents brighter sky while larger value represents darker sky. Detailed information can be found at https://nightsky.physics.hku.hk/en-hk/research/hong-kong-night-sky-brightness-map and http://globeatnight-network.org/

5. "The daily rise and set times of the celestial bodies" shows the times of rise and set of the celestial bodies on the current day.

6. "The information of special astronomical phenomena" shows the special astronomical events in the coming 30 days but not all events can be observed in Hong Kong. The information will be updated whenever there are any other ad hoc events or events of public interests.

7. The air temperature and relative humidity of each astronomical observation hot sport is using observation of the nearest automatic weather station(s) close to sea level operated by the Hong Kong Observatory.

8. From sunset every day to sunrise the next day, the night sky brightness provided by the Department of Physics of the University of Hong Kong is updated once every 5 minutes by the median value of the night sky brightness of the past 15 minutes.  The night sky brightness data is only available at night time.

9. The information of the "Astronomical Observation Weather Information" website is jointly provided by the Hong Kong Observatory, the Hong Kong Space Museum, the Department of Physics of the University of Hong Kong and and Ho Koon Nature Education cum Astronomical Centre (Sponsored by Sik Sik Yuen). The information is for general only.

10. The background geographical information on this page comes from OpenStreetMap and the usage is subject to OpenStreetMap's License Terms. The downloading speed depends on the responsiveness of its servers and sometimes it may take a longer time to complete the download.

11. This webpage is jointly organized by the Hong Kong Observatory, Hong Kong Space Museum, Department of Physics of the University of Hong Kong and Ho Koon Nature Education cum Astronomical Centre (Sponsored by Sik Sik Yuen).

12. For enquiries on astronomical service, please contact Scientific Officer (Geophysics Services) at 2926 8433
    
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