[amsat-bb] Web API to get the information necessary for tracking DESPATCH

Akihiro Kubota akihiro.kubota at nifty.com
Sun Sep 7 01:50:46 UTC 2014

Dear AMSAT members,

The ARTSAT Project is going to launch a deep-space sculpture/spacecraft “DESPATCH” this December. One of the main mission of DESPATCH is the trial reception of very weak signals from deep space, gathering fragmented data received by ham operators around the world. Further details are introduced in this document: https://dl.dropboxusercontent.com/u/1336163/despatch_abstract_en_ver1.0.1.pdf

Subsequently to this documentation, we developed a Web API to get the information necessary for tracking DESPATCH (e.g. elevation, azimuth angles, reception frequency, etc.). http://api.artsat.jp/web/despatch

The below URL provides this trajectory data in a formatted text file (CSV or JSON format). 
CSV format: http://api.artsat.jp/despatch/track_range.csv?begin=1417436200&end=1417437200&interval=100&lat=35.610603&lon=139.351124&alt=148
JSON format: http://api.artsat.jp/despatch/track_range.json?begin=1417436200&end=1417437200&interval=100&lat=35.610603&lon=139.351124&alt=148

The 6 parameters after “?” in the URLs are variables which are given to our data server. The location of your radio station is set by “lat”, “lon”, and “alt,” and our server provides the trajectory data in the period between “begin” and “end” at intervals of “interval” value. 

The example URLs above are set to our radio station (latitude: N 35.610603 [deg.]  longitude: E 139.351124 [deg.]  altitude: 148 [meter]), to the period between 13:16:40 UTC and 13:33:22 UTC, 1 December 2014, and to the intervals of 100 seconds.
The time system of “begin” and “end” are Unix-time, which is the number of seconds that have elapsed since 00:00:00 UTC, 1 January 1970 (http://en.wikipedia.org/wiki/Unix_time). To convert UTC to Unix-time, these web sites will be helpful: http://www.epochconverter.com/, http://www.onlineconversion.com/unix_time.htm. 

Since the ordinal TLE set is not available for DESPATCH in an earth escape orbit, we are asking for your helps in developing software to read this data file and to control the hardware, including the antenna-rotators and receivers in your radio station.

If you have any comments or suggestions about this trajectory data or any other else, please contact us freely. Thank you in advance.

Note: The launch date of DESATCH is not fixed.  The current trajectory data is calculated assuming that the launch day is 1 December 2014. At present, you can get the data int the period from the launch day to the day after a week.

All the best,
ARTSAT Project Team
info at artsat.jp

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