How to use the Network Earth Rotation Service

There are three levels of using the NERS:

Level 1: using your browser

 

Advantage of using NERS with a browser: you see what you get.

Disadvantage of using NERS client library: usually you need the Earth orientation parameters for computations.

Level 2: using at as Internet service

An internet service is a request to a HTTP server with parameters. The server returns the answer upon receiving the request. Although An internet service works with any browser, normally it used with a non-interactive client such as wget. Here are supported services:

Rotation matrix: wget -q -O - 'http://earthrotation.net/cgi-bin/eop_online.py?req_date=now&param=mat'
Rotation matrix rate: wget -q -O - 'http://earthrotation.net/cgi-bin/eop_online.py?req_date=now&param=matr'
Rotation matrix accl: wget -q -O - 'http://earthrotation.net/cgi-bin/eop_online.py?req_date=now&param=matrr'
UTC minus TAI: wget -q -O - 'http://earthrotation.net/cgi-bin/eop_online.py?req_date=now&param=utcmtai'
UT1 minus TAI: wget -q -O - 'http://earthrotation.net/cgi-bin/eop_online.py?req_date=now&param=ut1mtai'
X pole coordinate: wget -q -O - 'http://earthrotation.net/cgi-bin/eop_online.py?req_date=now&param=xpol'
Y pole coordinate: wget -q -O - 'http://earthrotation.net/cgi-bin/eop_online.py?req_date=now&param=ypol'
Δψ nutation angle: wget -q -O - 'http://earthrotation.net/cgi-bin/eop_online.py?req_date=now&param=dpsi'
Δε nutation angle: wget -q -O - 'http://earthrotation.net/cgi-bin/eop_online.py?req_date=now&param=deps'
UT1 rate: wget -q -O - 'http://earthrotation.net/cgi-bin/eop_online.py?req_date=now&param=ut1rat'
X pole rate: wget -q -O - 'http://earthrotation.net/cgi-bin/eop_online.py?req_date=now&param=xpolr'
Y pole rate: wget -q -O - 'http://earthrotation.net/cgi-bin/eop_online.py?req_date=now&param=ypolr'
Length of day: wget -q -O - 'http://earthrotation.net/cgi-bin/eop_online.py?req_date=now&param=lod'
Euler angle axis 1: wget -q -O - 'http://earthrotation.net/cgi-bin/eop_online.py?req_date=now&param=e1'
Euler angle axis 2: wget -q -O - 'http://earthrotation.net/cgi-bin/eop_online.py?req_date=now&param=e2'
Euler angle axis 3: wget -q -O - 'http://earthrotation.net/cgi-bin/eop_online.py?req_date=now&param=e3'

Value of parameter req_date can be replaced to the date string that is ISO 8601 compatible, i.e. in format YYYY.mm.ddTHH:MM:SS.SSSSS, for instance 20110.04.19T08:19:15.545

The advantage of using NERS as an internet Service is that you can include calls to internet serve in your program

The disadvantage of using NERS as an internet service: the internet server is relatively slow.

Level 3: using the client library ners

Download and install ners client library.

You need insert three calls to your program

  1. ners_init ( config_file, ners, time_tai_start, time_tai_stop, iuer ) — initialization of the ners object using configuration parameters from the config file, start and stop time.
  2. ners_get_eop ( ners, time_tai, cpar, m_par, l_par, pars, iuer ) — return an array of Earth orientation parameters cpar on the specified time.
  3. ners_quit ( code, ners ) — release dynamic memory allocated by ners.

The advantage of using NERS client library: it is very fast serve in your program.

The disadvantage of using NERS client library: you need to know how to program and be ale to write a simple program, compile it and link against NERS librarty.


Back to the Network Earth Rotation Service
This page was prepared by Leonid Petrov ()
Last update: 2016.06.28_11:34:23