<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">Hi all,<div class=""><br class=""></div><div class="">I’m getting some behavior I don’t understand from astropy.time. I’m trying to make a quick tool for printing out the current time in UT, MJD, and sidereal (LMST). When I run it, I get an error on the step of calculating the sidereal time:</div><div class=""><br class=""></div><div class=""><div class=""><font face="Monaco" class="">LST_string = now.sidereal_time('mean').to_string(sep=':', precision=1)</font></div></div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><div class=""><font face="Monaco" class="">Traceback (most recent call last):</font></div><div class=""><font face="Monaco" class=""> File "time_example.py", line 20, in <module></font></div><div class=""><font face="Monaco" class=""> LST_string = now.sidereal_time('mean').to_string(sep=':', precision=1)</font></div><div class=""><font face="Monaco" class=""> File "/Users/joshw/anaconda/lib/python2.7/site-packages/astropy/time/core.py", line 523, in sidereal_time</font></div><div class=""><font face="Monaco" class=""> gst = self._erfa_sidereal_time(available_models[model.upper()])</font></div><div class=""><font face="Monaco" class=""> File "/Users/joshw/anaconda/lib/python2.7/site-packages/astropy/time/core.py", line 539, in _erfa_sidereal_time</font></div><div class=""><font face="Monaco" class=""> for jd_part in ('jd1', 'jd2')]</font></div><div class=""><font face="Monaco" class=""> File "/Users/joshw/anaconda/lib/python2.7/site-packages/astropy/time/core.py", line 704, in __getattr__</font></div><div class=""><font face="Monaco" class=""> tm._set_scale(attr)</font></div><div class=""><font face="Monaco" class=""> File "/Users/joshw/anaconda/lib/python2.7/site-packages/astropy/time/core.py", line 372, in _set_scale</font></div><div class=""><font face="Monaco" class=""> args.append(get_dt(jd1, jd2))</font></div><div class=""><font face="Monaco" class=""> File "/Users/joshw/anaconda/lib/python2.7/site-packages/astropy/time/core.py", line 834, in _get_delta_ut1_utc</font></div><div class=""><font face="Monaco" class=""> delta = iers_table.ut1_utc(jd1, jd2)</font></div><div class=""><font face="Monaco" class=""> File "/Users/joshw/anaconda/lib/python2.7/site-packages/astropy/utils/iers/iers.py", line 234, in ut1_utc</font></div><div class=""><font face="Monaco" class=""> raise IndexError('(some) times are outside of range covered '</font></div><div class=""><font face="Monaco" class="">IndexError: (some) times are outside of range covered by IERS table.</font></div></div><div class=""><br class=""></div><div class="">When I go ahead and download the IERS table using the tools in astroplan:</div><div class=""><br class=""></div><div class=""><div class=""><font face="Monaco" class="">from astroplan import download_IERS_A</font></div><div class=""><font face="Monaco" class="">download_IERS_A()</font></div></div><div class=""><br class=""></div><div class="">the code works. But I need to do this download every time I run the code which is time consuming on code that I want to run many times. Shouldn’t this be cached?</div><div class=""><br class=""></div><div class="">Any idea why the download is needed every time?</div><div class=""><br class=""></div><div class="">thanks!</div><div class="">Josh</div><div class=""><br class=""></div><div class="">P.S. Entire code is pasted in below:</div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><div class=""><div class=""><font face="Monaco" class="">from datetime import datetime as dt</font></div><div class=""><font face="Monaco" class="">from astropy.time import Time</font></div><div class=""><font face="Monaco" class="">from astropy.coordinates import EarthLocation</font></div><div class=""><font face="Monaco" class="">import astropy.units as u</font></div><div class=""><font face="Monaco" class=""><br class=""></font></div><div class=""><font face="Monaco" class=""># from astroplan import download_IERS_A</font></div><div class=""><font face="Monaco" class=""># download_IERS_A()</font></div><div class=""><font face="Monaco" class=""><br class=""></font></div><div class=""><font face="Monaco" class="">utnow = dt.utcnow()</font></div><div class=""><font face="Monaco" class="">subaru = EarthLocation.from_geodetic(-155.476111111*u.degree,\</font></div><div class=""><font face="Monaco" class=""> 19.8255555556*u.degree,\</font></div><div class=""><font face="Monaco" class=""> height=4139.0*u.meter)</font></div><div class=""><font face="Monaco" class="">now = Time(utnow, location=subaru)</font></div><div class=""><font face="Monaco" class=""><br class=""></font></div><div class=""><font face="Monaco" class="">UTC_string = utnow.strftime('%H:%M:%S.%f')</font></div><div class=""><font face="Monaco" class="">print(UTC_string)</font></div><div class=""><font face="Monaco" class="">MJD_string = '{:20.8f}'.format(now.mjd)</font></div><div class=""><font face="Monaco" class="">print(MJD_string)</font></div><div class=""><font face="Monaco" class="">LST_string = now.sidereal_time('mean').to_string(sep=':', precision=1)</font></div><div class=""><font face="Monaco" class="">print(LST_string)</font></div></div></div><div class=""><br class=""></div></body></html>