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diff --git a/ast/erfa/ut1utc.c b/ast/erfa/ut1utc.c
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+#include "erfa.h"
+
+int eraUt1utc(double ut11, double ut12, double dut1,
+              double *utc1, double *utc2)
+/*
+**  - - - - - - - - - -
+**   e r a U t 1 u t c
+**  - - - - - - - - - -
+**
+**  Time scale transformation:  Universal Time, UT1, to Coordinated
+**  Universal Time, UTC.
+**
+**  Given:
+**     ut11,ut12  double   UT1 as a 2-part Julian Date (Note 1)
+**     dut1       double   Delta UT1: UT1-UTC in seconds (Note 2)
+**
+**  Returned:
+**     utc1,utc2  double   UTC as a 2-part quasi Julian Date (Notes 3,4)
+**
+**  Returned (function value):
+**                int      status: +1 = dubious year (Note 5)
+**                                  0 = OK
+**                                 -1 = unacceptable date
+**
+**  Notes:
+**
+**  1) ut11+ut12 is Julian Date, apportioned in any convenient way
+**     between the two arguments, for example where ut11 is the Julian
+**     Day Number and ut12 is the fraction of a day.  The returned utc1
+**     and utc2 form an analogous pair, except that a special convention
+**     is used, to deal with the problem of leap seconds - see Note 3.
+**
+**  2) Delta UT1 can be obtained from tabulations provided by the
+**     International Earth Rotation and Reference Systems Service.  The
+**     value changes abruptly by 1s at a leap second;  however, close to
+**     a leap second the algorithm used here is tolerant of the "wrong"
+**     choice of value being made.
+**
+**  3) JD cannot unambiguously represent UTC during a leap second unless
+**     special measures are taken.  The convention in the present
+**     function is that the returned quasi JD day UTC1+UTC2 represents
+**     UTC days whether the length is 86399, 86400 or 86401 SI seconds.
+**
+**  4) The function eraD2dtf can be used to transform the UTC quasi-JD
+**     into calendar date and clock time, including UTC leap second
+**     handling.
+**
+**  5) The warning status "dubious year" flags UTCs that predate the
+**     introduction of the time scale or that are too far in the future
+**     to be trusted.  See eraDat for further details.
+**
+**  Called:
+**     eraJd2cal    JD to Gregorian calendar
+**     eraDat       delta(AT) = TAI-UTC
+**     eraCal2jd    Gregorian calendar to JD
+**
+**  References:
+**
+**     McCarthy, D. D., Petit, G. (eds.), IERS Conventions (2003),
+**     IERS Technical Note No. 32, BKG (2004)
+**
+**     Explanatory Supplement to the Astronomical Almanac,
+**     P. Kenneth Seidelmann (ed), University Science Books (1992)
+**
+**  Copyright (C) 2013-2014, NumFOCUS Foundation.
+**  Derived, with permission, from the SOFA library.  See notes at end of file.
+*/
+{
+   int big1;
+   int i, iy, im, id, js;
+   double duts, u1, u2, d1, dats1, d2, fd, dats2, ddats, us1, us2, du;
+
+
+/* UT1-UTC in seconds. */
+   duts = dut1;
+
+/* Put the two parts of the UT1 into big-first order. */
+   big1 = ( ut11 >= ut12 );
+   if ( big1 ) {
+      u1 = ut11;
+      u2 = ut12;
+   } else {
+      u1 = ut12;
+      u2 = ut11;
+   }
+
+/* See if the UT1 can possibly be in a leap-second day. */
+   d1 = u1;
+   dats1 = 0;
+   for ( i = -1; i <= 3; i++ ) {
+      d2 = u2 + (double) i;
+      if ( eraJd2cal(d1, d2, &iy, &im, &id, &fd) ) return -1;
+      js = eraDat(iy, im, id, 0.0, &dats2);
+      if ( js < 0 ) return -1;
+      if ( i == - 1 ) dats1 = dats2;
+      ddats = dats2 - dats1;
+      if ( fabs(ddats) >= 0.5 ) {
+
+      /* Yes, leap second nearby: ensure UT1-UTC is "before" value. */
+         if ( ddats * duts >= 0 ) duts -= ddats;
+
+      /* UT1 for the start of the UTC day that ends in a leap. */
+         if ( eraCal2jd(iy, im, id, &d1, &d2) ) return -1;
+         us1 = d1;
+         us2 = d2 - 1.0 + duts/ERFA_DAYSEC;
+
+      /* Is the UT1 after this point? */
+         du = u1 - us1;
+         du += u2 - us2;
+         if ( du > 0 ) {
+
+         /* Yes:  fraction of the current UTC day that has elapsed. */
+            fd = du * ERFA_DAYSEC / ( ERFA_DAYSEC + ddats );
+
+         /* Ramp UT1-UTC to bring about ERFA's JD(UTC) convention. */
+            duts += ddats * ( fd <= 1.0 ? fd : 1.0 );
+         }
+
+      /* Done. */
+         break;
+      }
+      dats1 = dats2;
+   }
+
+/* Subtract the (possibly adjusted) UT1-UTC from UT1 to give UTC. */
+   u2 -= duts / ERFA_DAYSEC;
+
+/* Result, safeguarding precision. */
+   if ( big1 ) {
+      *utc1 = u1;
+      *utc2 = u2;
+   } else {
+      *utc1 = u2;
+      *utc2 = u1;
+   }
+
+/* Status. */
+   return js;
+
+}
+/*----------------------------------------------------------------------
+**  
+**  
+**  Copyright (C) 2013-2014, NumFOCUS Foundation.
+**  All rights reserved.
+**  
+**  This library is derived, with permission, from the International
+**  Astronomical Union's "Standards of Fundamental Astronomy" library,
+**  available from http://www.iausofa.org.
+**  
+**  The ERFA version is intended to retain identical functionality to
+**  the SOFA library, but made distinct through different function and
+**  file names, as set out in the SOFA license conditions.  The SOFA
+**  original has a role as a reference standard for the IAU and IERS,
+**  and consequently redistribution is permitted only in its unaltered
+**  state.  The ERFA version is not subject to this restriction and
+**  therefore can be included in distributions which do not support the
+**  concept of "read only" software.
+**  
+**  Although the intent is to replicate the SOFA API (other than
+**  replacement of prefix names) and results (with the exception of
+**  bugs;  any that are discovered will be fixed), SOFA is not
+**  responsible for any errors found in this version of the library.
+**  
+**  If you wish to acknowledge the SOFA heritage, please acknowledge
+**  that you are using a library derived from SOFA, rather than SOFA
+**  itself.
+**  
+**  
+**  TERMS AND CONDITIONS
+**  
+**  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.
+**  
+**  3 Neither the name of the Standards Of Fundamental Astronomy Board,
+**    the International Astronomical Union nor the names of its
+**    contributors may be used to endorse or promote products derived
+**    from this software without specific prior written permission.
+**  
+**  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 HOLDER 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.
+**  
+*/