diff --git a/skyfield/timelib.py b/skyfield/timelib.py
index <HASH>..<HASH> 100644
--- a/skyfield/timelib.py
+++ b/skyfield/timelib.py
@@ -691,10 +691,7 @@ class Time(object):
 
     @reify
     def ut1_fraction(self):
-        # Calling "self.delta_t" would cache a useless intermediate value, so:
-        table = self.ts.delta_t_table
-        delta_t = interpolate_delta_t(table, self.tt)
-        return self.tt_fraction - delta_t / DAY_S
+        return self.tt_fraction - self.delta_t / DAY_S
 
     @reify
     def delta_t(self):
Let Time.ut1_fraction also reify Time.delta_t

To save memory, I had avoided letting `.ut1_fraction` also save the
`.delta_t` array that it creates, but given that changes are about to
take place in `interpolate_delta_t()`, it seems best at this point to
opt for simplicity over a few percent savings in the memory footprint of
a typical Time.