A dense series of long and high time resolution light curves of the old nova V603 Aql , covering 22 nights ( 19 of which are consecutive ) , are analyzed in order to identify and characterize variations on the time scale of hours and days .
The well known 3.5 hour modulation , observed many times in the past and considered to be due to a long lasting , albeit not entirely stable superhump , is recovered at a period of 0.1453 days and an amplitude of \sim 0 \mbox { $ { } ^ { \raisebox { 1.29 pt } { \scriptsize m } } _ { \raisebox { 2.58 pt } { . } } $ } 062 .
Most interesting , however , is the detection of highly significant brightness variations with an amplitude of \sim 0 \mbox { $ { } ^ { \raisebox { 1.29 pt } { \scriptsize m } } _ { \raisebox { 2.58 pt } { . } } $ } 0. % 050 and a period of 5.85 days which is to a very high precision equal to twice the beat period between the orbital and the superhump period .
The latter is generally interpreted as the precession period of an eccentric accretion disk .
The origin of these long term variations remains unknown .

Keywords : Stars : novae , cataclysmic variables – Stars : individual : V603 Aql