The intermediate Palomar Transient Factory monitors M31 on a nightly cadence,
weather-permitting. Following ATel#6527, we examined our archive and found
no source at the location of M31N 2008-12a on Oct 2 11:14 UT, 10 hours before
the reported detection in ATel#6527. We then derived a 5-sigma limiting
magnitude of about 19.5 mag in g-band.
