[OIII]5007 on-band off-band images, obtained with the VLT and FORS2
spectrograph in two zones (center and outskirts) of the spiral galaxy NGC300,
are analyzed searching for emission line objects. In particular we search for
planetary nebula (PN) candidates to analyze their distribution and luminosity
properties, to perform follow-up spectroscopy, and to study the planetary
nebula luminosity function, PNLF. In the continuum-subtracted images, a large
number of emission line objects were detected. From this sample we selected as
PN candidates those objects with stellar appearance and no detectable central
star. [OIII]5007 instrumental magnitudes were measured and calibrated by using
spectrophotometric data from the follow-up spectroscopy. We identified more
than a hundred PN candidates and a number of compact HII regions. The PN sample
is the largest one reported for this galaxy so far. For all the objects we
present coordinates, instrumental [OIII]5007 magnitudes and apparent nebular
[OIII]5007 fluxes and magnitudes. The [OIII]5007 observed luminosity function
for PNe (PNLF) was calculated for the whole sample and for the central and
outskirts samples. The three PNLF are similar within uncertainties. We fit the
empirical PNLF to the observed PNLF for all the samples. From our best fit for
the whole sample we derived a maximum value for the apparent magnitudes of
m*(5007)=22.019\pm0.022 and we obtained a tentative estimate of the distance
modulus m(5007)-M(5007)= 26.29 {+0.12} {-0.22} mag, which agrees well with the
recent value derived from Cepheid stars.Comment: 8 pages, 3 figures, one long table. Accepted by A&
