UBV photoelectric observations of a total of 175 stars in the field of
NGC2323 were collected with the University of Toronto's 0.6 m telescope
at Las Campanas Observatory (LCO) and with the Cerro Tololo Inter-American
Observatory (CTIO) 0.9-m telescope, over a large number of photometric nights
from March 1984 to February 1987. Dry-ice cooled RCA1P21 and Ga-As
RCA31034 phototubes in single channel photometers with pulse-counting
electronics were used for all observations at LCO and CTIO, respectively.
Mean extinction coefficients at both observatories were employed and nightly
observations of about 13-17 standard stars taken from the lists of
Cousins
(1973, 1974), Landolt (1973) and Graham (1982) were used to transform instrumental magnitudes into
the UBV standard system. External and internal mean errors are nearly similar
to those in previous papers (e.g., Clariá et al. 1991). Typically
mag,
mag and 
mag for V<12 mag, increasing to 0.018, 0.022 and
0.027 for V>12 mag,
respectively. Table 1 lists V
magnitudes, U-B and B-V colours, and the number of measurements performed
in each filter for all the stars numbered in Fig. 1 (click here),
while Table 2 includes
the correlation of identifications with other authors.
Figure 1: Identification chart for stars in NGC2323
We compare our photoelectric photometry with the most extensive and recent
photographic survey carried out by Mostafa et al. (1983). As can be seen in
Fig. 2 (click here), there is no colour dependence between the magnitude scales, an
appreciable scatter being the principal feature. The resulting mean
differences (in the sense Mostafa et al. minus this study) for a total of 66
stars in common are 
, 
and 
for
the U, B and V magnitudes, respectively.
Figure 2: Magnitude differences (Mostafa et al. minus this study) versus
photoelectric colours
In addition, observations of five stars in the DDO system were carried out
with the purpose of obtaining additional information about their reddening,
probable membership, luminosity class, and metal content. These measurements
were made in April 1985 using the CTIO 0.9-m telescope with an 
photomultiplier. The transformation to the DDO standard system was done by
nightly observing between 12 to 16 standards from the list of
McClure (1976). All the measurements were performed with a single-channel photometer and pulse
counting electronics. The resulting external mean errors in the DDO colours
were found to be about or slightly smaller than 0.01 mag. In Table 3 (click here) we list
the DDO colours obtained for each star and the number n of individual
observations.
| Star | C(45-48) | C(42-45) | C(41-42) | n |
| 12 | 1.402 | 1.140 | 0.220 | 2 |
 0.002 | 0.002 | 0.016 | ||
| 38 | 1.254 | 1.009 | 0.303 | 2 |
| 0.007 | 0.004 | 0.017 | ||
| 42 | 1.221 | 0.972 | 0.217 | 2 |
| 0.011 | 0.005 | 0.022 | ||
| 53 | 1.496 | 1.394 | 0.230 | 2 |
| 0.006 | 0.013 | 0.016 | ||
| 121 | 1.486 | 1.307 | 0.289 | 2 |
| 0.008 | 0.020 | 0.002 | ||
|
|