Washington photometry of five star clusters in the Large Magellanic Cloud

We present CCD photometry in the Washington-system C and T-1 passbands down to T-1 similar to 22.5 mag in the fields of NGC 1697, SL 133; NGC 1997; SL 663; and OHSC 28, five mostly unstudied star clusters in the LAIC. Cluster radii were estimated from star counts in appropriately sized boxes distributed throughout the entire observed fields. We perform a detailed analysis of field-star contamination and derive cluster colour-magnitude diagrams (CMDs). Based on the best fits of isochrones computed by the Padova group to the (C - T-1,T-1) CMDs, the delta(T-1) index and the 'standard giant-branch' procedure; we derive metallicities and ages for the five clusters. With the exception of NGC 1697 (age = 0.7 Gyr, [Fe/H] = 0.0 dex), the remaining four clusters are of intermediate age (from 2.2 to 3.0 Gyr) and relatively metal poor ([Fe/H] = -0.7 dex). We combine our sample with clusters with ages and metallicities on a similar scale and examine relationships between position in the LMC, age and metallicity. We confirm previous results that clusters younger than similar to 1 Gyr were formed during an outside-in process; this occurred after a burst of cluster formation that took place mainly in the outer disk and peaked similar to 2 Cyr ago. Finally; the cluster and field age-metallicity relations (AMRs) show evidence for a metallicity offset but do overlap; particularly on the upper-envelope side of the cluster AMR.