A reanalysis of the ( seemingly very distant ) open cluster Shorlin 1 , the group of stars associated with WR 38 and WR 38a , is made on the basis of existing UBV and JHK _ { s } observations for cluster members .
The 2MASS observations , in particular , imply a mean cluster reddening of E _ { B - V } = 1.45 \pm 0.07 and a distance of 2.94 \pm 0.12 kpc .
The reddening agrees with the UBV results provided that the local reddening slope is described by E _ { U - B } / E _ { B - V } = 0.64 \pm 0.01 , but the distance estimates in the 2MASS and UBV systems agree only if the ratio of total-to-selective extinction for the associated dust is R = A _ { V } / E _ { B - V } = 4.0 \pm 0.1 .
Both results are similar to what has been obtained for adjacent clusters in the Eta Carinae region by similar analyses , which suggests that “ anomalous ” dust extinction is widespread through the region , particularly for groups reddened by relatively nearby dust .
Dust associated with the Eta Carinae complex itself appears to exhibit more “ normal ” qualities .
The results have direct implications for the interpretation of distances to optical spiral arm indicators for the Galaxy at \ell = 287 \arcdeg - 291 \arcdeg , in particular the Carina arm here is probably little more than \sim 2 kpc distant , rather than 2.5 - 3 kpc distant as implied in previous studies .
Newly-derived intrinsic parameters for the two cluster Wolf-Rayet stars WR 38 ( WC4 ) and WR 38a ( WN5 ) are in good agreement with what is found for other WR stars in Galactic open clusters , which was not the case previously .