Following its 2002 February eruption , V838 Mon developed a light echo that continues to expand and evolve as light from the outburst scatters off progressively more distant circumstellar and/or interstellar material .
Multi-filter images of the light echo , obtained with the South African Astronomical Observatory ( SAAO ) 1.0-m telescope between 2002 May and 2004 December , are analysed and made available electronically .
The expansion of the light echo is measured from the images and the data compared with models for scattering by a thin sheet and a thin shell of dust .
From these model results we infer that the dust is likely in the form of a thin sheet distant from the star , suggesting that the material is of interstellar origin , rather than being from earlier stages in the star ’ s evolution .
Although the fit is uncertain , we derive a stellar distance of \sim 9 kpc and a star-dust distance of \sim 5 pc , in good agreement with recent results reported from other methods .
We also present JHKL and Cousins UBVRI photometry obtained at the SAAO during the star ’ s second , third and fourth observing seasons post-outburst .
These data show complex infrared colour behaviour while V838 Mon is slowly brightening in the optical .