X-ray and optical-to-infrared follow-up observations of the transient X-ray burster SAX J1810.8-2609

We have performed a ROSAT follow-up observation of the X-ray transient SAX J1810.8-2609 on 1998 March 24 and detected a bright X-ray source (named RX J1810.7-2609) which was not detected during the ROSAT all-sky survey in September 1990. Optical-to-infrared follow-up observations of the 10″ radius ROSAT HRI X-ray error box revealed one variable object (R = 19.5 ± 0.5 on March 13, R > 21.5 on 1998 August 27) which we tentatively propose as the optical/IR counterpart of RX J1810.7-2609 ≡ SAX J1810.8-2609.