  GRB 970815 was a well-localized gamma-ray burst (GRB) detected by the All-Sky
Monitor (ASM) on the Rossi X-Ray Timing Explorer (RXTE) for which no afterglow
was identified despite follow-up ASCA and ROSAT pointings and optical imaging
to limiting magnitude R>23. While an X-ray source, AX/RX J1606.8+8130, was
detected just outside the ASM error box, it was never associated with the GRB
because it was not clearly fading and because no optical afterglow was ever
found. We recently obtained an upper limit for this source with Chandra that is
at least factor of 100 fainter than the ASCA detection. We also made deep
optical observations of the AX/RX J1606.8+8130 position, which is blank to
limits V>25.2 and I>24.0. In view of these extreme limits we conclude that
AX/RX J1606.8+8130 was indeed the afterglow of GRB 970815, which corresponds to
an optically "dark" GRB. AX/RX J1606.8+8130 can therefore be ruled out as the
counterpart of the persistent EGRET source 3EG J1621+8203. The early light
curves from BATSE and the RXTE ASM show spectral softening between multiple
peaks of prompt emission. We propose that GRB 970815 might be a case in which
the properties of an X-ray flash (XRF) and a "normal" GRB coincide in a single
event.
