Rapid submillimeter brightenings associated with a large solar flare

We present high time resolution observations of Active Region 8910 obtained simultaneously at 212 and 405 GHz during a large H alpha flare, which prod uced a soft X-ray class X1.1 event. Data were obtained with the new solar s ubmillimeter telescope recently installed at the El Leoncito Observatory to explore this poorly known part of the solar emission spectrum. A small slo w submillimeter enhancement (less than or equal to 300 sfu) was associated to bulk emissions at X-rays, H alpha, and microwaves. The event exhibited n umerous submillimeter-wave 100-300 ms duration spikes, the larger ones with fluxes on the order of 220 and 500 sfu (+/-20%) at 212 and 405 GHz, respec tively. A dramatic increase in the incidence rate of submillimeter spikes s ets in as a new large loop system appears in AR 8910, and X-ray emission in creases nearly 1 hr before the large flare. The brightening incidence rate (similar to 20 per minute) correlates well with the large flare light curve s at X-rays and H alpha. The submillimeter spikes may be associated to micr oflares, waves, or quakes in flaring active regions.