When it comes to SXSW serendipity, there's the time when you run into someone you trust who's just seen an unbelievably awesome band and they tell you you just have to see them and in fact they do have another showcase coming up and the line isn't too long, and yes, they do indeed turn out to be awesome.

Better still, there's the time when you're walking home along Red River Street - or, in this case, riding your bike - and though you know the wise thing to do would be to continue on to your hotel, you hear an inspired, impassioned, beautiful racket spill out of some open air venue and you think, okay, just one more band tonight. The blog can wait.

Marnie Stern.

That's how I wound up seeing Marnie Stern on Tuesday night at the Pitchfork party at Mohawk. From the street, it sounded like a guitar army, screeching at high volume but with enough melodicism to pull me off the street. Turned out to just be the New York guitar-shredder fronting her trio, tapping on the fretboard like Eddie Van Halen and looping her voice and licks in bursts of inspired chaos. Stern's new album, inevitably titled Chronicles of Marnia, comes out Tuesday.

This morning I shocked myself by getting out of bed in time to see Billy Bragg perform a session for the streaming-audio subscription web service Daytrotter, which is recording bands in Austin all week. "There are so many damn bands down here," said Bill Sagan, the Daytrotter owner, who was quick to give all credit to Sean Moeller and Phil Pracht, the music guys who are usually running the Daytrotter show from their home base in Illinois.  "We come down here because it's where the music is," said Sagan. "Yesterday we had one band from Finland, one from Iceland and one from Sweden."

As the L.A. band Hunter Hunted finished up its session inside, the bearded Bragg held court in the backyard on a bright clear morning, where the 55-year-old British songwriter was overheard to say, "I figure all the twentysomethings in Austin are walking around trying to look like they're old with their beards, looking like they might play Woody Guthrie songs. I've got one up on them because I am old, I have a beard, and I play Woody Guthrie songs."

Inside, as bright light streamed through the front room windows of the studio, and the session was nearly interrupted by a garbage collector making his rounds out front, Bragg played Guthrie's "I Ain't Got No Home," and two impressive new songs from Tooth & Nail, due out on Cooking Vinyl on March 19.

One was a warm, solidly built love song called "Handy Man Blues," and another "No One Know Nothing Anymore," pondered our ignorance regarding the universe's eternal questions even in these days of advanced particle physics. He closed by dedicating his 1991, far-seeing, anti-homophobia love song "Sexuality" to everyone fighting for equal marriage, a political song that was nonetheless in keeping with the tender, humane feel of the brief performance.

The four-song set will be archived on Daytrotter.com soon, and Bragg plays the Keswick Theater in Glenside on April 20.

Previously: SXSW Night One Follow In The Mix on Twitter