CHEMICAL REACTION: One of the brightest components of Chicago's overflowing post-rock scene heads our way this week. Comprised of three members of Tortoise -- drummers John Herndon and Dan Bitney, and guitarist Jeff Parker -- along with cornetist Rob Mazurek (who appeared at Club Congress earlier this year for an amazing show with the Chicago Underground Duo) and bassist Matt Lux (from Tranquility Bass), the collective known as Isotope 217 specializes in avant-jazz improvisation that ranges from ambient soundscapes to electro-organ jazz to frenetic, Miles Davis-inspired funk grooves, and back again.

The group is touring in support of its second full-length release, Utonian Automatic, on Thrill Jockey, which has been garnering nearly unanimous critical praise since its August release. Produced by studio mavens John McEntire (Tortoise, Stereolab) and Bundy K. Brown, the album is another noble attempt by Chicago's finest to virtually reinvent the way we listen to music.

I strongly urge anyone remotely interested in highbrow experimental music to check out Isotope 217, along with Calexico and Wasabi, at 8:30 p.m. Monday, November 29, at Datura, 31 E. Toole Ave. Cover is $7 at the door; call 884-0874 for more information.

HOMETOWN TURNCOATS: The Supersuckers are cruisin' for a bruisin'. The former Tucsonans skipped town in the early '90s for Seattle after getting signed to Sub Pop just as that label was beginning to explode. That's forgivable since it was a good career move. But with two new releases, a career-spanning greatest hits-plus-rarities compilation tongue-in-cheekily titled How the Supersuckers Became the Greatest Rock and Roll Band in the World (Sub Pop) and a new full-fledged punk-rock studio release (after 1997's country-rock detour Must've Been High, also on Sub Pop) called The Evil Powers of Rock and Roll, the band is sure to piss off some townies. (Incidentally, the album was set to come out earlier this year on Interscope, but the band was one of the casualties of the music industry mega-merger that left hundreds of bands without a label back in February. It was finally released last month on Aces & Eights/Koch Records, accompanied by a storm of well-deserved media attention).

Ironically, The Evil Powers is a true return to form, the best punk album the band has released since 1994's La Mano Cornuda. So why are they setting themselves up to catch hell from Tucsonans?

After paying homage to their alma mater in a tune called "Santa Rita High," they go on to diss Tucson denizens in "Goin' Back to Tucson": "Goin' back to Tucson, and I'm down. So I'm gettin' outta Tucson, takin' everything that ain't nailed down. Gonna wave goodbye to the unfortunate who stuck around." Can you say Rock Stars Who Have Gotten Too Big For Their Britches? If they don't get the shit beaten out of them beforehand, it should be one hell of a show.

Catch the Supersuckers, along with Jennifer Finch's (ex-L7) acclaimed new pop band, Other Star People, and local demon-worshipping metalloids Molten Leather, at 8 p.m. Saturday, November 27, at The Hut, 305 N. Fourth Ave. Advance tickets are available for $10 at CD Depot, Zip's University, Puff-N-Stuff on Speedway, Sticks and Strings and Majestik Tattoo. For more information, call 908-9313.

RISING STARS: Hailing from the border country between England and Scotland, and boasting an average age of only 21, Tarras is a five-piece band that manages, not unlike Lindisfarne, to successfully straddle the fence between traditional and modern Celtic music. The European press has been freaking out over them for quite a while, and now that their debut album, Rising (Rounder), has been released in the States, it's easy to see why.

Rising, which features eight self-penned tunes and five traditional ones, is comprised mostly of instrumentals with guitar, cittern, bass, accordion, mandolin and whistle all finding their place in the arrangements. But the two stunners of the album are the graceful violin work of 17-year-old (!) Emma Hancock, and the four songs with vocals. All five members sing, and their voices merge together gloriously in rough-hewn harmony on the wistful title track and the catchy-as-hell "Whiskeytown." Should make for a fabulous live show.

On their first U.S. tour, Tarras comes to town at 7:30 p.m. Friday, November 26, for a performance at St. Michael and All Angels Church, 602 N. Wilmot Road. Advance tickets are available for $11 at Hear's Music, Antigone Books, or by calling 881-3947. Call the same number for additional information.

HERALDING HAROLD: Two local jazz greats are teaming up this week for a tribute to songwriter Harold Arlen, best known for this work in The Wizard of Oz. Those songs and many of Arlen's others will be performed by trombonist Tom Ervin and pianist Jeff Haskell.

Ervin is professor of trombone and a jazz instructor at the UA, and is principal trombonist with the Tucson Symphony Orchestra and the TSO Brass Quintet, as well as a member of the Dixieland jazz band Jazzberry Jam. Haskell, professor of music and coordinator of jazz studies at the UA, has also been the director of the Tucson Boys Chorus (a 10-year stint) and associate conductor of the Tucson Symphony, and is currently musical director of the Tucson Jazz Orchestra (which he co-founded) and president of the Arizona Association of Jazz Educators. The performance will likely include a few Hoagy Carmichael tunes in honor of that songwriter's centennial birthday.

Tom Ervin and Jeff Haskell perform at 7:30 p.m. Monday, November 29, at UA Crowder Hall, located in the School of Music building at the southwest corner of Park Avenue and Speedway Boulevard. Admission is $10 general, $8 for UA employees, $6 for seniors 55 and over, and $5 for students with a valid student I.D. Call 621-1162 for tickets and information.

PEST CONTROL: And finally, members of the Bay Area's five-piece folk-rock band Ramona the Pest make their way back to our burg to showcase songs from their upcoming release, Little Knives (Kingtone), as well as ones from last year's impressive Cans of Worms (Kingtone). Vocalist and acoustic guitarist Valerie Esway and her new husband, electric guitarist and background vocalist Lucio Menegon, will perform the band's dark and deft songs as a duo this time around. The band has been compared to a less-bluesy PJ Harvey and a less-ethereal Cowboy Junkies.

Catch this stripped-down version of Ramona the Pest, along with Spacefish and Interlocking Grip, at 9 p.m. Saturday, November 27, at 7 Black Cats, 260 E. Congress St. Call 670-9202 for more details.

CORRECTION: Last week I wrote that Big Bottom was a three-piece band, when, in fact, they have four members. The omitted member is guitarist and vocalist Ryan Christie. My apologies to Ryan and the rest of the band.