The following article, published in the Jewish Exponent, mentions Moments of Wrong, the Mekor Habracha band:

Walls of abandoned buildings covered in graffiti surround a large empty lot on 5th street between Cecil B. Moore and Oxford streets in Northern Liberties.

A motorcyclist with long hair pulled up by the lot on May 6 and seeing a large bonfire raging at the area’s center and about 150 people milling around, asked curiously: “What’s going on in there?”

When told that it was a Jewish festival he insisted on knowing which one, and upon hearing that it was Lag B’Omer, he shrugged his shoulders and said, “I’m Jewish but I’ve never heard of that — looks cool,” before gunning his engine and speeding away.

The event, aptly titled Lag B’Omer Bonfire and Music Fest, was thrown by The Jewish Center of Northern Liberties, a Chabad affiliate, and has been running annually since at least 2007.

There was a drum circle, a couple of bands played — alternatively mixing in Jewish songs with tunes by Led Zeppelin and Tom Petty — and lots of barbeque and cotton candy.

When the Mekor Habracha Band, so named because the band members all attend the Orthodox Center City synagogue, closed out the evening, they dedicated a song to Rabbi Shimon bar Yohai, whose death anniversary is marked on the holiday.

Lag B’Omer is also explained by a Talmudic story about Rabbi Akiva of the Mishna era, who was bar Yohai’s mentor. According to the story, all but five of Rabbi Akiva’s 24,000 students died from plague, which was cast on them for not showing the proper respect for one another, emphasizing the importance of morality in the Torah. Bar Yohai was one of the five remaining disciples spared from the destruction.

Traditionally, Lag B’Omer is considered a brief respite from the semi-mourning period associated with the Counting of the Omer between Passover and Shavuot. Weddings, parties, listening to music, and, among Ashkenazi Jews, the first haircuts for boys over the age of three are commonly scheduled to coincide with this day.