A somber mood pervaded the Harvard campus yesterday as roughly 1,200 students observed the Jewish High Holy Day of Yom Kippur.

The holiday, which began Wednesday at sundown, is the traditional day of atonement for Jews, coming ten days after the New Year ceremony of Rosh Hashana.

It’s ceremony calls for a day of fasting while attending services.

Roughly 1,300 people congregated at Sanders theater Wednesday evening, including students, faculty, Cambridge residents, and University President Lawrence H. Summers.

Hillel Chair Benjamin Z. Galper ’02 said he appreciated Summers’ presence.

“It was very nice to have the president at services last night and to see him in the community,” he said.

Meanwhile, Hillel’s Executive Director Dr. Bernard Steinberg led a discussion at Hillel Wednesday night on the themes of Yom Kippur.

He touched upon the terrorist attacks of Sept. 11th—a theme that was common to many of the sermons delivered over the course of the holiday.

A more visible effect of the attacks was the heightened security present at all services held during the holidays.

Armed police stood guard in the lobby of Hillel, and guards checked IDs at the door.

Galper said the the heightened security was merely precautionary.

“We’re an open community, and we wanted to make sure that anyone who wanted to attend services could do so,” Galper said. “The purpose was to reassure people that things were secure.”

Yesterday, Yom Kippur services were held across campus—Reform Jews congregated at Memorial Church while Conservative services were held at Hillel, and Orthodox Jews gathered to observe the holiday at Burden Hall at the Business School.

“Break-fasts” were held at Hillel and in Kirkland House last night. There was also a break-fast for freshmen in the Ticknor Lounge in Boylston H all.

Jews typically fast in observance of the holiday.