Some very popular government websites, including the ultra-cute Giant Panda Cam, will go offline on Tuesday if Congress can't cut a budget deal. Also going AWOL: NASA TV and the brand-new online annotated Constitution.

Under the terms of the Antideficiency Act , only "excepted" areas in the government receive funds during a shutdown, and thus stay in operation. The act dates back to 1870 and it was amended in 1982 to deal specifically with what stays open, and what stays closed, during government shutdowns caused by funding gaps.

It looks like many functions within the government that deal with information technology fall outside of the list of "excepted" government functions. Other IT functions that deal with safety and national security will remain in place.

For example, electronic activities related to the government collection of data by the National Security Agency will continue, under guidelines issued by the Defense Department.

But folks won't be able to watch the exploits of the National Zoo's new Panda cub on its very popular webcam, sponsored by the Ford Motor Company Fund, starting on Tuesday.

Webcams focused on otters, leopards, lions and even the naked mole also will go dark on Tuesday.

The website Ars Technica had a brief list of other government-related websites that are expected to go offline during a shutdown, or offer greatly reduced services.

The Library of Congress website will go on hiatus if the shutdown happens, for starters. The Library just issued a new, massive online version of the annotated Constitution on September 17.

"In the event of a temporary shutdown of the federal government, beginning Tuesday, October 1, all Library of Congress buildings will close to the public and researchers. All public events will be cancelled and web sites will be inaccessible," the Library said in a statement on its website on Friday.

The National Park Service will also make its websites unavailable. The Smithsonian museums will be closed as well, and there will be a message on the Smithsonian website informing visitors about the closures.

The National Archives website will also not be updated during a shutdown, since its workers will be furloughed.  The agency may use Facebook and Twitter to publish some updates.

The Federal Trade Commission's website will also likely be offline during a government shutdown.

And don't look for much activity on NASA's website. Most of NASA's 18,000 employees will be placed on furlough status. NASA's website and its NASA TV channel will likely be taken offline during a shutdown.

One other indirect victim of a shutdown would be the initial public stock offering, or IPO, of the popular microblogging service Twitter.

Yahoo! News says the bankers behind the Twitter IPO won't file the paperwork for the stock offering, since the Securities and Exchange Commission won't be able to approve the move.