But death by scud is sudden. The whoosh of an incoming missile is followed almost instantaneously by the explosion.

Syria has fired dozens of scuds and other missiles at targets in northeastern Syria. According to the Syrian Missile Launch Database, maintained by the Washington Institute of Near East Policy, between December 2012 and March 2013 the Assad regime fired dozens of surface-to-surface missiles against opposition-held areas, including major cities and towns such as Aleppo, Al Raqqah, and Der Ez Zor. Human Rights Watch reported that four scuds fired on Aleppo in February killed 141 civilians, including 71 children.

Othman's scud early warning system began operating on Wednesday. It is called Aymta, which means "when" in Arabic. Users can opt to receive alerts by phone, text message, SMS, e-mail or RSS feed, or, if the regime cuts off internet access, as it often does, via a broadcast on satellite television or radio frequencies outside of regime control. Within the first 24 hours, 16,000 people viewed his website and 87 had registered to receive his alerts - although up to 40 percent of Syria was reportedly experiencing power outages at the time. Two satellite television stations also signed up for alerts. Some Syrians have already registered from abroad to track impending attacks on their hometowns and alert their families.

Reactions posted on Othman's social media pages range from joy to disbelief.

"Thank God," typed one fan over and over.

"The idea is great but this is a luxury," wrote another from Aleppo. "Most people here in Syria do not have communications or sometimes power and will never get these warnings."

Othman believes that forces loyal to President Bashir al-Assad have not fired a scud at civilians since a June 20 scud-D was fired at Aleppo at 11:45 p.m. from al Qalamon in the Damascus countryside. But when the next scud goes up, Othman is confident that his text messages will reach some people before the missile.

Syrians by the thousand are already risking their lives to document the war, material that may eventually provide rich evidence for war crimes prosecutions. Never have so many atrocities been chronicled so thoroughly for the networked world to view online. Yet this unprecedented crowd-sourced documentation effort has not had the desired effect of deterring atrocities.

Both government forces and rebel groups have committed war crimes and horrific abuses against civilians are a near-daily occurrence -- though the behavior of the Syrian government forces has been worse than that of the rebels, according to the latest report to the United Nations Human Rights Council.

Syrian authorities typically cut off cellphone and internet service prior to an attack, but even so, civilians are often the last to know what is about to befall them. It's not clear that Syrian civilians have been able to make much practical use of the torrent of YouTube videos and detailed military and atrocity reports that have been posted - unless one considers such citizen reporting to have helped millions of Syrians make a better-informed choice to run for their lives. At least 1.7 million have fled to Turkey, Jordan, and Lebanon.