PARIS — Satellite operator Spacecom of Israel has doubled its public float with a supplemental stock offering on the Tel Aviv Stock Exchange that will complete the financing needed to launch the Amos-3 telecommunications satellite in December, according to Spacecom officials.

Amos-3, a 1,250-kilogram satellite built by Spacecom shareholder Israel Aircraft Industries (IAI), is carrying a mixed Ku-/Ka-band payload and will replace the all-Ku Amos-1 satellite, which is expected to be retired in mid 2008.

Including launch and insurance, the Amos-3 program is costing Spacecom about $170 million. The final $33 million tranche was secured by a stock offering to institutional investors April 30. The stock sale increased Spacecom’s stock-market float to 40 percent of the company’s total equity, a figure that could rise to 56 percent if investors exercise all their options, Spacecom Business Development Vice President Omri Arnon said in a May 2 interview.

Amos-1 and Amos-2 — both located at 4 degrees west longitude — are being used to 90 percent of their capacity. Both satellites provide commercial and government telecommunications and television services in Israel and between the Middle East and North America. Spacecom expects to transfer Amos-1 customers to Amos-3 once the satellite is operational. Amos-3 carries 12 72-megahertz Ku-band transponders and two wide Ka-band beams.

Arnon said the Ka-band payload will find a market in the Middle East for commercial and government customers, but he declined to say whether the capacity had been pre-sold.

Amos-3 is scheduled for launch in December aboard what may be the first commercial flight of the Land Launch system managed by Sea Launch Co. of Long Beach, Calif. Land Launch is basically the same rocket that Sea Launch operates from a floating platform on the equator in the Pacific Ocean. But launched from the Russian-run Baikonur Cosmodrome in Kazakshstan, Land Launch has about half the 6,000-plus-kilogram payload-carrying power of Sea Launch.

In the case of Amos-3, Land Launch will place the satellite directly into geostationary orbit, not the transfer orbit where most telecommunications satellites are dropped off. Going directly to final geostationary position 36,000 kilometers above the equator means Amos-3 does not need to carry an apogee-boost engine. It also means Spacecom can expect at least 16 years of in-orbit service.

In a May 2 interview, Arnon said it remains unclear whether Amos-3 will be Land Launch’s first mission to geostationary orbit. A different version of the vehicle — without its upper stage — is scheduled to place a Russian military satellite into low Earth orbit this summer in what will be the inaugural launch from the refurbished launch pad.

Arnon said Amos-1 may be moved to an undisclosed orbital slot between 60 and 70 degrees east longitude, over Asia, once Amos-3 is operational. Spacecom has long harbored ambitions to expand its coverage to Asia and Arnon said the company is coordinating with other operators for the rights to occupy one of several slots in the region.

For the moment, Spacecom remains a modest-sized operator, with 2006 revenues of about $35 million — the same as 2005 — and a home region that presents obvious political challenges to marketing Israeli satellite capacity. Given this handicap, Spacecom continues to specialize on “using our capacity to bridge to the U.S.,” Arnon said. “Not all operators in our region can do this. We can, because of the advantages of the 4 degrees east slot.”

Arnon said Spacecom is continuing to discuss specifications for an Amos-4 satellite with IAI. He said the company is certain to order the satellite, with the order likely this year. Given its relatively modest revenues, Spacecom has an exceptionally large backlog — about $500 million.

Spacecom is far from the only satellite operator weighing an expanded presence in the Middle East. The intergovernmental Arabsat organization of Riyadh, Saudi Arabia, plans to add three more satellites to its fleet within the next three years, and Nilesat of Egypt has long said it will order a new satellite in addition to leasing a full satellite from Eutelsat of Paris.

Startup operator Yahsat, backed by the Mubadala Development Co. of Abu Dhabi, is scheduled to select a contractor this spring for two large telecommunications satellites for both government and commercial markets.