Spacecraft separation! The IRNSS 1C navigation satellite has deployed from the PSLV's fourth stage, completing the rocket's 28th mission and 24th flawless flight in a row.

T+plus 19 minutes. The fourth stage engines will shutdown in a few seconds to set up for deployment of the IRNSS 1C spacecraft, which is scheduled for T+plus 20 minutes, 18 seconds.

T+plus 16 minutes. The fourth stage engines continue firing, generating nearly 3,300 pounds of thrust.

T+plus 11 minutes, 20 seconds. The PSLV's solid-fueled third stage has jettisoned and the fourth stage is now firing. This burn of the fourth stage's two engines is expected to last 8 minutes, 29 seconds.

T+plus 6 minutes, 30 seconds. The PSLV's third stage has consumed its solid propellant supply, beginning a nearly five-minute coast phase before ignition of the fourth stage.

T+plus 4 minutes, 45 seconds. The solid-fueled third stage has ignited after separation of the PSLV's second stage. This burn will last approximately 112 seconds.

T+plus 3 minutes, 30 seconds. The 10.5-foot-diameter aluminum payload fairing has jettisoned now that PSLV has reached the thin upper atmosphere.

The liquid-fueled Vikas second stage engine continues firing.

T+plus 2 minutes, 15 seconds. ISRO confirms separation of the PSLV first stage and ignition of the second stage for a burn of two-and-a-half minutes.

T+plus 90 seconds. The six ground-lit boosters have jettisoned.

T+plus 30 seconds. Two strap-on boosters have ignited to give the PSLV an extra boost as it climbs into the sky atop more than 2 million pounds of thrust.

Liftoff of a Polar Satellite Launch Vehicle carrying a satellite to expand navigation coverage over India and its neighbors.

T-minus 90 seconds. In the final minute, computers will prepare the PSLV for launch by arming its solid-fueled motors.

T-minus 2 minutes and counting. When the countdown reaches zero, the PSLV's first stage, comprised of five solid-fueled segments, will ignite along with four of the launch vehicle's six ground-lit strap-on boosters.

The boosters will ignite in a staggered sequence two-tenths of a second apart. Two more boosters will ignite at T+plus 25 seconds after the PSLV clears the launch pad.

T-minus 3 minutes and counting. A check of the weather conditions show all parameters are acceptable for launch.

T-minus 5 minutes and counting.

T-minus 14 minutes and counting. The PSLV has received the final authorization to launch, and automated countdown sequence will oversee the final preparations to configure the 700,000-pound rocket for liftoff.

All systems are still "go" for launch at 2002 GMT (4:02 p.m. EDT; 1:32 a.m. Indian time).

T-minus 20 minutes and counting. Everything is on schedule for launch at 2002 GMT (4:02 p.m. EDT).

Today's launch will use the largest version of the Polar Satellite Launch Vehicle called the PSLV XL, with six strap-on motors with a length of 12 meters, or 39 feet.

The PSLV is a four-stage rocket with a solid-fueled first and third stages and liquid-fueled second and fourth stages.

We are now streaming live video from India's Satish Dhawan Space Center, where all launch preparations are on track for liftoff in 25 minutes.

The PSLV launch team reports the Sriharikota range and all weather conditions are "go" for an on-time launch.

T-minus 60 minutes. Today's launch will mark the:

28th PSLV launch since 1993

44th Indian space launch since 1979

7th PSLV XL launch since 2008

3rd PSLV launch of 2014

3rd Indian navigation satellite to be launched

62nd global space launch attempt in 2014

The mobile service tower at the PSLV launch pad has been retracted to the launch position 150 meters away from the rocket, and no problems are reported in the countdown. The launch window opens at 2002 GMT (4:02 p.m. EDT) and extends 15 minutes.

All launch preparations are on schedule for liftoff of the Polar Satellite Launch Vehicle on Wednesday at 2002 GMT (4:02 p.m. EDT).

The first activity after the countdown began Monday morning, Indian time, was the filling of the PSLV's liquid-fueled fourth stage with hydrazine and nitrogen tetroxide propellants.

The fourth stage will inject the IRNSS 1C navigation spacecraft into an elliptical orbit with an apogee of 12,831 miles (20,650 kilometers), a perigee of 176 miles (284 kilometers) and an inclination of 17.9 degrees. The twin-engine fourth stage, named the PS4 or L2.5, will fire for more than 8 minutes in the last phase of the launch.

The mobile gantry at the launch complex, located on Sriharikota Island on India's east coast, was retracted more than 150 feet from the rocket early Wednesday to prepare for fueling of the PSLV's second stage with liquid propellant, which was completed a few hours ago.

The PSLV's first and third stages, along with the six strap-on boosters, burn solid propellant already packed inside the motor casings.

Live video of the final countdown will begin about 30 minutes prior to launch, according to ISRO. The webcast will be seen on this page.

The third satellite for India's regional navigation network is set for liftoff Wednesday to join a growing fleet of spacecraft providing independent tracking and positioning services over India and its neighbors.

Read our full story.