The Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) is mandated by law, as the government agency tasked to keep and disseminate the Philippine Standard Time (PhST).

PAGASA atomic clock

History of PAGASA Time Service 

The Time Service Division was established as one of the major units in the then Weather Bureau sometime in 1949. Its master clock was a U. Nardin Marine Chronometer, with pendulum regulator, which was utilized as a dispatch clock. A short synchrome ensemble replaced the marine chronometer in 1951 and a quartz crystal clock improved the system in 1965.

Since then, there was no major improvement that had been done with the system, except for the acquisition of a Digitizing Oscilloscope. In 1988, the Time Service Division was downgraded to the Time Service Unit (TSU), together with the reorganization of the PAGASA. In 1996, the TSU acquired a Luminous Digital Clock and a Global Positioning System (GPS), which were installed in 1997, as its primary reference timing system.

In 2003, TSU was transferred to the newly renovated Transit Building of the PAGASA Astronomical Observatory, equipped with the new timing equipment, known as the Rubidium/Global Positioning System Common View (Rb/GPSCV) Time Transfer System. The said time equipment was decommissioned by the unit after it was hit by a lightning on June 09, 2013. An alternative time source had been obtained by PAGASA through the ICT group, ETSD by acquiring two secondary frequency standards that were installed at the WFFC building and at the Planetarium Building. The first is used to disseminate the PhST via NTP and the other one is utilized as a back-up. Another back-up support is a 5225B Time Node made by Oscilloquartz that was installed at the PAGASA Astronomical Observatory, in case the two S350’s bogged down.

In 2015, PAGASA acquired a new time equipment known as the PAGASA’s Precise Time-Scale System. This timing equipment is an independent timing chain (real-time clock) consisting of three high-performance cesium clocks, real-time clock steered to UTC using GNSS timing information, distribution for 5 MHz, 10MHz, AM/DC IRIG-B, 1 PPS and NTP. It is a world class timing system comparable to the best national time laboratories with commercial and hardware support. The new timing equipment was purchased by PAGASA to establish a national timing reference and to satisfy the requirement of the existing laws on time and frequency services in the country.

The time equipment was about the size of a large refrigerator, composed of three high performance of atomic cesium clocks for holdover redundancy and is plugged into the network time protocol (NTP) of the Philippine Standard Time. The atomic clock tells the time by measuring the oscillation of energized atoms in an electromagnetic field.

The time equipment is also capable of serving as a stratum 0 Network Time Protocol (NTP) server, providing Internet time dissemination. NTP is a means of synchronizing computer clock over the Internet. With this system, the Philippine Standard Time (PhST) kept by the time scale system, will be available on-line in the PAGASA website, and the NTP program will allow transfer of this time to clients accessing the site. Government and private TV stations shall be encouraged to avail of this service and pass on to the general public, through their regular time checks and their clocks shown on the TV screen, derived and synchronized time with PAGASA’s Precise Time-Scale System. Radio stations shall then be requested through the Kapisanan ng mga Brodkaster ng Pilipinas (KBP) to copy the time being broadcasted by these TV stations to provide an accurate and timely nationwide coverage of the PhST.


PAGASA Clock strata

PAGASA’s Time Scale System with three-high performance cesium clocks. This is also known as the reference clock of the Philippine Standard Time (PhST)

Symmetricom S350s and OSA 5225B Time Node, whose system clocks are synchronized to within a few microseconds to PAGASA’s Time Scale System. These are servers that are peered to each other for sanity checking and backup.

These are computers that are synchronized over a network to stratum 1 servers. PhST can be accessed via or by accessing the IP address

These are computers that are synchronized to stratum 2 servers. They employ exactly the same algorithms for peering and data sampling as stratum 2, and can themselves act as servers for stratum 4 computers, and so on.

The Philippine Standard Time (PhST)

  • Batas Pambansa Blg. 8, an act of defining the metric system and its units, providing for its implementation and for other purposes, under section 6b, states that: "PAGASA shall be responsible in the establishment, maintenance and operation of the National Standard for the second of time".
  • Presidential Decree 1149, assigning PAGASA as the official agency that will serve as the official time service agency of the Philippines.
  • Republic Act No. 10535, ‘The Philippine Standard Time (PhST) Act of 2013, requiring all national and local government offices to display the PhST on their official time devices, including bundy clocks, in accordance with the official time being provided by the PAGASA using its Network Time Protocol.

Functions of the Time Service Unit

  1. Maintains the national standard of time and frequency.
  2. Disseminates the precise time and frequency via Internet, radio broadcast and other means.
  3. Extends time synchronization and standardization services to industrial and scientific institutions.
  4. Exchanges data on time and frequency with overseas institutions.

For Philippine Standard Time (PhST):  Call Tel. No. (632) 929-1237