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News in 2015

The purpose of this page of the CDDIS web site is to post new items, activities, data sets, etc. of interest to the CDDIS user community. Users should also consult the meetings page to view a list of upcoming meetings and events of interest to the space geodesy community.

NASA logo

Brief network outages at GSFC on December 19, 2015 (11-Dec-2015)

Work will be performed on the NASA GSFC network infrastructure from 03:00 p.m. (20:00 UTC), Saturday, December 19, 2015 through 03:00 a.m. (08:00 UTC) on Sunday, December 20. Users can expect 10-15 minute interruptions during that time period.

Should the CDDIS be unaccessible, users can access one of the other data centers supporting the services:

We regret any problems this work may cause the user community.

SPOT-5 satellite

SPOT-5 de-orbited (02-Dec-2015)

The SPOT-5 satellite was de-orbited on December 1, 2015 after a successful 13 year mission. The satellite was decommissioned on March 31, 2015. DORIS data from the satellite have stopped. More information about SPOT-5 can be found at: http://www.satimagingcorp.com/satellite-sensors/other-satellite-sensors/spot-5/.

CDDIS logo

2015 User feedback survey (14-Sep-2015)

Beginning this week, NASA will be conducting a survey for users of NASA Earth science data and services, which includes the Crustal Dynamics Data Information System (CDDIS). The CDDIS is one of twelve NASA Earth Observing System Data and Information System (EOSDIS) science data centers evaluated by this survey. The purpose of this survey is to help NASA and the DAACs assess customer satisfaction and improve future services. Suggestions from past surveys have been implemented to improve the tools and services offered by the CDDIS.

The American Customer Satisfaction Index (ACSI) is the only national cross-industry measure of customer satisfaction in the United States. NASA commissioned the CFI Group, an independent research and consulting organization to conduct the survey. Presentations of these results given to NASA Earth science are available at: http://earthdata.nasa.gov/acsi.

Please participate! Your feedback affects our future performance and helps to identify science needs. You will be able to take the survey for each DAAC you use. If you use NASA Earth science data and services and would like to take the survey but did not receive an e-mail with the survey link, please contact surveyhelp@cfigroup.com. This is your opportunity to influence the priorities of the DAACs. Thank you in advance to all of you who are willing to spend a few minutes to complete the survey.

CDDIS logo

CDDIS archive downloads continue to increase (26-Aug-2015)

Over the past six month period, CDDIS downloads have continued to increase, with significant growth occurring from the international community. In July 2015 the CDDIS set a new monthly download record, with over 120M file downloads totaling over 12 Tbytes in volume. Downloads from international users accounted for over 65% of the total download bandwidth. In comparison, the total downloads for all of 2014 were 925M files/95 Tbytes in volume (monthly average of 77M files/8 Tbytes).

CDDIS logo

CDDIS Earthdata webinar, "Distributing Real-Time GNSS Data and Derived Products at the CDDIS" (22-Jul-2015)

The CDDIS held an Earthdata webinar titled, "Distributing Real-Time GNSS Data and Derived Products at the CDDIS". This webinar provides an overview of the Global Navigation Satellite System (GNSS), the International GNSS Service (IGS), Real-time GNSS, the CDDIS real-time data caster and protocol, the registration process before accessing the real-time data, and several demonstrations on configuring and using the client software.

Quasarville: the town that never moves.

NASA Explains Why June 30 Will Get Extra Second (26-Jun-2015)

The day will officially be a bit longer than usual on Tuesday, June 30, 2015, because an extra second, or "leap" second, will be added.

"Earth's rotation is gradually slowing down a bit, so leap seconds are a way to account for that," said Daniel MacMillan of NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

Strictly speaking, a day lasts 86,400 seconds. That is the case, according to the time standard that people use in their daily lives – Coordinated Universal Time, or UTC. UTC is "atomic time" – the duration of one second is based on extremely predictable electromagnetic transitions in atoms of cesium. These transitions are so reliable that the cesium clock is accurate to one second in 1,400,000 years.

However, the mean solar day – the average length of a day, based on how long it takes Earth to rotate – is about 86,400.002 seconds long. That's because Earth's rotation is gradually slowing down a bit, due to a kind of braking force caused by the gravitational tug of war between Earth, the moon and the sun. Scientists estimate that the mean solar day hasn't been 86,400 seconds long since the year 1820 or so.

This difference of 2 milliseconds, or two thousandths of a second – far less than the blink of an eye – hardly seems noticeable at first. But if this small discrepancy were repeated every day for an entire year, it would add up to almost a second. In reality, that's not quite what happens. Although Earth's rotation is slowing down on average, the length of each individual day varies in an unpredictable way.

Read more....

CDDIS Archive Explorer logo

CDDIS Archive Explorer is now available through the CDDIS website (11-Jun-2015)

This web application is a search/metadata interface tool for the CDDIS archive that will aid users in discovery of CDDIS data, products, and information. Users can specify any/all input parameters, such as temporal, spatial, target values. The resulting pages will present a map and list of sites satisfying the input parameters. Users can further drill down and view additional information about the sites. The CDDIS staff welcomes input on this new application.

ILRS logo

Leap second to be introduced into UTC on June 30, 2015 (04-Jun-2015)

UTC must be adjusted to maintain its correlation to mean solar time due to irregularities in the Earth's rotation. Therefore, a leap second will be introduced into UTC on June 30, 2015 at 23:59:59 UTC. More information about the leap second and preparing for it is available from the following websites:

NASA logo

NASA network connectivity outage (22-Apr-2015)

Starting this Sunday, April 26, there will be a scheduled outage for NASA network connectivity, from April 26 17:00 UTC through April 27 05:00 UTC. We have been told that the NASA network will be unavailable during the first four hours; intermittent outages of several minutes can be expected after that time until the end of the period specified above. During the outage, the ILRS, CDDIS, and Space Geodesy Project websites will not be accessible.

While the CDDIS is unavailable, users can access one of the other data centers supporting the services:

We regret any problems this outage may cause the user community.

World Map depicting location of GNSS sites

Real-Time GNSS Data and Products now available through the CDDIS (10-Apr-2015)

The CDDIS staff is pleased to announce that its real-time caster is now operational, supporting the International GNSS Service (IGS) Real-Time Service (RTS). The IGS RTS, based on a cooperative global infrastructure of stations, data centers, and analysis centers, provides GNSS orbit and clock corrections that enable precise point positioning (PPP) and related applications, such as time synchronization and disaster monitoring at global scales. The CDDIS caster utilizes the NTRIP (Networked Transport of RTCM via Internet Protocol) software to disseminate these real-time streams to registered users.

The CDDIS has incorporated the EOSDIS User Registration System (URS) to handle user signup and access authentication. At this time, the CDDIS is making real-time data available from 155 sites (see map) as well as 37 product streams. Future plans include the addition of more station data streams and computation and conversion of these data streams into high‐rate data files for the CDDIS online archive. More information about the CDDIS caster and real-time data and products is available from the CDDIS website: