# 2. UTCDateTime

All absolute time values within ObsPy are consistently handled with the `UTCDateTime` class. It is based on a high precision POSIX timestamp and not the Python datetime class because precision was an issue.

## 2.1. Initialization

    >>> from obspy.core import UTCDateTime
    >>> UTCDateTime("2012-09-07T12:15:00")
    UTCDateTime(2012, 9, 7, 12, 15)
    >>> UTCDateTime(2012, 9, 7, 12, 15, 0)
    UTCDateTime(2012, 9, 7, 12, 15)
    >>> UTCDateTime(1347020100.0)
    UTCDateTime(2012, 9, 7, 12, 15)

In most cases there is no need to worry about timezones, but they are supported:

    >>> UTCDateTime("2012-09-07T12:15:00+02:00")
    UTCDateTime(2012, 9, 7, 10, 15)

## 2.2. Attribute Access

    >>> time = UTCDateTime("2012-09-07T12:15:00")
    >>> time.year
    2012
    >>> time.julday
    251
    >>> time.timestamp
    1347020100.0
    >>> time.weekday
    4

## 2.3. Handling time differences

    >>> time = UTCDateTime("2012-09-07T12:15:00")
    >>> print(time + 3600)
    2012-09-07T13:15:00.000000Z
    >>> time2 = UTCDateTime(2012, 1, 1)
    >>> print(time - time2)
    21644100.0

## 2.4. Exercises

- Calculate the number of hours passed since your birth. Optional: Include the correct time zone. The current date and time can be obtained with

    >>> UTCDateTime()

- Get a list of 10 UTCDateTime objects, starting yesterday at 10:00 with a spacing of 90 minutes.
- The first session starts at 09:00 and lasts for 3 hours and 15 minutes. Assuming we want to have the coffee break 1234 seconds and 5 microseconds before it ends. At what time is the coffee break?
- Assume you had your last cup of coffee yesterday at breakfast. How many minutes do you have to survive with that cup of coffee?

### Thank you!

We would like to thank our contributors, whose efforts make this software what it is. These people have helped by writing code and documentation, and by testing. They have created and maintained this product, its associated libraries and applications, our build tools and our web sites.

#### Contributors

- Ackerley, Nick
- Allgeyer, Sebastien
- Ammon, Charles J.
- Antunes, Emanuel
- Arnarsson, Ólafur St.
- Bank, Markus
- Barsch, Robert
- Behr, Yannik
- Bernardi, Fabrizio
- Bernauer, Felix
- Bes de Berc, Maxime
- Beyreuther, Moritz
- Boltz, Shawn
- Bonaimé, Sébastien
- Carothers, Lloyd
- Chamberlain, Calum
- Chambers, Derrick
- Chen, Zhao
- Clark, Adam
- Danecek, Peter
- Egdorf, Sven
- Engels, Fabian
- Ermert, Laura
- Eulenfeld, Tom

- Fabbri, Tommaso
- Falco, Nicholas
- Fee, Jeremy
- Grellier, Clément
- Grunberg, Marc
- Hammer, Conny
- Heimann, Sebastian
- Heiniger, Lukas
- Hope, Gaute
- Igel, Heiner
- Inza, Adolfo
- Isken, Marius
- Ketchum, David
- Koymans, Mathijs
- Kremers, Simon
- Kress, Victor
- Krieger, Lars
- Krischer, Lion
- Kula, Damian
- Käufl, Paul
- Köhler, Andreas
- Lecocq, Thomas
- Leeman, John
- Legovini, Paride

- Lesage, Philippe
- Li, Yulin
- Lomax, Anthony
- Lopes, Rui L.
- MacCarthy, Jonathan
- Maggi, Alessia
- Martin, Henri
- Medlin, Andrew
- Megies, Tobias
- Meschede, Matthias
- Michelini, Alberto
- Miller, Nathaniel C.
- Morgenstern, Bernhard
- Nof, Ran Novitsky
- Panning, Mark P.
- Parker, Tom
- Pestourie, Romain
- Rapagnani, Giovanni
- Reyes, Celso
- Ringler, Adam
- Rothenhäusler, Nicolas
- Russo, Emiliano
- Sales de Andrade, Elliott

- Satriano, Claudio
- Saul, Joachim
- Scheingraber, Chris
- Schneider, Simon
- Sippl, Christian
- Snoke, Arthur
- Stange, Stefan
- Stähler, Simon C.
- Sullivan, Benjamin
- Tian, Dongdong
- Trabant, Chad
- Trani, Luca
- Uieda, Leonardo
- Walker, Andrew
- Walther, Marcus
- Wassermann, Joachim
- Williams, Mark C.
- Winkelman, Andrew
- Zaccarelli, Riccardo
- Zad, Seyed Kasra Hosseini
- Zhu, Lijun
- van Driel, Martin
- van Wijk, Kasper

#### Funds

ObsPy was partially funded by the

- German Science Foundation (DFG) via grant DFG IG 16/9-1
- German Ministry for Education and Research (BMBF), GEOTECHNOLOGIEN grant 03G0646H.
- NERA project (Network of European Research Infrastructures for Earthquake Risk Assessment and Mitigation) under the European Community's Seventh Framework Programme (FP7/2007-2013) grant agreement n° 262330
- Leibniz Institute for Applied Geophysics (LIAG)
- VERCE EU-FP7 project (no. 283543)