The MEarth Project


MEarth Parallaxes of Nearby M Dwarfs

M dwarfs are excellent targets for transiting exoplanet searches, but they sometimes pose a big challenge too: the distances to many of them have never been measured. Until now! Using MEarth imaging, we have estimated trigonometric parallax measurements to 1507 of the nearby M dwarfs in our sample. Jason Dittmann led the analysis for this project and describes the work in Dittmann et al. (2013, accepted). Click the link below to access a data table containing these new parallaxes:

MEarth Trigonometric Parallaxes for 1507 Nearby M Dwarfs

The stars in this table represent a significant fraction of the Northern hemisphere mid-to-late M dwarfs within 25pc. Based on the new parallaxes, we provide updated estimates of the masses and radii of these stars, which are more precise and more accurate than the previously available estimates for most targets. We hope exoplaneteers and stellar astronomers alike will find these data useful!

MEarth Photometric Data Release

The MEarth team is pleased to release to the community all our M dwarf light curves taken during the first four official years of the survey. We have used these light curves to search for transiting planets, eclipsing binaries, and photometric rotation periods, but maybe you can find something we missed!

Release Schedule

Each year of MEarth observations is punctuated by a summer monsoon season in Arizona. Shut-down and start-up dates vary from year-to-year, but no observations are ever gathered during the month of August, when the observatory is officially closed. The data released here comprise observations gathered starting after the end of the 2008 monsoon and leading up until the start of the 2012 monsoon. In the years to come, we plan to release new light curves one year after the monsoon following the year in which they were taken.

This page contains MEarth's Data Release 2 (DR2), which was posted 1 September 2013. It has been superseded by a more up-to-date data release. Click here for the most recent MEarth Data Release!

Before you Begin

Please read the release notes! We strongly encourage anyone interested in using MEarth light curves to do so. In addition to descriptions of the format and organization of the light curve files, they contain important information regarding the properties and limitations of the data. Additionally, see Irwin et al. (2011) for a general discussion of measuring rotation periods in MEarth light curves and Berta et al. (2012) for issues pertaining to transit-finding in MEarth data. For interested readers, we also include a description of the data processing pipeline.

Light Curves

The light curves are presented in three batches, grouped by season and by which filter was used to gather the observations (see release notes). For ease of reading, light curves are presented as plain text ASCII files. On the following three pages, you will have the option either to download light curves (and finder charts) for individual stars of interest or to download the entire sample of light curves as a gzipped tar file:

2008-2010 MEarth Target Light Curves (broad RG715 filter)
2010-2011 MEarth Target Light Curves (interference filter)
2011-2012 MEarth Target Light Curves (broad RG715 filter)

The files available for download should be thought of as working copies of the MEarth light curves. As we identify improvements that can be made to the data reduction, we may reprocess the data and post the updates here, in addition to our regularly scheduled yearly releases. Archives of all previous releases will remain available through this site.

Known Objects

Among the ensemble of MEarth M dwarfs included here for download, this data release includes discovery and/or characterization light curves of the super-Earth GJ1214b (=LSPMJ1715+0457), the eclipsing brown dwarf NLTT41135 (=one component of LSPMJ1546+0441, unresolved in MEarth photometry), the short-period double-lined eclipsing binary GJ3236 (=LSPMJ0337+6910), and the 41-day double-lined eclipsing binary LSPMJ1112+7626.

The light curves contributing to our initial sample of photometric rotation periods for field M dwarfs with known parallaxes are also contained within this data release. We are actively working to broaden the sample of rotation periods to the more recent data and to stars without literature parallaxes, and plan to publish this analysis soon.


If your work with these data results in a publication, please consider inviting us to join that publication as coauthors. This is not a requirement for using the data, but having put a lot of effort making MEarth data useful for public analysis, we would appreciate the courtesy. At a minimum, please cite Berta et al. (2012) as a qualitative description of the dataset and include the following statement of acknowledgement in your paper: "This paper makes use of data from the MEarth Project, which is a collaboration between Harvard University and the Smithsonian Astrophysical Observatory. The MEarth Project acknowledges funding from the David and Lucile Packard Fellowship for Science and Engineering and the National Science Foundation under grants AST-0807690, AST-1109468, and AST-1004488 (Alan T. Waterman Award), and a grant from the John Templeton Foundation."