The 2MASS Sampler (1998 December), was the first release of 2MASS
data to the community. The Sampler included data from one night (1997 Nov 16
UT) obtained at the northern 2MASS facility on Mt. Hopkins.
The 2MASS 1999 Spring Data Release is the first of the "Incremental" issues of Survey data products. The Incremental releases include the Catalogs and Image products produced from data processing performed while Survey observations are ongoing. Their scope includes survey data acquired and/or processed each consecutive 6-8 months during the Survey; the phase lag between data acquisition and initial release will decrease as the Survey progresses. Each release is therefore "differential", accumulating growing Incremental Release Point and Extended Source Catalogs. The 1999 Spring release also includes the data from the 2MASS Sampler.
The 2MASS Incremental releases are scheduled to occur approximately every 6-12 months until the end of Survey data acquisition. It is anticipated that the next Incremental release will take place in the Fall of 1999, and will include data covering approximately 20%-25% of the sky observed from both the northern and southern 2MASS facilities.
The 2MASS Incremental release data are
representative of the scope and quality of the final data products,
but should still be viewed as preliminary products because they
do not benefit from all experiences that will be gained over the full
Survey, in particular the analyses of the full-sky dataset, nor have they
undergone all the rigorous analyses that accompany data releases at the
end of mission.
Following the end of 2MASS Survey operations the release of the last Incremental data products, the full set of raw data will undergo a complete reprocessing. The reprocessing is intended to allow an opportunity to improve processing algorithms, adapt to challenges found in the data, and to incorporate global information obtained over the life of the Survey and from the analyses of global relationships in the data. The 2MASS Final Catalogs and Image Products will be released following this complete reprocessing.
[Last Update: 1999 May 6; R. Cutri]