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Paper text:
3d - hst is an hst treasury program executed in cycles 18 and 19 .
the survey uses the acs and wfc3 grisms , providing slitless spectroscopy for all objects in the fields of these instruments .
the primary and most innovative aspect of the survey is 2-orbit depth wfc3/g141 spectroscopy , covering the wavelength range @xmath4 m 
1.65@xmath5 m .
owing to the low sky background from space and the excellent sensitivity of wfc3 we reach a point - source continuum depth of @xmath6 at @xmath7 in 2 orbits .
in addition to the g141 grism data the 3d - hst data comprise direct wfc3 images in the @xmath8 filter , parallel acs g800l grism exposures , and direct images in the acs @xmath9 filter .
the survey fields are four of the fields of the candels multi - cycle treasury program : goods - south , uds , aegis , and cosmos . the fifth candels field , goods - north ,
was observed by program go-11600 ( pi : weiner ) in cycle 17 to the same 2-orbit g141 depth as 3d - hst ( but without parallel acs grism data ) .
we have included these goods - north data in our analysis .
candels is primarily an imaging survey , providing @xmath10 and @xmath11 data at two different depths over the five fields .
the 3d - hst grism data cover approximately 80% of the area of the candels fields , and form a spectroscopic complement to the candels imaging .
the reduction , analysis , and interpretation of the slitless spectroscopy is not straightforward .
the spectra of neighboring objects can overlap , which means a full 2d model of all spectra needs to be constructed and subtracted prior to analyzing the object of interest .
furthermore , the `` psf '' of the grism spectra is effectively the ( wavelength - dependent ) morphology of the galaxy , complicating the fitting procedure .
stsci provides software to analyze grism spectra but this is not optimized for faint - object spectroscopy ; we therefore developed fully independent , custom packages that enable optimal modeling and fitting of interlaced 2d spectra .
we find that these tools work very well , even on the deepest ( 17-orbit ) grism data that are currently available ( see below ) .
a further complication is that the grism spectra are often difficult to interpret without information from other wavelengths , as correct identification of faint emission lines usually requires some prior information on the likely redshifts of the objects
. data at other wavelengths are also crucial for measuring stellar masses , rest - frame colors , star formation rates , and other parameters . with these goals in mind
we have created photometric catalogs in the 3d - hst fields , as a first and necessary step to interpret the grism spectra .
we are providing the g141 grism spectra in the only region of the survey which was observed multiple times : the hubble ultra deep field .
we have used this field to test our fitting procedures and to extract and analyze the deepest near - ir spectra of faint galaxies currently available .
the g141 spectra are based on a combination of 8 orbits of 3d - hst data and 9 orbits of candels supernova follow - up data .
an analysis of the 17-orbit spectrum of a candidate @xmath12 galaxy in this field was presented in brammer et al.(2013 ) .
we provide @xmath0 spectra and redshifts over the @xmath13 udf .
this density of @xmath14 spectra per arcmin@xmath15 far exceeds what has been achieved in any other survey or can reasonably be done from the ground .      as part of our commitment to release all ancillary data used in the 3d - hst program we are providing our reduced wfc3 mosaics of all five 3d - hst / candels fields as part of data release v3.0 .
the mosaics include the deep and wide @xmath16 data obtained as part of the candels program , the 3d - hst @xmath8 imaging , and the early release science observations ( and udf flanking fields ) in goods - south .
the candels project has also released several of the imaging mosaics .
our reduction uses the same tangent point and pixel scale as candels , which means 3d - hst and candels objects can be trivially matched and compared .
we are preparing to release our photometric catalogs in these five fields , including derived photometric redshifts and stellar population parameters . the catalog release ( v3.1 )
will be accompanied by a paper describing the reduction of the mosaics and the making of the catalogs ( skelton et al .
, in preparation ) .
information on the 3d - hst survey , as well as links to the data release , publications , pointing layout , and other information can be obtained from the 3d - hst website :          we have created several tools to explore the data release . for the ultra deep field we provide an html table with image thumbnails and spectra , which can be ordered according to i d , magnitude or redshift .
an interactive image browser displays grism redshifts on udf objects and allows users to scroll around the field using a google maps - like interface .
clicking on an object brings up the html table with the object at the top .
* * http://monoceros.astro.yale.edu/release_v3.0/spectra/udf/web/udf_3dhst_redshift_v1.0.html[udf html catalog with rgb thumbnails , spectra , and fits ] * * * http://monoceros.astro.yale.edu/release_v3.0/spectra/udf/web/hudf_ijh.html#03:32:39.73,-27:46:11.3[udf interactive image browser ] *      * * http://monoceros.astro.yale.edu/release_v3.0/photometry/rgb/aegis3/aegis_ijh.html#14:20:19.49,+53:02:03.8[aegis @xmath17 rgb mosaic ] * * * http://monoceros.astro.yale.edu/release_v3.0/photometry/rgb/cosmos3/cosmos_ijh.html#10:00:17.97,+02:18:05.5[cosmos @xmath17 rgb mosaic ] * * * http://monoceros.astro.yale.edu/release_v3.0/photometry/rgb/gs3/gs_ijh.html#03:32:14.96,-27:42:25.9[goods-south @xmath17 rgb mosaic ] * * * http://monoceros.astro.yale.edu/release_v3.0/photometry/rgb/gn3/gn_ijh.html#12:37:21.09,+62:12:46.8[goods-north @xmath18 rgb mosaic ] * * * http://monoceros.astro.yale.edu/release_v3.0/photometry/rgb/uds3/uds_ijh.html#02:17:37.17,-05:13:30.1[uds @xmath18 rgb mosaic ] *    * acknowledgements : * the 3d - hst survey , programs hst - go-12177 and hst - go-12328 , is based on observations made with the nasa / esa hubble space telescope , obtained at the space telescope science institute , which is operated by the association of universities for research in astronomy , inc .
, under nasa contract nas 5 - 26555 . financial support for this program is gratefully acknowledged . besides data from the 3d - hst survey itself we used observations from programs 11600 ( pi : weiner ) , candels ( 12060 - 12064 and 12440 - 12445 ; pis : faber , ferguson ) , the wfc3 early release science program ( 11359 ; pi : oconnell ) , goods ( 9425 and 9573 ; pi : giavalisco ) , hudf-09 ( 11563 ; pi : illingworth ) , and hudf-12 ( 12498 ; pi : ellis ) as delivered by the hst archive .
we thank our colleagues for providing these extraordinary data to the community .
3d - hst is a 248-orbit treasury program to provide wfc3 and acs grism spectroscopy over four extra - galactic fields ( aegis , cosmos , goods - south , and uds ) , augmented with previously obtained data in goods - north . 
 we present a new data release of the 3d - hst survey , version v3.0 . 
 this release follows the initial v0.5 release that accompanied the survey description paper ( brammer et al . 2012 ) . 
 the new v3.0 release includes the deepest near - ir hst grism spectra currently in existence , extracted from the 8 - 17 orbit depth observations in the hubble ultra deep field . 
 contamination - corrected 2d and 1d spectra , as well as derived redshifts , are made available for @xmath0 objects in this @xmath1 field . 
 the spectra are of extraordinary quality , and show emission features in many galaxies as faint as f140w@xmath2 , absorption features in quiescent galaxies at @xmath3 , and several active galactic nuclei . 
 in addition to these extremely deep grism data we provide reduced wfc3 f125w , f140w , and f160w image mosaics of all five 3d - hst / candels fields .