SUPPLEMENTARY INFORMATION doi:10.1038/nature12657 • R P(z>[zsample − 2])dz ≥ 0.5 • zbest >zsample − 2 1Sample Selection • R P(z>[zsample − 2])dz ≥ 0.5 Our sample of high-redshift galaxies in the GOODS-North field 2 • χ• < 60 − was selected using an updated version of the criteria presented in pre- zbest >zsample 2 1Sample15,22 Selection vious papers; the full sample will be published in Finkelstein et al. 2 Our sample of high-redshift galaxies in the GOODS-North fieldThese are• χ very< similar60 to the criteria used in our previous publications, in prep.was selected These papers using can an updated be consulted version for of more the criteria details, presented but here we in pre-and they have been shown to produce samples which match up very 15,22 15 brieflyvious recap papers; our process.the full sample will be published in Finkelstein et al.wellThese with available are very similarspectroscopic to the criteria redshifts used at z< in our7. previous publications, 28 Thein prep. optical These imaging papers comes canfrom be consulted the GOODS for more survey, details,and webut used here we Theand selectedthey have sources been shownwere visually to produce inspected samples to reject which artifacts match such up very 15 the v2.0briefly ACS recap imaging, our process. consisting of mosaics in the F435W, F606W, as diffractionwell with spikesavailable and spectroscopic oversplit regions redshifts of bright at z< galaxies.7. Addition- 28 F775WThe and optical F850LP imaging filters. comes The near-infraredfrom the GOODS data survey, comes fromand we the usedally, theThe colors selected of galaxy sources candidates were visually were inspected compared to to reject the artifactsexpected such CANDELSthe v2.0 survey, ACS imaging, and we used consisting the CANDELS of mosaics team’s in the early F435W, data prod- F606W,colorsas diffractionof M, L and spikes T-dwarf and stars, oversplit and regionsany sources of bright with galaxies. star-like colors Addition- uctsF775W (v0.1) in and the F850LP F105W, filters.F125WThe and F160W near-infrared filters. data The comes CANDELS from thewhichally, were the also colors unresolved of galaxy were candidates rejected from were the compared sample. to Finally, the expected the surveyCANDELS obtained survey, data atand two we depths, used denotedthe CANDELS as “WIDE” team’s and early “DEEP”. data prod-opticalcolors bands of M, were L andalso T-dwarf inspected stars, to ensure and any that sources they visually with star-like appeared colors Theucts imaging (v0.1) used in thehere F105W, consists F125W of the full and depth F160W in the filters. Northeast The CANDELS WIDE to containwhich were no significant also unresolved (>1.5σ were) flux rejected (in practice, from the sources sample. with Finally, sig- the region, and about half of the full depth of the DEEP region. The 5σ survey obtained data at two depths,′′ denoted as “WIDE” and “DEEP”.nificantoptical optical bands flux were would also have inspected already to beenensure rejected that they by visually our selection appeared limitingThe magnitudes,imaging used measured here consists in 0.4 of the-diameter full depth apertures, in the Northeast for the ACS WIDEcriteria).to contain Our final no significant galaxy samples (>1.5 consistσ) flux of (in 175 practice, candidate sources galaxies with at sig- bandsregion, are: 28.1, and about 28.3, 27.8 half ofand the 27.7 full mag, depth respectively of the DEEP (all region. magnitudes The 5σz ≈ 6, 85 at z ≈ 7 and 25 at z ≈ 8. 29 ′′ nificant optical flux would have already been rejected by our selection are quotedlimiting in magnitudes, the AB system measured). For in the 0.4 three-diameter WFC3 apertures, bands, the for exist- the ACS criteria). Our final galaxy samples consist of 175 candidate galaxies at σ ing DEEPbandsare: 5 depths 28.1, 28.3, are 27.9, 27.8 27.9 and and27.7 27.7 mag, mag, respectively while for (all the magnitudes WIDE 2z Spectroscopic≈ 6, 85 at z ≈ 7 and Followup 25 at z ≈ Sample8. region, the depths are 27.4, 27.4 and29 27.3 mag, respectively. Addition- are quoted in the AB system ). For the three WFC3 bands, the exist- From our parent sample of candidate galaxies, we selected those ally, we add to ourσ analysis new, extremely deep, optical data obtained ing DEEP 5 depths are 27.9, 27.9 and 27.7 mag, while for the WIDEfor spectroscopic2 Spectroscopic followup with Followup MOSFIRE Sample via two criteria: 1) appar- withregion, ACS in the parallel depths to are the 27.4, CANDELS 27.4 and observations. 27.3 mag, respectively. These data Addition- were ent F160WFrom magnitude, our parent and sample 2) maximizing of candidateR galaxies,P(7.0 <z< we selected8.2)dz those obtainedally, we in the add F814W to our analysis filter, and new, have extremely an exposure deep, timeoptical of data 57,000 obtained s (whichfor spectroscopic corresponds to followup the redshift with rangeMOSFIRE placing via Ly twoα criteria:in the MOS- 1) appar- at thewith position ACS in of parallel z8 GND to5296, the CANDELS showing no observations. detectable flux These within data a were ′′ FIREentY F160W-band grating). magnitude, We and first 2) prioritized maximizing basedR P on(7 brightness,.0 <z< and8.2)dz 0.4 obtained-diameter in aperture the F814W 5σ depth filter, of and 28.8. have We an created exposure photometry time of cata- 57,000 s 30 then(which within corresponds each magnitude to the bin, redshift we prioritized range placing based Lyonα thein highest the MOS- logsat with the the position Source of Extractor z8 GND software,5296, showingusing no a weighted detectable sum flux of within the a ′′ valueFIRE of theY -band integral grating). defined We above. first We prioritized input these based catalogs on brightness, into the and F125W0.4 and-diameter F160W aperture images 5 asσ depth the detection of 28.8. image. We created We measured photometry col- cata- F1 MAGMAthen within software each, magnitude which was bin, created we by prioritized the MOSFIRE based team on the to de-highest ors inlogs small with elliptical the Source apertures, Extractor setting software, the Kron30 using aperture a weighted parameters sum to of the signvalue mask of configurations. the integral defined The software above. searches We input a large these (user-defined) catalogs into the KronF125Wfact=1.2 and and F160W min imagesradius= as1.7. the Aperture detection corrections image. We were measured mea- col- F1 parameterMAGMA space software in both right, which ascension, was created declination by the MOSFIRE and position team an- to de- suredors in in the small F160W elliptical band apertures, by comparing setting the the flux Kron in this aperture small parameters aperture to gle tosign maximize mask configurations. the total priority The of software sources. searches We designed a large two (user-defined) masks: to thatKron in thefact default=1.2 and MAG minAUTOradius= aperture,1.7. Aperture which is corrections representative were of mea- GOODSNparameterMask1, space with in both a position right ascension, angle of 34 declination degrees, containing and position 24 an- the totalsured flux. in the Photometry F160W band was by performed comparing on the the flux DEEP inthis andsmall WIDE aperture re- candidategle to maximizehigh-redshift the galaxies, total priority and of GOODSN sources. WeMask2, designed with twoa posi- masks: gionsto separately. that in the Photometry default MAG errorsAUTO were aperture, obtained which by providing is representative Source of tionGOODSN angle of −9.5Mask1, degrees, with containing a position 19. angle of 34 degrees, containing 24 Extractorthe total with flux. accurate Photometry RMS images. was performed on the DEEP and WIDE re- candidate high-redshift galaxies, and GOODSN Mask2, with a posi- Nogions RMS separately. map was Photometry available for errors the were F814W obtained data, butby providing we followed Source tion angle of −9.5 degrees, containing 19. theExtractor same procedures with accurate usedRMS to calibrate images. noise maps for the standard 3 Observations and Data Reduction 31 CANDELSNo RMS HST mapdata was products available. We for measured the F814W the data, RMS but and we auto- followed Our observations took place on UT 18-19 April 2013 under clear, Y correlationthe same function procedures of the used background to calibrate noise noise near mapsthe position for the of standard our mostly3 photometric Observations conditions. and Data We used Reduction MOSFIRE with the -band 31 grating, which observes ∼0.97 – 1.12 µm, and set the slit widths to object,CANDELS after masking HST outdata sources. products We. scaled We measured the correlation-corrected the RMS and auto- ′′ Our observations took place on UT 18-19 April 2013 under clear, RMScorrelation to the number function of pixels of the in thebackground elliptical noisephotometry near the aperture, position find- of our0.7 mostly. We observed photometric each conditions. configuration We for used one MOSFIRE night, taking with 180 the Y sec-band ing a total 1σ F814W flux uncertainty of 5 nJy. This is a factor of exposuresgrating, with which an observesABAB dither∼0.97 pattern, – 1.12 withµm, dither and set positions the slit widthssepa- to object, after masking out sources. We scaled the correlation-corrected ′′ ′′ aboutRMS 3× todeeper the number than the of GOODSpixels in theF775W elliptical or F850LP photometry imaging aperture, at this find-rated0.7 by. 2.5 We, yielding observed a each total exposureconfiguration time for of 5.6 one hr night, for the taking first con- 180 sec position. These F814Wσ data were not available at the time of our ob- figurationexposures and with4.45 anhr for ABAB the second. dither pattern, The data with were dither reduced positions using sepa- ing a total 1 F814W flux uncertainty of 5 nJy.