Optical/IR imaging

Multiwavelength imaging is required both to quantify the spectroscopic completeness and to determine the stellar masses and star formation histories of our galaxies. In particular, broad wavelength coverage is crucial for classifying galaxies from their rest-frame colours. We also require good photometric redshifts to understand the relevant completeness for cluster members (van der Burg et al. 2013). Well calibrated photometric redshifts will allow us to determine membership at radii outside of those probed by our GMOS spectroscopy.

The nine group targets have existing deep, multiwavelength imaging spanning the full optical-NIR spectrum from COSMOS and SXDS, and we will obtain comparably deep coverage in the same bands (ugrizYJK) for the other systems. All but three of our clusters have publicly available deep (AB=23.1) [3.6]μm imaging from Spitzer IRAC. Most of the data come from SERVS (Mauduit et al. 2012), S-COSMOS (Sanders et al. 2007) and SpUDS (PI J. Dunlop, as described in Galametz et al. 2013). The three SPT clusters were observed as PI programs (PI Brodwin, from program ID 70053 and 60099). The remaining three clusters only had imaging from the shallow SWIRE (Lonsdale et al. 2003) survey. We therefore obtained 1200s/pixel integrations over 3×2 maps at [3.6]μm and [4.5]μm from Cycle 13 (PI McGee, GO program 13046).

Optical and NIR Imaging

Cluster
Target Depth (AB)		u/Ug/B/V
26.5		r/R
26.5		i/I
25.0		z'/z
26.0		Y/J1
24.5		J
24.0		Ks
23.5		[3.6μm]
23.1
SpARCS0035VIMOSVIMOSVIMOSVIMOSGMOS/VIMOSFourstarHAWK-IHAWK-ISERVS
SPT0205VIMOSVIMOSVIMOSVIMOSGMOS/VIMOSFourstarFourstarFourstarPI Brodwin
SpARCS0219VIMOSVIMOSVIMOSVIMOSGMOS/VIMOSFourstarFourstarFourstarSERVS
SpARCS0335VIMOSVIMOSVIMOSVIMOSGMOS/VIMOSHAWK-IFourstarFourstarGOGREEN
SPT0546VIMOSVIMOSVIMOSVIMOSGMOS/VIMOSFourstarFourstarFourstarPI Brodwin
SpARCS1033SuprimeCamSuprimeCamSuprimeCamGMOS/HSCHSC(MMIRS)(MMIRS)GOGREEN
SpARCS1034SuprimeCamSuprimeCamSuprimeCamGMOS/HSCHSC+WIRCAM(WIRCAM)WIRCAMGOGREEN
SpARCS1051MegacamSuprimeCamSuprimeCamSuprimeCamGMOS/HSCHSC(WIRCAM)(WIRCAM)SERVS
SpARCS1616MegacamSuprimeCamSuprimeCamSuprimeCamGMOS/HSCHSC(WIRCAM)(WIRCAM)SERVS
SpARCS1634MegacamSuprimeCamSuprimeCamSuprimeCamGMOS/(HSC)(HSC)(WIRCAM)(WIRCAM)SERVS
SpARCS1638MegacamSuprimeCamSuprimeCamSuprimeCamGMOS/(HSC)(HSC)SERVS
SPT2106VIMOSVIMOSVIMOSVIMOSGMOS/VIMOSFourstarFourstarHAWK-IPI Brodwin
Deep imaging observations of the SpARCS and SPT clusters in our sample to date. Table entries indicate instruments from which imaging data have been obtained, or for which observations are scheduled. These are GMOS (z'), VIMOS (UBVRIz) on the VLT, Suprimecam (SC) and HyperSuprimeCam (HSC) on Subaru (grizY), Fourstar on Magellan (J_1JK_s), HAWK-I on VLT (YJKs), MMIRS on MMT (JKs) and WIRCAM on CFHT (YJK_s). Target depths are indicated in the column headings, and listed observations are expected to be close to those depths. We do not list a target depth for u/U as this band is more heterogeneous. All targets also have deep Spitzer IRAC imaging with depths of at least 23.1 at 3.6μm; the source of the data is given in the Table. Entries in parenthesis are scheduled but not yet executed.
Examples of the imaging footprints for typical clusters, SPT-0205 (left) and SpARCS1034 (right). The smaller circle marks the cluster location and the larger circle is 1 Mpc (physical) at the cluster redshift, z=1.32 and 1.40 respectively. The rectangles (from smallest to largest) show the imaging fields of GMOS, FOURSTAR, and VIMOS (left) and GMOS, WIRCAM, and Suprime-Cam (right). For the four chip mosaic cameras (FOURSTAR, WIRCAM, HAWK-I and VIMOS), the cluster has been placed at the centre of one quadrant to ensure the full exposure depth is reached around the cluster centre in a single chip. The gaps in these mosaic cameras result in a region of lower exposure time in a central cross of the image.

BIK colour images are shown below for five southern clusters; galaxies with spectroscopic redshifts are circled.  Cluster members are shown in green.