The cluster candidates were selected primarily based on their high-magnification lensing properties. They were also vetted for other considerations. Comments and suggestions were considered.
- The clusters are known to be massive and highly efficient lenses.
- The clusters have several sets of known multiple image systems confirmed with spectroscopic redshifts.
- Most of the clusters have high-quality magnification maps based on data in hand.
- The clusters were selected based on initial estimates of the number counts of lensed high redshift sources detectable within the WFC3-IR FOV.
- The area enclosed interior to the critical curve for z~4-10 sources can be fully captured within a single pointing of WFC3-IR.
- Clusters with higher redshifts will have less area masked by cluster galaxies, fainter intracluster light, and less contamination in the parallel blank fields.
| Cluster | z | RA | DEC |
|---|---|---|---|
| Abell 370 | 0.37 | 02:39:52.8 | -01:34:36 |
| MACSJ0329.6-0211 | 0.45 | 03:29:40.3 | -02:11:42 |
| MACSJ0416.1-2403 | 0.42 | 04:16:08.4 | -24:04:21 |
| MACSJ0451.0+0006 | 0.429 | 04:51:54.6 | +00:06:17 |
| MACSJ0717.5+3745 | 0.545 | 07:17:35.6 | +37:44:44 |
| MACSJ0744.9+3927 | 0.686 | 07:44:52.8 | +39:27:24 |
| MACSJ1149.5+2223 | 0.543 | 11:49:35.7 | +22:23:55 |
| MACSJ1423.8+2404 | 0.54 | 14:23:48.3 | +24:04:47 |
| Abell 2744 | 0.308 | 00:14:23.4 | -30:23:26 |
| MACSJ0257-2325 | 0.505 | 02:57:08.8 | -23:26:03 |
| MACSJ0520.7-1328 | 0.340 | 05:20:42.0 | -13:28:48 |
In addition to their lensing properties, we weighed the following additional criteria:
- ecliptic latitude and zodiacal foreground
- accessibility to ground-based observatories, including ALMA
- Galactic latitude, extinction and foreground emission
- scheduling constraints of HST and Spitzer
- JWST follow-up optimization
Other candidates that were considered but eliminated include the following:
- MACSJ0647.7+7015 (bright stars in field, no ALMA)
- Bullet Cluster (larger than WFC3-FOV)
- Abell 1689 (low redshift, larger than WFC3-FOV)
- Abell 1703 (low redshift, larger than WFC3-FOV)
- Abell 2537 (high zodical background)
- MACSJ1206.2-0747 (high zodical background)
- MACSJ2129.4-0741 (high zodical background)
- MACSJ2214.9-1359 (high zodical background)
- RCS2-2327.4-04 (high zodical background)
- RXJ1347.5-1144 (high zodical background)
- MACSJ0454.1-0300 (moderate zodical background, weaker lenser)
Ultimately, the first four cluster selections were announced in late 2012:
- Abell 2744
- MACSJ0416.1-2403
- MACSJ0717.5+3745
- Abell 370
Top contenders for the final two fields were MACS0329.6-2011, MACS0451.0+0006, AbellS1063, MACSJ1149.5+2223, MACSJ1423.8+2404, and MACSJ0257.0-2209. In February 2013, the final two selections were announced:
- MACSJ1149.5+2223
- Abell S1063
