ner_tags: O O O O O O O O O O B-Instrument O O O O O O O O O O O O O O O B-Wavelength O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-CelestialRegion I-CelestialRegion O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Telescope O O O O B-Instrument I-Instrument O O O B-Instrument O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Telescope O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O
tokens: have half-light radii of 60pc, would be barely resolved with NIRCam. 3.2.2 The main epoch of GC formation Each individual GCP will be totally dark (in UV) before experiencing its main (1G) burst of star formation, quickly reaching its peak SFR and brightness, then followed by rapid decline, possibly punctuated by a series of secondary (2G) bursts. Then rapidly turning passive and fading well below observability. A uniform GC formation rate between z 8 and 3 has been assumed above, but it may well be that the GC formation rate is initially very low, then peaks at a specific redshift and then declines, with few clusters still forming at lower redshifts. Having explored this redshift range, observations should then be able to identify such a golden age of GC formation, therefore establishing the relative timing of GC and galaxy formation, and providing, incidentally, a straight check for local GC ages as inferred from isochrones. 3.2.3 Clustering GC are not uniformly distributed in the local Universe, but clusters around their parent galaxies. This must be the case also at high redshift, while they are forming, though the parent galaxy may not be in place yet. Thus, one expects candidate GCPs to be highly clustered, lying within groups of 100kpc, or 20arcsec size (see Table 1 ). With sufficient statistics, it should be possible to directly establish the connection between the peak of GC formation and the stage of development of the host galaxy: clusters of GCPs as signposts of incipient massive galaxy formation. 4 DISCUSSION AND SUMMARY GCPs identified via BB photometry will need a spectroscopic confirmation, and the most obvious and timely follow up will be with JWST itself, either with the NIRCam grizm capability or with NIRSpec. In the longer run, 3040m class telescopes with their adaptive optics capabilities will offer unparalleled resolution. However, even before spectroscopic observations, some confirmation may come for those GCP candidates detected in more than one band, with SED fits providing age, mass and redshift constraints. Of course, more information could be gathered for those objects detected with NB filters, but they could be at most just a few. Designing a specific observing plan is far beyond the scope of this Letter. From the estimates given here it is relatively easy to infer what kind of information could be obtained for given invested observing time. On the other hand, deep multiband imaging over many fields, either primary or parallel, will certainly be done with JWST . This exercise has demonstrated that GCPs can be detected, with the number of detections critically depending on the mass of the progenitors, i.e. on the mass budget factor f MB . If GCPs were just marginally more massive than their present-day progeny then only the most massive ones could be detected, i.e. would have BB fluxes at formation above the thresholds given in Table 2 , scaled to the actual integration time. If this were the case, than the massive