The James Webb Space Telescope (JWST) was conceived and built to answer one of the most fundamental questions that humans can address empirically: "How did the Universe make its first stars?". This can be attempted in classical stare mode and by still photography -with all the pitfalls of crowding and multiband redshifts of objects of which a spectrum was never obtained. Our First Lights At REionization (FLARE) project transforms the quest for the epoch of reionization from the static to the time domain. It targets the complementary question: "What happened to those first stars?". It will be answered by observations of the most luminous events: supernovae and accretion on to black holes formed by direct collapse from the primordial gas clouds. These transients provide direct constraints on star-formation rates and the truly initial initial mass function, and they may identify possible stellar seeds of supermassive black holes. Furthermore, our knowledge of the physics of these events at ultra-low metallicity will be much expanded. JWST's unique capabilities will detect these most luminous and earliest cosmic messengers easily in fairly shallow observations. However, these events are very rare at the dawn of cosmic structure formation and so require large area coverage. Time domain astronomy can be advanced to an unprecedented depth by means of a shallow field of JWST reaching 27 mag (AB) in 2 µm and 4.4 µm over a field as large as 0.1 square degree visited multiple times each year. Such a survey may set strong constraints or detect massive Population III supernovae at redshifts beyond 10, pinpointing the redshift of the first stars, or at least their death. Based on our current knowledge of superluminous supernovae, such a survey will find one or more superluminous supernovae at redshifts above 6 in five years and possibly several direct collapse black holes.In addition, the large scale structure that is the trademark of the epoch of reion--3ization will be detected. Although JWST is not designed as a wide field survey telescope, we show that such a wide field survey is possible with JWST and is critical in addressing several of its key scientific goals.

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We apply statistically rigorous methods of nonparametric risk estimation to the problem of inferring the local peculiar velocity field from nearby supernovae (SNIa). We use two nonparametric methods -Weighted Least Squares (WLS) and Coefficient Unbiased (CU) -both of which employ spherical harmonics to model the field and use the estimated risk to determine at which multipole to truncate the series. We show that if the data are not drawn from a uniform distribution or if there is power beyond the maximum multipole in the regression, a bias is introduced on the coefficients using WLS. CU estimates the coefficients without this bias by including the sampling density making the coefficients more accurate but not necessarily modeling the velocity field more accurately. After applying nonparametric risk estimation to SNIa data, we find that there are not enough data at this time to measure power beyond the dipole. The WLS Local Group bulk flow is moving at 538 ± 86 km s −1 towards (l, b) = (258 • ± 10 • , 36 • ± 11 • ) and the CU bulk flow is moving at 446 ± 101 km s −1 towards (l, b) = (273 • ± 11 • , 46 • ± 8 • ). We find that the magnitude and direction of these measurements are in agreement with each other and previous results in the literature.

We present ultraviolet (UV) spectroscopy and photometry of four Type Ia supernovae (SNe 2004dt, 2004ef, 2005M, and 2005cf) obtained with the UV prism of the Advanced Camera for Surveys on the Hubble Space Telescope. This dataset provides unique spectral time series down to 2000 Å. Significant diversity is seen in the near-maximum-light spectra (∼ 2000-3500 Å) for this small sample. The corresponding photometric data, together with archival data from Swift Ultraviolet/Optical Telescope observations, provide further evidence of increased dispersion in the UV emission with respect to the optical. The peak luminosities measured in the uvw1/F250W filter are found to correlate with the B-band light-curve shape parameter ∆m 15 (B), but with much larger scatter relative to the correlation in the broad-band B band (e.g., ∼ 0.4 mag versus ∼ 0.2 mag for those with 0.8 < ∆m 15 (B) < 1.7 mag). SN 2004dt is found as an outlier of this correlation (at > 3σ), being brighter than normal SNe Ia such as SN 2005cf by ∼ 0.9 mag and ∼ 2.0 mag in the uvw1/F250W and uvm2/F220W filters, respectively. We show that different progenitor metallicity or line-expansion velocities alone cannot explain such a large discrepancy. Viewing-angle effects, such as due to an asymmetric explosion, may have a significant influence on the flux emitted in the UV region. Detailed modeling is needed to disentangle and quantify the above effects.

In this paper we advance the simple analytic photometric redshift estimator for Type Ia supernovae (SNe Ia) proposed by Wang, and use it to study simulated SN Ia data. We find that better than 0.5 per cent accuracy in zphot{with σ[(zphot−zspec)/(1 +zspec)] < 0.005} is possible for SNe Ia with well‐sampled light curves in three observed passbands (riz) with a signal‐to‐noise ratio of 25 at peak brightness, if the extinction by dust is negligible. The corresponding bias in zphot (the mean of zphot−zspec) is 5.4 × 10−4. If dust extinction is taken into consideration in the riz observer‐frame light curves, the accuracy in zphot deteriorates to 4.4 per cent, with a bias in zphot of 8.0 × 10−3. Adding the g‐band light curve improves the accuracy in zphot to 2.5 per cent, and reduces the bias in zphot to − 1.5 × 10−3. Our results have significant implications for the design of future photometric surveys of SNe Ia from both ground and space telescopes. Accurate and precise photometric redshifts boost the cosmological utility of such surveys.