Accurate photometric redshifts are calculated for nearly 200,000 galaxies to a 4.5 micron flux limit of ~13 uJy in the 8.5 deg^2 Spitzer/IRAC Shallow survey. Using a hybrid photometric redshift algorithm incorporating both neural-net and template-fitting techniques, calibrated with over 15,000 spectroscopic redshifts, a redshift accuracy of \sigma = 0.06(1+z) is achieved for 95% of galaxies at 01) galaxy clusters. We present one such spectroscopically confirmed cluster at =1.24, ISCS J1434.5+3427. Finally, we present a measurement of the 4.5 micron-selected galaxy redshift distribution.Comment: 14 pages, 9 Figures, 5 Tables. ApJ in press. For a version with full-resolution figures, please see http://www.astro.utoronto.ca/~brodwin/papers/0607450.pd

We report the discovery of a galaxy cluster at . ISCS J143809ϩ341419 was found in the Spitzer/ z p 1.41 IRAC Shallow Survey of the Boötes field in the NOAO Deep Wide-Field Survey carried out using IRAC. The cluster candidate was initially identified as a high-density region of objects with photometric redshifts in the range . Optical spectroscopy of a limited number of objects in the region shows that five galaxies 1.3 ! z ! 1.5 within an ∼120Љ diameter region lie at . Most of these member galaxies have broadband colors z p 1.41 ‫ע‬ 0.01 consistent with the expected spectral energy distribution of a passively evolving elliptical galaxy formed at high redshift. The redshift of ISCS J143809ϩ341419 is the highest currently known for a spectroscopically confirmed cluster of galaxies.

Using the Florida Multi-object Imaging Near-IR grism Observational Spectrometer (FLAMINGOS), we have conducted the FLAMINGOS Extragalactic Survey (FLAMEX), a deep imaging survey covering 7.1 square degrees within the 18.6 sq. deg NOAO Deep Wide-Field Survey (NDWFS) regions. FLAMEX is the first deep, wide-area near-infrared survey to image in both the J and Ks filters, and is larger than any previous NIR surveys of comparable depth. The intent of FLAMEX is to facilitate the study of galaxy and galaxy cluster evolution at 11 galaxy clusters detected using the joint FLAMEX, NDWFS, and Spitzer IRAC Shallow Survey data sets.Comment: Accepted to ApJ, 11 pages, 13 figures. For higher resolution figures, see http://flamingos.astro.ufl.edu/extragalactic

We built an optimal basis of low-resolution templates for galaxies over the wavelength range from 0.2 to 10 m using a variant of the algorithm presented by Budavari and coworkers. We derived them using 11 bands of photometry from the NDWFS, FLAMEX, zBoötes, and IRAC Shallow surveys for 16,033 galaxies in the NDWFS Boötes field with spectroscopic redshifts measured by the AGN and Galaxy Evolution Survey. We also developed algorithms to accurately determine photometric redshifts, K-corrections, and bolometric luminosities using these templates. Our photometric redshifts have an accuracy of z / 1 þ z ð Þ¼0:04 when clipped to the best 95%. We used these templates to study the spectral type distribution in the field and to estimate luminosity functions of galaxies as a function of redshift and spectral type. In particular, we note that the 5-8 m color distribution of galaxies is bimodal, much like the optical g À r colors.

We report 139 photometric observations through the B, V, and I filters of the supernova SN 1998bw, an object which is associated with the Gamma-Ray Burst GRB 980425. Detailed light curves of this unique supernova can be compared to theoretical models, so we report here our light curve for 123 days between 27 June 1998 and 28 October 1998. The light curve of SN 1988bw is consistent with those of the Type Ic class. We find that the magnitude-versus-time relation for this supernova is linear to within 0.05 mags in all colors over the entire duration of our study. Our measured uniform decline rates are 0.0141 ± 0.0002, 0.0184 ± 0.0003, and 0.0181 ± 0.0003 magnitudes per day in the B, V, and I bands. The linear decline and the rate of that decline suggest that the late time light curve is powered by the radioactive decay of cobalt with some leakage of the gamma rays.