Rubin-LSST

Abstract:

In this paper we present the results of a survey for radio transients using data obtained from the Very Large Array archive. We have reduced, using a pipeline procedure, 5037 observations of the most common pointings - i.e. the calibrator fields. These fields typically contain a relatively bright point source and are used to calibrate `target' observations: they are therefore rarely imaged themselves. The observations used span a time range ~ 1984 - 2008 and consist of eight different pointings, three different frequencies (8.4, 4.8 and 1.4 GHz) and have a total observing time of 435 hours. We have searched for transient and variable radio sources within these observations using components from the prototype LOFAR transient detection system. In this paper we present the methodology for reducing large volumes of Very Large Array data; and we also present a brief overview of the prototype LOFAR transient detection algorithms. No radio transients were detected in this survey, therefore we place an upper limit on the snapshot rate of GHz frequency transients > 8.0 mJy to rho less than or equal to 0.032 deg^-2 that have typical timescales 4.3 to 45.3 days. We compare and contrast our upper limit with the snapshot rates - derived from either detections or non-detections of transient and variable radio sources - reported in the literature. When compared with the current Log N - Log S distribution formed from previous surveys, we show that our upper limit is consistent with the observed population. Current and future radio transient surveys will hopefully further constrain these statistics, and potentially discover dominant transient source populations. In this paper we also briefly explore the current transient commissioning observations with LOFAR, and the impact they will make on the field.

Abstract:

Using (9.32, 5.88) million Υ(2S,3S) decays taken with the CLEO III detector, we obtain five product branching fractions for the exclusive processes Υ(2S)→γχb0,1,2(1P)→γγΥ(1S) and Υ(3S)→γχb1,2(1P) →γγΥ(1S). We observe the transition χb0(1P) →γΥ(1S) for the first time. Using the known branching fractions for B[Υ(2S)→γχbJ(1P)], we extract values for B[χbJ(1P)→γΥ(1S)] for J=0, 1, 2. In turn, these values can be used to unfold the Υ(3S) product branching fractions to obtain values for B[Υ(3S)→γχb1,2(1P)] for the first time individually. Comparison of these with each other and with the branching fraction B[Υ(3S)→γχb0] previously measured by CLEO provides tests of relativistic corrections to electric dipole matrix elements. © 2011 American Physical Society.