Optical polarization observations with the MASTER robotic net

Abstract

We present results of optical polarization observations performed with the MASTER robotic net for three types of objects: gamma-ray bursts, supernovae, and blazars. For the Swift gamma-ray bursts GRB100906A, GRB110422A, GRB121011A, polarization observations were obtained during very early stages of optical emission. For GRB100906A it was the first prompt optical polarization observation in the world. Photometry in polarizers is presented for Type Ia Supernova 2012bh during 20 days, starting on March 27, 2012. We find that the linear polarization of SN 2012bh at the early stage of the envelope expansion was less than 3%. Polarization measurements for the blazars OC 457, 3C 454.3, QSO B1215+303, 87GB 165943.2+395846 at single nights are presented. We infer the degree of the linear polarization and polarization angle. The blazars OC 457 and 3C 454.3 were observed during their periods of activity. The results show that MASTER is able to measure substantially polarized light; at the same time it is not suitable for determining weak polarization (less than 5%) of dim objects (fainter than 16$^m$). Polarimetric observations of the optical emission from gamma-ray bursts and supernovae are necessary to investigate the nature of these transient objects.Comment: 31 pages, 12 figures, 4 tables; Exposure times in Table 2 have been correcte

The optical identification of events with poorly defined locations: the case of the Fermi GBM GRB 140801A

“…Results of polarization measurements of GRB 100906A, GRB 110422A, and GRB 121011A by MASTER have been reported by Gorbovskoy et al (2012);Pruzhinskaya et al (2014). For GRB 100906A, from 0.01 to 0.19 h after T0, it was found that the time-averaged dimensionless Stokes parameter was less than the standard deviation of that of the field stars (2 per cent for that case).…”

“…Thus, one MASTER telescope, when observing alone, is able to measure one Stokes parameter. Details on the Stokes parameter derivation and the calibration of polarization measurements are given in Pruzhinskaya et al (2014). The differences between the signals obtained by MASTER-Tunka in two polarizers for the time interval from 202.8 to 315.7 s yield the dimensionless time-averaged Stokes parameter Q = 2.4 ± 2.5 per cent.…”

Master Optical Polarization Variability Detection in the Microquasar V404 Cyg/Gs 2023+33

“…The MASTER robotic telescopes 1 are a network of identical instruments deployed over several continents and equipped with identical CCD cameras capable of performing B,V,R J ,I (Johnson/Bessell) photometric and linear polarimetric observations (Lipunov et al 2010;Kornilov et al 2012;Pruzhinskaya et al 2014). Each MASTER-II observatory has twin 0.40-m f/2.5 wide field reflectors (Hamilton design; see Kornilov et al (2012)) and a prime focus 4k x 4k CCD camera, which provide a total 8 square-degree field and reaches to a white-light magnitude of 20-21 (in 180s exposure).…”

“…The technique of polarimetric measurements used on MASTER network telescopes is considered in detail in (Pruzhinskaya et al 2014). It allows detecting the linear polarization at 1-2% level for objects brighter then 14mag.…”

“…More than 100 observations of GRBs were made by the MASTER global robotic net. Optical emission was detected for ∼ 20 GRBs (Lipunov et al 2007;Gorbovskoy et al 2012;Pruzhinskaya et al 2014). The GRB 100906A, GRB 110422A, and GRB 121011A events deserved attention because their optical observations were carried out during the prompt gamma-ray emission.…”