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Discovery of the Optical Counterpart and Early Optical Observations of GRB 990712


Sahu, KC and Vreeswijk, P and Bakos, G and Menzies, JW and Bragaglia, A and Frontera, F and Piro, L and Albrow, MD and Bond, IA and Bower, R and Caldwell, JAR and Castro-Tirado, AJ and Courbin, F and Dominik, M and Fynbo, JU and Galama, T and Glazebrook, K and Greenhill, JG and Gorosabel, J and Hearnshaw, J and Hill, KM and Hjorth, J and Kane, S and Kilmartin, PM and Kouveliotou, C and Martin, R and Masetti, N and Maxted, P and Minniti, D and Moller, P and Muraki, Y and Nakamura, T and Noda, S and Ohnishi, K and Palazzi, E and van Paradijs, J and Pian, E and Pollard, KR and Rattenbury, NJ and Reid, M and Rol, E and Saito, T and Sackett, PD and Saizar, P and Tinney, C and Permaak, P and Watson, RD and Williams, A and Yock, P and Dar, A, Discovery of the Optical Counterpart and Early Optical Observations of GRB 990712, The Astrophysical Journal, 540, (Sep 1) pp. 74-80. ISSN 0004-637X (2000) [Refereed Article]

DOI: doi:10.1086/309340


We present the discovery observations of the optical counterpart of the gamma-ray burst GRB 990712 taken 4.16 hr after the outburst and discuss its light curve observed in the V, R, and I bands during the first ∼35 days after the outburst. The observed light curves were fitted with a power-law decay for the optical transient (OT), plus an additional component that was treated in two different ways. First, the additional component was assumed to be an underlying galaxy of constant brightness. The resulting slope of the decay is 0.97+0.05-0.02 and the magnitudes of the underlying galaxy are V = 22.3 ± 0.05, R = 21.75 ± 0.05, and I = 21.35 ± 0.05. Second, the additional component was assumed to be a galaxy plus an underlying supernova with a time-variable brightness identical to that of GRB 980425, appropriately scaled to the redshift of GRB 990712. The resulting slope of the decay is similar, but the goodness of fit is worse, which would imply that either this GRB is not associated with an underlying supernova or the underlying supernova is much fainter than the supernova associated with GRB 980425. The galaxy in this case is fainter: V = 22.7 ± 0.05, R = 22.25 ± 0.05, and I = 22.15 ± 0.05, and the OT plus the underlying supernova at a given time is brighter. Measurements of the brightnesses of the OT and the galaxy by late-time Bubble Space Telescope observation and ground-based observations can thus assess the presence of an underlying supernova.

Item Details

Item Type:Refereed Article
Research Division:Physical Sciences
Research Group:Astronomical sciences
Research Field:Galactic astronomy
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the physical sciences
UTAS Author:Greenhill, JG (Dr John Greenhill)
UTAS Author:Hill, KM (Dr Kym Hill)
UTAS Author:Kane, S (Dr Stephen Kane)
UTAS Author:Watson, RD (Dr Bob Watson)
ID Code:20117
Year Published:2000
Web of Science® Times Cited:43
Deposited By:Physics
Deposited On:2000-08-01
Last Modified:2001-05-07

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