ar X iv : a st ro - p h / 98 07 19 4 v 1 2 0 Ju l 1 99 8 The Extinction Towards the GRB 970228 Field

ar X iv : a st ro - p h / 97 11 26 0 v 1 2 1 N ov 1 99 7 1 The optical light curve of GRB 970228 refined

We present the R and V light curves of the optical counterpart of GRB 970228. A critical analysis of all the available data is made in light of the results achieved in the recent GRB Symposium held in Huntsville and by considering the latest information from the HST images on the underlying nebulosity.

ar X iv : a st ro - p h / 98 11 19 7 v 1 1 2 N ov 1 99 8 The ‘ bare ’ strange stars might not be bare

ar X iv : a st ro - p h / 97 10 33 8 v 1 2 9 O ct 1 99 7 OPTICAL

B, V and R optical photometry performed on the field of the GRB 970111 soon after its detection by BeppoSAX is presented. No remarkable optical object is found inside the corrected error box. The optical counterpart of an X–ray and radio source and a suspected red variable (probably an eclipsing binary) have been detected inside the field of GRB 970111.

ar X iv : a st ro - p h / 97 06 06 0 v 1 6 J un 1 99 7 The afterglow of gamma ray bursts II

Highly radiative expansion of a relativistic shell is shown to explain all observed features of the afterglows of the two bursts GRB 970228 and GRB 970508. In particular, in the first case the observed time–dependence ∝ t −1.32 of the soft X–ray flux is easily reproduced. The same model, when the surrounding matter density scales as a r −2 , explains the afterglow of GRB 970508, which may at fi...

ar X iv : a st ro - p h / 98 07 18 4 v 1 1 7 Ju l 1 99 8 The Polarisation Signatures of Microlensing

It has already been shown that microlensing can give rise to a non-zero variable polarisation signal. Here we use realistic simulations to demonstrate the additional information that can be gained from polarimetric observations of lensing events.