TITLE: GCN CIRCULAR NUMBER: 6321 SUBJECT: GRB 070419B: optical afterglow confirmation DATE: 07/04/19 20:08:51 GMT FROM: Alberto Castro-Tirado at Inst.de Astro. de Andalucia A. de Ugarte Postigo, M. Jelínek (IAA-CSIC Granada), P. Tristram (MOA, Univ. of Canterbury), I. Bond (Massey Univ.), Ph. Yock (Univ. of Auckland), J. Hearnshaw (Univ. of Christchurch) and A. J. Castro- Tirado (IAA-CSIC), on behalf of a larger collaboration, report: "We have continued the BVRI optical monitoring of the proposed optical afterglow (Tristram et al. GCNC 6312) to GRB 070419B (Parson et al. GCNC 6305) with the 0.6m B&C telescope at the Mt. John Observatory on Lake Tekapo. We confirm the detection in the VRI -bands and a derive a complex lightcurve (preliminary analysis shows a steep decline up to T0 + 0.2 days and a plateau phase lasting until the end of our observations at T0 + 0.3 days with R ~ 21.0). A more accurated astrometry (+/- 0.5") yields: AR(2000): 21:02:49.78 Dec(2000): -31:15:48.8 A finding chart is posted at: http://www.iaa.es/~deugarte/GRBs/070419B/GRB070419B.gif Spectroscopic and photometric observations are encouraged." This message can be quoted.