TITLE: GCN CIRCULAR NUMBER: 40282 SUBJECT: EP250428b: SAO RAS optical upper limit DATE: 25/04/29 23:39:13 GMT FROM: Alexander Moskvitin at SAO RAS mosk@sao.ru
A. S. Moskvitin, O. I. Spiridonova (SAO RAS) report on behalf of the GRB follow-up team.
We observed the field of the X-ray transient EP250428b (Liu et al., GCN 40277) with the SAO RAS 1-m telescope Zeiss-1000 on April 29, 20:47:38--21:28:24 UT (t_mid - T0 = 1.6267 days). We obtained 7 x 300 sec. images in Rc band.
Within the FXT error circle we detect several sources which are presented in the PanSTARRS images: R.A. Decl. R_mag +/- err #1 14:41:50.4 +02:06:18.0 20.20 +/- 0.10 #2 14:41:50.7 +02:06:13.4 22.86 +/- 0.21 #3 14:41:49.8 +02:05:55.9 22.57 +/- 0.17
Within the FXT error circle we did not detect any new sources down to the limiting magnitude of R_lim = 23.2 (calibrated against R2 magnitudes of nearby UNSO-B1 stars and not corrected for the MW extinction).
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