TITLE: GCN CIRCULAR NUMBER: 38417 SUBJECT: LIGO/Virgo/KAGRA S241102br: GRAWITA wide-field optical observations DATE: 24/12/02 12:09:28 GMT FROM: Andrea Reguitti at INAF - Osservatorio Astronomico di Brera andreareguitti@gmail.com

*A. Reguitti (INAF-OABr / INAF-OAPd), P. D’Avanzo (INAF-OAB), L. Tomasella (INAF-OAPd), Y. Hu (INAF-OABr), A. Rossi (INAF-OAS), E. Cappellaro (INAF-OAPd) et al. on behalf of the GRAWITA collaboration*

We carried out optical follow-up observations of the well-localized LIGO/Virgo/KAGRA GW trigger S241102br (LVK Collaboration, GCN #38043) with the Schmidt telescope sited at the INAF Asiago observatory (Italy). Observations started on 2024-11-02 at 17:08 UT (~4.5 hours after the GW trigger) with the Sloan-r filter. We covered 12 square degrees within the 90% localisation region of the S241102br GW event, almost covering the totality of the final 7 deg2 50% localisation region. The 12 pointings of 1 square degree each are centered at J2000 celestial coordinates: (344.4023, 38.1139); (344.3944, 39.0544); (344.3862, 39.9948); (344.3775, 40.9352); (344.3684, 41.8757); (344.3589, 42.8161); (345.6411, 42.8161); (345.6316, 41.8757); (345.6225, 40.9352); (345.6138, 39.9948); (345.6056, 39.0544); (345.5977, 38.1139). These observations covered ~ 43% of the final 90% credible region (LVK Collaboration, GCN #38043). The typical 3 sigma limiting AB magnitudes are r ~ 21.1 mag. Preliminary analysis, which includes image subtraction with the template images from the PanSTARRS all-sky survey, shows no clear candidate counterparts.

We carried out a specific search for transients in the galaxies located within the S241102br volume. We note that one of the NED galaxies (Cook et al. 2024, GCN #38044) at z = 0.08, a distance consistent with the estimation for the S241102br GW event (0.069<z<0.093), has been proposed in the past as the host galaxy of GRB 051109B (Perley et al. 2006, GCN #5387).

We thank the staff at Padova Astronomical Observatory for their excellent support.

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