TITLE:   GCN CIRCULAR
NUMBER:  46080
SUBJECT: GRB261029A: Early infrared detection with MDM/MIRAGE
DATE:    26/10/29 05:34:18 GMT
FROM:    Kishalay De at Columbia University <kd3038@columbia.edu>

K. De (Columbia U), S. Manyan (Columbia U), G. Mo (Caltech/Carnegie), V. Karambelkar (Columbia U), D. Schiminovich (Columbia U) report:

We observed the field of GRB 261029A detected by Fermi (Fermi GBM Team, GCN 46071) and SVOM (Goto et al., GCN 46072), with a reported optical counterpart candidate from GOTO (O'Neill et al. GCN 46073, He et al. GCN 46078, Wang et al. GCN 46079) in the near-infrared J and Hs band with the MDM InfraRed Astronomy inGaas Experiment (MIRAGE) instrument on the MDM 1.3m telescope.

Observations began at 2026-10-27T03:08 (1.5 hours after GRB trigger) in the J band lasting 1080 s, and in the Hs band lasting 1590 s. We clearly detect a bright infrared source at the reported optical position with J = 16.32 +/- 0.01 AB mag and Hs = 16.45 +/- 0.02 AB mag. 

MIRAGE is a new robotic YJHs-band near infrared imager for the MDM 1.3 m telescope. We thank the Mt Cuba astronomical foundation for supporting development of MIRAGE and MDM Observatory staff for supporting the observations.