MDM/MIRAGE discovery of a pronounced infrared brightening in the luminous nova AT2026aabo in M31
ATel #18048; Viraj Karambelkar, Kishalay De, Salma Ibrahim, David Schiminovich (Columbia University)
on 16 Sep 2026; 03:48 UT
Credential Certification: Viraj Karambelkar (vk2588@columbia.edu)
Subjects: Infra-Red, Nova
Referred to by ATel #: 18096
We report near-infrared (NIR) monitoring observations of the bright nova AT2026aabo (ATel #18027, #18029, Astronote 2026-268) conducted with the MDM-Infrared InGaAs Experiment (MIRAGE) camera on the 1.3m telescope at the MDM observatory. MIRAGE is a new robotic YJHs InGaAs imager in routine operations since March 2026 (Ibrahim & De 2026).
MIRAGE monitoring of AT2026aabo began on UT 2026-09-11 with 2 night cadence in J and Hs bands. The data are reduced as part of an automated pipeline (De et al. 2020) including astrometric and photometric calibration against the 2MASS catalog. Our observations show that the source has been steadily brightening in the near-IR J and Hs filters, from Hs = 17.39 +/- 0.03 mag (AB) on UT 2026-09-11 to Hs = 16.71 +/- 0.02 mag (AB) on UT 2026-09-16. During this period, the source reddened substantially from a color of J - Hs ~ -0.1 mag to J - Hs ~ +0.5 mag.
Contemporaneous optical observations from ATLAS show that the source continues to fade in the optical bands during the same period, reddening to a color of c - Hs ~ 2.5 mag on MJD 61298. The simultaneous optical fading and infrared brightening indicate rapid onset of dust formation in the nova (e.g. Raj et al. 2017, Chong et al. 2025), within 2 weeks of the outburst. Additional follow-up observations, particularly in infrared bands are encouraged.
We thank the Mt Cuba Astronomical Foundation for supporting the development of MIRAGE.
