PRIME discovery and IRTF confirmation of a bright nova PRIME26aaabsh at the Galactic center
ATel #17743; R. Hamada (UOsaka), K. De (Columbia U), D. Suzuki (UOsaka), T. Sumi (UOsaka), K. Nunota (UOsaka), T. Suen (Columbia U), A. Masegian (Columbia U), T. Tamaoki (UOsaka), S. Makida (UOsaka), R. Oishi (UOsaka), R. Ogawa (UOsaka), H. Ose (UOsaka)
on 7 Apr 2026; 15:49 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Kishalay De (kde@flatironinstitute.org)
Subjects: Infra-Red, Optical, Cataclysmic Variable, Nova, Transient
We report the discovery and spectroscopic classification of a very bright NIR transient during the Galactic bulge survey carried out by the PRime-focus Infrared Microlensing Experiment (PRIME). PRIME is a 1.8m telescope with 1.56 square degree FOV (0.5 arcsec/pixel) located in Sutherland, South Africa at the South African Astronomical Observatory (Sumi et al. 2025). PRIME26aaabsh was first detected as a candidate transient generated in our custom image reduction and subtraction pipeline based on the ZOGY algorithm (Zackay et al. 2016, De et al. 2020) at a H-band mag of 11.4 +/- 0.1 mag (in the Vega system) on UT 2026-03-10, and at J2000 coordinates
RA 17:46:20.70
Dec -29:04:18.81
The transient is located ~10 arcmins away from the Galactic center, with a corresponding integrated line of sight extinction of ~130 mags in V-band (Schalfly et al. 2011). We caution that the first detection of the transient was immediately after the resumption of 2026 Galactic bulge observations; therefore the transient erupted likely before and was brighter than the quoted measurement. There is no source at this position in archival VVV H-band images, suggesting an outburst amplitude > 7 mags. The source has been subsequently fading to H ~ 12 mag by 2026-03-17.
On UT 2026-04-02, we obtained a near-infrared spectrum of the source with the SpeX spectrograph on the IRTF telescope as part of our program 2026A048 (PI: De). The reduced spectrum shows a steep red continuum with broad emission lines of He I, Pa gamma and Pa beta with FWHM ~ 1000 km/s. The large amplitude outburst, subsequent fading and spectrum with broad emission lines suggest the source to be a new classical nova towards the Galactic center.
We encourage multi-wavelength follow-up of the source. We thank the IRTF staff for assistance with scheduling these observations.
