DRAFT
2026-04-03 00:01:27
Type: Object/s-Data/Analysis
Bibcode: 2026TNSAN..93....1S
Spectroscopic Observations of AT 2026hir/ZTF26aapviim, the counterpart to EP260324A
Authors: Robert Stein (UMD/JSI/NASA GSFC), Kaustav Das (Caltech), Christoffer Fremling (Caltech), Tomas Ahumada (NOIRLab), Akash Anumarlapudi (UNC CH), Ryan Chornock (UC Berkeley), Michael C. Davis (UMN), K-Ryan Hinds (Caltech), Mansi Kasliwal (Caltech), Jillian Rastinejad (UMD), Gokul Srinivasaragavan (UMD), Yuhan Yao (UC Berkeley) on behalf of the ZTF collaboration
Source Group: ZTF
Keywords: Time-domain, Transient, TDE, X-rays
Abstract:
We report the spectroscopic observations of AT 2026hir/ZTF26aapviim, the counterpart to EP260324A. The source has a blue continuum, and possibly exhibits an additional broad feature that could be He II. The spectrum and nuclear location are consistent with a TDE origin, but additional data are required to confirm this. The source remains bright (mg=17.3) and additional observations are encouraged.

We observed AT 2026hir/ZTF26aapviim, the optical counterpart (Anumarlapudi et al, GCN #44120) to EP260324A (Wu et al., ATEL #17728), with the Next Generation Palomar Spectrograph (NGPS; AstroNote 2024-340) on the Palomar 5.1m Hale Telescope (P200). Our observations began on 2026-03-27T03:51:37 (~3 days after the EP trigger), and data were reduced using the standard NGPS pipeline.

The spectrum was extremely blue, as also noted by Zhu et al. (Astronote 2026-87). From our spectrum, in addition to the continuum, we see an excess that would be consistent with broad He II with a velocity of ~15000 km / s. However, we have not performed host galaxy subtraction, and we caution that the SNR is insufficient to be certain whether this broad feature is real.

In any case, given the nuclear location (GCN #44120) and blue spectrum which is either featureless or has broad He, our observations would be consistent with a TDE-F or TDE-He classification for this source. However, we plan for and encourage additional multi-wavelength observations to secure the classification. The transient is bright (mg=17.3 in the latest ZTF data), so remains accessible to a wide variety of ground-based telescopes.

Show current TNS values
Catalog Name Reported RA Reported DEC Reported Obj-Type Reported Redshift Host Name Host Redshift Remarks TNS RA TNS DEC TNS Obj-Type TNS Redshift
TNS 2026hir [ZTF26aapviim] 08:44:12.377 +82:01:11.36 08:44:12.377 +82:01:11.36 TDE 0.088
AstroNote Publication Timestamp Title Authors
2026-87 2026-03-27 01:13:02 Identification of the redshift of EP Transient EP260324a Jiazheng Zhu (USTC), Ning Jiang (USTC), Linna Xu (USTC), Yibo Wang (USTC), Tinggui Wang (USTC), Mingxin Wu (USTC), Shifeng Huang (USTC).

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