AT2024ahr (ZTF24aacrbua/Gaia24apk/PS24aun/ATLAS24bwz) was first reported by ZTF at MJD 60325.489 (approximately 50 days ago) with an r-band magnitude of 19.458 ± 0.169. The transient has been rising continuously since that time, reaching r=17.45 in the most recent observations (MJD 60374.456). Follow-up imaging with Liverpool Telescope IO:O observations (MJD 60373.151) shows the transient to have remained relatively blue, with a g-r colour (correcting for Galactic reddening) of -0.08 ± 0.04. The transient was recently identified as a candidate superluminous supernova (SLSN) in AstroNote 2024-62 based on these characteristics.
We observed AT2024ahr with the Alhambra Faint Object Spectrograph and Camera (ALFOSC) on the Nordic Optical Telescope at MJD 60375.145. The spectrum appears blue, with prominent absorption troughs in the blue characteristic of OII, similar to those seen in Type I superluminous supernovae. A comparison to template spectra from previously classified transients using Next Generation Superfit (NGSF, Goldwasser et al. 2022) shows good fits to the SLSN-I events PTF12dam, SN2017egm and SN2015bn at a redshift range of z = 0.08-0.11. At this redshift, the current absolute magnitude (AB, at a rest frame central wavelength of ~5700 Angstroms) is between -20.2 and -21.0, with further increase in luminosity likely in the coming weeks.
UV/optical photometry with Swift has been requested. Additional follow-up is encouraged.
| 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 | 2024ahr [ZTF24aacrbua] | 14:21:59.270 | -12:30:22.07 | SLSN-I | 0.09 | 14:21:59.270 | -12:30:22.07 | SLSN-I | 0.1 |