We report spectroscopic observations of the quickly-evolving transient, AT2024hif/ZTF24aalbxfh, taken with the Low Resolution Imaging Spectrometer (LRIS) on the Keck Telescope.
AT2024hif was discovered by the Zwicky Transient Facility (ZTF) on MJD 60429.286 at a position (J2000) of:
RA = 10:43:10.54
Dec = +82:41:00.47
which corresponds to a galactic latitude of 33 degrees. From Schlafly and Finkbeiner (2011), the extinction at this location is E(B-V) = 0.02.
The first detections were at g = 18.318 +/- 0.064, and r = 18.476 +/- 0.076. The source faded at a rate of around 0.15 mag/day in g band and 0.12 mag/day in r band in the following days. Because the source was offset by 0.6 arcseconds from a source in Legacy Survey DR9 (Dey et al. 2019) classified as extended with a photo-z of z = 0.426 +/- 0.168, implying a high peak luminosity, we followed up the source spectroscopically with several facilities. These were the SPectrograph for the Rapid Acquisition of Transients (SPRAT) on the Liverpool Telescope on MJD 60432.88, Kools-IFU on the Seimei telescope on MJD 60433.67, the DeVeny Spectrograph on the Lowell Discovery Telescope on MJD 60434.17, and the Double Spectrograph (DBSP) on the Palomar 200-inch Telescope on MJD 60436.40. These spectra showed hints of P-Cygni features, but no conclusive features or a redshift were able to be established.
We then obtained a spectrum using LRIS on MJD 60438.27. The presence of narrow Hydrogen features (Hɑ and Hβ) at z = 0 confirm that the source is galactic. Further follow-up observations are 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 | 2024hif [ZTF24aalbxfh] | 10:43:10.555 | +82:41:00.42 | 0 | 10:43:10.555 | +82:41:00.42 | CV |