{
  "circularId": 36094,
  "subject": "EP240414a: Kinder optical counterpart candidate possibly associated with the galaxy SDSS J124601.99-094309.3",
  "submittedHow": "web",
  "createdOn": 1713114921990,
  "submitter": "Janet Chen at National Central University <janetstars@gmail.com>",
  "eventId": "EP240414a",
  "bibcode": "2024GCN.36094....1A",
  "body": "A. Aryan (NCUIA), S. Yang (HNAS), T.-W. Chen, W.-J. Hou, C.-H. Lai, A. Sankar.K, Y.-C. Pan (all NCUIA), S. J. Smartt (Oxford/QUB), K. W. Smith (QUB), H.-Y. Hsiao, M.-H. Lee, C.-C. Ngeow, C.-S. Lin, H.-C. Lin, J.-K. Guo (all NCUIA), J. Gillanders, L. Rhodes, S. Srivastav (all Oxford), T. Moore and M. Fulton (both QUB) report:\n\nWe observed the field of EP240414a (Lian et al., GCN 36091) using the Lulin One-meter Telescope (LOT) at Lulin Observatory in Taiwan as part of the Kinder collaboration (Chen et al., AstroNote 2021-92). The first LOT epoch of observations started at 12:50 UT on 14 of April 2024 (MJD=60414.535), 3.13 hours after the EP trigger. \n\nWe used the Kinder pipeline (Yang et al. A&A 646, A22) to stack the images and subtract the stacked images with the Legacy Survey DR10 template images. We detected an optical transient candidate in the difference image, at RA=12:46:01.7248, Dec=-9:43:08.872 (which is 1.56 arcmins away from the reported coordinate of EP240414a). We note an extended source in the Legacy Survey image, which is likely its host galaxy. We cross-matched it with the SDSS DR15 catalogue and found it could correspond to the galaxy, SDSS J124601.99-094309.3, with r-band magnitude as 19.04 mag. \n\nThe details of the observations and measured PSF magnitudes (in the AB system) of the possible counterpart of EP240414a are as follows:\n\nTelescope | Filter | MJD | t-t0 | Exposure | Magnitude | Seeing | Airmass\nLOT | r | 60414.535 | 3.13 hrs | 300 sec * 6 | 21.52 +/- 0.12 | 1\".7 | 1.31 \nLOT | i | 60414.564 | 3.68 hrs | 300 sec * 6 | 21.40 +/- 0.16 | 1\".2 | 1.43\n\nThe presented magnitudes are calibrated using the field stars from the SDSS catalog and are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V) = 0.03 mag in the direction of the burst (Schlafly & Finkbeiner 2011).\n\nAccordint to SDSS, for the likely host galaxy, SDSS J124601.99-094309.3, its photo-z is 0.299 +/- 0.0426, and the distance module is then 40.80. Assuming r-band can be roughly k-corrected to g-band, with the Milky Way extinction correction, the optical counterpart candidate has the rest-frame M_g = -19.07 mag and M_r = -19.18 mag. \n\nWe are still continuously observing this source. Further follow-up observations are encouraged to identify the nature of this X-ray transient. \n\nWe thank the Einstein Probe team for useful communication.\n"
}