2024ApJ...971L...2C

We present early-phase good-cadence (hour-to-day) simultaneous multiband (ugi and vrz bands) imaging of the nearby supernova SN 2024ggi, which exploded in the nearby galaxy NGC 3621. A quick follow-up was conducted within less than a day after the explosion and continued for ∼23 days. The uvg band light curves display a rapid rise (∼1.4 mag day^–1) to maximum in ∼4 days and absolute magnitude M_g ∼ -17.75 mag. The postpeak decay rate in redder bands is ∼0.01 mag day^–1. Different colors (e.g., u - g and v - r) of SN 2024ggi are slightly redder than SN 2023ixf. A significant rise (∼12.5 kK) in blackbody temperature (optical) was noticed within ∼2 days after the explosion, which successively decreased, indicating shock break out inside a dense circumstellar medium surrounding the progenitor. Using semianalytical modeling, the ejecta mass and progenitor radius were estimated as 1.2 M_☉ and ∼550 R_☉. The archival deep images (g, r, i, and z bands) from the Dark Energy Camera Legacy Survey were examined, and a possible progenitor was detected in each band (∼22-22.5 mag) and had a mass range of 14-17 M_☉.