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ABSTRACT We present the volumetric rates and luminosity functions (LFs) of Type Ia supernovae (SNe Ia) from the V-band All-Sky Automated Survey for Supernovae (ASAS-SN) catalogues spanning discovery dates from UTC 2014 January 26 to UTC 2017 December 29. Our standard sample consists of 404 SNe Ia with $$m_{\mathrm{{\it V},peak}} \lt 17\, \mathrm{mag}$$ and Galactic latitude |b| > 15°. Our results are both statistically more precise and systematically more robust than previous studies due to the large sample size and high spectroscopic completeness. We make completeness corrections based on both the apparent and absolute magnitudes by simulating the detection of SNe Ia in ASAS-SN light curves. We find a total volumetric rate for all subtypes of $$R_{\mathrm{tot}} = 2.28^{+0.20}_{-0.20} \times 10^{4}\, \mathrm{yr}^{-1}\, \mathrm{Gpc}^{-3}\, h^{3}_{70}$$ for $$M_{\mathrm{{\it V},peak}} \lt -16.5\, \mathrm{mag}$$ ($$R_{\mathrm{tot}} = 1.91^{+0.12}_{-0.12} \times 10^{4}\, \mathrm{yr}^{-1}\, \mathrm{Gpc}^{-3}\, h^{3}_{70}$$ for $$M_{\mathrm{{\it V},peak}} \lt -17.5\, \mathrm{mag}$$) at the median redshift of our sample, zmed = 0.024. This is in agreement (1σ) with the local volumetric rates found by previous studies. We also compile LFs for the entire sample as well as for subtypes of SNe Ia for the first time. The major subtypes with more than one SN include Ia-91bg, Ia-91T, Ia-CSM, and Ia-03fg with total rates of $$R_{\mathrm{Ia-91bg}} = 1.4^{+0.5}_{-0.5} \times 10^{3}\, \mathrm{yr}^{-1}\, \mathrm{Gpc}^{-3}\, h^{3}_{70}$$, $$R_{\mathrm{Ia-91T}} = 8.5^{+1.6}_{-1.7} \times 10^{2}\, \mathrm{yr}^{-1}\, \mathrm{Gpc}^{-3}\, h^{3}_{70}$$, $$R_{\mathrm{Ia-CSM}} = 10^{+7}_{-7}\, \mathrm{yr}^{-1}\, \mathrm{Gpc}^{-3}\, h^{3}_{70}$$, and $$R_{\mathrm{Ia-03fg}} = 30^{+20}_{-20}\, \mathrm{yr}^{-1}\, \mathrm{Gpc}^{-3}\, h^{3}_{70}$$, respectively. We estimate a mean host extinction of $$E(V-r) \approx 0.2\, \mathrm{mag}$$ based on the shift between our V band and the Zwicky Transient Facility r-band LFs. 

ABSTRACT We report the All-Sky Automated Survey for SuperNovae discovery of the tidal disruption event (TDE) ASASSN-23bd (AT 2023clx) in NGC 3799, a LINER galaxy with no evidence of strong active galactic nucleus (AGN) activity over the past decade. With a redshift of z = 0.01107 and a peak ultraviolet (UV)/optical luminosity of (5.4 ± 0.4) × 1042 erg s−1, ASASSN-23bd is the lowest-redshift and least-luminous TDE discovered to date. Spectroscopically, ASASSN-23bd shows H α and He i emission throughout its spectral time series, there are no coronal lines in its near-infrared spectrum, and the UV spectrum shows nitrogen lines without the strong carbon and magnesium lines typically seen for AGN. Fits to the rising ASAS-SN light curve show that ASASSN-23bd started to brighten on MJD 59988$$^{+1}_{-1}$$, ∼9 d before discovery, with a nearly linear rise in flux, peaking in the g band on MJD $$60 \, 000^{+3}_{-3}$$. Scaling relations and TDE light curve modelling find a black hole mass of ∼106 M⊙, which is on the lower end of supermassive black hole masses. ASASSN-23bd is a dim X-ray source, with an upper limit of $$L_{0.3-10\, \mathrm{keV}} \lt 1.0\times 10^{40}$$ erg s−1 from stacking all Swift observations prior to MJD 60061, but with soft (∼0.1 keV) thermal emission with a luminosity of $$L_{0.3-2 \, \mathrm{keV}}\sim 4\times 10^{39}$$ erg s−1 in XMM-Newton observations on MJD 60095. The rapid (t < 15 d) light curve rise, low UV/optical luminosity, and a luminosity decline over 40 d of ΔL40 ≈ −0.7 dex make ASASSN-23bd one of the dimmest TDEs to date and a member of the growing ‘Low Luminosity and Fast’ class of TDEs.