VizieR Online Data Catalog: Type Ia SN 2020nlb opt. photometry & spectra (Sand+, 2021)

SN 2020nlb was discovered on 2020 June 25.25 UT (MJD 59025.25) by the Asteroid Terrestrial impact Last Alert System (ATLAS) survey. The last non-detection from ATLAS was 2 days earlier (2020 June 23.28). The field of SN 2020nlb was also monitored by the Itagaki Astronomical Observatory's 0.35m telescope in Okayama, Japan, which obtained a tighter non-detection epoch of 2020 June 24.57 (MJD 59024.57) before also detecting the SN on 2020 June 26.56.

We display a UBVgri light curve of SN 2020nlb in the left panel of Figure 1, taken with the 0.4 and 1.0m telescope network of Las Cumbres Observatory as part of the Global Supernova Project. An additional, high cadence data set was obtained by the 0.7m Thacher Observatory in the g, r, i, z bands. Observations from the Neil Gehrels Swift Observatory Ultra-Violet Optical Telescope (UVOT) were also obtained. In the right panel of Figure 1, we show a spectrum taken with the FLOYDS robotic spectrograph at Faulkes Telescope North on 2020 July 12 06:32 UTC (+0.5 day with respect to B-band maximum). An additional low resolution optical spectrum was obtained with the Blue Channel spectrograph at the MMT on 2021 January 28 21:06 UTC (+179 days), see Figure 4. See Section 2.2.

The Swift XRT observed both SN 2017cbv and SN 2020nlb extensively. We gathered Swift XRT data of SN 2017cbv taken between 2017 March 10.5 and April 15.46, corresponding to ~1.5 and 37.5 days from our adopted explosion epoch, with a total accumulated exposure time of 62.2ks. A sequence of Swift XRT data was taken of SN 2020nlb, starting on 2020 June 25.76 UTC. We gathered all data taken through 2020 August 07.2 UTC (43days after our adopted explosion epoch), a total of 27.5ks. Deep X-ray follow-up of both SN 2017cbv and SN 2020nlb were obtained with the Chandra X-ray Observatory under Director's Discretionary Time proposals. Observations of SN 2017cbv began on 2017 March 27 (PI: Drout; Proposal 1850876; Obs ID 20055), and the total exposure time was 51ks. Chandra observations of SN 2020nlb (PI: Sand; Proposal 21508740; Obs ID 23314, 23315) 19 were split into two blocks for a total exposure time of 75 ks. The first observation (totaling 63ks) began on 2020 July 09 23:58 (UT), while the second observation (12ks) began ~1.5days after the end of the first one on 2020 July 12 04:15. See Section 3.

(5 data files).