VizieR Online Data Catalog: Follow-up photometry of ASASSN-14ko (Payne+, 2021)

On 2014 November at 14.28 UT, the All-Sky Automated Survey for SuperNovae (ASAS-SN; Shappee+ 2014, J/ApJ/788/48 ; Kochanek+ 2017PASP..129j4502K) triggered on a nuclear transient associated with ESO 253-G003 at V~17.0mag and reported it as ASASSN-14ko (Holoien+ 2014ATel.6732....1H & 2017, J/MNRAS/464/2672).

UltraViolet/Optical Telescope (UVOT) and X-Ray Telescope (XRT) observations by the Neil Gehrels Swift Observatory were taken on UT 2014 November 16, 19, 21, 23, and 27 (PI: T. W.-S. Holoien, ToO ID: 33529). We again requested Swift data (ToO IDs: 13836, 13979, 14005) to monitor ASASSN-14ko during quiescence and then during the outburst predicted for UT 2020 May 18.5. There are three additional observations of ESO 253-G003 in the Swift data archive under the identification SWIFT J0525.3-600 (Obs ID: 37354, PI: C.B. Markwardt). See Section 2.2 and 2.8.

As part of ongoing work to examine the long-term behavior of AGNs observed by ASAS-SN, a full light curve of ESO 253-G003 was extracted in 2020 February. The complete V- and g-band light curve 2014-2020 is shown in Figure 1. ASAS-SN is a network of 20 robotic telescopes hosted by the Las Cumbres Observatory Global Telescope (LCOGT) at five sites around the globe. See Section 2.1.

The Asteroid Terrestrial-impact Last Alert System (ATLAS survey; Tonry+ 2018PASP..130f4505T) consists of two 0.5m f/2 Wright Schmidt telescopes on Haleakala and at the Mauna Loa Observatory. Designed primarily for detecting hazardous asteroids, the telescopes obtain four 30s exposures of 200-250 fields per night. ATLAS uses two broadband filters, the "cyan" (c) filter covering 420-650nm and the "orange" (o) filter covering 560-820nm. We performed forced photometry on the subtracted ATLAS images of ASASSN-14ko. See Section 2.3.

ASASSN-14ko was observed by the Transiting Exoplanet Survey Satellite (TESS) during Sectors 4-6, which occurred between 2018 October 18 and 2019 January 7. TESS observes in a single broadband filter, spanning roughly 6000-10000Å with an effective wavelength of ~7500Å. TESS magnitudes are calibrated to the Vega system. See Section 2.4.

We obtained photometric observations from the LCOGT. The B-, V-, g', r', and i'-band observations were taken using the 1m telescope at Siding Spring Observatory in New South Wales, Australia. The LCOGT photometric observations began on 2020 April 13 in quiescence and continued through the midpoint of the 2020 May outburst. See Section 2.5.

Amateur astronomers at four different observatories observed ASASSN-14ko starting shortly after it was discovered to be periodically flaring. Data were taken at the Moondyne Observatory, east of Perth, Australia, using a 0.4m telescope with AOX adaptive optics between 2020 April 28 and June 8 and on a daily cadence between 2020 May 10 and 28. B_C-, V-, G_S-, R_S-, and I_C-band images were obtained with guided 120s exposures. Data were also collected using a 41 cm telescope at Savannah Skies Observatory from Queensland, Australia. ASASSN-14ko was observed from Bronberg Observatory in South Africa using 14- and 12-inch telescopes in the R band with 15s exposures. Finally, ASASSN-14ko was observed from Dogsheaven Observatory in Brazil. See Section 2.6.

We also obtained seven spectra with the LCOGT Folded Low Order whYte-pupil Double-dispersed Spectrograph (FLOYDS) at the robotic 2m Faulkes Telescope South located at Siding Spring Observatory. These observations were taken on 2020 April 12, 15, 24, 25, 27, 2020 May 16, and 2020 May 17. See Section 2.7.

(1 data file).