Swift Observations of OGLE-2018-NOVA-01

ATel #11410; K. L. Page (U. Leicester), N. P.M. Kuin (UCL/MSSL) & M. Henze (SDSU)
on 12 Mar 2018; 18:20 UT
Credential Certification: Kim Page (kpa@star.le.ac.uk)

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OGLE-2018-NOVA-01, a recurrent nova explosion of Nova LMC 1996, erupted on 2018 Feb 27.07770 UT, but was only discovered and announced on 2018 Mar 08. Observations by the Neil Gehrels Swift Observatory began shortly after, on 2018 Mar 09.

UVOT grism data were collected on Mar 09 (day 10.7-10.8 after outburst). The 2.6 ks exposure provides a spectrum that shows the presence of a broad Mg II 2800 Å emission line, and UV absorption features of the iron curtain. The iron curtain lifts later in the UV than in the optical. Due to the presence of this absorption and a noisy spectrum, only a rough estimate of the FWZI of 10,000 km s^-1 for the Mg II line can be made.

The Swift-UVOT photometry between days 10.7 and 12.2 is given in the table below. The central wavelengths for the UVOT filters are v ~ 5468 Å, b ~ 4392 Å, u ~ 3465 Å, uvw1 ~ 2600 Å, uvm2 ~ 2246 Å and uvw2 ~ 1928 Å. The UV and optical brightness faded by ~0.1-0.2 magnitudes in each filter between days 10.7 and 12.2, with the exception of the v-band, where the magnitude stayed constant.

 
Date         Day   v mag       b mag       u mag       uvw1 mag    uvm2 mag    uvw2 mag 
2018-03-09.8 10.7  15.10±0.05  14.57±0.02  13.51±0.03  13.39±0.02  13.57±0.05  13.270±.02 
2018-03-09.9 10.8                                      13.69±0.03 
2018-03-11.2 12.2  15.09±0.09  14.81±0.05  13.71±0.04  13.65±0.04  13.77±0.03  13.41±0.03 

No X-ray emission has so far been detected from OGLE-2018-NOVA-01. In the 5.3 ks of Swift-XRT data collected between day 10.7 and 12.2, we place an upper limit of 2.4x10^-3 count s^-1 on the 0.3-10 keV XRT count rate.

We wish to thank the Swift Team for the rapid scheduling of the ToO observations, in particular B. Cenko, the duty scientists, and the science planners.