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ATEL #15871							    ATEL #15871

Title:	LEIA detected a bright outburst from LMC X-4
Author:	D. Y. Li, H. Sun, H. W. Pan, Z. X. Ling, Y. Liu, C. Zhang,
		H. Q. Cheng, C. Z. Cui, D. W. Fan, H. B. Hu, J. W. Hu, M. H. Huang,
		C. C. Jin, J. Q. Li, H. Y. Liu, M. J Liu, W. X. Wang, Y. L. Wang,
		Q. Y. Wu, X. P. Xu, Y. F. Xu, H. N Yang, M. Zhang, W. D. Zhang, D.
		H. Zhao and W. Yuan  (NAOC, CAS), on behalf of the LEIA and Einstein
		Probe team
Queries:	ep_ta@nao.cas.cn
Posted:	22 Jan 2023; 15:13 UT
Subjects:X-ray, Binary, Nova

We report a bright outburst from the high mass X-ray binary LMC X-4 detected
by LEIA (Lobster Eye Imager for Astronomy), also known as EP-WXT Pathfinder.
The detected source position by LEIA is R.A. = 83.18 deg, DEC = -66.36
deg with an uncertainty of 2.2 arcmin (radius, 90% C.L. statistical and
systematic), which is 55 arcsec away from LMC X-4.

LMC X-4 was covered twice by LEIA on January 20, 2023, and it brightened
by more than an order of magnitude within 2 hours, with its 0.5 - 4.0 keV
count rate increasing from 0.067 to 0.680 counts per second. During the
outburst phase, the X-ray spectra can be fitted by a powerlaw with a photon
index of 2.3 +/- 0.1 modified by Galactic absorption,  and its 0.5 - 4.0
keV flux was ~1.6e-9 erg/s/cm2. This flux is comparable to the brightest
fluxes of the outbursts of LMC X-4 as recorded by MAXI from August 2009
to January 2023.

Follow-up observations are encouraged to investigate this bright outburst
from LMC X-4 in detail.

LEIA (Zhang et al. 2022, ApJL, 941, 2) is a soft X-ray Lobster-eye imager
(0.5 - 4.0 keV) with a FoV of 340 square degrees aboard the experimental
satellite SATech-01 of the CAS, launched on July 27, 2022. The above result
is preliminary and the final result will be published elsewhere.

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Password Certification: Yuan Liu (liuyuan@bao.ac.cn)
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