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ATEL #16158							    ATEL #16158

Title:	LEIA observations of the outburst from Aql X-1
Author:	M. J. Liu (NAOC, CAS), W. J. Zhang (NAOC, CAS), Y. Liu (NAOC,
		CAS), Z. X. Ling (NAOC, CAS), C. Zhang (NAOC, CAS), H. Q. Cheng (NAOC,
		CAS), C. Z. Cui (NAOC, CAS), D. W. Fan (NAOC, CAS), H. B. Hu (NAOC,
		CAS), J. W. Hu (NAOC, CAS), M. H. Huang (NAOC, CAS), C. C. Jin (NAOC,
		CAS), D. M. Li (BNU), D. Y. Li (NAOC, CAS), Q. X. Li (BNU), H. Y.
		Liu (NAOC, CAS), H. Sun (NAOC, CAS), H. W. Pan (NAOC, CAS), C. Y.
		Wang (THU), W. X. Wang (NAOC, CAS), Y. L. Wang (NAOC, CAS), Q. Y.
		Wu (NAOC, CAS), X. P. Xu (NAOC, CAS), Y. F. Xu (NAOC, CAS), H. N.
		Yang (NAOC, CAS), M. Zhang (NAOC, CAS), W. D. Zhang (NAOC, CAS), Y.
		J. Zhang (THU), D. H. Zhao (NAOC, CAS) and W. Yuan (NAOC, CAS), on
		behalf of the LEIA and Einstein Probe team
Queries:	ep_ta@bao.ac.cn
Posted:	28 Jul 2023; 09:47 UT
Subjects:X-ray, Neutron Star, Transient

We report on the detection of the new X-ray outburst from the neutron star
low-mass X-ray binary Aql X-1 by LEIA (Lobster Eye Imager for Astronomy).
The position of the LEIA source is R.A. = 287.801 deg, Dec = -0.585 deg
with an uncertainty of 1.7 arcmin (radius, 90%C.L. statistical and systematic).
XB-NEWS and MAXI detected the new yearly recurrent outburst of Aql X-1
since July 23, 2023 (ATel #16147). A follow-up observation by NICER showed
that Aql X-1 was in the hard state during this outburst (ATel #16153).

LEIA has covered the location of Aql X-1 five times since 2023-07-23 T13:31:44.
Aql X-1 was first detected by LEIA at 2023-07-23 T15:05:59 with an unabsorbed
flux of 1.5e-10 erg cm^-2 s^-1 in 0.5-4 keV (assuming the same spectral
shape with that of the next detection), which increased to 5.8e-10 erg
cm^-2 s^-1 at 2023-07-26T13:46:39. Its spectrum obtained in the observation
at 2023-07-26T13:46:39 can be fitted with an absorbed power-law with fixed
Galactic N_H =4.3e21 cm^-2 and a photon index of 1.43(+0.42/-0.41).

LEIA (Zhang et al, 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 SATech-01 satellite
of CAS, launched on July 27, 2022.  

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Password Certification: Yuan Liu (liuyuan@bao.ac.cn)
https://www.astronomerstelegram.org/?read=16158
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