SIMBAD references

At 18:19 UT on May 8th, 2011, Swift began a 1 ks long target of opportunity observation of the error circle of MAXI J1543-564 (Negoro et al., ATEL #3330), a newly found X-ray transient near the galactic plane discovered by MAXI. Utilizing 1 ks of Photon Counting mode data, and correcting for the astrometric errors utilizing Swift/UVOT data using the method described by Evans et al. (2009, MNRAS, 2009, 397, 1177) and Goad et al. (2008, A&A, 476, 1401), we find a bright, uncatalogued X-ray source at the following location, RA/Dec (J2000) = 235.82283, -56.41358, which is equivalent to:

RA(J2000) = 15^h 43^m 17.48^s

Dec(J2000) = -56^o 24' 48.9''

with an estimated uncertainty of 1.8 arc-seconds radius (90% containment).

This position lies inside the reported MAXI error circle, 1.2 arc-minutes

from the center of the MAXI error circle (Negoro et al., ATEL #3330). This position does not match any catalogued X-ray source. The closest catalogued

object to MAXI J1543-564 is 2MASS 15431782-5624467, which has a magnitude of J=15.3, and although this lies outside of the 90% confidence XRT error circle, 3.5 arc-seconds from the Swift/XRT position.

The spectrum of the source can be well described by an absorbed power-law fit, with a measured photon index of 1.45 ± 0.20, and absorption of N_H = 0.9 x 10²² cm^-2, compared to the expected Galactic absorption in that direction of ∼1.5 x 10²² cm^-2. The measured flux is 4.4 ± 0.5 x 10^-10 erg/s/cm² (0.3-10 keV), or ∼6.3 x 10^-10 erg/s/cm² (0.3-10 keV) corrected for absorption. During the 1ks observation the source flux remains consistent with a constant value.