GRB 221006A: MAXI/GSC detection

The MAXI/GSC nova alert system triggered on a bright uncatalogued X-ray transient source at 2022-10-06T00:57:09 UT. Assuming that the source flux was constant over the transit, we obtain the source position at (R.A., Dec) = (337.328 deg, 15.703 deg) = (22 29 18, +15 42 10) (J2000) with a statistical 90% C.L. elliptical error region with long and short radii of 0.11 deg and 0.09 deg, respectively. The roll angle of long axis from the north direction is 26.0 deg counterclockwise. There is an additional systematic uncertainty of 0.1 deg (90% containment radius). The X-ray flux averaged over the scan was 909 +- 81 mCrab (4.0-10.0keV, 1 sigma error). There was no significant excess flux in the previous transit at 10/5 23:24 UT with an upper limit of 20 mCrab.