GCN Circular 37643

The AMON group reports:

We requested follow-up time for the AMON alert NuEM 240926A (GCN ).
The follow-up looked for any x-ray sources inside the 90% region of the AMON
alert:

RA (J2000): 149.97 deg
Dec (J2000): 46.22 deg
Location uncertainty (90% containment): 0.41 deg

We used the online analysis software in www.swift.ac.uk

Swift-XRT started the follow-up on 2024-09-26 at 21:33:07 UT, 
which is ~2.5hrs after the AMON alert. 
It collected 6,745 seconds of photon counting (PC) mode data in a 7-tile mosaic.

Four uncatalogued sources were detected. 

Source 1:
	RA: 09h 59m 9.62s (149.790 deg)
        Dec: 46deg 00’ 15.2” (46.004 deg)
	Error: 5.6”
	
Source 2:
	RA: 10h 00m 15.04s (150.063 deg)
	Dec: 45d 58’ 49.2” (45.980 deg)
	Error: 5.0”
	
Source 3:
	RA: 10h 2m 35.8s (150.649 deg)
	Dec: 46d 21’ 43.8” (46.362 deg)
	Error: 6.0”
	
Source 4:
	RA: 9h 58m 18.95s (149.578 deg)
	Dec: 46d 8’ 20.5” (46.139 deg)
	Error: 9.0”

The 4FGL J0959.6+4606, located at (149.89, 46.10), is close to source 1, 
which is inside the 4FGL PSF region (0.2 deg above 10GeV). 
This 4FGL source has been considered as the counterpart of the radio-galaxy 2MASX J09591976+4603515 with coordinates (149.88,46.10) (Pena-Herazo et al. 2021). 
However, we find here that Source 1 from the XRT follow-up is  on top of  the Seyfert 1 Galaxy SDSSJ095909.51+460014.3 (149.789,46.003).
We requested one more follow-up on Source 1 from XRT. We will report on it after observations are done.

Source detection is based on Evans, et al. 2020 ApJ Supplemental, 247

AMON seeks to perform a real-time correlation analysis of the
high-energy signals across all known astronomical messengers. More
information about AMON can be found in https://www.amon.psu.edu/
Information on the IceCube collaboration: http://icecube.wisc.edu/
Information on the HAWC collaboration: https://www.hawc-observatory.org