{
  "bibcode": "2019GCN.23882....1K",
  "body": "J. A. Kennea (PSU), H. A. Krimm (NSF/USRA), K. L. Page (U Leicester)\nand A. Tohuvavohu (PSU) report on behalf of the Neil Gehrels Swift\nObservatory Team:\n\nAt 14:28:41 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated 4U 1901+03 (trigger=888312). The BAT on-board calculated \nlocation is RA, Dec 285.972, +3.242 which is \n   RA(J2000) = 19h 03m 53s\n   Dec(J2000) = +03d 14' 30\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  \n\nThis source, 4U 1901+03 is a HMXB X-ray pulsar, which appears to be \ngoing into another outburst.  The rate has been rising in the \nSwift/BAT transient monitor since 6 February 2019 (MJD 58520) - see\nhttps://swift.gsfc.nasa.gov/results/transients/weak/4U1901p03/ - \nand is currently at 0.016 +/-  0.005 ct s^-1 cm^-2 (15-50 keV; 70 mCrab).  \nThe rise is also seen in MAXI. \n\nThe last reported outburst of this source was in December 2011 (Sootome et al.,\nATel 3829). \n\nDue to a Sun observing constraint, Swift cannot slew to the BAT\nposition until 13:00 UT on 2019 February 17. There will thus be no XRT\nor UVOT data for this trigger before this time.",
  "circularId": 23882,
  "createdOn": 1549723905000,
  "email": "klp5@leicester.ac.uk",
  "subject": "Trigger 888312: Swift detection of 4U 1901+03",
  "submitter": "Kim Page at U.of Leicester  <klp5@leicester.ac.uk>"
}