Dear all, The reason for contacting you is that we are trying to perform TODAY a coordinated X-ray and optical monitoring of the newly discovered black hole transient XTE J1859+226. The BeppoSAX X-ray observation is scheduled to start on Nov 7, 16:54 UT and ending on Nov 8, 15:12 UT, so we are trying to get world-wide optical monitoring in order to get simultaneous optical (R-band) and X-ray observations. A recent R photometric observation in Loiano taken on Oct. 28 showed that the R magnitude is approximately the same (~16) as measured on Oct. 14. The position of the X-ray transient is: AR(2000) = 18 58 41.58, Dec(2000) = +22 39 29 and the identification chart can be found at: http://cfa-www.harvard.edu/~peterg/gosox/j1859.jpg A revised UBVRI photometry file for this field provided by Aren Henden (USNO) can be found on http://ftp.nofs.navy.mil/pub/outgoing/aah/sequence/j1859.dat We suggest to use the R-band filter and, if possible, keep the integration time to few minutes, depending of the telescope size (about 1-min for medium size telescopes larger than 1-m in diameter). Variations of 0.1 mag or larger are expected during the night . Thank you very much in advance for your cooperation. Sincerely yours, Alberto Castro-Tirado Celia Sanchez-Fernandez LAEFF-INTA, Madrid 7 Nov 1999 Cc: Daniele Dal Fiume , Eliana Palazzi (ITESRE, Bologna) Taichi Kato (Kyoto)