Circular No. 6726 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions) BMARSDEN@CFA.HARVARD.EDU or DGREEN@CFA.HARVARD.EDU (science) URL http://cfa-www.harvard.edu/cfa/ps/cbat.html Phone 617-495-7244/7440/7444 (for emergency use only) GRB 970828 R. Remillard, A. Wood, D. Smith, and A. Levine, Massachusetts Institute of Technology, communicate: "The RXTE All Sky Monitor has detected the gamma-ray burst of Aug. 28.73931 UT that was logged as BATSE trigger no. 6350. The burst was detected by ASM camera 1 with a mean flux of 756 mCrab (2-12 keV) averaged over the 40 s in which the burst was seen before the camera was rotated. Ninety seconds later, ASM camera 2 scanned over the source and determined a crossing line of position and an average flux of 238 mCrab, declining in an exponential-like fashion with a 30-s time constant. The x-ray emission began roughly simultaneously with the gamma-ray trigger, but was detectable with the ASM over at least 160 s. The combined camera detections yield an x-ray position of R.A. = 18h08m29s, Decl. = +59o18'.0 (equinox 2000.0; 1-sigma uncertainties of +/- 3'.2 in R.A. and +/- 1'.2 in Decl.). Optical observations are urgently needed." XTE J1755-324 R. N. Ogley and T. D. C. Ash, Open Univeristy; and R. P. Fender, Sussex University, report that a search was made on Aug. 18.17-18.69 UT for a radio counterpart to the recently detected x- ray source XTE J1755-324 (IAUC 6710). Observations were made using the Australia Telescope Compact Array at 1384 and 2496 MHz, and no radio emission was detected down to a level of 0.3 mJy (1384 MHz) and 0.2 mJy (2496 MHz) within the 1' error box of XTE. The nearest source detected was 7' from the reported position of the x-ray source. At the time of these observations, XTE J1755-324 had an x- ray (2-12 keV) flux of about 7 counts/s, measured by the ASM on XTE. COMET C/1997 P2 (SPACEWATCH) Extension to ephemeris on IAUC 6719 (elements MPEC 1997-Q02): 1997 TT R. A. (2000) Decl. Delta r Elong. Phase m1 Aug. 20 21 36.76 - 6 30.6 3.197 4.202 172.2 1.9 18.8 30 21 32.67 - 6 24.0 3.216 4.198 164.6 3.7 18.8 Sept. 9 21 29.19 - 6 19.0 3.261 4.195 154.9 5.8 18.8 19 21 26.68 - 6 13.9 3.332 4.195 145.0 7.9 18.8 29 21 25.39 - 6 07.1 3.425 4.196 135.2 9.7 18.9 Oct. 9 21 25.49 - 5 57.5 3.538 4.198 125.6 11.2 19.0 19 21 27.05 - 5 43.9 3.666 4.203 116.3 12.3 19.1 (C) Copyright 1997 CBAT 1997 August 28 (6726) Daniel W. E. Green