Circular No. 2915 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION Postal Address: Central Bureau for Astronomical Telegrams Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. Cable Address: SATELLITES, NEWYORK Western Union: RAPID SATELLITE CAMBMASS X-RAY BURST FROM AQUILA G. Clark, Massachusetts Institute of Technology, reports that the SAS-3 Group has detected a brief, intense burst of x-rays from a source in a region far from the galactic center and within a circle of radius 12o centered at R.A. = 19h29m, Decl. = +7o.9 (l = 44o.6, b = -5o.1). The burst occurred on 1975 July 15 17h33m14s UT; it rose in less than 2s to an intensity comparable to that of the Crab Nebula in the energy range 1-10 keV and decayed in about 10s. The average spectrum was harder than that of the Crab. The burst resembles those reported from the globular cluster NGC 6624 (IAUC 2879, 2907) and from a direction near the galactic center (IAUC 2911). 1976 AA Further precise positions have been reported as follows: 1976 UT R. A. (1950) Decl. Mag. Observer Jan. 21.50000 5 13 57.97 +45 51 05.3 14.5 Urata 21.50139 5 13 57.17 +45 51 14.9 " 23.41200 4 57 50.72 +48 50 23.3 15 " 23.41866 4 57 47.27 +48 50 59.2 " 28.18611 4 17 43.68 +54 39 35.8 Giclas 28.20417 4 17 34.15 +54 40 37.8 " Feb. 3.19375 3 31 30.02 +59 19 58.3 Helin 3.30382 3 30 40.54 +59 23 35.0 " T. Urata (JCPM Jakiimo Sta.). From Nihondaira Obs. Circ. No. 732. H. L. Giclas (Lowell Observatory). Measurer: M. L. Kantz. E. Helin (Palomar Mountain Observatory). Measurer: S. J. Bus. The following improved orbital elements, by the undersigned, are from 46 observations Jan. 7 to Feb. 3: T = 1976 May 20.1283 ET Peri. = 147.7204 e = 0.183139 Node = 108.0836 1950.0 a = 0.966801 AU Incl. = 19.0549 n = 1.036808 q = 0.789742 AU P = 0.951 year 1976 ET R. A. (1950) Decl. Delta r Mag. Mar. 13 0 39.12 +66 42.0 0.312 0.939 17.4 18 0 22.99 +66 20.3 23 0 07.92 +65 35.4 0.329 0.907 17.6 28 23 54.53 +64 24.7 Apr. 2 23 43.43 +62 45.9 0.339 0.875 17.7 7 23 35.13 +60 36.9 12 23 30.00 +57 56.3 0.343 0.847 17.8 17 23 28.25 +54 44.3 22 23 29.90 +51 02.6 0.346 0.822 17.9 27 23 34.73 +46 55.0 May 2 23 42.42 +42 26.8 0.353 0.804 17.9 7 23 52.61 +37 45.2 12 0 04.93 +32 59.3 0.369 0.793 18.0 17 0 19.02 +28 19.1 22 0 34.54 +23 53.9 0.399 0.799 18.1 Mag. = 18.0 + 5 log Delta + 5 log r + 0.023 (phase angle) COMET BRADFIELD (1975d) Extension of the ephemeris on IAUC 2842: 1976 ET R. A. (1950) Decl. Delta r m2 Mar. 23 11 49.93 +25 58.5 3.680 4.589 19.4 Apr. 2 11 43.00 +26 59.7 12 11 37.05 +27 41.9 4.011 4.783 19.8 22 11 32.35 +28 06.7 May 2 11 29.06 +28 16.2 4.430 4.974 20.2 12 11 27.21 +28 13.1 22 11 26.76 +27 59.7 4.899 5.162 20.6 m2 = 10.0 + 5 log Delta + 10 log r NOTICE TO TELEGRAM SUBSCRIBERS IN NORTH AMERICA Several subscribers appear to have misunderstood the remark on IAUC 2911, which refers to our telegram service, rather than to these postcard Circulars. In any case, it appears to be impracticable to use night letters, because collect service requires a 100-word minimum. Telegram subscribers will have noticed that Western Union's domestic service has deteriorated recently, and while we have taken this matter up with the Company, there is obviously nothing we can do about the costs, which have risen enormously (overseas cablegrams can often be sent more cheaply!). For this reason, we recommend that telegram subscribers attempt to acquire access to TWX or telex facilities. Another possibility would be to make greater use of the telephone, although we stress that it would be quite impossible for the Central Bureau to contact more than four subscribers in this way; we could select those subscribers on the basis of their willingness to pass on the messages to other subscribers. We are aware that some amateur groups relay information in this way but would welcome participation by professionals. We hereby solicit advice on the subject and any offers of assistance. 1976 February 24 (2915) Brian G. Marsden
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