[en] J. Crovisier, P. Colom, N. Biver, and D. Bockelee-Morvan, LESIA, Observatoire de Paris, report on a search for the 18-cm OH lines in comet 2I/Borisov with the Nancay radio telescope. Fifteen hours of observations were secured during Oct. 2-25, when the OH maser inversion was expected to be between 0.38 and 0.50. The average spectrum scaled to the 1667-MHz line shows a marginal line with an integrated intensity of 15 (+/- 4) mJy*km/s. Assuming an expansion velocity of 0.5 km/s for the OH parent molecules, a tentative production rate of 3.3 (+/- 0.9) x 10**27 molecules/s is estimated. <P />E. Jehin, Y. Moulane, J. Manfroid, F. Pozuelos, and D. Hutsemekers report that they have been monitoring comet 2I/2019 Q4 with the robotic 0.6-m "Transiting Planets and Planetesimals Small Telescope" (TRAPPIST-North) at Oukaimden, Morocco, since Sept. 10. The group detected CN with a narrow-band filter for the first time on Oct. 18, and they have not been able to detect OH or C_2 via spectroscopy. As of Oct. 31, Q(CN) had not increased in the previous two weeks. Production rates at a distance of 10000 km from the comet's nucleus have been computing using a Haser model (V_p = V_d = 1 km/s): Q(CN) = 1.69 +/- 0.56 x 10E24 molecules/s; Q(C_2) < 1.16 +/- 0.62 x 10E24 molecules/s. They also find the dust-production rate proxy Af(rho) by profile-fitting at 100000 km (and correcting for the phase angle on Oct. 31: A(0)f[rho(R)] = 138.4 +/- 7.4 cm. Their results for 2I/Borisov have been posted at website URL https://arxiv.org/abs/1910.09078. <P />A. Nakamura forwards unfiltered CCD measurements of the magnitude and coma diameter by K. Yoshimoto (Hirao, Yamaguchi, Japan) from images obtained with a 43.1-cm f/4 reflector: Sept. 8.82 UT, 17.8, 0'.4 (tail in p.a. 280 deg); 26.48, 17.4, 0'.3 (tail 0'.4 long in p.a. 315 deg). <P />H. Sato, Tokyo, Japan, reports that CCD images taken of comet 2I with a 0.43-m f/6.8 astrograph near Mayhill, NM, USA, on Oct. 10.48 UT show a strongly condensed coma 15" in diameter with a 40" tail toward p.a. 315 degrees; the magnitude was 16.7 as measured within a circular aperture of radius 9".6. <P />S. Nakano, Sumoto, Japan, provides the following revised orbital elements (cf. CBET 4670) from 1372 observations spanning 2019 Aug. 30-Nov. 2 (mean residual 0".64). <P />Epoch = 2019 Dec. 23.0 TT <P />T = 2019 Dec. 8.56312 TT Peri. = 209.13141 <P />e = 3.3552527 Node = 308.14563 2000.0 <P />q = 2.0062689 AU Incl. = 44.05474 These elements yield original and future 1/a values with respect to the solar-system barycenter of -1.174272 and -1.173806 AU**-1, respectively (+/- 0.000286). The original barycentric eccentricity was 3.3656 at r = 922 AU in the year 1885; the future barycentric eccentricity will be 3.3619 in the year 2165 when at r = 996 AU.
