OBSERVATIONS of 9P/Tempel 1 THE TARGET OF DEEP IMPACT

Nicolas Biver 30 May 2005

Some results of IRAM-30m observations

People involved in the "Chemical investigation of comet 9P/Tempel 1, prior to and after Deep Impact" are:
  • Nicolas Biver, Dominique Bockelée-Morvan, Jérémie Boissier, Jacques Crovisier, Pierre Colom, Alain Lecacheux and Raphael Moreno, from Paris Observatory (France)
  • Gabriel Paubert, from IRAM Granada (Spain)
  • Mike A'Hearn, Deep Impact PI, from Univ. of Maryland (USA)
  • and Karen Meech, from Univ. of Hawaii (USA)

    Text published in IAU circular 8538 (and CBET 157, 26 May 2005):

  • N.Biver, D.Bockelée-Morvan, P.Colom, J.Crovisier, A. Lecacheux, Observatoire de Paris, and G. Paubert, Institut de Radioastronomie Millimétrique (IRAM) report: "Comet 9P/Tempel 1 was observed with the IRAM 30-m radio telescope from May 4.8 to 9.0 UT. The HCN J=3-2 and J=1-0 lines were detected with mean integrated intensities of 111 +/- 8 mK km/s and 31 +/- 4 mK km/s respectively. Day-to-day variations in the HCN line intensities are observed and reveal periodic variability in HCN production from 5 to 10E24 molecules/s. The periodicity is 1.7 days, and is consistent with the estimated nucleus rotational period. H_2S and CH_3OH were also marginally detected; CO, CS and H_2CO were searched for and undetected. The production rate ratios, or their upper limits, of these molecules relative to HCN are 5.5, 21, <110, <1.1 and <17, respectively. All lines are blue shifted suggesting preferential sunward outgassing."

    Summary of observation results:

    Dates rh [AU] D [AU] Lines Tmbdv Doppler shift Production rate
    2005/05/05.78-09.04 1.617 0.712 HCN(3-2) 111+-8 mKkm/s -118+-42 m/s 5.7+-0.4E24 mol./s
    2005/05/04.76-08.04 1.620 0.712 HCN(1-0) 31+-4 mKkm/s -196+-63 m/s 6.6+-0.9E24 mol./s
    2005/05/05.78-07.04 1.621 0.712 H2S(110-101) 30+-8 mKkm/s -279+-132 m/s 3.2+-0.8E25 mol./s
    2005/05/05.78-09.04 1.615 0.712 CH3OH(303+403+503) 55+-8 mKkm/s -126+-80 m/s 16+-3E25 mol./s
    2005/05/04.76-08.04 1.619 0.712 CO(2-1) < 25 mKkm/s - < 7.4E26 mol./s
    2005/05/08.79-09.04 1.611 0.713 CS(5-4) < 45 mKkm/s - < 11.1E24 mol./s
    2005/05/04.76-05.04 1.625 0.712 H2CO(312-211) < 62 mKkm/s - < 11.5E25 mol./s
    HCN(3-2) line: averages of days when QHCN was low (and weather was by chance very good) and when it was high (lower plot -- the sky opacity was also higher, so the noise too)

    PDF version
    HCN production rates and sinusoidal fit: Xhi2 minimisation yields: Q = 7.2E24+2.9E24*sin (2pi*(t-6.53)/1.67), Tp = 1.67+-0.07 days

    Nancay results
    Warning: These data cannot be used for reproduction without approval of the observation program investigators
    For contacts: Nicolas.Biver_at_obspm.fr
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