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23432Observational report on NEOCP 04F0011: possible cometary outburst

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    Apr 16, 2010
      Telescope: 2.0-m Faulkes Telescope South (f/10.0 Ritchey-Chretien + CCD)
      Observing window: 2010 Apr 16 12:02-12:27 UT
      Total of 13 images made in 1.5 arcsec FWHM seeing using B,V,R,g',r',i' and Z

      The PSF of object is slightly non-stellar in that, for example, the
      brightest pixel of star of similar magnitude (R=12.7) = 15480 adu (fwhm =
      1.5") whilst the brightest pixel of object (R=12.7) = 9641 adu (fwhm =

      Precise Sloan filter photometry relative to SDSSJ133859.27+044740.0
      (r'=14.647, g'-r'=0.408) using 4.2 arcsec radius photometric apertures
      yields the following:

      NEOCP Object: 04F0011
      2010 Apr 16 (UT)
      12:14:20 r'=12.973
      12:16:20 g'=13.469
      12:19:30 i'=12.853
      12:26:27 r'=12.959

      Hence g'-r'=0.503 and r'-i'=0.113 and the r' magnitude may have brightened
      by 0.014 mag in 12.1 min. The absolute uncertainty i n the photometry is
      expected to be 0.015 mag, the relative uncertainty is expected to be less
      than 0.005 mag (SNR of comparison star >500).

      Photometry using 4.2 arcsec apertures of three other R-filter images
      indicate brightening of the object amounting to 0.012 mag in 18.6 min.

      Astrometry has been reported to the Minor Planet Center.

      No extended coma is visible in any image.

      No obvious co-moving object is evident in the frames.

      Conclude that this moving object is slightly non-stellar and at the epoch of
      the observations was brightening at a rate of 0.05 mag/hr.

      Richard Miles
      British Astronomical Association
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