From: quai@eps.harvard.edu
  Date: May 16, 2016 at 9:49:42 PM PDT
  Subject: CBET 4278: 20160517 : NEPTUNE

                                                  Electronic Telegram
  No. 4278
  Central Bureau for Astronomical Telegrams
  Mailing address: Hoffman Lab 209; Harvard University;
  20 Oxford St.; Cambridge, MA 02138; U.S.A.
  e-mail: cbatiau@eps.harvard.edu (alternate cbat@iau.org)
  URL http://www.cbat.eps.harvard.edu/index.html
  Prepared using the Tamkin Foundation Computer Network


  NEPTUNE 
      M. H. Wong, University of California at Berkeley; P. M. Fry, University
  of Wisconsin; and A. A. Simon, Goddard Space Flight Center, NASA, report that
  they detected a dark spot on Neptune at wavelengths < 600 nm, in images taken
  with the Hubble Space Telescope (+ WFC3/UVIS) on May 16 UT.  This confirms the
  existence of a dark spot first imaged by WFC3/UVIS on 2015 Sept. 18 UT as part
  of the OPAL program (Simon et al. 2015, Ap.J. 812, 55).  They provisionally
  refer to the feature as SDS-2015 (southern dark spot discovered in 2015).
  SDS-2015 was centered at planetographic latitude 45 degrees south in 2015 and
  at 46 degrees south in 2016, and was observed at longitude about 138 deg west
  on 2016 May 16.178 UT.  The width is at least 14 deg of longitude.  Longer-
  wavelength data reveal the continued presence of bright companion clouds
  associated with SDS-2015, supporting the interpretation that it is an
  anti-cyclonic vortex (e.g., Smith et al. 1989, Science 246, 1422).  The
  Hubble observing team also includes I. de Pater, J. Tollefson, K. de Kleer,
  H. Hammel, S. Cook, R. Hueso, A. Sanchez-Lavega, M. Delcroix, L. Sromovsky,
  G. Orton, and C. Baranec.


  NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
      superseded by text appearing later in the printed IAU Circulars.

                          (C) Copyright 2016 CBAT
  2016 May 17                     (CBET 4278)             Daniel W.
  E. Green