Alert Notice 554: Observations of V420 Aur (HD 34921) needed to support spectroscopy

Note added October 4, 2016: In the original version of this Alert Notice, V420 Aur was referred to as V420 Oph in the sections on creating charts and reporting observations. Also, the range was given as V=7.15-7.35  when the correct value is V=7.35-7.51. The text below has been corrected. Apologies to the PI's for the error.

Alert Notice 397: Request for optical photometry of the bright X-ray binary V884 Sco (4U 1700-377)

June 30, 2009

Dr. Jerome Orosz (SDSU) has requested the assistance of southern bright star observers in observing the high-mass X-ray binary star V884 Sco (== 4U 1700-377). Orosz and collaborators are attempting to measure the mass of the compact object to clarify whether the object is a black hole or a neutron star. Optical photometry of the ellipsoidal variations of V884 Sco will be used in conjunction with optical spectroscopy to be performed at Las Campanas in mid-July and early August 2009 to measure the dynamical properties of the system.