Latest News

• NICER Observations of the 2020 X-ray Minimum of eta Carinae (24 Feb 2020)
  NICER has observed the 2020 X-ray minimum of eta Carinae, a long-period eccentric binary system which produces X-ray emission from the collision of the powerful stellar winds from the two stars. X-ray monitoring observations with NICER showed that the X-ray minimum began on 2020-02-13, at which time the observed X-ray flux dropped by about two orders of magnitude from the peak flux seem about 1 month earlier. The NICER observations help establish variations in the stellar wind mass loss and provide a probe of the dense inner wind of the Luminous Blue Variable primary star.
• Re-brightening and decaying of MAXI J1348-630 as observed with NICER (11 Feb 2020)
  NICER observations of a new black hole candidate MAXI J1348-630 from Feb. 7 to 10 showed the source declining in X-ray flux by about a factor of 2 during this interval. NICER spectra show that the source is currently in the hard state. NICER will continue monitoring the source about once per day until the outburst fades.
• Initial NICER observations of the mysterious source Swift J0840.7-3516 (aka GRB 200205A) and detection of short X-ray flaring activity (07 Feb 2020)
  The source Swift J0840.7-3516 was originally reported as a Gamma-ray burst sourcce by the Swift BAT on February 5. Followup observations by the Swift XRT showed X-ray emission that was inconsistent with a GRB, along with the possible detection of an 8.96 seconds. Followup X-ray observations with NICER showed X-ray flaring during which the X-ray flux increasd by a factor of 4, but did not confirm the X-ray period.
• NICER observes a new outburst of V4641 Sgr (04 Feb 2020)
  V4641 Sgr is a binary system that contains a 6.4 solar mass black hole which went into X-ray outburst in early January. Observations by NICER on January 31 provided the best measure of the 2-10 keV spectrum and showed an inner disk radius temperature of about 1.5 keV, with no visible features in the power spectrum in the short NICER observation.
• NICER sees a state change in MAXI J0637-430 (30 Jan 2020)
  NICER observations of the newly-discovered X-ray transient MAXI J0637-430 indicate that the source is a black hole X-ray binary system. Recent observations detail the decline of the soft, thermal X-ray emission from the source which entered a hard state on January 14, 2020, indicating a signficant change in the accretion disk around the black hole.

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