UltraCompCAT A Catalogue of Ultra-Compact and Short Orbital Period X-ray Binaries

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ID# 13

MAXI J0911-655

Swift J0911.9−6452

Confirmed UCXB

RA                 Dec     [hh:mm:ss.ss]          [dd:mm:ss.ss] 09:12:02.43  -64:52:06.4                      [ICRS]

ℓ                      b [deg]                            [deg] 282.195949  -11.256788

Year of discovery: 2016

(Serino2016)

Basic data

Location in Globular Cluster	NGC 2808
Type of accretor	NS AMXP (339.97 Hz / 2.94 ms)	Transient Sanna2017
Distance [kpc] (other distances)	10.060 +0.112-0.111	Baumgardt2021 Harris2010Watkins2015
z [kpc]	-1.95	Baumgardt2021
Orbital period (Porb) [min]	44.332218±0.000007	Sanna2017
Porb determination method	X-ray pulsation
Thermonuclear X-ray burst	IB	Nakajima2020
Peak X-ray flux [erg s-1 cm-2] (2 - 10 keV)	1.37E-10	Sanna2017
NH [x1022 cm-2]	0.25±0.01	Sanna2017
E(B-V) [mag]	0.22±0.02	Harris2010
Magnitude
Proposed companion

NOTES

No radio counterpart was detected down to a 5σ upper limit of 70 μJy during the 2016 outburst (5.5 and 9 GHz; Tudor2016). NICER observations performed in July 2021 suggested that the source never returned to quiescence since it was first discovered in 2016 (Ng2021b), although it briefly dipped in flux around June 2019 (Parikh2019).

Spectral data

UV
Optical
X-ray	Fe Kα (6.5 - 6.6 keV)	Sanna2017

Peak Optical/NIR magnitudes

If the system is transient, quiescent magnitudes are indicated with a "q" superindex

Aladin finding chart

Scroll to zoom. Set survey image in "Manage layers"
Default image: DSS2 Red

MAXI J0911-655 in Simbad

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References to finding charts

Servillat2008