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

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ID# 5

4U 1850-087

X 1850-087, 4U 1850-086, A 1850-08

Confirmed UCXB

RA                 Dec     [hh:mm:ss.ss]          [dd:mm:ss.ss] 18:53:04.88  -08:42:20.0                      [ICRS]

ℓ                      b [deg]                            [deg] 025.355515  -04.319866

Year of discovery: 1975-1976

(Seward1976Swank1976)

Basic data

Location in Globular Cluster	NGC 6712
Type of accretor	NS	Persistent
Distance [kpc] (other distances)	7.382 +0.240-0.233	Baumgardt2021 Peterson1993Kuulkers2003Harris2010
z [kpc]	-0.56	Baumgardt2021
Orbital period (Porb) [min]	20.6	Homer1996
Porb determination method	UV modulation
Thermonuclear X-ray burst	Short-B IB	Swank1976Hoffman1980 IntZand2014b
Peak X-ray flux [erg s-1 cm-2] (2 - 10 keV)	1.04E-10	Juett2005
NH [x1022 cm-2]	0.4±0.2	Sidoli2006
E(B-V) [mag]	0.45±0.04	Harris2010
Magnitude	B=21.2±0.2	Auriere1992
Proposed companion	Ne excess, not CO (X-ray spectral modelling)	Juett2001

NOTES

Radio luminosity = 33.8 ± 0.9 E+27 erg/s (5 GHz; Zhao2021). Mean cm radio flux density < 0.3 mJy (Fender2000).

Spectral data

UV	Featureless	Downes1996
Optical	Featureless	Auriere1992Downes1996
X-ray	Ne (0.7 keV)	Juett2001

Peak Optical/NIR magnitudes

If the system is transient, quiescent magnitudes are indicated with a "q" superindex Homer1996 Auriere1992
F555W (V)=20.34±0.07 (STMAG), B=21.2±0.2

Aladin finding chart

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4U 1850-087 in Simbad

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Pan-STARRS1 finding chart

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References to finding charts

Homer1996Gottwald1991