BlackCAT A Catalog of Stellar-Mass Black Holes in X-ray Binaries

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ID# 4

4U 1755-338

V4134 Sgr

(Bradt1983)

RA     (ICRS)     DEC [hh:mm:ss.ss]          [dd:mm:ss.ss] 17:58:40.04  -33:48:26.80

ℓ                      b [deg]                            [deg] 357.2155210  -04.87236175

Year of discovery: 1971  
(Giacconi1972)

# of outbursts after discovery: 1

Basic data

Distance [kpc]	6.5±2.5	Angelini2003
Distance to the plane (z) [kpc]	-0.6±0.2	Angelini2003
Orbital period (Porb) [h]	∼4.4	White1984
Peak X-ray flux [erg s-1 cm-2] [keV]	1.17E-09 [2-10]	Giacconi1974
Outburst magnitude (AB)	V∼18.5	Mason1985
Quiescent magnitude (AB)	V>21.96	Wachter1998
E(B-V) [mag]	0.624	Schlafly2011
Spectral type

NOTES

4U 1755-338 is a quasi persistent system. This system stayed in outburst for 25yr until 1996 (Roberts1996,Angelini2003). It showed another outburst in 2020 (Mereminskiy2020) after 24 years in quiescence. The distance is uncertain. The X-ray fluxed measured by NuSTAR in the 2020 would imply a distance of at least 15 kpc for a 3M☉ BH (Draghis2020), much higher that the one proposed by Angelini2003 (6.5 kpc).

Optical/NIR magnitudes

Mag. Outburst (AB) Mason1985
	V∼18.5
Mag. Quiescent (AB) Wachter1998
	V>21.96		R>21.6
	I>21.3

Additional information

Other finding charts in Wachter1998 and Jernigan1978 (object #6)

Aladin finding chart

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4U 1755-338 in Simbad

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