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     [J2000]     DEC

[]          []

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]
Outburst magnitude (AB) V∼18.5 Mason1985
Quiescent magnitude (AB) V>21.96 Wachter1998
E(B-V) [mag] 0.624 Schlafly2011
Spectral type


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)
Mag. Quiescent (AB)
V>21.96 R>21.6
Aladin finding chart
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4U 1755-338 in Simbad

Finding chart

This research has made use of NASA's Astrophysics Data System (ADS) and the SIMBAD database operated at CDS (Strasbourg, France)
Please acknowledge the use of this catalogue in any published work you derive from it.

Last modified: 27 August 2021.