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

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ID# 6

3A 1524-617

KY TrA

(YanesRizo2023)

RA     (ICRS)     DEC

[hh:mm:ss.ss]          [dd:mm:ss.ss]

15:28:16.93  -61:52:57.95

ℓ                      b

[deg]                            [deg]

320.3188498  -04.4268531

Year of discovery: 1974  
(Pounds1974Holt1974)

# of outbursts after discovery: 1


Basic data
Distance [kpc] 8.0±0.9 YanesRizo2023
Distance to the plane (z) [kpc] -0.6±0.1 YanesRizo2023
Orbital period (Porb) [h] 6.2±0.2 YanesRizo2023
Peak X-ray flux [erg s-1 cm-2]
[keV]		 4.66E-08
[2-10]		 Kaluzienski1975
Outburst magnitude (AB) B=17.3 Murdin1977
Quiescent magnitude (AB) I=21.61±0.09 Zurita2015YanesRizo2023
E(B-V) [mag] 0.629 Schlafly2011

Strictly speaking it is not a dynamical BH but there is either a robust mass function or mass determination suggesting the presence of a BH


NOTES
KY TrA showed another outburst in 1990 (Barret1992).
It has an interloper with similar brightness 0.64” away with coordinates ICRS α=15:28:16.97 and δ=-61:52:58.52 (YanesRizo2023).
There is no formal dynamical solution for the system but YanesRizo2023 derived some dynamical parameters (see below) using the FWHM (Hα) - K2 relation (Casares2015).

Dynamical parameters
Orbital period [h] 6.2±0.2 YanesRizo2023
Star's spectral type ≥ K2 YanesRizo2023
Star's radial velocity amplitude (K2) [km/s] 501±52 YanesRizo2023
Mass function 'f(M1)' [M☉] 3±1 YanesRizo2023
BH mass (M1) [M☉] 5.8+3.0-2.4 YanesRizo2023
Mass ratio (q=M2/M1) ≤0.31 YanesRizo2023
Inclination angle (i) [deg] 57±13 YanesRizo2023



Optical/NIR magnitudes
Mag. Outburst (AB)
Murdin1977
B=17.3
Mag. Quiescent (AB)
Zurita2015YanesRizo2023
V=23.6±0.1 R=22.4±0.1
I=21.61±0.09
Aladin finding chart
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Default image: DSS2 Red
3A 1524-617 in Simbad

Finding charts

Orientation: North up, East left. Object marked
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Finding chart reference: Zurita2015

Finding chart
Finding chart
Finding chart

Comparison stars (AB mag)

Murdin1977
BS=14.99 VS=14.29
BT=17.07 VT=16.36
BX=18.44 VX=17.56
BQ=19.44 VQ=17.86


This research has made use of NASA's Astrophysics Data System (ADS), the SIMBAD database operated at CDS (Strasbourg, France) and APLpy
Please acknowledge the use of this catalogue in any published work you derive from it.
Last modified: 22 September 2025.