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

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ID# 18

NGC 6440 X-2

CXOG1b J174852.7-202124

Confirmed UCXB

RA                 Dec     [hh:mm:ss.ss]          [dd:mm:ss.ss] 17:48:52.76  -20:21:24.0                      [ICRS]

ℓ                      b [deg]                            [deg] 007.731804  03.802875

Year of discovery: 2009

(Heinke2010)

Basic data

Location in Globular Cluster	NGC 6440
Type of accretor	NS AMXP (205.89 Hz / 4.86 ms)	Transient Altamirano2010
Distance [kpc] (other distances)	8.248 +0.248-0.241	Baumgardt2021 Ortolani1994Pallanca2021Harris2010
z [kpc]	0.54	Baumgardt2021
Orbital period (Porb) [min]	57.3±0.6	Altamirano2010
Porb determination method	X-ray pulsation
Thermonuclear X-ray burst
Peak X-ray flux [erg s-1 cm-2] (2 - 10 keV)	1.58E-10	Heinke2010
NH [x1022 cm-2]	0.69±0.06	Heinke2010
E(B-V) [mag]	1.07±0.10	Harris1996
Magnitude	g'>22 qV>21.0	Heinke2010 Heinke2010
Proposed companion

NOTES

Bult2015 did not detected an orbital period derivative to an upper limit of ±8E-11 s/s. No counterpart in quiescence was found in Chandra archival data (Heinke2010).

Spectral data

UV
Optical
X-ray	Fe Kα (6.6-6.7 keV)	Heinke2010Koliopanos2021

Peak Optical/NIR magnitudes

If the system is transient, quiescent magnitudes are indicated with a "q" superindex Heinke2010
qV>21.0, qB>22, K>17, J>18.5, g'>22

Aladin finding chart

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NGC 6440 X-2 in Simbad

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Pan-STARRS1 finding chart

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References to finding charts

Heinke2010