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

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ID# 40

4U 1722-30

4U 1724-30, GRS 1724-308, 1E 1724-3045

Candidate UCXB

RA                 Dec     [hh:mm:ss.ss]          [dd:mm:ss.ss] 17:27:33.15    -30:48:07.8                      [ICRS]

ℓ                      b [deg]                            [deg] 356.319615  02.298083

Year of discovery: 1975

(Swank1977)

Basic data

Location in Globular Cluster	Terzan 2
Type of accretor	NS	Persistent
Distance [kpc] (other distances) Gaia [kpc]	7.753 +0.332-0.318 6.6+2.8-4	Baumgardt2021 Harris2010Valenti2010Kuulkers2003Galloway2020Galloway2008Chelovekov2011Chelovekov2017 Arnason2021
z [kpc]	0.31	Baumgardt2021
Orbital period (Porb) [min]
Porb determination method
Thermonuclear X-ray burst	Short-B	Swank1977Kuulkers2003
Peak X-ray flux [erg s-1 cm-2] (2 - 10 keV)	5.74E-10	Lin2018
NH [x1022 cm-2]	1.1	Kashyap2022
E(B-V) [mag]	1.87±0.19	Harris2010Valenti2010
Magnitude
Proposed companion

NOTES

Radio flux < 0.28 mJy (6 cm; Grindlay1986). Altamirano2008b proposed an orbital periodicity of ~90 days (see also Tarana2018).

Spectral data

UV
Optical
X-ray	Weak Fe emission line (~6.4 keV)	Barret2000

Peak Optical/NIR magnitudes

If the system is transient, quiescent magnitudes are indicated with a "q" superindex

Aladin finding chart

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4U 1722-30 in Simbad

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Pan-STARRS1 finding chart

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