Sources in the SMC: comments to the Table 3

J0032.9-7348
(RX J0032.9-7348)
This source was discovered by Kahabka & Pietch (1996) in ROSAT pointed observations made in 1992 December and 1993 April. Stevens, Coe & Buckley (1999) identified two Be stars within PSPC error circle of RX J0032.9-7348.

J0045.6-7313
(RX J0045.6-7313)
This source was detected once in the 0.9-2.0 keV band of the ROSAT PSPC. An emission-line object in the error circle suggests a Be/X-ray binary (Haberl & Sasaki (2000)).

J0047.3-7312
(RX J0047.3-7312, 2E 0045.6-7328, XMMU J004723.7-731226, SXP 264, AX J0047.3-7312?)
Haberl & Sasaki (2000) proposed RX J0047.3-7312 as a Be/X-ray binary candidate because this source exhibits a flux variation with a factor of 9 and has an emission-line object 172 in (Meyssonnier & Azzopardi (1993)) as a counterpart. A probable binary period of 48.8±0.6 days has been detected in observations of the optical counterpart to this X-ray source (Edge, Coe & Galache (2005)). Analysis of the OGLE light curve found an ephemeris of MJD 50592 ± 2 + n × 49.2 ± 0.2 d (Edge 2005). Schmidtke & Cowley (2005) found a 49.1 d period in OGLE data. The relationship between this orbital period and the pulse period of 264 s is within the normal variance found in the Corbet diagram (Corbet (1984)). Pulsed fraction obtained from 0.2-10.0 keV EPIC-PN pulse profiles is 22 ± 9 % (Haberl, Eger & Pietsch (2008)).

J0048.2-7309
(AX J0048.2-7309)
AX J0048.2-7309 was detected in two ASCA observations and shows a hard spectrum and a flux variability with a factor of ~5 (Yokogawa, Imanishi, Tsujimoto et al. (2003)). An emission-line object, No. 215 in (Meyssonnier & Azzopardi (1993)), was found in the error circle of AX J0048.2-7309. Data suggest that this source is a Be/X-ray binary.

J004814.1-731003
(XMMU J004814.1-731003)
XMMU J004814.1-731003 is located within the error circle of the transient ASCA source AX J0048.2-7309 , but its position is inconsistent with that of the proposed optical counterpart of AX J0048.2-7309 (Haberl, Eger, Pietsch et al. (2008)). The precise X-ray position allows Haberl, Eger, Pietsch et al. (2008) to identify a Be star as the optical counterpart. They estimate the spectral class of the optical counterpart from its B−V colour index to B3 or later. It remains unclear if XMMU J004814.1-731003 is associated with AX J0048.2-7309. Pulsed fraction obtained from 0.2-10.0 keV EPIC-PN pulse profiles is 45 ± 15 % (Haberl, Eger & Pietsch (2008)).

J0048.5-7302
(RX J0048.5-7302, XMMU J004834.5-730230)
The emission-line object 238 in (Meyssonnier & Azzopardi (1993)) is the brightest optical object in the error circle of RX J0048.5-7302 (Haberl & Sasaki (2000)). A Be/X-ray binary interpretation is suggested by Haberl & Sasaki (2000).

J0049-729
(AX J0049-729, AX J0049-728, RX J0049.0-7250, RX J0049.1-7250, XTE J0049-729, SXP 74.7)
This source was discovered with ROSAT (Kahabka & Pietch (1996)) in pointed observations. Yokogawa & Koyama (1998) reported X-ray pulsations in ASCA data of this source. The X-ray flux in the band 0.7-10 keV was 1.2 x 10^-11 erg cm^-2 s^-1, with sinusoidal pulse modulation. Kahabka & Pietch (1998) suggested the highly variable source RX J0049.1-7250 as a counterpart. Stevens, Coe & Buckley (1999) identified two Be stars, one only 3" from the X-ray position and one just outside the error circle given by Kahabka & Pietch (1996). Yokogawa, Imanishi, Tsujimoto et al. (1999) reported on the results of two ASCA observations of this X-ray source. The pulse fraction was ~70% independent of the X-ray energy. Using MACHO and OGLE-II data, Schmidtke & Cowley (2004) found a strong periodicity at P=33.3 days, which is likely the orbital period, in good agreement with the relation between orbital and pulse periods first recognized by Corbet (1984). Laycock, Corbet, Coe et al. (2005) derived a possible orbital period of 642 ± 59 d based on the separation between the outbursts.

J0049.2-7311
(RX J0049.2-7311, XMMU J004913.8-731136)
The position of Hα bright object coincides with this X-ray source. Coe, Edge, Galache & McBride (2004) proposed this object as a more likely counterpart to the ASCA SXP9.13 pulsar. However, other authors have proposed RX J0049.4-7310, as the correct identification for SXP9.13 pulsar (Filipovic, Haberl, Pietsch & Morgan (2000); Schmidtke, Cowley, Levenson & Sweet (2004)).

J0049-732
(AX J0049-732, RX J0049.4-7310, SXP 9.13)
This source was discovered as an X-ray pulsar by Imanishi, Yokogawa & Koyama (1998) with ASCA. The X-ray flux at 2-10 keV was about 8 x 10^-13 erg cm^-2 s^-1. A more likely scenario for AX J0049-732 is either a Be/X-ray binary or an anomalous X-ray pulsar. Direct information to distinguish these two possibilities can be obtained by measuring the pulse period derivative and its orbital modulation. Two sources, No. 427 and No. 430, in the ROSAT PSPC catalogue of Haberl, Filipovic, Pietsch & Kahabka (2000) are possible counterparts of AX J0049-732. Filipovic, Pietsch & Haberl (2000) searched for optical counterparts of these ROSAT sources, and found an emission line object, possibly a Be star, at the position of source No. 427, but found no counterpart for source No. 430. Hence, they suggest that source No. 427 is more likely to be a counterpart of AX J0049-732. However, the angular separation of these sources of 1'.43 is significantly larger than the ASCA error radius. And Ueno, Yokogawa, Imanishi & Koyama (2000) propose that No. 430 is a more likely counterpart. Schmidtke, Cowley, Levenson & Sweet (2004) found an orbital period of 91.5 days for RX J0049.4-7310 in the MACHO data. A period of 77.2 d is found by Galache, Corbet, Coe et al. (2008) using Lomb-Scargle analysis of X-ray light curve. They derive the ephemeris of MJD 52380.5 ± 2.3 + n × 77.2 ± 0.3 d.

J004929.7-731058
(CXO J004929.7-731058, SXP 892)
This source was first identified by Laycock, Zezas & Hong (2008) as part of their deep Chandra study of one region in the Small Magellanic Cloud. It has a pulse period of 892s. The pulse fraction is 65 ± 15 % (0.35-8 keV) (Laycock, Zezas & Hong (2008)).

J0049.5-7331
(RX J0049.5-7331, AX J0049.5-7330)
This source is most likely identified with the emission-line object 302 in (Meyssonnier & Azzopardi (1993)) according to Haberl & Sasaki (2000).

J0049.7-7323
(AX J0049.4-7323, AX J0049.5-7323, RX J0049.7-7323)
This X-ray source has been detected 5 times to date, 3 times by the ASCA observatory (Yokogawa, Imanishi, Ueno & Koyama (2000)) and 2 times by the RossiXTE spacecraft (Laycock, Corbet, Coe et al. (2004)). Ueno, Yokogawa, Imanishi & Koyama (2000) reported an ASCA observation which revealed coherent pulsations of period 755.5±0.6 s from a new source in the Small Magellanic Cloud. The spectrum was characterized by a flat power-law function with photon index 0.7 and X-ray flux 1.1 x 10^-12 erg cm^-2 s^-1 (0.7-10 keV). They noted that the possible Be/X-ray binary RX J0049.7-7323 (Haberl & Sasaki (2000)) was located within the ASCA error region. Edge & Coe (2003) reported on the spectroscopic and photometric analysis of possible optical counterparts to AX J0049.4-7323. They detected strong Hα emission from the optical source identified with RX J0049.7-7323 within error circle for AX J0049.4-7323 and concluded that these are one and the same object. They noted that the profile of the curve exhibits a distinct double peak. This is consistent with Doppler effects which would be expected from a circumstellar disc viewed in the plane of rotation. There is also definite V/R asymmetry between the peaks. It is a compelling evidence for the presence of a Be star. Cowley & Schmidtke (2003) analyzed the long term light curve of the optical counterpart obtained from the MACHO date base. They showed that the optical object exhibited outbursts every 394 d which they proposed to be the orbital period of the system. They also showed the presence of a quasi-periodic modulation with a period $\sim$ 11d which they associated with the rotation of the Be star disk. The phase of two RXTE detections is exactly syncronised with the ephemeris derived from the optical outbursts. Therefore, as Coe & Edge (2004) concluded, the period of 394 d can represent the binary period of a system with X-ray outbursts syncronised with the periastron passage of the neutron star. Galache, Corbet, Coe et al. (2008) derived an orbital ephemeris MJD 52196.1 ± 3.9 + n × 389.9 ± 7.0 d. Pulsed fraction obtained from 0.2-10.0 keV EPIC-PN pulse profiles is 25 ± 5 % (Haberl, Eger & Pietsch (2008)).

J0050.7-7316
(DZ Tuc, AX J0051-732, RX J0050.6-7315, RX J0050.7-7316, AX J0051-733, RX J0050.8-7316, SXP 323)
This X-ray source was detected in Einstein IPC, ROSAT PSPC and HRI archival data and 18 year history shows flux variations by at least a factor of 10 (Imanishi, Yokogawa, Tsujimoto & Koyama (1999)). The source was reported as a 323 s pulsar by Yokogawa & Koyama (1998) and Imanishi, Yokogawa, Tsujimoto & Koyama (1999). Cowley, Schmidtke, McGrath et al. (1997) identified the optical counterpart as a Be star. This system has been found to exhibit optical and IR variability at periods of ∼ 0.7 and 1.4 d (Coe, Haigh, Laycock et al. (2002)) and 1.695 d (Coe, Edge, Galache & McBride (2005)). These periods are too short to be the orbital period of the system and are most likely non-radial pulsations in the Be star. In addition, the combination of the pulse period and such a binary period violates the Corbet relationship for such systems (Corbet (1986)). Raguzova & Lipunov (1998) calculated the critical orbital period for the existence of a Be+X-ray pulsar binary, which is ~10-20 d. They proposed an explanation for the lack of Be stars with accreting neutron star as companions with orbital periods less than 10 days as caused by synchronization of Be star during its evolution. Laycock, Corbet, Coe et al. (2005) suggest an orbital period of 109 ± 18 d from X-ray data. Galache, Corbet, Coe et al. (2008) derived the ephemeris of MJD 52336.9 ± 3.5 + n × 116.6 ± 0.6 d. Pulsed fraction obtained from 0.2-10.0 keV EPIC-PN pulse profiles is 31 ± 7 % (Haberl, Eger & Pietsch (2008)).

J0050.7-7332
(RX J0050.7-7332)
This source was only once detected by the ROSAT PSPC. The emission-line object in the error circle suggests a Be/X-ray binary identification (Haberl & Sasaki (2000)).

J0050.9-7310
(RX J0050.9-7310, RX J0050.8-7310, XMMU J005057.6-731007)
This source is most likely identified with the emission-line object 414 in (Meyssonnier & Azzopardi (1993)), suggesting a Be/X-ray binary (Haberl & Sasaki (2000)).

J0051-722
(AX J0051-722, RX J0051.3-7216, SXP 91.1, SXP 89.0?)
This source was at first detected as a 91.12 s pulsar in RXTE observations (Corbet, Marshall, Lochner et al. (1997)). Although it was initially confused with the nearby 46 s pulsar 1WGA J0053.8-7226 (Buckley, Coe, Stevens et al. (1997)). Stevens, Coe & Buckley (1999) estimated the magnitude of the optical component (Be star) as V~15 from Digitized Sky Survey images. The spacing of flares observed from AX J0051-722 suggests an orbital period of about 120 days (Israel, Stella, Campana et al. (1998)). Schmidtke, Cowley, Levenson & Sweet (2004) found an optical period of 88.25 days using MACHO data. Galache, Corbet, Coe et al. (2008) suggested that SXP 91.1 and SXP 89.0 may be one and the same pulsar.

J0051.3-7250
(RX J0051.3-7250)
Two close emission-line objects are found near this source, suggesting RX J0051.3-7250 as Be/X-ray binary,

J0051-727
(XTE J0051-727, SXP 293, RX J0058.2-7231?)
Corbet, Markwardt, Coe et al. (2004) have detected this new transient X-ray pulsar in the direction of the SMC with the RXTE Proportional Counter Array. No position available. The object showed the 1.6-1.7 mCrab flux in the 2-10 keV band. Galache, Corbet, Coe et al. (2008) derived an orbital ephemeris MJD 52327.3 ± 4.5 + n × 151 ± 1 d. XTE J0051-727 and RX J0058.2-7231 are very likely the same source.

J0050-732#1
(XTE J0050-732#1, SXP 16.6)
This source was discovered by Lamb, Macomb, Prince & Majid (2002) from archival data of RXTE. SXP 16.6 remains unassociated with any known source, although it is often still mistakenly referred to as RX J0051.8−7310. From Lomb-Scargle analysis of X-ray light curve Galache, Corbet, Coe et al. (2008) found a strong modulation at 33.72 d, which they proposed as the orbital period of the system. They derived an orbital ephemeris MJD 52373.5 ± 1.0 + n × 33.72 ± 0.05 d.

J0050-732#2
(XTE J0050-732#2, SXP 51.0)
This source was discovered by Lamb, Macomb, Prince & Majid (2002) from archival data of RXTE. Was erroneously proposed as a new 25.5 s pulsar in paper by Lamb, Macomb, Prince & Majid (2002) from a deep 121 ks observation. Laycock (2002) identified the 25.5 s peaks in the power spectrum as harmonics of SXP 51.0 true pulse period. No position is available.

J0051.8-7310
(2E 0050.2-7326, RX J0051.8-7310, AX J0051.6-7311, RX J0051.9-7311, XMMU J005152.2-731033, SXP 172)
This X-ray source was detected by Cowley, Schmidtke, McGrath et al. (1997) during ROSAT HRI observations of Einstein IPC source 25 and identified with a Be star by Schmidtke, Cowley, Crane et al. (1999). Period P= 147±24 days determined by Laycock, Corbet, Coe et al. (2005) from a string of 6 evenly spaced brighter outbursts. Schmidtke & Cowley (2005) found period P=69.9 days, which also may be the orbital period of the binary system.

J0051.8-7231
(2E 0050.1-7247, RX J0051.8-7231, 1E 0050.1-7247, 1WGA J0051.8-7231, SXP 8.88)
2E 0050.1-7247 was discovered in Einstein observations. The X-ray luminosity, time variability and hard spectrum led Kahabka & Pietch (1996) to suggest a Be/X-ray binary nature for the source. Israel, Stella, Angelini et al. (1995) discovered 8.9 s X-ray pulsations in 2E 0050.1-7247 during a systematic search for periodic signals in a sample of ROSAT PSPC light curves. The signal had a nearly sinusoidal shape with a 25-percent pulsed fraction. The source was detected several times between 1979 and 1993 at luminosity levels ranging from 5 x 10³⁴ erg s^-1 up to 1.4 x 10³⁶ erg s^-1 with both the Einstein IPC and ROSAT PSPC. The X-ray energy spectrum is consistent with a power-law spectrum that steepens as the source luminosity decreases. Israel, Stella, Angelini et al. (1997) revealed a pronounced Hα activity from at least two B stars in the X-ray error circles. These results strongly suggest that the X-ray pulsar 2E 0050.1-7247 is in a Be-type massive binary. Corbet, Coe, Edge et al. (2004) derived an orbital ephemeris of MJD 52850 ± 2 + n × 28.0 ± 0.3 d. Coe, Edge, Galache & McBride (2005) have proposed an orbital period of 185±4 days from the red light data. Schmidtke & Cowley (2006) find an optical period of 33.4 d in OGLE and MACHO data.

J0051.9-7255
(RX J0051.9-7255, WW 26)
Haberl & Sasaki (2000) suggested a Be/X-ray binary nature for this object. They have found two emission-line objects 521 and 487 from (Meyssonnier & Azzopardi (1993)) near this source.

0050-727
(SMC X-3, H 0050-727, 2S 0050-727, 3A 0049-726, 1H 0054-729, H 0048-731, 1XRS 00503-727, SXP 7.78)
SMC X-3 was detected by Li, Jernigan & Clark (1977) with SAS 3 during a strong X-ray outburst with 7 x 10³⁷ erg s^-1. This long-known X-ray source was not detected by the ROSAT PSPC, but it is included in the HRI catalogue. SMC X-3 has been identified with a previously detected 7.78s RXTE pulsar by using the Chandra data archive (Edge, Coe, Galache et al. (2004)). The Be star counterpart corresponds to object 531 in (Meyssonnier & Azzopardi (1993)). Corbet, Edge, Laycock et al. (2003) proposed an orbital period from a series of recurrent X-ray outbursts of 45.1 ± 0.4 d. An optical modulation in MACHO data was reported by Cowley & Schmidtke (2004) (44.86 d) and Coe, Edge, Galache & McBride (2005) (44.6 ± 0.2 d). Edge (2005) also found a strong 44.8 ± 0.2 d modulation in the OGLE counterpart, present even when there was no significant X-ray activity. Timing analysis of the complete X-ray light curve (Galache, Corbet, Coe et al. (2008)) reveals a clear period at 44.92 d. This Be/X-ray pulsar is unique in that, despite the spin up observed during each of the individual outburst episodes, the overall spin evolution seems to show a long-term spin down (Galache, Corbet, Coe et al. (2008)). Pulsed fraction obtained from 0.2-10.0 keV EPIC-PN pulse profiles is 18 ± 6 % (Haberl, Eger & Pietsch (2008).

J0052.1-7319
(1E 0050.3-7335, 2E 0050.4-7335, RX J0052.1-7319, SXP 15.3)
The X-ray transient RX J0052.1-7319 was discovered by Lamb, Prince, Macomb & Finger (1999) with the analysis of ROSAT HRI and BATSE data. They estimate the luminosity to be ∼ 10³⁷ erg s⁻¹ with a pulse fraction of ∼ 27%. Edge (2005) found an ephemeris of MJD 50376.1 + n × 75.1 ± 0.5 d describes the modulation in the MACHO and OGLE light curves. The object showed a period of 15.3 s (Kahabka (1999a); Kahabka (1999b)) and a flux in the 0.1-2 keV band of 2.6 x 10^-11 erg cm^-2 s^-1. Covino, Negueruela, Campana et al. (2001) reported on the discovery and confirmation of the optical counterpart of this transient X-ray pulsar. They found a V=14.6 O9.5IIIe star (a classification as a B0Ve star is also possible since the luminosity class depends on the uncertainty on the adopted reddening).

J005245.0-722844
(CXOU J005245.0-722844)
...

J005252.1-721715
(XMMU J005252.1-721715, CXO J005252.2-721715, SXP 326, SXP 327)
This source was first identified by Laycock, Zezas & Hong (2008) as part of their deep Chandra study of one region in the Small Magellanic Cloud. It has a pulse period of 327s (Coe, Schurch, Corbet et al. (2008)). The pulse fraction measured by Coe, Schurch, Corbet et al. (2008) from the folded lightcurve as (F_max − F_min )/(F_max + F_min) comes out as 8.5% which is very low. One reason for this low value could be the contribution of other non-pulsing SMC sources to the base-line signal. However, if we assume a pulsed fraction of ~10% then the X-ray luminosity rises to ~1×10³⁷ erg s^-1 (3-10 keV) (Coe, Schurch, Corbet et al. (2008)). The optical period of 46 days and the X-ray pulse period of 327s, places SXP327 on the edge of the distribution of such objects on the Corbet diagram (Corbet (1986)), but not far enough away to suggest it could be a rare supergiant system. The optical magnitude supports the identification of this system as Be/X-ray binary in the SMC (Coe, Schurch, Corbet et al. (2008)).

J0052-725
(XTE J0052-725, SXP 82.4)
This X-ray pulsar was originally detected by RXTE in 2002 (Corbet, Markwardt, Marshall et al. (2002)). Timing analysis revealed a period of 82.46±0.18 s at a confidence level of > 99%. The lower energy band (0.3-2.5 keV) contained about 60% of the photons but had a pulsed fraction of only 28%±2% as compared to 42%±3% in the higher energy band (2.5-10 keV). This source has been identified with the optical counterpart MACS J0052-726#004 (Tucholke, de Boer & Seitter (1996)). Galache, Corbet, Coe et al. (2008) found a very significant peak at ~362 d with a number of harmonics from the Lomb-Scargle periodogram for the X-ray light curve; the ephemeris derived is MJD 52089.0 ± 3.6 + n × 362.3 ± 4.1 d.

J0052-723
(XTE J0052-723, SXP 4.78)
Corbet, Marshall & Markwardt (2001) discovered this transient X-ray pulsar in the direction of the Small Magellanic Cloud from RXTE PCA observations made on 2000 December 27 and 2001 January 5. Pulsations were seen with a period of 4.782±0.001 s and with a double-peaked pulse profile. Spectroscopy of selected optical candidates (Laycock, Corbet, Coe et al. (2003)) has identified the probable counterpart which is a B0V-B1Ve SMC member exhibiting a strong, double peaked Hα emission line. Another possible ciunterpart is suggested be Coe, Edge, Galache & McBride (2005) as the star AzV129 is found to have a 23.9 d period in both MACHO colours, which would agree with the expected orbital period inferred from the Corbet diagram.

0051.1-7304
(2E 0051.1-7304, AzV 138)
This source is listed as entry 31 in the Einstein IPC catalogue (Wang & Wu (1992)). The Be star AzV 138 (Garmany & Humphreys (1985)) was proposed as an optical counterpart for 2E 0051.1-7304. 2E 0051.1-7304 was not detected in ROSAT observations.

J0052.9-7158
(2E 0051.1-7214, RX J0052.9-7158, XTE J0054-720, AX J0052.9-7157, SXP 169)
This source was detected as an X-ray transient by Cowley, Schmidtke, McGrath et al. (1997) during ROSAT HRI observations of Einstein IPC source 32. The strong variability and the hard X-ray spectrum imply a Be/X-ray transient consistent with the suggested Be star counterpart (Schmidtke, Cowley, Crane et al. (1999)). The X-ray source was detected by ROSAT and is located near the edge of the error circle of XTE J0054-720. The transient pulsar XTE J0054-720 with spin period ~ 169 s was discovered with RXTE (Lochner, Marshall, Whitlock & Brandt (1998)). Yokogawa, Imanishi, Tsujimoto et al. (2003) detected coherent pulsations with 167.8 s period from AX J0052.9-7157 and determined its position accurately. They found that AX J0052.9-7157 is located within the error circle of XTE J0054-720 and has a variable Be/X-ray binary, RX J0052.9-7158, as a counterpart. From the nearly equal pulse period and the positional coincidence, they concluded that the ASCA, ROSAT, and RXTE sources are identical. The pulsed fraction, defined as (pulsed flux)/(total flux) without background, is 44% in 2.0-7.0 keV (Yokogawa, Torii, Kohmura & Koyama (2001)). From Lomb-Scargle analysis of X-ray light curve Galache, Corbet, Coe et al. (2008) found a clear period, and the outbursts are described by the ephemeris MJD 52240.1 ± 2.1 + n × 68.54 ± 0.15 d, in agreement with the optical period.

J005323.8-722715
(CXOU J005323.8-722715, RX J0053.5-7227, SXP 138)
A precise ROSAT HRI position coincident with the emission-line star 667 in (Meyssonnier & Azzopardi (1993)) (it is the brightest object in the error circle) makes RX J0053.4-7227 a likely Be/X-ray binary (Haberl & Sasaki (2000)). The position of this pulsar is coincident also with MACHO object 207.16202.50. The latter shows an evidence of a period of 125±1.5 days. This period would be consistent with that predicted from the Corbet diagram (Corbet (1986)) for a 138 s Be/X-ray pulsar. Pulsed fraction obtained from 0.2-10.0 keV EPIC-PN pulse profiles is 42 ± 8 % (Haberl, Eger & Pietsch (2008)).

XTE SMC 95
(XTE SMC 95, SXP 95.2)
The source has been revealed during RXTE observations of the Small Magellanic Cloud. The pulsar was detected in three Proportional Counter Array (PCA) observations during an outburst (Laycock, Corbet, Perrodin et al. (2002)). The source is proposed to be a Be/neutron star system on the basis of its pulsations, transient nature and characteristically hard X-ray spectrum. The 2-10 keV X-ray luminosity implied by observations is 2 x 10³⁷ erg s^-1.

J0055-727
(XTE J0055-727, XMMU J004911.4-724939, SXP 18.3)
This source was detected with the RXTE PCA (Corbet, Markwardt, Coe et al. (2003)). Regular monitoring of the Small Magellanic Cloud with the RXTE PCA has revealed a periodicity of 34.8 days in the pulsed flux from this X-ray pulsar (Corbet, Markwardt, Marshall et al. (2004)). The regular nature of outbursts strongly suggests that they show the orbital period of this system. The combination of pulse and orbital periods is consistent with XTE J0055-727 being a Be star system. Corbet, Markwardt, Coe et al. (2003) noted the presence of the emission line objects AzV164 and 829 in (Meyssonnier & Azzopardi (1993)) close to the center of the error box of this source. A period of 17.73 d is found by Galache, Corbet, Coe et al. (2008) using Lomb-Scargle analysis of X-ray light curve. Analysis of the detrended OGLE III optical data of the counterpart to this X-ray source revealed a strong coherent period of 17.83 d (Udalski & Coe (2008)). This period, and the pulse period of 18 s, would place the source comfortably in the centre of the Corbet diagram for such systems. They concluded that the period of 17.8 d represents the binary period of SXP 18.3. Pulsed fraction obtained from 0.2-10.0 keV EPIC-PN pulse profiles is 21 ± 3 % (Haberl, Eger & Pietsch (2008)).

XTE Position A
(XTE Position A, SXP 89.0)
This source was detected in the RXTE Proportional Counter Array observations. The source position is not accurately known. Galache, Corbet, Coe et al. (2008) found a period of ~88 days between X-ray outbursts that could be expected to be the orbital period. The ephemeris derived is MJD 52337.5 ± 6.1 + n × 87.6 ± 0.3 d.

J0053.8-7226
(RX J0053.9-7226, 1WGA J0053.9-7226, 1E 0052.1-7242, 2E 0052.1-7242, RX J0053.8-7226, 1WGA J0053.8-7226, XTE J0053-724, SXP 46.6, XTE SMC 46.4s)
This object was serendipitously discovered as an X-ray source in the SMC in the ROSAT PSPC archive and also was observed by the Einstein IPC. Its X-ray properties, namely the hard X-ray spectrum, flux variability and column density indicate a hard, transient source with a luminosity of 3.8 x 10³⁵ erg s^-1 (Buckley, Coe, Stevens et al. 2001)). XTE and ASCA observations have confirmed the source to be an X-ray pulsar, with a 46 s spin period. Optical observations (Buckley, Coe, Stevens et al. 2001)) revealed two possible counterparts to this source. Both exhibit strong Hα and weaker H emission. Optical colors indicate that both objects are Be stars. The transient X-ray system XTE J0053-724 was also detected in one observation by RXTE. Pulsations of 46.6±0.1 s were observed with a pulse fraction about 25% (Lochner (1998)). Lochner (1998) suggested a possible orbital period of this Be/X-ray system about 139 days which is determined from the periodicity of X-ray outbursts.

J005403.8-722632
(XMMU J005403.8-722632)
This X-ray source was found by Haberl, Eger & Pietsch (2008) during eight XMM-Newton observations toward the Small Magellanic Cloud (SMC), performed between October 2006 and June 2007. The pulse period was determined to 341.87±0.15 s. The pulse period of XMMU J005403.8-722632 is close to the value of SAX J0103.2-7209 (345.2±0.1 s). The two pulsars are separated by 45.2′. As optical counterpart of XMMU J005403.8-722632 Haberl, Eger & Pietsch (2008) identified a star with V∼14.9 which shows large (0.7 mag, 0.5 mag) variations in the MACHO (R-band, B-band) light curves. Pulsed fraction obtained from 0.2-10.0 keV EPIC-PN pulse profiles is 54 ± 12 % (Haberl, Eger & Pietsch (2008)).

0053-739
(SMC X-2, 3A 0042-738, H 0052-739, 2S 0052-739, H 0053-739, RX J0054.5-7340)
SMC X-2 was one of the first three X-ray sources which were discovered in the SMC (Clark, Doxsey, Li et al. (1978)). It was also detected in the HEAO 1 A-2 experiment (Marshall, Boldt, Holt et al. (1979)), but not in the Einstein IPC survey (Seward & Mitchell (1981)). In ROSAT observations this transient source was detected only once (Kahabka & Pietch (1996)). It is thought to be a Be/X-ray binary, since a Be star was found as its optical counterpart (Murdin, Morton & Thomas (1979)). In early 2000, the RXTE All-Sky Monitor detected an outburst at the position of SMC X-2 (Corbet, Marshall, Coe et al. (2001)) and a pulse period of 2.374±0.007 s was determined (Corbet & Marshall (2000); Torii, Kohmura, Yokogawa & Koyama (2000)). The source was in low luminosity state during the XMM-Newton observation (Sasaki, Pietsch & Haberl (2003)). In order to estimate the flux upper limit Sasaki, Pietsch & Haberl (2003) used spectral parameters derived by Yokogawa, Torii, Kohmura & Koyama (2001) from the ASCA spectrum during the outburst. They obtained an upper limit for the un-absorbed flux of 1.5 x 10^-14 erg cm^-2 s^-1, corresponding to L_x =  6.5 x 10³³ erg s^-1 (0.3-10.0 keV).

J0054.5-7228
(RX J0054.5-7228)
Haberl & Sasaki (2000) have found six emission-line objects from (Meyssonnier & Azzopardi (1993)) as possible counterparts to this X-ray source. It is therefore a likely Be/X-ray binary but the optical counterpart remains ambiguous.

J005446.2-722523
(CXOU J005446.2-722523)
...

J0054.8-7244
(AX J0054.8-7244, RX J0054.9-7245, XMMU J005455.4-724512, CXOU J005455.6-724510, SXP 504)
Small ROSAT error box of this source contains an emission-line star (809 in (Meyssonnier & Azzopardi (1993))) with typical Be star characteristics, it is the brightest object in the area of localization. A factor of five X-ray flux variability strengthens the identification as Be/X-ray binary. A probable binary period of 268 days has been detected in the optical counterpart (Edge, Coe & Galache (2005)). The relationship between this orbital period and the pulse period of 504s is within the normal variance found in the Corbet diagram (Corbet (1984)). Schmidtke & Cowley (2005) found a period of 273 d in OGLE data. Galache, Corbet, Coe et al. (2008) derived the ephemeris of MJD 52167.4 ± 8.0 + n × 265.3 ± 2.9 d. This source displays a lot of activity in between periastron passages, which might be indicative of a low eccentricity orbit (Galache, Corbet, Coe et al. (2008)). Pulsed fraction obtained from 0.2-10.0 keV EPIC-PN pulse profiles is 39 ± 16 % (Haberl, Eger & Pietsch (2008)).

J0054.9-7226
(2E 0053.2-7242, RX J0054.9-7226, 1WGA J0054.9-7226, SAX J0054.9-7226, RX J0054.9-7227, XTE J0055-724, SXP 59.0)
RX J0054.9-7226 is known to be an X-ray binary pulsar with a pulse period of  58.969±0.001 s (Marshall, Lochner, Santangelo et al. (1998); Santangelo, Cusumano, dal Fiume et al. (1998)). Lochner, Whitlock, Corbet & Marshall (1999) have suggested the orbital period equal to 65 days from subsequent X-ray outbursts. Laycock, Corbet, Coe et al. (2004) have obtained the orbital period about 123 days based on the timing analysis. In the timing analysis of the XMM-Newton data, the pulse period was verified to be 59.00±0.02 s (Sasaki, Pietsch & Haberl (2003)). The optical counterpart, a Be star, is identified with the variable star OGLE J005456.17-722647.6 (Zebrun, Soszynski, Wozniak et al. (2001)). Pulsed fraction obtained from 0.2-10.0 keV EPIC-PN pulse profiles is 90 ± 23 % (Haberl, Eger & Pietsch (2008)).

J005517.9-723853
(XMMU J005517.9-723853, SXP 701)
This bright X-ray source was detected during XMM-Newton observation of the SMC region around XTE J0055-727 (Haberl, Pietsch, Schartel et al. (2004)). The optical brightness and colors are consistent with expectations for a Be star companion, and the X-ray spectra are consistent with Be/X-ray binary. Using MACHO and OGLE-II data, Schmidtke & Cowley (2004) obtained the data showing a possible long-term period of 413 days, but further analysis is needed to confirm it.

J0055.4-7210
(RX J0055.4-7210, 2E 0053.7-7227, CXOU J005527.9-721058, WW 36, SXP 34.1)
Timing analysis on this object revealed a period of 34.08±0.03 s with a confidence of 98.5% (Edge, Coe, Galache et al. (2004)). The position of this pulsar is within 3 arcsec of the ROSAT source 2RXP J005527.1-721100. The latter is coincident with a 16.8 V magnitude optical source having a B-V color index of -0.116 (Zaritsky, Harris, Thompson et al. (2002)) which would be consistent with the value expected from the optical companion in a Be/X-ray binary.

J005535.2-722906
(XMMU J005535.2-722906)
This X-ray source was found by Haberl, Eger & Pietsch (2008) during eight XMM-Newton observations toward the Small Magellanic Cloud (SMC), performed between October 2006 and June 2007. The pulse period is 644.55±0.72 s. As optical counterpart they identify a star with V∼14.6 which shows a sudden brightness increase by ∼0.85 mag and ∼0.6 mag in the MACHO R- and B-band light curves. Pulsed fraction obtained from 0.2-10.0 keV EPIC-PN pulse profiles is 14 ± 14 % (Haberl, Eger & Pietsch (2008)).

0054.4-7237
(2E 0054.4-7237, XMMU J005605.2-722200, WW 38, SXP 140)
The error circle of the Einstein source 2E 0054.4-7237 contains an emission line object. Therefore, it was suggested as a Be/X-ray binary candidate (Sasaki, Pietsch & Haberl (2003)). In the XMM-Newton data, a source consistent with the position of the emission line object was detected (XMMU J005605.2–722200) and pulsations from this source were discovered (Sasaki, Pietsch & Haberl (2003)). XMMU J005605.2-722200 is most likely consistent with 2E 0054.4-7237. The pulsar period is 140.1±0.3 s. The probable orbital period is 197±5 days (Schmidtke & Cowley (2006)).

J0057.4-7325
(AX J0057.4-7325, RX J0057.3-7325, SXP 101)
Six ROSAT observations have covered the position of AX J0057.4-7325. Coherent pulsations with a barycentric period of 101.45±0.07 s were discovered by Yokogawa, Torii, Kohmura et al. (2000) with ASCA. McGowan, Coe, Schurch et al. (2007) have determined that the optical counterpart is the star MACS J0057-734 10. They found a period of 21.94±0.10 days in both the OGLE III and MACHO data. Schurch, Coe, McGowan et al. (2007) estimated the luminosity class of the optical counterpart to be about Ib-II. A luminosity class of Ib-II would make the counterpart a supergiant and not a Be star. This luminosity classification should be treated cautiously due to the methods used (Schurch, Coe, McGowan et al. (2007)). The flux variability, the hard X-ray spectrum, and the long pulse period are consistent with the hypothesis that AX J0057.4-7325 is an X-ray binary pulsar with a companion which is either a Be, an OB supergiant, or a low-mass star. Yokogawa, Torii, Kohmura et al. (2000) note that OB supergiant X-ray binaries in the SMC (only SMC X-1 and EXO 0114.6-7361) are both located in the eastern wing and this fact may lead us to suspect that AX J0057.4-7325 would be the third example.

J005736.2-721934
(CXOU J005736.2-721934, XMMU J005735.6-721934, XMMU J005736.5-721936, SXP 565)
CXOU J005736.2-721934 was originally discovered in Chandra observation in 2001 (Macomb, Fox, Lamb & Prince (2003)) where it was reported to have a pulse period of 565.83s. This X-ray source was also found by Sasaki, Pietsch & Haberl (2003) in XMM-Newton EPIC data. XMMU J005735.6-721934 has a hard spectrum and positionally coincides with emission line object 1020 in (Meyssonnier & Azzopardi (1993)). An optical period of 95.3 d has been reported for this system (Schmidtke, Cowley, Levenson & Sweet (2004)), but this period is not seen in OGLE data (Edge (2005)). Galache, Corbet, Coe et al. (2008) derived the ephemeris of MJD 52219.0 ± 13.7 + n × 151.8 ± 1.0 d.

J0057.8-7202
(AX J0058-720, RX J0057.8-7202, SXP 280)
The pulse period of AX J0058-720 was determined from the ASCA data as 280.4±0.3 s (Yokogawa & Koyama (1998)). Sasaki, Pietsch & Haberl (2003) confirmed this value using the XMM-Newton data:  281.1±0.2 s. The source has been suggested to be a Be/X-ray candidate due to a likely optical counterpart, which is an emission line object. The outburst period is 127.3±1.0 days (Schmidtke, Cowley & Udalski (2006)).

J0057.8-7207
(CXOU J005750.3-720756, RX J0057.8-7207, XMMU J005749.9-720756, XMMU J005750.3-720758, SXP 152)
This source is a Be/X-ray candidate with an emission line object 1038 in (Meyssonnier & Azzopardi (1993)) suggested as a likely optical counterpart (Haberl & Sasaki (2000)). Sasaki, Pietsch & Haberl (2003) discovered pulsations in the new XMM-Newton data and derived a pulse period of 152.34±0.05 s. For this source, a pulsar period was independently found in Chandra data by Macomb, Fox, Lamb & Prince (2003).

J0057.9-7156
(RX J0057.9-7156)
This source is a Be/X-ray binary candidate because of a positional coincidence with the emission-line object 1044 in (Meyssonnier & Azzopardi (1993)), according to Haberl & Sasaki (2000).

J0058.2-7231
(RX J0058.2-7231, RX J0058.3-7229)
Schmidtke, Cowley, Crane et al. (1999) reported the detection of this very weak X-ray source by ROSAT HRI. Its optical counterpart is a variable Be star in the SMC, OGLE 00581258-7230485 (Zebrun, Soszynski, Wozniak et al. (2001)). Schmidtke, Cowley, Levenson & Sweet (2004) have proposed the orbital period of 59.72 days using V, R and I data from the MACHO and OGLE-II surveys. The pulse period is 291.327 ± 0.057 (Haberl, Eger & Pietsch (2008)). Pulsed fraction obtained from 0.2-10.0 keV EPIC-PN pulse profiles is 17 ± 6 (Haberl, Eger & Pietsch (2008)). XTE J0051-727 and RX J0058.2-7231 are very likely the same source.

J0059.3-7223
(RX J0059.3-7223, XMMU J005921.0-722317, XMMU J005920.8-722316, SXP 202)
This X-ray pulsar was discovered by Majid, Lamb & Macomb (2004). There are two variable stars in both the OGLE (OGLE 151891) and MCPS (MCPS 3345630) catalogs which are suggested as the optical counterparts for this X-ray source. The angular distance between these two catalog stars is only 0.3 arcseconds, consistent with being the same source (Majid, Lamb & Macomb (2004)). The absolute B magnitude (-4.1) of this star is approximately consistent with a B0 star. Galache, Corbet, Coe et al. (2008) noted that a ~91 d orbital period would agree with the 6 X-ray outburst detections.

J005929.0-723703
(XMMU J005929.0-723703)
This X-ray source was found by Haberl, Eger & Pietsch (2008) during eight XMM-Newton observations toward the Small Magellanic Cloud (SMC), performed between October 2006 and June 2007. The pulse period is 202.52±0.02 s. From the X-ray position they identify a Be star as optical counterpart. The light curves obtained from the MACHO database show a long-term brightness increase with ~0.05 mag variations on top of it. Haberl, Eger & Pietsch (2008) applied an FFT analysis to the MACHO R-band data to look for periodicity. The power spectrum showed the strongest peaks at 334 days and 220 days (with power of 26 and 16, respectively). Haberl, Eger & Pietsch (2008) concluded that although similarly long orbital periods were suggested for SMC Be/X-ray binaries, the broad peaks indicate more quasi-periodic variations as they might be expected from changes in the Be disk. Schurch & Udalski (2008) proposed the binary period of the system to be 229.9 d from Lomb-Scargle analysis. This period combined with the pulse period (202s) places the source directly in the centre of the distribution of Be/X-ray binaries on the Corbet diagram. Pulsed fraction obtained from 0.2-10.0 keV EPIC-PN pulse profiles is 12.4 ± 0.1 % (Haberl, Eger & Pietsch (2008)).

J0059.2-7138
(RX J0059.2-7138)
The supersoft source RX J0059.2-7138 was detected serendipitously with the ROSAT PSPC in 1993 and was seen almost simultaneously by ASCA (Hughes (1994); Kylafis (1996)). Previously, it had failed to be detected by either the Einstein Observatory or EXOSAT in the early 1980s,or in pointed ROSAT observations of 1991. The transient nature of this source is clearly established. The best fit to the X-ray spectrum consists of three components (Kylafis (1996)): two power laws with indices 0.7 and 2.0 fit the spectrum in the > 3 KeV and 0.5-3.0 keV bands respectively. Furthermore, the emission is pulsed at levels of ~35% and ~20% in these respective bands, with a period of ~2.7 s (Hughes (1994)). Southwell & Charles (1996) identified the probable optical counterpart of this source with a 14th-magnitude B1 III emission star lying within the X-ray error circle. Schmidtke, Cowley & Udalski (2006) have proposed the orbital period of 82.1±0.4 days.

J010030.2-722035
(XMMU J010030.2-722035)
This X-ray source was found by Sasaki, Pietsch & Haberl (2003) in XMM-Newton EPIC data. XMMU J010030.2-722035 has a hard spectrum and positionally coincides with emission line object 1208 in (Meyssonnier & Azzopardi (1993)). This source was very faint during the XMM-Newton observation. It was suggested as a new Be/X-ray candidate.

J0101.0-7206
(RX J0101.0-7206, CXOU J010102.7-720658, XMMU J010103.1-720702, XMMU J010102.5-720659, SXP 304)
The X-ray transient RX J0101.0-7206 was discovered in the course of ROSAT observations of the SMC in October 1990 (Kahabka & Pietch (1996)) at a luminosity of 1.3 x 10³⁶ erg s^-1. The source showed a luminosity of 3 x 10³³ erg s^-1 in the ROSAT band (0.1-2.4 keV) during two XMM-Newton observations (Sasaki, Pietsch & Haberl (2003)). Pulsations with a period of  304.49±0.13 s were discovered in Chandra data (Macomb, Fox, Lamb & Prince (2003)). This period could not be verified in the XMM-Newton observation, because the source was too faint. Edge & Coe (2003) presented results on the optical analysis of likely counterparts, discussing two objects (Nos. 1 and 4) in the ROSAT PSPC error circle. They conclude that the optical counterpart is object No. 1 which is confirmed to be a Be star. A possible orbital period of 520 days is suspected, but further data are needed to confirm this (Schmidtke & Cowley (2005)). Macomb, Fox, Lamb & Prince (2003) measured an unusually high pulse fraction of 90 ± 8% at a luminosity of L_x = 1.1 × 10³⁴ erg s⁻¹.

J0101.3-7211
(RX J0101.3-7211, SXP 452)
The source was detected in ROSAT observations and proposed by Haberl & Sasaki (2000) as a Be/X-ray candidate. Pulsations were detected in XMM observations during 2001 at 455 ± 2 s and in 1993 ROSAT data at 450 – 452 s (Sasaki, Haberl, Keller & Pietsch et al. (2001)). The optical counterpart was identified as a Be star by Sasaki, Haberl, Keller & Pietsch et al. (2001). Schmidtke, Cowley, Levenson & Sweet et al. (2004) proposed an orbital period of 74.7 d for this system based on its optical variability.

J0101.6-7204
(RX J0101.6-7204)
Haberl & Sasaki (2000) suggested the identification of RXJ0101.6–7204 with object 1277 in (Meyssonnier & Azzopardi (1993)) from two accurate positions from ROSAT HRI and PSPC observations. The factor of three variability supports a Be/X-ray binary nature of this source.

J0101.8-7223
(AX J0101.8-7223, XMMU J010152.4-722336)
Haberl & Sasaki (2000) suggested this source as a Be/X-ray binary. They proposed the emission-line star 1288 in (Meyssonnier & Azzopardi (1993)) as a probable optical counterpart. This star exhibits magnitudes typical for a Be star in the SMC and is located near the overlapping area of HRI and PSPC error circles.

J010206.6-714115
(CXOU J010206.6-714115)
CXOU J010206.6-714115 is one of the pulsars detected on 06 February 2006 in the SMC wing survey (Schurch, Coe, McGowan et al. (2007)). The position of this pulsar coincides with the emission line star [MA93] 1301 (Meyssonnier & Azzopardi (1993)), the V = 14.6 mag O9 star AzV 294. This strongly suggests the identification of this object as a Be/X-ray binary. Timing analysis of this object revealed a period of 700.54±34.53 s with a confidence of > 99% (McGowan, Coe, Schurch et al. (2007)). Haberl, Eger & Pietsch (2008) reanalysed the Chandra data of CXOU J010206.6-714115 and suggested that the period of 700 s is caused by the satellite dithering. Their Bayesian analysis yielded 966.97±0.47 s for the pulse period. Pulsed fraction obtained from 0.2-10.0 keV EPIC-PN pulse profiles is 32±17 (Haberl, Eger & Pietsch (2008)). The OGLE III light curve shows a strong period at 267.38±15.10 d (McGowan, Coe, Schurch et al. (2007)).

J0103-728
(XTE J0103-728, SXP 6.85)
This source was detected with the RXTE Proportional Counter Array (Corbet, Markwardt, Marshall et al. (2003)). The precise localization in the EPIC images allowed Haberl, Pietch & Kahabka (2007) to identify the optical counterpart of XTE J0103-728 which shows optical brightness and colours consistent with a Be star. Schmidtke & Cowley (2007) found a weak optical periodicity at P=24.82 days. Galache, Corbet, Coe et al. (2008) found a significant X-ray period of 112.5 days which is the minimum time lapse between any two X-ray outbursts.

J0103-722
(AX J0103-722, 2E 0101.5-7225, SAX J0103.2-7209, CXOU J010314.1-720915, 1E 0101.5-7226, SXP 348)
For the Be/X-ray binary AX J0103-722 a pulse period of 345.2±0.1 s was determined by Israel, Stella, Campana et al. (1998). In the XMM-Newton data, pulsations were confirmed with a period of  341.7±0.4 s (Sasaki, Pietsch & Haberl (2003)). This source was detected with a nearly constant flux in all the Einstein, ROSAT and ASCA pointings which surveyed the relevant region of the SMC. Analysis of the I photometry shows a weak period at 93.9 days (Schmidtke & Cowley (2006)). The Chandra source is coincident with object 1367 (Meyssonnier & Azzopardi (1993)), a Be star (Hughes & Smith (1994), Israel, Stella, Campana et al. (1998)).

J0103.6-7201
(RX J0103.6-7201)
Haberl & Sasaki (2000) identified this source with object 1393 in (Meyssonnier & Azzopardi (1993)). RX J0103.6-7201 shows variability by a factor of three between the ROSAT observations, consistent with a Be/X-ray binary. Haberl & Pietsch (2005) reported the discovery of 1323 s periodicity of this source. Schmidtke & Cowley (2006) found three strong periods for this source from OGLE II data: 0.41 d, 0.88 d and 26.16 d. They attributed the first two to non-radial pulsations of the Be star but suggest the latter might be the orbital period.

J0104.1-7244
(RX J0104.1-7244)
The most likely identification with emission-line star 1440 in (Meyssonnier & Azzopardi (1993)) suggests RX J0104.1-7244 as a Be/X-ray binary (Haberl & Sasaki (2000)).

J0104.5-7221
(RX J0104.5-7221, RX J0105.5-7221)
Haberl & Sasaki (2000) reported that this source was not detected by the ROSAT PSPC but the accurate HRI position included only the emission-line object 1470 from (Meyssonnier & Azzopardi (1993)) as a bright object in the error circle. RX J0104.5-7221 is therefore very likely a Be/X-ray binary.

J0105-722
(AX J0105-722, RX J0105.3-7210, RX J0105.1-7211, SXP 3.34)
Yokogawa & Koyama (1998) reported AX J0105-722 as an X-ray pulsar with a period of 3.34 s. From ROSAT PSPC images Filipovic, Haberl, Pietsch & Morgan (2000) resolved this source into several X-ray sources. They combined X-ray, radio-continuum and optical data to identify the sources: for RX J0105.1-7211 they proposed an emission line star from the catalogue of Meyssonier & Azzopardi in the X-ray error circle as a likely optical counterpart. This catalogue contains several known Be/X-ray binaries strongly suggesting RX J0105.1-7211 as a new Be/X-ray binary in the SMC.

J0105.9-7203
(RX J0105.9-7203, AX J0105.8-7203)
A single bright object (the emission-line star 1557 in (Meyssonnier & Azzopardi (1993))) was found in the small ROSAT PSPC error circle (source 120) (Haberl & Sasaki (2000)), which made the identification of RX J0105.9–7203 as Be/X-ray very likely. Eger & Haberl (2008) report the discovery of X-ray pulsations with a long period of ~726 s in seven XMM-Newton observations and confirm a V ~15.6 mag star as the optical counterpart. The hard X-ray spectrum was well represented by a simple absorbed power-law, typical for Be/X-ray binary pulsars, with peak intrinsic luminosity 1.58 x 10³⁵ erg s^-1 (0.2-10.0 keV). They estimate the spectral class of the optical counterpart from its B-V colour index to B0.5-B3. They expect an orbital period between ~63 days and ~251 days based on the Corbet diagram (Corbet (1986)).

J0106.2-7205
(SNR 0104-72.3, RX J0106.2-7205, 2E 0104.5-7221)
SNR 0104-72.3 contains a pointlike X-ray source with a blue optical counterpart and Hα emission.

J010712.6-723533
(CXOU J010712.6-723533, RX J0107.1-7235, AX J0107.2-7234, 2E 0105.7-7251, SXP 65.8)
Haberl & Sasaki (2000) have identified this source with the emission-line star 1619 in (Meyssonnier & Azzopardi (1993)). Observations of a varying Hα emission line and a classification of B1-B1.5 confirm SXP 65.8 as a Be/X-ray binary (Schurch, Coe, McGowan et al. (2007)). A 110.6 d period has been observed in the MACHO data for this object (Schmidtke & Cowley 2007b). Pulsed fraction obtained from 0.2-10.0 keV EPIC-PN pulse profiles is 31 ± 9 % (Haberl, Eger & Pietsch (2008)).

0107-750
(1H 0103-762, H 0107-750)
This source is a very bright UV object with prominent Hα and H emission.

J0111.2-7317
(XTE J0111.2-7317, XTE J0111-732(?), SXP 31.0)
The X-ray transient XTE J0111.2-7317 was discovered by the RXTE X-ray observatory in November 1998 (Chakrabarty, Levine, Clark et al. (1998)). Analysis of ASCA observation (Chakrabarty, Takeshima, Ozaki et al. (1998); Yokogawa, Imanishi, Tsujimoto et al. (2000)) identified this source as a 31 s X-ray pulsar with a flux in the 0.7-10 keV band of  3.6 x 10^-10 erg cm^-2 s^-1 and ~45% pulsed fraction. The detection was also confirmed from the BATSE telescope on the CGRO satellite which detected the source in the hard 20-50 keV band with a flux ranging from 18 to 30 mCrab (Wilson & Finger (1998)). The source was not detected by ROSAT. In the X-ray error box of XTE J0111.2-7317 Covino, Negueruela, Campana et al. (2001) found a relatively bright object (V=15.4) which has been classified as a B0.5-B1Ve star and that was later confirmed by Coe, Haigh & Reig (2000) as the most plausible counterpart for XTE J0111.2-7317. There is also evidence for the presence of a surrounding nebula, possibly a supernova remnant (Covino, Negueruela, Campana et al. (2001)). Analysis of the OGLE-III photometry reveals a pronounced orbital period at P=90.4±0.5 days (Schmidtke, Cowley & Udalski (2006)).

J0117.6-7330
(RX J0117.6-7330, SXP 22.1)
This X-ray transient was discovered by the PSPC on board ROSAT (Clark, Remillard & Woo (1996); Clark, Remillard & Woo (1997)). Soria (1999) conducted spectroscopic and photometric observations of the optical companion of the X-ray transient RX J0117.6-7330 during a quiescent state. The primary component was identified as a B0.5 IIIe star. Macomb, Finger, Harmon et al. (1999) reported on the detection of pulsed, broadband, X-ray emission from this transient source. The pulse period of 22 s was detected by the ROSAT/PSPC instrument and by the Compton Gamma-Ray Observatory/BATSE instrument. The total directly measured X-ray luminosity during the ROSAT observation was  1.0 x 10³⁸ erg s^-1. The pulse frequency increased rapidly during the outburst with a peak spin-up rate of  1.2 x 10^-10 Hz s^-1 and a total frequency change of 1.8%. The pulsed percentage was 11.3% from 0.1-2.5 keV, increasing to at least 78% in the 20-70 keV band. These results established RX J0117.6-7330 as a transient Be binary system.

J0119.6-7330
(RX J0119.6-7330)
This source was detected once in the 0.9-2.0 keV band of the ROSAT PSPC. An emission-line object in the error circle suggests an Be/X-ray binary (Haberl & Sasaki (2000)).

J0119-731
(XTE J0119-731, SXP 2.16)
This source was detected in the RXTE Proportional Counter Array observations with intensity about 0.625 mCrab, and a period of 2.1652±0.0001 s (Corbet, Markwardt, Marshall et al. (2003)). Coe & Gaensicke (2003) identified two emission-line optical counterparts were first identified by searching the XTE error box using SIMBAD : 1864 in (Meyssonnier & Azzopardi (1993)) and Lin 526. The second source, Lin 526, exhibited strong Hα and H emission. Coe & Gaensicke (2003) proposed Lin 526 as the most likely counterpart to XTE J0119-731.

J0209.6-7427
(RX J0209.6-7427)
The discovery of an X-ray binary RX J0209.6-7427 in the outer wing of the SMC is reported by Kahabka & Hilker (2005) from two archival ROSAT PSPC observations. The data show variability in the X-ray light curve with a timescale of ~40 days that probably is related to the binary orbital period of the system (Kahabka & Hilker (2005)). A V=14 mag star in the X-ray error circle of the source is the likely optical counterpart. The optical spectrum of the star shows Hα emission. The spectral type of the star is constrained as B0-B1.5IV-Ve and consistent with that of a Be star (Kahabka & Hilker (2005)). The mean X-ray luminosity of the source is derived to be ~1.0×10³⁸ erg s^-1 (for a distance of 60 kpc), which is comparable to luminosities derived for Be-type X-ray binaries in the body of the SMC (Kahabka & Hilker (2005)). This makes RX J0209.6-7427 the first candidate Be-type X-ray binary discovered in the outer SMC wing that directly extends into the Magellanic Bridge.

XTE SMC144s
(XTE SMC144s, SXP 144)
The source position is not accurately known. Corbet, Laycock, Marshall et al. (2003) have detected this transient X-ray pulsar in the Small Magellanic Cloud with the RXTE Proportional Counter Array. They interpreted the outburst recurrence period as the orbital period of a neutron/Be star binary with outbursts occurring at periastron passage.