1 IGR J17454-2919: the nature of this transient source is still unclear. 
 1  Paizis et al. (2015ApJ...808...34P) has proposed that 
 1  2MASS J17452768-2919534 is the IR counterpart although it is 2.4" away from 
 1  the X-ray position.
 2 IGR J17451-3022 has shown periodicity in its light curve of ~6.3h Jaisawal 
 2  et al. (2015ATel.7361....1J) which would imply a >70{deg} inclination. 
 2  However the nature of the compact object is still unclear and it might be a 
 2  magnetar Heinke et al. (2014ATel.6459...1H).
 3 MAXI J1836-194: There is a field star 0.37" away from the position of the 
 3  BH candidate Russell2014.
 4 MAXI J1543-564 has no clear counterpart in optical/IR. Rau et al. 
 4  (2011ATel.3365....1R) reported 3 possible objects close or within the radio 
 4  (Miller-Jones et al., 2011ATel.3364....1M) and X-ray (Kennea et al.,
 4  2011ATel.3336....1K) error circles.
 5 Swift J1357.2-0933 in rigour is not a dynamical BHT because it lacks a 
 5  detection of the secondary star but it has robust mass function 
 5  determination (Corral-santana et al., 2013Sci...339.1048C; Mata Sanchez et
 5  al., 2015MNRAS.454.2199M). The distance is still uncertain (see 
 5  Rau et al., 2011ATel.3140....1R; Shahbaz et al., 2013MNRAS.434.2696S;
 5  Mata Sanchez et al., 2015MNRAS.454.2199M).
 6 XTE J1652-453 has no clear counterpart in IR and there are doubts between 
 6  close objects.
 7 Swift J174540.2-290005 is 1pc from Sgr A* assuming an 8.5kpc distance 
 7  (Kennea et al., 2006ATel..920....1K, 2006ATel..921....1K). If this transient
 7  is an X-ray binary it would be a LMXB (Wang et al., 2006ATel..935....1W).
 8 IGR J17497-2821 seems to be blended with a bright star SE of the target 
 8  (Torresi et al., 2006ATel..909....1T). Probably located in the Galactic 
 8  bulge.
 9 Swift J1753.5-0127 remains in a low/hard X-ray state since its outburst 
 9  in 2005.
10 IGR J17091-3624 showed outbursts in 2007 (Capitanioi et al., 
10  2009ApJ...690.1621C) and 2011 (Krimm et al., 2011ATel.3144....1K). 
10  Re-examination of archival data showed that is was also active in 1994, 
10  1996 and 2001 (Revnivtsev et al., 2003ATel..150....1R, int'Zand et al., 
10  2003ATel..160....1I; Capitanio et al., 2009ApJ...690.1621C).
11 XTE J1118+480 showed an outburst in 2005 (Zurita et al., 2005ATel..383....1Z)
12 XTE J2012+381 is blended with a star at 1.1" (Hynes et al., 
12  1999MNRAS.305L..49H).
13 XTE J1748-288 showed hard spectrum. No counterpart has been found. An 
13  unresolved radio source was detected (Hjellmingi et al., 1998, BAAS, 
13  30, 103.08) but it was located 1' away from the center of the 1' 
13  uncertainty RXTE position (Strohmayer & Marshall, 1998IAUC.6934R...1S).
14 XTE J1550-564 showed a second complete outburst in 2000 (Smithi et al.,
14  2000IAUC.7399Q...1S) and other three faint mini-outbursts in 2001, 2002 and 
14  2003 (Tomsicki et al., 2001IAUC.7575....2T; Belloni et al., 
14  2002A&A...390..199B; Dubath et al., 2003IAUC.8100....1D).
15 XTEJ1755-324 has an error radius of 1' in the coordinates (Remillardi et al.,
15  1997IAUC.6710Q...1R).
16 GRS 1737-31 is supposed to be close to the Galactic center (Ueda et al.,
16  1997IAUC.6627R...1U).
17 GRS 1739-278 showed another outburst in 2014 (Milleri et al., 
17  2015ATel..7612....M).
18 XTE J1856+053 has shown two consecutive outbursts with ~70 days interval 
18  between them (Sala et al., 2008A&A...489.1239S). This behaviour was seen in 
18  the 1996 and 2007 outbursts (Levine & Remillard, 2007ATel.1024....1L); 
18  Krimm et al., 2007ATel.1093....1K; Sala et al., 2008A&A...489.1239S). 
18  This also appeared in the the recent 2015 outburst (Suzukii et al.,
18  2015ATel.7233....1S; Negoro et al., 2015ATel.7579....1N).
19 KS 1730-312 has an error radius in the astrometry of 3' (Vargas et al.,
19  1996A&A...313..828V).
20 GRO J1655-40 (N. Sco 1994) has shown several outburst.
21 GRS J1915+105 has remained in outburst since its discovery in 1992 
21  (Castro-Tirado et al., 1992IAUC.5590....1C). It is included here because it 
21  was detected as a transient source.
22 GS 2023+338 (V404 Cyg) showed two outbursts detected in plate scales (1938 
22  and 1956) prior to its detection in X-rays in 1989 (Wachmann, 1948,
22  Berlin, Akademie-Verlag; Richter, 1989IBVS.3362....1R. It has shown another
22  outburst in 2015 (Barthelmy et al., 2015GCN.17929....1B).
23 GS 1354-64 (BW Cir) is associated with MX 1353-64 which showed an outburst in
23  1971-1972. It showed another outburst in 1997 (Remillard et al., 
23  1997IAUC.6710R...1G) and 2015 (Miller et al., 2015ATel.7612....1M).
24 EXO 1846-031 does not have a known counterpart. The error radius in the 
24  coordinates is 11" (ParmarR et al., 1993A&A...279..179P).
25 SLX 1746-331 is a galactic centre source and therefore suffer of large 
25  extinction. It showed outbursts in 2003 (Markwardt & Swank, 
25  2003ATel..133....1M) and 2007 (Markwardt & Swank, 2007ATel.1235....1M). 
25 It also showed some activity in 2011 (Ozawa et al., 2011ATel.3098....1O).
26 H 1743-322 has shown several outbursts.
27 3A 0620-003 showed an outburst in 1917 detected in plate scales prior to its 
27  detection in X-rays in 1975 (REachus et al., 1976ApJ...203L..17E). .
28 KY TrA showed another outburst in 1990 (Barreti et al., 1992ApJ...392L..19B).
29 1H J1659-487 (GX 339-4) is a quasi persistent source.
30 4U 1755-338 is a quasi persistent system. This system stayed in outburst for
30  25yr until 1996 (Roberts et al., 1996IAUC.6302R...1R); 
30  Angelini & White, 2003ApJ...586L..71A).
31 4U 1543-475 have shown outbursts in 1984, 1992 and 2002 (Kitamoto et al., 
31  1984PASJ...36..799K; Harmon et al., 1992IAUC.5504....1H; Miller & Remillard 
31  (2002ATel...98....1M)
32 4U 1630-472: It has shown quasi-periodic outbursts with recurrence times of 
32  ~600-700d and durations of 100-200d (Kuulkerscw et al., 1997MNRAS.291...81K)
33 Cen X-2 is the first transient XRB ever discovered. It has an uncertain 
33  position. Kitamoto (1990ApJ...361..590K) proposed that it might be 
33  GS 1354-64 (BW Cir), rediscovered in 1987. However, if this were true, it 
33  would imply an extreme X-ray flux at its distance of 25kpc 
33  (Casares et al., 2009ApJS..181..238C).