Date and Time of the Query: 2022-01-18 T08:09:05 PST
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Notes for object MESSIER 080

2 note(s) found in NED.

1. 2001A&A...368..137V
Re:NGC 6093
3.18 NGC 6093/M 80
The ROSAT PSPC observation of this cluster shows one source in the center,
which may or not be the nova 1860 T Sco (Hakala et al. 1997). The ROSAT
image contains many sources, from which I retain in Table 2 only those with
nominal positional accuracy better than 10". Three sources with good X-ray
positions can be identified with stars. Two of these X-ray sources, those
identified with the T Tau star VV Sco (an M 1 star with B = 12, X1) and
with HD 146516 (a G1 V star with V = 10.14, X14) are listed as extended by
the EXSAS software. I therefore determine the offset between X-ray and
optical coordinates from X7 only, identified with HD 146457 (an A5III/IV
star with V = 8.46). The offset is applied to the X-ray positions, and the
resulting positions are listed in Table 2. The uncertainties {DELTA} in the
source positions as listed in the table are the nominal uncertainties for
the detector position only; to these must be added in quadrature the random
uncertainty in positions for PSPC sources of 3", which remains even after a
bore sight correction has been applied (Hasinger et al. 1998). The
uncertainty in the bore sight correction thus is 3.5" (assuming a 1" error
in the optical position). The offset between the central source X10 and
T Sco is 8.7" +/- 6.6", and the identification is possible. The core radius
of NGC 6093 is about 9", and the uncertainty of the position of X10 is such
that it could be identified with any source located in the cluster core. I
consider the identification of X10 with T Sco to be unproven.

2. 1918PLicO..13....9C
Re:NGC 6093
Small, bright, globular cluster; the diameter of the brighter part is 3'. 5 s.n.

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