This was generated with James on Monday, September 14
There's some confusion about which source in the Carina field is HD93129B

James has analyzed the longest single OBS ID of the seven grating observations of the HD93129 field. See James's annotated image with extracted sources: 

http://astro.swarthmore.edu/~jmacart1/HD_93129/obs5/extraction_region.png
http://astro.swarthmore.edu/~jmacart1/HD_93129/field_ids.PNG

Is source 5 or 4 HD93129B?  

Source 4 seems to agree with the Skiff catalog position of the star, but the GOSC (Maiz-Apellaniz et al.) lists a different position - one closer to component A (A is source 6 in James's map) - similar to our source 5.  Subsequently (18Sep09) Yael wrote to say that the position in the Skiff catalog for B is wrong. 

Simbad
A: 		    10 43 57.46 -59 32 51.3
B: 		    10 43 57.4516 -59 32 51.409
IDS 10401-5901 D:   10 43 57.6 -59 32 56 

(Note: It looks like B really isn't in simbad; those coords are essentially the same as A's.) 

Source Detect of Chandra grating data (my original labeling, the IDS obj is what Skiff says is B)
A 		    160.98944 -59.54761   ==> 10 43 57.46548 -59 32 51.3960
B 		    160.99019 -59.548228  ==> 10 43 57.64548 -59 32 53.6208
IDS 10401-5901 D:   160.98998 -59.549369  ==> 10 43 57.59508 -59 32 57.7284

Galactic O Star Catalog (GOSC)
A 10 43 57.462 -59 32 51.27
B 10 43 57.638 -59 32 53.50

Skiff
A 10 43 57.46 -59 32 51.3
B 10 43 57.55 -59 32 56.9


Yael says: 

We found a problem with the Skiff catalog : the coordinates of HD93129B
are wrong. They whould be 10:43:57.638 -59:32:53.5, with V=8.9 and
B-V=0.22.

David says (22sep09): 

The position of our source 6 does indeed correspond to the consensus position of HD93129A. 

And the position of our source 5 corresponds with the position of HD93129B, according to the GOSC. The offset between the Chandra position of source 5 and the GOSC position is ~0.15 arcsec.

Source 4 corresponds quite well to the position of the source SIMBAD calls IDS 10401-5901 D.  Is this object the one Skiff assumed was HD93129B?  Well... the offset between Skiff's HD93129B position and source 4 is a bit over 1 arcsec.  So...maybe, but that offset seems a little big.  

Once final image of the Chandra HETGS HD93129 field: 
http://astro.swarthmore.edu/~cohen/projects/carina/HD93129B_iding.PNG
which shows the relative angular separations of the three sources.