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(fwd) re NSV 16694 and 16693 The following message is from John Greaves: Well, it's tricky, but the IRAS source and nebulosity seem to be more associated with NSV 16693 ~30" to the north, though the whole complex seems to be included together by some. Also known as IRS1 (....3) and IRS2 (....4), again usually lumped together as a system, although with separate measurements. http://vizier.u-strasbg.fr/viz-bin/getCatFile?J/A%2bA/352/228/north/h075.ps http://vizier.u-strasbg.fr/viz-bin/getCatFile?J/A%2bA/352/228/south/fig05482.ps Though I'm having difficulty deciding whether the NSV object to the north is actually stellar. There's even linearly polarized radio waves from neutral hydrogen it seems, with the polarization flux a quarter to a fifth as strong as the overall flux. At the edge of, and probably being part of, dark nebula L1617, and it looks like the extinction in this part of Orion is higher than average (probably with E(B-V) ~ 0.6 here, pulling (B-V)_0 back to ~ 0), before even considering the nebulosity immediately surrounding the star(s). Maybe in the OMC? A&A 352 228 is just that bit too recent to be available online. Unfortunately, due to the scale on the sky and the relative displacement of all the objects and nebulosity, you've got to worry a little as to whether some ccd and photographic based magnitude variations are real or more consequent on varying seeing, especially low amplitude ones, though the higher amplitude stuff seems valid enough, eg: http://vsnet.astrouw.edu.pl/cgi-asas/asas_lc/055054+0307.5 Cheers John
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