  A 96-ks Chandra X-ray observation of rho Ophiuchus cloud core A detected 87
sources, of which 60 were identified with counterparts at other wavelengths.
The X-ray detections include 12 of 14 known classical T Tauri stars in the
field, 15 of 17 known weak-lined TTS, and 4 of 15 brown dwarf candidates. The
X-ray detections are characterized by hard, heavily absorbed emission. The mean
photon energy of a typical source is 3 keV, and more than half of the
detections are variable. Prominent X-ray flares were detected in the unusual
close binary system Oph S1, the X-ray bright WTTS DoAr 21, and the brown dwarf
candidate GY 31. Time-resolved spectroscopic analysis of the DoAr~21 flare
clearly reveals a sequence of secondary flares during the decay phase which may
have reheated the plasma. We find that the X-ray luminosity distributions and
spectral hardnesses of CTTS and WTTS are similar. We also conclude that the
X-ray emission of detected brown-dwarf candidates is less luminous than T Tauri
stars, but spectroscopically similar. Simultaneous multifrequency VLA
observations detected 31 radio sources at 6 cm, of which ten were also detected
by Chandra. We report new radio detections of the optically invisible IR source
WLY 2-11 and the faint H-alpha emission line star Elias 24. We confirm circular
polarization in Oph S1 and report a new detection of circular polarization in
DoAr 21. We find no evidence that X-ray and radio luminosities are correlated
in the small sample of TTS detected simultaneously with Chandra and the VLA. We
describe a new non-parametric method for estimating X-ray spectral properties
from unbinned photon event.
