Lynds dark cloud LDN1622 represents one of the best examples of anomalous
dust emission, possibly originating from small spinning dust grains. We present
Cosmic Background Imager (CBI) 31 GHz data of LDN1621, a diffuse dark cloud to
the north of LDN1622 in a region known as Orion East. A broken ring with
diameter g\approx 20 arcmin of diffuse emission is detected at 31 GHz, at
\approx 20-30 mJy beam−1 with an angular resolution of \approx 5 arcmin.
The ring-like structure is highly correlated with Far Infra-Red emission at
12−100μm with correlation coefficients of r \approx 0.7-0.8, significant
at ∼10σ. Multi-frequency data are used to place constraints on other
components of emission that could be contributing to the 31 GHz flux. An
analysis of the GB6 survey maps at 4.85 GHz yields a 3σ upper limit on
free-free emission of 7.2 mJy beam−1 (\la 30 per cent of the observed
flux) at the CBI resolution. The bulk of the 31 GHz flux therefore appears to
be mostly due to dust radiation. Aperture photometry, at an angular resolution
of 13 arcmin and with an aperture of diameter 30 arcmin, allowed the use of
IRAS maps and the {\it WMAP} 5-year W-band map at 93.5 GHz. A single modified
blackbody model was fitted to the data to estimate the contribution from
thermal dust, which amounts to \sim10percentat31GHz.Inthismodel,anexcessof1.52±0.66Jy(2.3σ)isseenat31GHz.Futurehighfrequency\sim100−1000GHzdata,suchasthosefromthePlancksatellite,arerequiredtoaccuratelydeterminethethermaldustcontributionat31GHz.CorrelationswiththeIRAS100 \mumgaveacouplingcoefficientof18.1\pm4.4 \muK(MJy/sr)^{-1}$, consistent with the values found for
LDN1622.Comment: 8 pages, 3 figures, 3 tables, submitted to MNRA