Scientific abstract

Please note that during visit to PDEC (May 29-31 1995), plan
for T-o-O observations have been changed slightly - proposal
now requests observations with PHT32 and CAM01 (once in
microscanning and one in 'stare' mode) on three separate
occasions. See more details in modified justification file.
Note CAM03 no longer used.

ORIGINAL PROPOSED ABSTRACT :

We propose to use CAM01, CAM03 and PHT03 to observe Cygnus X-3
while in radio outburst. At such times this source ejects
huge numbers of relativistic electrons into a double-lobed
jet structure at approximately 0.3c. The high-frequency tail
of the synchrotron emission from this source has been found
to be higher than predicted during quiescence and has never
been observed shortward of 1.3 mm during an outburst. Given
the trigger for observation of 2 Jy at 3.6 cm we would expect
highly variable fluxes of up to 1 Jy  (certainly > 100 mJy)
to be observed in the spectral region covered by ISO. These
would be the first mid- to long-infrared observations of an evolved
galactic jet source in outburst and would provide vital new data
relating to beams, jets and ejection mechanisms. The 2 Jy at
3.6 cm trigger also sets off VLBI observations of Cyg X-3 which
would automtically provide cm flux and spatial data to compare
against the ISO data. Cyg X-3 is monitored in the radio daily.

Observations of the high-frequency tail of the flare emission
would effectively allow observations deeper down the jet
towards its origin than would ever be possible from ground-
based observations. This would shed new light on all stellar
jets, particularly those from system containing evolved
objects. Cyg X-3 is the brightest such source (when in
outburst) to study such behaviour.

Determination of degree of polarisation of synchrotron emission
would provide info. on Faraday depol. processes associated with
some local medium.