A careful photometry of moustaches is carried out to reveal asymmetry of their emission in the far wings (z12 >i 1/~), if it exists. The presence of background continuous emission in spectra of moustaches demands special care with the photometry, and makes the current method of comparison of rest-intensities inadequate. The other sources of errors are also discussed. The blue asymmetry, as a systematic difference of intensities between the blue and the red wing shows itself in some cases, being 2-3 times larger than the probable errors. In most moustaches investigated, the accompanying background continuous emission shows a rapid increase to the violet.
The nature of the transient emissions called moustaches (or bombs) is not quite clear, and a correct interpretation can only be given when it is known whether the emission is symmetric, or whether there is some excess of intensity in the blue (or red) wing, and whether one wing is wider than the other. Earlier photometric investigations (Severny, 1957) pointed to a blue asymmetry in general, and an examination of moustaches near the line centre (at distances 1A21~<1.5 A) showed that the red asymmetry is, almost as frequent as the blue one, and due to dark filaments (Koval, 1965). However the behaviour in the far wings (1A21 >i 1 A) has not been examined carefully; moreover, a photometry based on a comparison of the rest-intensities r a in the line profiles of moustaches with those for the adjacent undisturbed atmosphere are not adequate, because: a) moustaches appear frequently above the additional background -the band of non-stationary continuous emission, b) the uncertainty in fixing the level of the continuous spectrum enters twice -in disturbed (lg) and undisturbed (Io) parts of the spectrum.
From more than 500 spectra of moustaches taken since 1955 we selected nine with good images quality and good contrast, mainly in the Ha and Hfl lines, and of Fig. 1. Spectra of some moustaches considered.