Figure 2: Pure
[OII]
, H
, [OIII]
,
[SII]
and [SIII]
emission line frames
In this section we present the catalog of HII regions of NGC4736.
Table 3
furnishes for each HII region: Col. 1,
the identification number; Col. 2, Hodge & Kennicutt's
(1983) identification; Cols. 3 and 4, the coordinates in arc seconds
with respect to the galaxy nucleus, with X toward the East and Y toward
the North; Col. 5, the halo
diameter; Cols. 6, 7, 8, 9, 10 and 11,
[OII], H , [OIII], H
,
[SII]
, and [SIII]
, emission line
fluxes (
) respectively; Col. 12, the internal extinction
in the H line;
Col. 13 the H equivalent width and Col. 14 the H luminosity.
Table 4a gives, for the HII regions, the flux of the continuum
adjacent to each line.
Pure line flux and continua frames were deconvolved with the seeing
profile in order to measure accurate positions and diameters (we
remark that fluxes were not measured in deconvolved frames). This
procedure is mainly useful to separate members of crowded groups of
HII regions.
The deconvolution was accomplished by means of a Maximum Entropy
Method, using astronomical routines of the IDL package. The point
spread function (PSF) was obtained through stellar profiles measured
in the coadded continuum images. After 100 iterations the
deconvolution reduced the FWHM from 
to 
.
The method allows to obtain positions with an uncertainty of 
pixel.
HII regions diameters were measured in the H deconvolved image by
isophotal areas, as described in Sect. 4.1 (click here).
Figure 1 (click here)a shows NGC4736 pure H frame and Fig. 1 (click here)b is an identification chart of the HII regions.
Features that looks like an
HII region, whose brightness is below a threshold of three times the
background RMS deviation were disregarded.