3 Reductions

The photometry was done with the MIDAS package developed by ESO. The images were combined, bias-subtracted and flatfielded using standard procedures. The images were flat-fielded using combined morning and evening twilight flat-fields as well as dome flats. The following reduction steps were done within the SURFPHOT context in MIDAS. The background was determined by fitting a tilted plane with FIT/BACKGROUND and was checked for correctness by measuring the sky level in different locations in the frames in regions unaffected by the objects. We chose to restrict the sky fitting to a tilted plane to avoid introducing features which are difficult to assess, as would be the case if we had used a polynomial fit. This also stresses the need for precise flat-fielding. The photometric calibration was done using standard methods. The calibration fields were chosen to be close on the sky to the observed galaxies. These were taken from Smith et al. (1985). The calibration stars were imaged before and after imaging every second galaxy, so one could have a handle on eventual transparency variations on a time scale of two hours. For each galaxy the center and the ellipse-fit parameters, i.e. ellipticity and position angle (counted counter-clockwise from the horizontal axis), were determined at the level of $\sim25^{\mathrm{th}}~\mathrm{mag}/\ifmmode\hbox{\rlap{$\sqcap$ }$\sqcup$ }\else... ...} \parfillskip=0pt\finalhyphendemerits=0\endgraf}\fi{\hbox{$^{\prime\prime}$ }}$ by the ellipse fitting routine FIT/ELL3 and are given in Table 2.

 

 

Table 2: Ellipse fit parameters at the level of $25 \,\mathrm{mag}/\ifmmode\hbox{\rlap{$\sqcap$ }$\sqcup$ }\else{\unskip\nobreak... ...} \parfillskip=0pt\finalhyphendemerits=0\endgraf}\fi{\hbox{$^{\prime\prime}$ }}$

No.	Galaxy	PA [$^\circ$]	$a[\hbox{$^{\prime\prime}$ }]$	$b[\hbox{$^{\prime\prime}$ }]$	b/a
1.	UGC 06541	039	39.9	21.2	0.5
2.	UGC 06565	069	91.0	71.6	0.8
3.	UGC 06572	105	35.9	27.8	0.8
4.	UGC 06817	150	84.1	39.2	0.5
5.	UGC 07047	123	81.3	46.4	0.6
6.	UGC 07165	057	61.6	43.2	0.7
7.	UGC 07199	094	53.0	35.2	0.7
8.	UGCA 276	126	53.8	34.1	0.6
9.	UGC 07298	047	23.0	15.3	0.7
10.	UGC 07335	020	87.6	37.6	0.4
11.	UGC 07356	062	25.9	17.6	0.7
12.	UGC 07369	151	29.9	24.2	0.8
13.	UGC 07559	056	64.5	38.1	0.6
14.	UGC 07599	038	43.5	22.4	0.5
15.	UGC 07639	056	56.3	30.2	0.5

These parameters were used to obtain the total light profile, i.e. growth curve, by integrating the galaxy light in elliptical aperture of fixed ellipticity and position angle but with increasing equivalent ( $r = \sqrt {ab}$) radius. Bright sources were removed by hand from the frames before integrating the light.