Table 3: Color indices for H31G optical knots.
Knot Aperture $B_{\rm mag}$ B-V B-R B-I

Galaxy 25 $^{\prime \prime }$ 14.87 0.43 0.90 1.23

1 2 $.\!\!^{\prime\prime}$ 9 18.96 0.31 0.77 0.94

2 2 $.\!\!^{\prime\prime}$ 9 18.56 0.26 0.70 0.90

3 2 $.\!\!^{\prime\prime}$ 9 18.88 0.37 0.75 0.89

4 2 $.\!\!^{\prime\prime}$ 9 18.54 0.31 0.77 1.05

5 2 $.\!\!^{\prime\prime}$ 9 18.62 0.35 0.74 0.98

6 2 $.\!\!^{\prime\prime}$ 9 18.50 0.40 0.80 1.16

7 2 $.\!\!^{\prime\prime}$ 9 19.21 0.55 0.93 1.29

8 2 $.\!\!^{\prime\prime}$ 9 17.71 0.39 0.82 1.23

**Table 3:** Color indices for H31G optical knots.
Knot	Aperture	$B_{\rm mag}$	B-V	B-R	B-I
Galaxy	25 $^{\prime \prime }$	14.87	0.43	0.90	1.23
1	2 $.\!\!^{\prime\prime}$ 9	18.96	0.31	0.77	0.94
2	2 $.\!\!^{\prime\prime}$ 9	18.56	0.26	0.70	0.90
3	2 $.\!\!^{\prime\prime}$ 9	18.88	0.37	0.75	0.89
4	2 $.\!\!^{\prime\prime}$ 9	18.54	0.31	0.77	1.05
5	2 $.\!\!^{\prime\prime}$ 9	18.62	0.35	0.74	0.98
6	2 $.\!\!^{\prime\prime}$ 9	18.50	0.40	0.80	1.16
7	2 $.\!\!^{\prime\prime}$ 9	19.21	0.55	0.93	1.29
8	2 $.\!\!^{\prime\prime}$ 9	17.71	0.39	0.82	1.23

Source LaTeX | All tables | In the text

	1 Introduction
	2 Observations
	3 The members and environment of HCG 31
	4 The galaxies
	5 Intragroup material
	6 Discussion
	7 Conclusions
	References