IV. 2MASS Data Processing

5. Extended Source Identification and Photometry

a. Algorithms, Analysis and Results

vii. XSC -- Virgo Galaxy Cluster: Low-Resolution, 50 deg² Large Mosaic

In order to test the XSC completeness on a much larger scale, we employ a large mosaic with low spatial resolution. The mosaic has been binned to 3´´×3´´ pixels, covering 9300 × 7200 pixels, for a full field-of-view of 7.8°×6°. In Figure 1 we the color composite JHK_s image.

Results

The Virgo mosaic was split into 99 pieces, each 800×800 pixels (approximately 40´ on a side). In Figures 1-99, in Table 1 below, the extended sources from the working database are indicated with blue circles, and the XSC sources are indicated with green circles. The subimages were then visually inspected, concentrating on clearly delineated Virgo galaxies which are not in the XSC (i.e., sources not circled in green). These sources (indicated with red circles) represent incompleteness in the XSC. (Items to note: "chaff" in proximity to large and bright galaxies is mostly eliminated from the XSC; artifacts from bright stars; airglow and background gradients; source confusion; faint or compact sources provide little, if any, information for this experiment.)

Table 1

1 2 3 4 5 6 7 8 9 10 11
1 Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11
2 Figure 12 Figure 13 Figure 14 Figure 15 Figure 16 Figure 17 Figure 18 Figure 19 Figure 20 Figure 21 Figure 22
3 Figure 23 Figure 24 Figure 25 Figure 26 Figure 27 Figure 28 Figure 29 Figure 30 Figure 31 Figure 32 Figure 33
4 Figure 34 Figure 35 Figure 36 Figure 37 Figure 38 Figure 39 Figure 40 Figure 41 Figure 42 Figure 43 Figure 44
5 Figure 45 Figure 46 Figure 47 Figure 48 Figure 49 Figure 50 Figure 51 Figure 52 Figure 53 Figure 54 Figure 55
6 Figure 56 Figure 57 Figure 58 Figure 59 Figure 60 Figure 61 Figure 62 Figure 63 Figure 64 Figure 65 Figure 66
7 Figure 67 Figure 68 Figure 69 Figure 70 Figure 71 Figure 72 Figure 73 Figure 74 Figure 75 Figure 76 Figure 77
8 Figure 78 Figure 79 Figure 80 Figure 81 Figure 82 Figure 83 Figure 84 Figure 85 Figure 86 Figure 87 Figure 88
9 Figure 89 Figure 90 Figure 91 Figure 92 Figure 93 Figure 94 Figure 95 Figure 96 Figure 97 Figure 98 Figure 99

Table 1
	1	2	3	4	5	6	7	8	9	10	11
1	Figure 1	Figure 2	Figure 3	Figure 4	Figure 5	Figure 6	Figure 7	Figure 8	Figure 9	Figure 10	Figure 11
2	Figure 12	Figure 13	Figure 14	Figure 15	Figure 16	Figure 17	Figure 18	Figure 19	Figure 20	Figure 21	Figure 22
3	Figure 23	Figure 24	Figure 25	Figure 26	Figure 27	Figure 28	Figure 29	Figure 30	Figure 31	Figure 32	Figure 33
4	Figure 34	Figure 35	Figure 36	Figure 37	Figure 38	Figure 39	Figure 40	Figure 41	Figure 42	Figure 43	Figure 44
5	Figure 45	Figure 46	Figure 47	Figure 48	Figure 49	Figure 50	Figure 51	Figure 52	Figure 53	Figure 54	Figure 55
6	Figure 56	Figure 57	Figure 58	Figure 59	Figure 60	Figure 61	Figure 62	Figure 63	Figure 64	Figure 65	Figure 66
7	Figure 67	Figure 68	Figure 69	Figure 70	Figure 71	Figure 72	Figure 73	Figure 74	Figure 75	Figure 76	Figure 77
8	Figure 78	Figure 79	Figure 80	Figure 81	Figure 82	Figure 83	Figure 84	Figure 85	Figure 86	Figure 87	Figure 88
9	Figure 89	Figure 90	Figure 91	Figure 92	Figure 93	Figure 94	Figure 95	Figure 96	Figure 97	Figure 98	Figure 99

Missing Sources

Table 2 presents the sources identified from the Virgo mosaic that do not have an XSC counterpart. The columns for the table are: (ip,jp), panel number, from Table 1 above; (x,y), pixel coordinates; (ra,dec), J2000 equatorial coordinates; radius, circular aperture radius in arcsec; J mag; J-band rms uncertainty; and, "zoomed" image.

Bottom Line: Most of the missing galaxies are low surface brightness, with SNR well below the Level-1 science requirements. With regard to clearly delineated galaxies (well-extended, diameters > 10´´-20´´), the XSC completeness requirement in Virgo is comfortably satisfied.

Table 2

IP JP x y ra dec radius ba pa ib mag msig image
2 1 1574.0 6789.0 189.89700 16.09676 10.0 1.000 0.0 j 10.602 0.017 Figure 100
2 1 1011.0 6611.0 190.38402 15.94341 10.0 1.000 0.0 j 15.303 0.531 Figure 101
5 1 3271.0 6687.0 188.42320 16.02272 10.0 1.000 0.0 j 12.536 0.044 Figure 102
9 1 6851.0 7020.0 185.31224 16.29564 10.0 1.000 0.0 j 11.401 0.021 Figure 103
1 2 765.0 5968.0 190.58885 15.40313 10.0 1.000 0.0 j 10.759 0.017 Figure 104
4 2 2993.0 6186.0 188.66069 15.60322 10.0 1.000 0.0 j 14.414 0.235 Figure 105
5 2 3233.0 5663.0 188.45021 15.16779 30.0 1.000 0.0 j 10.960 0.033 Figure 106
6 2 4043.0 6335.0 187.75063 15.73193 20.0 1.000 0.0 j 13.771 0.261 Figure 107
8 2 6062.0 5873.0 186.00397 15.34307 10.0 1.000 0.0 j 11.494 0.022 Figure 108
11 2 8577.0 6120.0 183.82355 15.52952 10.0 1.000 0.0 j 10.812 0.017 Figure 109
2 3 1046.0 5122.0 190.33504 14.70030 20.0 1.000 0.0 j 13.029 0.132 Figure 110
2 3 1340.0 5136.0 190.08134 14.71495 20.0 1.000 0.0 j 13.335 0.175 Figure 111
3 3 2365.0 5156.0 189.19589 14.74003 10.0 1.000 0.0 j 14.758 0.322 Figure 112
4 3 2933.0 5435.0 188.70737 14.97699 10.0 1.000 0.0 j 11.185 0.019 Figure 113
6 3 4406.0 5488.0 187.43617 15.02460 10.0 1.000 0.0 j 14.632 0.287 Figure 114
7 3 5551.0 5403.0 186.44835 14.95258 10.0 1.000 0.0 j 14.185 0.190 Figure 115
8 3 5951.0 5550.0 186.10144 15.07395 10.0 1.000 0.0 j 14.456 0.244 Figure 116
1 4 669.0 4715.0 190.65535 14.35658 30.0 1.000 0.0 j 12.044 0.082 Figure 117
2 4 867.0 4013.0 190.47626 13.77326 20.0 1.000 0.0 j 13.056 0.135 Figure 118
3 4 1871.0 4364.0 189.61604 14.07648 10.0 1.000 0.0 j 14.797 0.334 Figure 119
4 4 2673.0 4238.0 188.92514 13.97610 10.0 1.000 0.0 j 16.289 1.317 Figure 120
5 4 3942.0 4398.0 187.83443 14.11453 20.0 1.000 0.0 j 13.147 0.147 Figure 121
7 4 5117.0 4438.0 186.82368 14.14832 10.0 1.000 0.0 j 9.619 0.015 Figure 122
9 4 7050.0 4786.0 185.15776 14.43055 10.0 1.000 0.0 j 10.427 0.016 Figure 123
9 4 6687.0 4716.0 185.47018 14.37450 10.0 1.000 0.0 j 11.664 0.024 Figure 124
10 4 7519.0 4253.0 184.75838 13.98232 20.0 1.000 0.0 j 13.552 0.213 Figure 125
3 5 2367.0 3381.0 189.18237 13.25933 20.0 1.000 0.0 j 11.469 0.035 Figure 126
4 5 2877.0 3742.0 188.74702 13.56346 10.0 1.000 0.0 j 12.157 0.033 Figure 127
4 5 2434.0 3836.0 189.12794 13.63930 10.0 1.000 0.0 j 15.003 0.403 Figure 128
7 5 5229.0 3739.0 186.72859 13.56505 10.0 1.000 0.0 j 14.515 0.258 Figure 129
7 5 5543.0 3299.0 186.46030 13.19734 10.0 1.000 0.0 j 14.779 0.328 Figure 130
8 5 6194.0 3647.0 185.90085 13.48533 10.0 1.000 0.0 j 10.377 0.016 Figure 131
8 5 5625.0 3335.0 186.38992 13.22715 10.0 1.000 0.0 j 14.781 0.329 Figure 132
11 5 8524.0 3829.0 183.89851 13.61878 10.0 1.000 0.0 j 14.737 0.316 Figure 133
11 5 8723.0 3643.0 183.72972 13.46134 20.0 1.000 0.0 j 13.856 0.282 Figure 134
1 6 681.0 2418.0 190.61783 12.43990 10.0 1.000 0.0 j 15.155 0.464 Figure 135
5 6 3787.0 2651.0 187.96327 12.65685 20.0 1.000 0.0 j 13.182 0.152 Figure 136
5 6 3547.0 2789.0 188.16890 12.77129 30.0 1.000 0.0 j 12.976 0.190 Figure 137
5 6 3782.0 2441.0 187.96704 12.48164 10.0 1.000 0.0 j 14.451 0.243 Figure 138
6 6 4141.0 2632.0 187.66058 12.64171 10.0 1.000 0.0 j 11.172 0.019 Figure 139
7 6 4882.0 2938.0 187.02690 12.89728 10.0 1.000 0.0 j 14.686 0.301 Figure 140
6 6 4777.0 2850.0 187.11679 12.82392 10.0 1.000 0.0 j 13.853 0.141 Figure 141
7 6 5305.0 2479.0 186.66576 12.51382 10.0 1.000 0.0 j 14.278 0.207 Figure 142
2 7 916.0 2183.0 190.41440 12.24731 20.0 1.000 0.0 j 13.628 0.229 Figure 143
3 7 2171.0 2217.0 189.34230 12.28696 20.0 1.000 0.0 j 13.936 0.304 Figure 144
10 7 7967.0 2346.0 184.39139 12.38756 30.0 1.000 0.0 j 13.547 0.320 Figure 145
1 8 168.0 911.0 191.03928 11.17695 20.0 1.000 0.0 j 13.955 0.309 Figure 146
8 8 5713.0 1393.0 186.32016 11.60663 10.0 1.000 0.0 e 14.832 0.344 Figure 147
1 9 509.0 314.0 190.74284 10.68192 10.0 1.000 0.0 j 14.817 0.340 Figure 148
2 9 1119.0 59.0 190.22218 10.47653 30.0 1.000 0.0 j 13.664 0.357 Figure 149
3 9 2369.0 796.0 189.16568 11.10242 20.0 1.000 0.0 j 13.709 0.246 Figure 150
4 9 2578.0 595.0 188.98608 10.93676 20.0 1.000 0.0 j 14.755 0.645 Figure 151
5 9 3376.0 581.0 188.30785 10.92808 10.0 1.000 0.0 j 15.073 0.430 Figure 152
7 9 5101.0 504.0 186.84235 10.86667 20.0 1.000 0.0 j 12.302 0.069 Figure 153
7 9 5236.0 264.0 186.72801 10.66521 30.0 1.000 0.0 j 13.658 0.355 Figure 154
11 9 8516.0 331.0 183.94168 10.70014 30.0 1.000 0.0 j 13.580 0.330 Figure 155

Table 2
IP	JP	x	y	ra	dec	radius	ba	pa	ib	mag	msig	image
2	1	1574.0	6789.0	189.89700	16.09676	10.0	1.000	0.0	j	10.602	0.017	Figure 100
2	1	1011.0	6611.0	190.38402	15.94341	10.0	1.000	0.0	j	15.303	0.531	Figure 101
5	1	3271.0	6687.0	188.42320	16.02272	10.0	1.000	0.0	j	12.536	0.044	Figure 102
9	1	6851.0	7020.0	185.31224	16.29564	10.0	1.000	0.0	j	11.401	0.021	Figure 103
1	2	765.0	5968.0	190.58885	15.40313	10.0	1.000	0.0	j	10.759	0.017	Figure 104
4	2	2993.0	6186.0	188.66069	15.60322	10.0	1.000	0.0	j	14.414	0.235	Figure 105
5	2	3233.0	5663.0	188.45021	15.16779	30.0	1.000	0.0	j	10.960	0.033	Figure 106
6	2	4043.0	6335.0	187.75063	15.73193	20.0	1.000	0.0	j	13.771	0.261	Figure 107
8	2	6062.0	5873.0	186.00397	15.34307	10.0	1.000	0.0	j	11.494	0.022	Figure 108
11	2	8577.0	6120.0	183.82355	15.52952	10.0	1.000	0.0	j	10.812	0.017	Figure 109
2	3	1046.0	5122.0	190.33504	14.70030	20.0	1.000	0.0	j	13.029	0.132	Figure 110
2	3	1340.0	5136.0	190.08134	14.71495	20.0	1.000	0.0	j	13.335	0.175	Figure 111
3	3	2365.0	5156.0	189.19589	14.74003	10.0	1.000	0.0	j	14.758	0.322	Figure 112
4	3	2933.0	5435.0	188.70737	14.97699	10.0	1.000	0.0	j	11.185	0.019	Figure 113
6	3	4406.0	5488.0	187.43617	15.02460	10.0	1.000	0.0	j	14.632	0.287	Figure 114
7	3	5551.0	5403.0	186.44835	14.95258	10.0	1.000	0.0	j	14.185	0.190	Figure 115
8	3	5951.0	5550.0	186.10144	15.07395	10.0	1.000	0.0	j	14.456	0.244	Figure 116
1	4	669.0	4715.0	190.65535	14.35658	30.0	1.000	0.0	j	12.044	0.082	Figure 117
2	4	867.0	4013.0	190.47626	13.77326	20.0	1.000	0.0	j	13.056	0.135	Figure 118
3	4	1871.0	4364.0	189.61604	14.07648	10.0	1.000	0.0	j	14.797	0.334	Figure 119
4	4	2673.0	4238.0	188.92514	13.97610	10.0	1.000	0.0	j	16.289	1.317	Figure 120
5	4	3942.0	4398.0	187.83443	14.11453	20.0	1.000	0.0	j	13.147	0.147	Figure 121
7	4	5117.0	4438.0	186.82368	14.14832	10.0	1.000	0.0	j	9.619	0.015	Figure 122
9	4	7050.0	4786.0	185.15776	14.43055	10.0	1.000	0.0	j	10.427	0.016	Figure 123
9	4	6687.0	4716.0	185.47018	14.37450	10.0	1.000	0.0	j	11.664	0.024	Figure 124
10	4	7519.0	4253.0	184.75838	13.98232	20.0	1.000	0.0	j	13.552	0.213	Figure 125
3	5	2367.0	3381.0	189.18237	13.25933	20.0	1.000	0.0	j	11.469	0.035	Figure 126
4	5	2877.0	3742.0	188.74702	13.56346	10.0	1.000	0.0	j	12.157	0.033	Figure 127
4	5	2434.0	3836.0	189.12794	13.63930	10.0	1.000	0.0	j	15.003	0.403	Figure 128
7	5	5229.0	3739.0	186.72859	13.56505	10.0	1.000	0.0	j	14.515	0.258	Figure 129
7	5	5543.0	3299.0	186.46030	13.19734	10.0	1.000	0.0	j	14.779	0.328	Figure 130
8	5	6194.0	3647.0	185.90085	13.48533	10.0	1.000	0.0	j	10.377	0.016	Figure 131
8	5	5625.0	3335.0	186.38992	13.22715	10.0	1.000	0.0	j	14.781	0.329	Figure 132
11	5	8524.0	3829.0	183.89851	13.61878	10.0	1.000	0.0	j	14.737	0.316	Figure 133
11	5	8723.0	3643.0	183.72972	13.46134	20.0	1.000	0.0	j	13.856	0.282	Figure 134
1	6	681.0	2418.0	190.61783	12.43990	10.0	1.000	0.0	j	15.155	0.464	Figure 135
5	6	3787.0	2651.0	187.96327	12.65685	20.0	1.000	0.0	j	13.182	0.152	Figure 136
5	6	3547.0	2789.0	188.16890	12.77129	30.0	1.000	0.0	j	12.976	0.190	Figure 137
5	6	3782.0	2441.0	187.96704	12.48164	10.0	1.000	0.0	j	14.451	0.243	Figure 138
6	6	4141.0	2632.0	187.66058	12.64171	10.0	1.000	0.0	j	11.172	0.019	Figure 139
7	6	4882.0	2938.0	187.02690	12.89728	10.0	1.000	0.0	j	14.686	0.301	Figure 140
6	6	4777.0	2850.0	187.11679	12.82392	10.0	1.000	0.0	j	13.853	0.141	Figure 141
7	6	5305.0	2479.0	186.66576	12.51382	10.0	1.000	0.0	j	14.278	0.207	Figure 142
2	7	916.0	2183.0	190.41440	12.24731	20.0	1.000	0.0	j	13.628	0.229	Figure 143
3	7	2171.0	2217.0	189.34230	12.28696	20.0	1.000	0.0	j	13.936	0.304	Figure 144
10	7	7967.0	2346.0	184.39139	12.38756	30.0	1.000	0.0	j	13.547	0.320	Figure 145
1	8	168.0	911.0	191.03928	11.17695	20.0	1.000	0.0	j	13.955	0.309	Figure 146
8	8	5713.0	1393.0	186.32016	11.60663	10.0	1.000	0.0	e	14.832	0.344	Figure 147
1	9	509.0	314.0	190.74284	10.68192	10.0	1.000	0.0	j	14.817	0.340	Figure 148
2	9	1119.0	59.0	190.22218	10.47653	30.0	1.000	0.0	j	13.664	0.357	Figure 149
3	9	2369.0	796.0	189.16568	11.10242	20.0	1.000	0.0	j	13.709	0.246	Figure 150
4	9	2578.0	595.0	188.98608	10.93676	20.0	1.000	0.0	j	14.755	0.645	Figure 151
5	9	3376.0	581.0	188.30785	10.92808	10.0	1.000	0.0	j	15.073	0.430	Figure 152
7	9	5101.0	504.0	186.84235	10.86667	20.0	1.000	0.0	j	12.302	0.069	Figure 153
7	9	5236.0	264.0	186.72801	10.66521	30.0	1.000	0.0	j	13.658	0.355	Figure 154
11	9	8516.0	331.0	183.94168	10.70014	30.0	1.000	0.0	j	13.580	0.330	Figure 155

The following figures show some of the largest Virgo galaxies missing from the XSC. The images belong to the 2MASS Large Galaxy Atlas (LGA), and the integrated fluxes come from the LGA. Note that even these "large" examples are low surface brightness. Figure 156 shows NGC 4523, with isophotal size and mags (r, J, H, K_s)= 25.5´´, 13.014±0.049, 12.392±0.074, 12.155±0.086 mag; image size = 4.8´×4.8´. Figure 157 shows NGC 4633, with isophotal size and mags (r, J, H, K_s)=30.8´´, 12.234±0.032, 11.573±0.043, 11.382±0.054 mag; image size = 3.9´×3.9´. Figure 158 shows IC 3074, with isophotal size and mags (r, J, H, K_s)=21.2´´, 13.914±0.091, 13.396±0.121, 12.984±0.160 mag; image size = 3.9´×3.9´.

Figure 156 Figure 157 Figure 158

Future Work

See IV.5a8. Use the full-resolution (1´´ pixel) mosaic of the "heart of Virgo" (approximately 1.4° × 1.4°) to investigate the completeness of the fainter, more compact population. Here, it would be useful to overlay existing catalogs (via NED) to glean the maximum sensitivity of the 2MASS images.

[Last Updated: 2002 Oct 9 ; by T. Jarrett]

Return to Section IV.5a.