--- a
+++ b/sample_locs/GSN256.sfp
@@ -0,0 +1,259 @@
+FidNz      0.00000      10.7078     -2.23364
+FidT9     -6.93522     0.197600     -3.70686
+FidT10      6.93522     0.197599     -3.70686
+E1      5.75790      6.62432     -1.53854
+E2      5.52174      7.30351     0.694727
+E3      4.95349      7.94930      2.56738
+E4      3.85574      8.54117      3.99289
+E5      2.71961      7.72178      6.00262
+E6      1.92314      6.72239      7.15184
+E7      1.25910      5.30906      8.01133
+E8      0.00000      3.65242      8.59563
+E9     -1.27938      1.38207      8.83781
+E10      4.33076      9.10489    -0.456432
+E11      3.71990      9.45601      1.36974
+E12      2.90818      9.80075      2.98281
+E13      1.79771      9.48181      4.59757
+E14      1.22587      8.24023      6.41240
+E15      0.00000      6.83756      7.55893
+E16     -1.25910      5.30906      8.01133
+E17     -1.95277      2.97498      8.31184
+E18      2.67867      10.3805   -0.0708818
+E19      1.77016      10.4704      1.52597
+E20      1.00632      10.4147      3.22706
+E21      0.00000      9.70113      5.05936
+E22     -1.22587      8.24023      6.41240
+E23     -1.92314      6.72239      7.15184
+E24     -2.88633      4.65900      7.53095
+E25     0.898575      10.9643    -0.127806
+E26     -1.00632      10.4147      3.22706
+E27     -1.79771      9.48181      4.59757
+E28     -2.71961      7.72178      6.00262
+E29     -3.62712      6.13348      6.42186
+E30      0.00000      10.6438     -1.81009
+E31    -0.898575      10.9643    -0.127806
+E32     -1.77016      10.4704      1.52597
+E33     -2.90818      9.80075      2.98281
+E34     -3.85574      8.54117      3.99289
+E35     -4.07060      7.21250      5.11643
+E36     -2.67867      10.3805   -0.0708818
+E37     -3.71990      9.45601      1.36974
+E38     -4.95349      7.94930      2.56738
+E39     -5.25861      6.86154      3.64378
+E40     -5.25689      5.40776      5.06291
+E41     -4.72603      4.06397      6.49209
+E42     -3.74965      2.61469      7.53390
+E43     -2.87131     0.831389      8.28815
+E44     -1.90213    -0.759280      8.69498
+E45     -4.33076      9.10489    -0.456432
+E46     -5.52174      7.30351     0.694727
+E47     -6.02820      6.13210      1.91938
+E48     -6.31200      4.75572      3.38583
+E49     -6.12044      3.26214      5.00780
+E50     -5.57852      1.87022      6.25549
+E51     -4.63946     0.258372      7.33882
+E52     -3.42838     -1.27134      8.08914
+E53     -5.75790      6.62432     -1.53854
+E54     -6.36271      5.27478     0.164284
+E55     -6.78901      4.08492      1.40691
+E56     -7.04518      2.54581      2.94754
+E57     -6.75706      1.25264      4.56985
+E58     -6.44532   -0.0694811      5.58243
+E59     -5.19342     -1.63703      6.99357
+E60     -6.57224      4.35910     -1.80338
+E61     -7.00281      3.09259    -0.148059
+E62     -7.35939      1.89135      1.10228
+E63     -7.47446     0.552676      2.55808
+E64     -7.21629     -1.13867      4.08258
+E65     -6.60933     -2.25159      5.32786
+E66     -6.90761      2.72130     -3.87155
+E67     -7.03205      1.69512     -2.07023
+E68     -7.39816     0.486697    -0.419844
+E69     -7.69904    -0.963886     0.996840
+E70     -7.49455     -1.90576      2.43981
+E71     -7.17268     -2.71354      3.48190
+E72     -6.53038      1.34611     -6.19274
+E73     -7.50334     -1.83444    -0.353166
+E74     -7.34131     -3.05263     0.725688
+E75     -7.05095     -4.02598      2.25103
+E76     -6.47072     -4.31379      4.35851
+E77     -5.43994     -4.21068      6.07138
+E78     -3.71250     -3.69419      7.54817
+E79     -2.07885     -3.01495      8.40273
+E80      0.00000     -2.35814      8.81349
+E81     -6.26831     0.425343     -7.95707
+E82     -7.24073     -3.13627     -2.18818
+E83     -7.03505     -3.94507    -0.825989
+E84     -6.78840     -4.87309     0.842564
+E85     -6.19129     -5.84623      2.64445
+E86     -5.24315     -6.18197      4.61339
+E87     -4.00975     -5.93756      6.01370
+E88     -2.15155     -5.22992      7.40642
+E89      0.00000     -4.28973      8.20648
+E90     -5.93170    -0.326612     -9.25207
+E91     -6.16243     -1.50709     -7.97157
+E92     -6.63032     -2.88778     -5.78296
+E93     -6.71597     -4.08433     -4.31242
+E94     -6.59524     -5.04495     -2.59194
+E95     -6.16011     -6.13035    -0.660797
+E96     -5.59034     -7.05503     0.665566
+E97     -5.01497     -7.31906      2.90869
+E98     -3.55593     -7.44472      4.47981
+E99     -2.00737     -7.02777      5.86462
+E100      0.00000     -6.27852      6.81554
+E101     -5.40912     -1.55133     -10.9424
+E102     -5.66028     -2.67606     -9.18007
+E103     -5.60464     -3.59070     -7.58251
+E104     -5.81044     -4.57212     -6.05619
+E105     -5.96798     -5.71059     -4.29892
+E106     -5.65113     -6.80705     -2.43987
+E107     -4.84519     -7.87060    -0.720284
+E108     -3.91097     -8.54609      1.03933
+E109     -2.96459     -8.61861      2.74870
+E110     -1.46882     -8.23756      4.26985
+E111      0.00000     -7.72692      5.23884
+E112     -4.57738     -4.25921     -9.42499
+E113     -4.51575     -5.06660     -7.72097
+E114     -4.61298     -6.17683     -6.17752
+E115     -4.53958     -7.41821     -4.39725
+E116     -3.86894     -8.58666     -2.35023
+E117     -3.09048     -9.23476    -0.533743
+E118     -1.75042     -9.47414      1.07781
+E119    -0.964285     -9.16409      2.32552
+E120      0.00000     -8.61961      3.79683
+E121     -3.47042     -5.89857     -9.20197
+E122     -3.55763     -6.39016     -7.50694
+E123     -3.35280     -7.54959     -6.05863
+E124     -2.62691     -8.49471     -4.75557
+E125     -2.01785     -9.41827     -2.52632
+E126    -0.958566     -9.88857    -0.741855
+E127      0.00000     -9.73794     0.766790
+E128     0.964285     -9.16409      2.32552
+E129      1.46882     -8.23756      4.26985
+E130      2.00737     -7.02777      5.86462
+E131      2.15155     -5.22992      7.40642
+E132      2.07885     -3.01495      8.40273
+E133      1.90213    -0.759280      8.69498
+E134     -2.56859     -6.67651     -9.20561
+E135     -2.11945     -7.38543     -7.66441
+E136     -1.57294     -8.15509     -6.24421
+E137     -1.05855     -9.10944     -4.46274
+E138      0.00000     -9.71661     -2.71232
+E139     0.958566     -9.88857    -0.741855
+E140      1.75042     -9.47414      1.07781
+E141      2.96459     -8.61861      2.74870
+E142      3.55593     -7.44472      4.47981
+E143      4.00975     -5.93756      6.01370
+E144      3.71250     -3.69419      7.54817
+E145      3.42838     -1.27134      8.08914
+E146     -1.23669     -7.65431     -9.15612
+E147    -0.758553     -7.90446     -7.62359
+E148      0.00000     -8.34512     -6.12448
+E149      1.05855     -9.10944     -4.46274
+E150      2.01785     -9.41827     -2.52632
+E151      3.09048     -9.23476    -0.533743
+E152      3.91097     -8.54609      1.03933
+E153      5.01497     -7.31906      2.90869
+E154      5.24315     -6.18197      4.61339
+E155      5.43994     -4.21068      6.07138
+E156      5.19342     -1.63703      6.99357
+E157     0.758553     -7.90446     -7.62359
+E158      1.57294     -8.15509     -6.24421
+E159      2.62691     -8.49471     -4.75557
+E160      3.86894     -8.58666     -2.35023
+E161      4.84519     -7.87060    -0.720284
+E162      5.59034     -7.05503     0.665566
+E163      6.19129     -5.84623      2.64445
+E164      6.47072     -4.31379      4.35851
+E165      6.60933     -2.25159      5.32786
+E166      1.23669     -7.65431     -9.15612
+E167      2.11945     -7.38543     -7.66441
+E168      3.35280     -7.54959     -6.05863
+E169      4.53958     -7.41821     -4.39725
+E170      5.65113     -6.80705     -2.43987
+E171      6.16011     -6.13035    -0.660797
+E172      6.78840     -4.87309     0.842564
+E173      7.05095     -4.02598      2.25103
+E174      7.17268     -2.71354      3.48190
+E175      2.56859     -6.67651     -9.20561
+E176      3.55763     -6.39016     -7.50694
+E177      4.61298     -6.17683     -6.17752
+E178      5.96798     -5.71059     -4.29892
+E179      6.59524     -5.04495     -2.59194
+E180      7.03505     -3.94507    -0.825989
+E181      7.34131     -3.05263     0.725688
+E182      7.49455     -1.90576      2.43981
+E183      7.21629    -0.659263      4.14978
+E184      6.44532   -0.0694811      5.58243
+E185      4.63946     0.258372      7.33882
+E186      2.87131     0.831389      8.28815
+E187      1.27938      1.38207      8.83781
+E188      3.47042     -5.89857     -9.20197
+E189      4.51575     -5.06660     -7.72097
+E190      5.81044     -4.57212     -6.05619
+E191      6.71597     -4.08433     -4.31242
+E192      7.24073     -3.13627     -2.18818
+E193      7.50334     -1.83444    -0.353166
+E194      7.69904    0.0210864      1.13490
+E195      7.47446     0.552676      2.55808
+E196      6.75706      1.25264      4.56985
+E197      5.57852      1.87022      6.25549
+E198      3.74965      2.61469      7.53390
+E199      1.95277      2.97498      8.31184
+E200      4.57738     -4.25921     -9.42499
+E201      5.60464     -3.59070     -7.58251
+E202      6.63032     -2.88778     -5.78296
+E203      7.39816     0.486697    -0.419844
+E204      7.35939      1.89135      1.10228
+E205      7.04518      2.54581      2.94754
+E206      6.12044      3.26214      5.00780
+E207      4.72603      4.06397      6.49209
+E208      2.88633      4.65900      7.53095
+E209      5.66028     -2.67606     -9.18007
+E210      6.16243     -1.50709     -7.97157
+E211      7.03205      1.69512     -2.07023
+E212      7.00281      3.09259    -0.148059
+E213      6.78901      4.08492      1.40691
+E214      6.31200      4.75572      3.38583
+E215      5.25689      5.40776      5.06291
+E216      3.62712      6.13348      6.42186
+E217      5.40912     -1.55133     -10.9424
+E218      5.93170    -0.326612     -9.25207
+E219      6.26831     0.425343     -7.95707
+E220      6.53038      1.34611     -6.19274
+E221      6.90761      2.72130     -3.87155
+E222      6.57224      4.35910     -1.80338
+E223      6.36271      5.27478     0.164284
+E224      6.02820      6.13210      1.91938
+E225      5.25861      6.86154      3.64378
+E226      4.07060      7.21250      5.11643
+E227      6.06869      5.71823     -3.21657
+E228      6.52883      4.49674     -4.69960
+E229      6.44900      2.92003     -6.04545
+E230      6.16935      2.08181     -7.92954
+E231      5.81164      1.30701     -9.31030
+E232      5.08583     0.121009     -11.0429
+E233      5.73569      5.71538     -6.44150
+E234      6.03905      4.24157     -7.44683
+E235      5.93203      3.07676     -8.95744
+E236      5.32716      1.97640     -10.6333
+E237      5.12817      2.76425     -8.72939
+E238      5.31962      6.19299     -7.56377
+E239      5.46165      5.03876     -8.74178
+E240      5.34669      4.04690     -10.1039
+E241      3.25991      8.37938     -6.92283
+E242     -3.25991      8.37938     -6.92283
+E243     -5.12817      2.76425     -8.72939
+E244     -5.31962      6.19299     -7.56377
+E245     -5.46165      5.03876     -8.74178
+E246     -5.34669      4.04690     -10.1039
+E247     -5.73569      5.71538     -6.44150
+E248     -6.03905      4.24157     -7.44683
+E249     -5.93203      3.07676     -8.95744
+E250     -5.32716      1.97640     -10.6333
+E251     -6.06869      5.71823     -3.21657
+E252     -6.52883      4.49674     -4.69960
+E253     -6.44900      2.92003     -6.04545
+E254     -6.16935      2.08181     -7.92954
+E255     -5.81164      1.30701     -9.31030
+E256     -5.08583     0.121009     -11.0429