diff --git a/.gitignore b/.gitignore
index e84ac77..ecc85c6 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,8 @@
 *.pyc
 
+#chart configurations I use to debug
+test/
+
 # Distribution / packaging
 develop-eggs/
 dist/
diff --git a/README.md b/README.md
index 0cc7a85..c97ce26 100644
--- a/README.md
+++ b/README.md
@@ -209,6 +209,7 @@ The following settings can be included in a `StarCharter` configuration file:
 * `grid_col` - Colour to use when drawing grid of RA/Dec lines
 * `label_ecliptic` - Boolean (0 or 1) indicating whether to label the months along the ecliptic, showing the Sun's annual progress
 * `label_font_size_scaling` - Scaling factor to be applied to the font size of all star and DSO labels (default 1.0)
+* `label_meridian` Boolean (0 or 1) indicating whether to label declination lines multiple of 10 degrees along the vernal meridian 
 * `language` - The language used for the constellation names. Either "english" or "french".
 * `mag_alpha` - The multiplicative scaling factor to apply to the radii of stars differing in magnitude by one <mag_step>
 * `mag_max` - Used to regulate the size of stars. A star of this magnitude is drawn with size mag_size_norm. Also, this is the brightest magnitude of star which is shown in the magnitude key below the chart.
@@ -220,6 +221,7 @@ The following settings can be included in a `StarCharter` configuration file:
 * `maximum_dso_label_count` - The maximum number of deep sky objects which may be labelled
 * `maximum_star_count` - The maximum number of stars to draw. If this is exceeded, only the brightest stars are shown.
 * `maximum_star_label_count` - The maximum number of stars which may be labelled
+* `meridian_col` - Colour to use when drawing a line along the vernal meridian
 * `messier_only` - Boolean (0 or 1) indicating whether we plot only Messier objects, and no other deep sky objects
 * `must_show_all_ephemeris_labels` - Boolean (0 or 1) indicating whether we show all ephemeris text labels, even if they collide with other text.
 * `output_filename` - The target filename for the star chart. The file type (svg, png, eps or pdf) is inferred from the file extension.
@@ -229,6 +231,7 @@ The following settings can be included in a `StarCharter` configuration file:
 * `plot_equator` - Boolean (0 or 1) indicating whether to draw a line along the equator
 * `plot_galactic_plane` - Boolean (0 or 1) indicating whether to draw a line along the galactic plane
 * `plot_galaxy_map` - Boolean (0 or 1) indicating whether to draw a shaded map of the Milky Way behind the star chart
+* `plot_meridian` - Boolean (0 or 1) indicating whether we plot the vernal meridian
 * `plot_stars` - Boolean (0 or 1) indicating whether we plot any stars
 * `position_angle` - The position angle of the plot - i.e. the tilt of north, counter-clockwise from up, at the centre of the plot
 * `projection` - Select projection to use. Set to either flat, peters, gnomonic, sphere or alt_az
@@ -244,8 +247,26 @@ The following settings can be included in a `StarCharter` configuration file:
 * `star_mag_labels` - Boolean (0 or 1) indicating whether we label the magnitudes of stars
 * `star_names` - Boolean (0 or 1) indicating whether we label the English names of stars
 * `star_variable_labels` - Boolean (0 or 1) indicating whether we label the variable-star designations of stars, e.g. V337_Car
+* `dec_ticks_on_round_edge` - Boolean (o or 1) indicating whether lines of constant declination (or galactic latitude) put a tick on the round edge of an Alt_Az chart
+* `ra_ticks_on_round_edge` - Boolean (o or 1) indicating whether lines of constant right ascension (or galactic longitude) put a tick on the round edge of an Alt_Az chart
 * `title` - The heading to write at the top of the star chart
 * `width` - The width of the star chart, in cm
 * `x_label_slant` - A slant to apply to all labels on the horizontal axes
 * `y_label_slant` - A slant to apply to all labels on the vertical axes
 * `zodiacal_only` - Boolean (0 or 1) indicating whether we plot only the zodiacal constellations
+
+# Changelog
+
+## Functionalities
+
+* Extended `alt_az` plotting to draw charts of arbitrary (<360°) angular width. E.G., this is useful to plot a chart of all stars you can see throughout the year
+* Implemented ticks on round edge of the chart in `alt_az` mode, with the possibility to choose whether RA, Dec or both lines put ticks on it
+* Possibility to plot the vernal meridian, with the option to put a tick on it every 10° of declination
+
+## New configuration parameters
+
+* `label_meridian`
+* `meridian_col`
+* `plot_meridian`
+* `dec_ticks_on_round_edge`
+* `ra_ticks_on_round_edge`
diff --git a/src/astroGraphics/constellations.c b/src/astroGraphics/constellations.c
index 0d81988..28820c3 100644
--- a/src/astroGraphics/constellations.c
+++ b/src/astroGraphics/constellations.c
@@ -66,7 +66,7 @@ void plot_constellation_boundaries(chart_config *s, line_drawer *ld) {
 
     // Set up line-drawing class
     ld_pen_up(ld, GSL_NAN, GSL_NAN, NULL, 1);
-    ld_label(ld, NULL, 1, 1);
+    ld_label(ld, NULL, 1, 1, 1);
 
     // Open file defining the celestial coordinates of the constellation boundaries
     file = fopen(SRCDIR "../data/constellations/downloads/boundaries.dat", "r");
diff --git a/src/astroGraphics/ephemeris.c b/src/astroGraphics/ephemeris.c
index 3133888..b5ed046 100644
--- a/src/astroGraphics/ephemeris.c
+++ b/src/astroGraphics/ephemeris.c
@@ -518,7 +518,7 @@ void plot_ephemeris(chart_config *s, line_drawer *ld, cairo_page *page, int trac
     // Set line colour
     ld_pen_up(ld, GSL_NAN, GSL_NAN, NULL, 1);
     cairo_set_source_rgb(s->cairo_draw, s->ephemeris_col.red, s->ephemeris_col.grn, s->ephemeris_col.blu);
-    ld_label(ld, NULL, 1, 1);
+    ld_label(ld, NULL, 1, 1, 1);
 
     // Loop over the points in the ephemeris, and draw a line across the star chart
     const ephemeris *e = &s->ephemeris_data[trace_num];
@@ -591,7 +591,7 @@ void plot_ephemeris(chart_config *s, line_drawer *ld, cairo_page *page, int trac
 
             // Draw tick mark
             ld_pen_up(ld, GSL_NAN, GSL_NAN, NULL, 1);
-            ld_label(ld, NULL, 1, 1);
+            ld_label(ld, NULL, 1, 1, 1);
             ld_point(ld, x + graph_coords_tick_len * sin(theta), y - graph_coords_tick_len * cos(theta), NULL);
             ld_point(ld, x - graph_coords_tick_len * sin(theta), y + graph_coords_tick_len * cos(theta), NULL);
             ld_pen_up(ld, GSL_NAN, GSL_NAN, NULL, 1);
@@ -894,4 +894,4 @@ double draw_ephemeris_table(chart_config *s, double legend_y_pos, int draw_outpu
     }
 
     return legend_y_pos;
-}
\ No newline at end of file
+}
diff --git a/src/astroGraphics/greatCircles.c b/src/astroGraphics/greatCircles.c
index 60e87e4..6b7949f 100644
--- a/src/astroGraphics/greatCircles.c
+++ b/src/astroGraphics/greatCircles.c
@@ -61,7 +61,7 @@ static void plot_great_circle(double ra0, double dec0, chart_config *s, line_dra
     dec0 = dec0 * M_PI / 180;
     ld_pen_up(ld, GSL_NAN, GSL_NAN, NULL, 1);
     for (i = 0; i <= N_SAMPLES; i++) {
-        const double l = 2 * M_PI * ((double) i) / N_SAMPLES;
+        const double l = 2 * M_PI * ((double) i) / (N_SAMPLES-1);
         double a[3] = {cos(l), sin(l), 0.};
         double ra, dec, x, y;
 
@@ -97,6 +97,56 @@ static void plot_great_circle(double ra0, double dec0, chart_config *s, line_dra
         }
 }
 
+//small modification to print half circle, useful for meridians.
+
+static void plot_great_half_circle(double ra0, double dec0, chart_config *s, line_drawer *ld,
+                              cairo_page *page, int n_labels, gc_label *labels, colour colour) {
+    int i;
+    ra0 = ra0 * M_PI / 180;
+    dec0 = dec0 * M_PI / 180;
+    ld_pen_up(ld, GSL_NAN, GSL_NAN, NULL, 1);
+    for (i = 0; i <= N_SAMPLES; i++) {
+        const double l = M_PI * ((double) i) / (N_SAMPLES-1);
+        double a[3] = {cos(l), sin(l), 0.};
+        double ra, dec, x, y;
+
+        rotate_xz(a, a, dec0 - (M_PI / 2));
+        rotate_xy(a, a, ra0);
+
+        dec = asin(a[2]);
+        ra = atan2(a[1], a[0]);
+        plane_project(&x, &y, s, ra, dec, 0);
+        ld_point(ld, x, y, NULL);
+    }
+    ld_pen_up(ld, GSL_NAN, GSL_NAN, NULL, 1);
+
+    if (n_labels)
+        for (i = 0; i < n_labels; i++) {
+            const double l = M_PI*(labels[i].xpos) / 180;
+            double a[3] = {cos(l), sin(l), 0.};
+            double ra, dec, x, y, xtemp, ytemp;
+
+            rotate_xz(a, a, dec0 - (M_PI / 2));
+            rotate_xy(a, a, ra0);
+
+            dec = asin(a[2]);
+            ra = atan2(a[1], a[0]);
+            plane_project(&x, &y, s, ra, dec, 0);
+	    plane_project(&xtemp, &ytemp, s, ra-0.0000000001/(dec-M_PI/2), dec, 0);
+	    //very, VERY brutal 1st order approximation
+            ld_point(ld, x+(xtemp-x)/sqrt((x-xtemp)*(x-xtemp)+(y-ytemp)*(y-ytemp))/50, y+(ytemp-y)/sqrt(((x-xtemp)*(x-xtemp))+((y-ytemp)*(y-ytemp)))/50, NULL);
+            ld_point(ld, x, y, NULL);
+	    plane_project(&xtemp, &ytemp, s, ra+0.000000001/(dec-M_PI/2), dec, 0);
+	    ld_point(ld, x+(xtemp-x)/sqrt((x-xtemp)*(x-xtemp)+(y-ytemp)*(y-ytemp))/50, y+(ytemp-y)/sqrt(((x-xtemp)*(x-xtemp))+((y-ytemp)*(y-ytemp)))/50, NULL);
+            ld_pen_up(ld, GSL_NAN, GSL_NAN, NULL, 1);
+	    plane_project(&xtemp, &ytemp, s, ra+0.1/(dec-M_PI/2), dec, 0);
+
+            chart_label_buffer(page, s, colour, labels[i].label,
+                               &(label_position) {x+(xtemp-x)/sqrt(((x-xtemp)*(x-xtemp))+((y-ytemp)*(y-ytemp)))/25, y+(ytemp-y)/sqrt(((x-xtemp)*(x-xtemp))+((y-ytemp)*(y-ytemp)))/25, 0, 0, -1}, 1,
+                               0, 1, 2.0, 1, 0, 0, -0.5);
+        }
+}
+
 //! plot_equator - Draw a line along the celestial equator
 //! \param s - A <chart_config> structure defining the properties of the star chart to be drawn.
 //! \param ld - A <line_drawer> structure used to draw lines on a cairo surface.
@@ -110,6 +160,34 @@ void plot_equator(chart_config *s, line_drawer *ld, cairo_page *page) {
 
     plot_great_circle(0, 90, s, ld, page, 0, NULL, s->equator_col);
 }
+// plots RA=0 meridian
+void plot_meridian(chart_config *s, line_drawer *ld, cairo_page *page) {
+    gc_label labels[17] = {{"-80", 10},
+                           {"-70", 20},
+                           {"-60", 30},
+                           {"-50", 40},
+                           {"-40", 50},
+                           {"-30", 60},
+                           {"-20", 70},
+                           {"-10", 80},
+                           {"0", 90},
+                           {"10", 100},
+                           {"20", 110},
+                           {"30", 120},
+			   {"40", 130},
+			   {"50", 140},
+			   {"60", 150},
+			   {"70", 160},
+			   {"80", 170},
+    };
+    // Set line colour
+    ld_pen_up(ld, GSL_NAN, GSL_NAN, NULL, 1);
+    cairo_set_source_rgb(s->cairo_draw, s->meridian_col.red, s->meridian_col.grn, s->meridian_col.blu);
+    cairo_set_line_width(s->cairo_draw, s->great_circle_line_width);
+
+    plot_great_half_circle(-90, 0, s, ld, page, s->label_meridian ? 17 : 0, labels,
+                      s->meridian_col);
+}
 
 //! plot_galactic_plane - Draw a line along the plane of the Milky Way
 //! \param s - A <chart_config> structure defining the properties of the star chart to be drawn.
@@ -161,7 +239,7 @@ void plot_ecliptic(chart_config *s, line_drawer *ld, cairo_page *page) {
 //! \param legend_y_pos - The vertical pixel position of the top of the next legend to go under the star chart.
 
 double draw_great_circle_key(chart_config *s, double legend_y_pos) {
-    const int N = (s->plot_equator != 0) + (s->plot_ecliptic != 0) + (s->plot_galactic_plane != 0);
+    const int N = (s->plot_meridian != 0) + (s->plot_equator != 0) + (s->plot_ecliptic != 0) + (s->plot_galactic_plane != 0);
     const double w_left = 0.4; // The left margin
     const double w_item = 4.2 * s->font_size; // The width of each legend item (cm)
 
@@ -188,12 +266,12 @@ double draw_great_circle_key(chart_config *s, double legend_y_pos) {
     // Reset font weight
     cairo_select_font_face(s->cairo_draw, s->font_family, CAIRO_FONT_SLANT_NORMAL, CAIRO_FONT_WEIGHT_NORMAL);
 
-    // Draw item on legend showing the colour of the equator
+     // Draw item on legend showing the colour of the meridian
     if (s->plot_equator != 0) {
-        const char *label = "The Equator";
+        const char *label = "Vernal Meridian";
 
         // Draw a line in the right colour
-        cairo_set_source_rgb(s->cairo_draw, s->equator_col.red, s->equator_col.grn, s->equator_col.blu);
+        cairo_set_source_rgb(s->cairo_draw, s->meridian_col.red, s->meridian_col.grn, s->meridian_col.blu);
         cairo_new_path(s->cairo_draw);
         cairo_move_to(s->cairo_draw, x * s->cm, y1 * s->cm);
         cairo_line_to(s->cairo_draw, (x + size) * s->cm, y1 * s->cm);
@@ -216,6 +294,30 @@ double draw_great_circle_key(chart_config *s, double legend_y_pos) {
     if (s->plot_ecliptic != 0) {
         const char *label = "Ecliptic Plane";
 
+   // Draw item on legend showing the colour of the equator
+    if (s->plot_equator != 0) {
+        const char *label = "The Equator";
+
+        // Draw a line in the right colour
+        cairo_set_source_rgb(s->cairo_draw, s->equator_col.red, s->equator_col.grn, s->equator_col.blu);
+        cairo_new_path(s->cairo_draw);
+        cairo_move_to(s->cairo_draw, x * s->cm, y1 * s->cm);
+        cairo_line_to(s->cairo_draw, (x + size) * s->cm, y1 * s->cm);
+        cairo_stroke(s->cairo_draw);
+
+        // Write a text label next to it
+        cairo_set_source_rgb(s->cairo_draw, 0, 0, 0);
+        cairo_text_extents(s->cairo_draw, label, &extents);
+        cairo_move_to(s->cairo_draw,
+                      (x + 0.1 + size * 1.25) * s->cm - extents.x_bearing,
+                      y1 * s->cm - extents.height / 2 - extents.y_bearing
+        );
+        cairo_show_text(s->cairo_draw, label);
+
+        // Advance horizontally to draw the next item in the legend
+        x += w_item;
+    }
+
         // Draw a line in the right colour
         cairo_set_source_rgb(s->cairo_draw, s->ecliptic_col.red, s->ecliptic_col.grn, s->ecliptic_col.blu);
         cairo_new_path(s->cairo_draw);
diff --git a/src/astroGraphics/greatCircles.h b/src/astroGraphics/greatCircles.h
index 48b7a78..95e637d 100644
--- a/src/astroGraphics/greatCircles.h
+++ b/src/astroGraphics/greatCircles.h
@@ -31,6 +31,8 @@
 
 void plot_equator(chart_config *s, line_drawer *ld, cairo_page *page);
 
+void plot_meridian(chart_config *s, line_drawer *ld, cairo_page *page);
+
 void plot_galactic_plane(chart_config *s, line_drawer *ld, cairo_page *page);
 
 void plot_ecliptic(chart_config *s, line_drawer *ld, cairo_page *page);
diff --git a/src/astroGraphics/raDecLines.c b/src/astroGraphics/raDecLines.c
index 6669ce2..e9f4f5e 100644
--- a/src/astroGraphics/raDecLines.c
+++ b/src/astroGraphics/raDecLines.c
@@ -144,7 +144,8 @@ void plot_ra_dec_lines(chart_config *s, line_drawer *ld) {
 
         // Tell the line drawing class what label should be placed on the edge of the star chart when we cross it
         // Lines of constant RA only create tick labels on the horizontal axes, not the vertical axes
-        ld_label(ld, label, 1, 0);
+	// Lines of constant declination create a tick on the round edge of the chart in Alt_Az mode if and only if ordered to do so
+        ld_label(ld, label, 1, 0, s->ra_ticks_on_round_edge);
 
         // Trace the path of this line across chart
         for (j = 0; j < N_POINTS; j++) {
@@ -214,7 +215,8 @@ void plot_ra_dec_lines(chart_config *s, line_drawer *ld) {
 
         // Tell the line drawing class what label should be placed on the edge of the star chart when we cross it
         // Lines of constant declination only create tick labels on the vertical axes, not the horizontal axes
-        ld_label(ld, label, 0, 1);
+	// Lines of constant declination create a tick on the round edge of the chart in Alt_Az mode if and only if ordered to do so
+        ld_label(ld, label, 0, 1, s->dec_ticks_on_round_edge);
 
         // Trace the path of this line across chart
         for (j = 0; j < N_POINTS; j++) {
diff --git a/src/main.c b/src/main.c
index 347c002..42b7fdc 100644
--- a/src/main.c
+++ b/src/main.c
@@ -80,11 +80,14 @@ void render_chart(chart_config *s) {
     plot_background_image(s);
 
     // Initialise module for tracing lines on the star chart
-    ld_init(&ld, s, page.x_labels, page.x2_labels, page.y_labels, page.y2_labels);
+    ld_init(&ld, s, page.x_labels, page.x2_labels, page.y_labels, page.y2_labels, page.r_labels);
 
     // Draw the line of the equator
     if (s->plot_equator) plot_equator(s, &ld, &page);
 
+    // Draw the line of the vernal meridian
+    if (s->plot_meridian) plot_meridian(s, &ld, &page);
+
     // Draw the line of the galactic plane
     if (s->plot_galactic_plane) plot_galactic_plane(s, &ld, &page);
 
@@ -350,7 +353,19 @@ int main(int argc, char **argv) {
             CHECK_KEYVALNUM("axis_ticks_value_only")
             settings_destination->axis_ticks_value_only = (int) key_val_num;
             continue;
-        } else if (strcmp(key, "axis_label") == 0) {
+        } else if (strcmp(key, "ra_ticks_on_round_edge") == 0) {
+            //! ra_ticks_on_round_edge - If 1, constant RA labels will place ticks on the round edge in Alt_Az mode. 
+	    //! If 0, they won't
+            CHECK_KEYVALNUM("ra_ticks_on_round_edge")
+            settings_destination->ra_ticks_on_round_edge = (int) key_val_num;
+            continue;
+	} else if (strcmp(key, "dec_ticks_on_round_edge") == 0) {
+//! dec_ticks_on_round_edge - If 1, constant Dec labels will place ticks on the round edge in Alt_Az mode.                   
+            //! If 0, they won't		
+	    CHECK_KEYVALNUM("dec_ticks_on_round_edge")
+            settings_destination->dec_ticks_on_round_edge = (int) key_val_num;
+            continue;
+	} else if (strcmp(key, "axis_label") == 0) {
             //! axis_label - Boolean (0 or 1) indicating whether to write "Right ascension" and "Declination" on the
             //! vertical/horizontal axes
             CHECK_KEYVALNUM("axis_label")
@@ -476,7 +491,7 @@ int main(int argc, char **argv) {
             } else if (strcmp(key_val, "alt_az") == 0) {
                 settings_destination->projection = SW_PROJECTION_ALTAZ;
                 settings_destination->aspect = 1.;
-                settings_destination->angular_width = 180.;
+		//settings_destination->angular_width = 180.;
             } else {
                 snprintf(temp_err_string, FNAME_LENGTH,
                          "Bad input file. projection should equal 'flat', 'gnomonic', 'sphere' or 'alt_az'.");
@@ -720,7 +735,18 @@ int main(int argc, char **argv) {
             CHECK_KEYVALNUM("plot_equator")
             settings_destination->plot_equator = (int) key_val_num;
             continue;
-        } else if (strcmp(key, "ecliptic_col") == 0) {
+	}else if (strcmp(key, "plot_meridian") == 0) {
+            //! plot_meridian - Boolean (0 or 1) indicating whether to draw a line along the vernal meridian
+            CHECK_KEYVALNUM("plot_meridian")
+            settings_destination->plot_meridian = (int) key_val_num;
+            continue;
+	} else if (strcmp(key, "label_meridian") == 0) {
+            //! label_meridian - Boolean (0 or 1) indicating whether to label Dec degrees along the
+            //! vernal meridian, useful to label Dec lines in Alt_Az charts
+            CHECK_KEYVALNUM("label_meridian")
+            settings_destination->label_meridian = (int) key_val_num;
+            continue;
+	} else if (strcmp(key, "ecliptic_col") == 0) {
             //! ecliptic_col - Colour to use when drawing a line along the ecliptic
             settings_destination->ecliptic_col = colour_from_string(key_val);
             continue;
@@ -732,6 +758,10 @@ int main(int argc, char **argv) {
             //! equator_col - Colour to use when drawing a line along the equator
             settings_destination->equator_col = colour_from_string(key_val);
             continue;
+	} else if (strcmp(key, "meridian_col") == 0) {
+            //! meridian_col - Colour to use when drawing a line along the equator
+            settings_destination->meridian_col = colour_from_string(key_val);
+            continue;
         } else if (strcmp(key, "plot_galaxy_map") == 0) {
             //! plot_galaxy_map - Boolean (0 or 1) indicating whether to draw a shaded map of the Milky Way behind
             //! the star chart
diff --git a/src/mathsTools/projection.c b/src/mathsTools/projection.c
index 70b4bc0..5465933 100644
--- a/src/mathsTools/projection.c
+++ b/src/mathsTools/projection.c
@@ -67,7 +67,14 @@ void galactic_project(double ra, double dec, double *l_out, double *b_out) {
 //! to be converted into galactic coordinates.
 
 void plane_project(double *x, double *y, chart_config *s, double lng, double lat, int grid_line) {
-    double azimuth, radius = 0, zenith_angle;
+    double azimuth, radius = 0, zenith_angle/*, cap_angle*/;
+    
+    /*cap_angle=M_PI/2;
+    if (s->angular_width/2>cap_angle) {
+	    cap_angle=(s->angular_width)/2;
+    }*/
+    //cap_angle=(s->angular_width)/2;
+    //printf("angular_width = %f", s->angular_width);
 
     if ((s->coords == SW_COORDS_GAL) && (!grid_line))
     {
@@ -97,15 +104,27 @@ void plane_project(double *x, double *y, chart_config *s, double lng, double lat
     }
     make_zenithal(&zenith_angle, &azimuth, lng, lat, s->ra0, s->dec0);
     azimuth -= s->position_angle * M_PI / 180;
-    if (zenith_angle > M_PI / 2) {
-        // Opposite side of sphere!
-        *x = *y = GSL_NAN;
-        return;
+    //if (zenith_angle > M_PI / alpha) {
+    if(s->projection == SW_PROJECTION_ALTAZ){
+	//if (zenith_angle > s->angular_width/2) { //does this make intersections happen?
+	if (zenith_angle>M_PI){
+	// Opposite side of sphere!
+                *x = *y = GSL_NAN;
+                return;
+        }
+    } else{
+    	if (zenith_angle > M_PI/2) {
+    	// Opposite side of sphere!
+        	*x = *y = GSL_NAN;
+        	return;
+    	}
     }
 
     if (s->projection == SW_PROJECTION_GNOM) radius = tan(zenith_angle);
     else if (s->projection == SW_PROJECTION_SPH) radius = sin(zenith_angle);
-    else if (s->projection == SW_PROJECTION_ALTAZ) radius = zenith_angle / (M_PI / 2);
+    //else if (s->projection == SW_PROJECTION_ALTAZ) radius = zenith_angle /(M_PI/alpha);
+    else if (s->projection == SW_PROJECTION_ALTAZ) radius = 2*zenith_angle /s->angular_width;
+
 
     *y = radius * cos(azimuth);
     *x = radius * -sin(azimuth);
@@ -120,10 +139,15 @@ void plane_project(double *x, double *y, chart_config *s, double lng, double lat
 
 void inv_plane_project(double *ra, double *dec, chart_config *s, double x, double y) {
     double za = 0.0;
+    double cap_angle=M_PI/2;
+    if (s->angular_width/2>cap_angle) {
+            cap_angle=(s->angular_width)/2;
+    }
 
     if (s->projection == SW_PROJECTION_GNOM) za = atan(hypot(x, y));
     else if (s->projection == SW_PROJECTION_SPH) za = asin(hypot(x, y));
-    else if (s->projection == SW_PROJECTION_ALTAZ) za = hypot(x, y) * (M_PI / 2);
+    //else if (s->projection == SW_PROJECTION_ALTAZ) za = hypot(x, y) * (M_PI / 2);
+    else if (s->projection == SW_PROJECTION_ALTAZ) za = hypot(x, y) * s->angular_width/2;
 
     if (s->projection == SW_PROJECTION_FLAT) {
         double pa = s->position_angle * M_PI / 180.;
@@ -141,13 +165,22 @@ void inv_plane_project(double *ra, double *dec, chart_config *s, double x, doubl
         double az = atan2(-x, y) + s->position_angle * M_PI / 180.;
 
         double altitude = M_PI / 2 - za;
+	//double altitude = cap_angle - za;
         double a[3] = {cos(altitude) * cos(az), cos(altitude) * sin(az), sin(altitude)};
 
-        if (altitude < 0) {
-            *ra = *dec = GSL_NAN;
-            return;
-        }
-
+        //if (altitude < 0) {
+	//! Voglio disegnare solo le cose sopra la soglia che imposto, non sopra l'orizzonte
+	//!if (altitude < 1.4) {
+	if(s->projection == SW_PROJECTION_ALTAZ){
+		if(altitude<M_PI/2-cap_angle) {
+            	*ra = *dec = GSL_NAN;
+            	return;
+        	}
+	} else{
+		if(altitude<0){
+			*ra = * dec = GSL_NAN;
+		}
+	}
         rotate_xz(a, a, -(M_PI / 2) + s->dec0);
         rotate_xy(a, a, s->ra0);
 
diff --git a/src/settings/chart_config.c b/src/settings/chart_config.c
index 571ebb1..543c1b3 100644
--- a/src/settings/chart_config.c
+++ b/src/settings/chart_config.c
@@ -41,6 +41,8 @@ void default_config(chart_config *i) {
     i->position_angle = 0.0;
     i->font_size = 1.0;
     i->axis_ticks_value_only = 1;
+    i->ra_ticks_on_round_edge = 1;
+    i->dec_ticks_on_round_edge = 1;
     i->ra_dec_lines = 1;
     i->x_label_slant = 0;
     i->y_label_slant = 0;
@@ -94,9 +96,11 @@ void default_config(chart_config *i) {
     i->label_ecliptic = 0;
     i->plot_galactic_plane = 1;
     i->plot_equator = 1;
+    i->plot_meridian = 0;
     i->ecliptic_col = (colour) {0.8, 0.65, 0};
     i->galactic_plane_col = (colour) {0, 0, 0.75};
     i->equator_col = (colour) {0.65, 0, 0.65};
+    i->meridian_col = (colour) {0.1, 0.8, 1};
     i->constellation_stick_col = (colour) {0, 0.6, 0};
     i->grid_col = (colour) {0.7, 0.7, 0.7};
     i->constellation_boundary_col = (colour) {0.5, 0.5, 0.5};
@@ -118,7 +122,7 @@ void default_config(chart_config *i) {
     strcpy(i->galaxy_map_filename, SRCDIR "../data/milkyWay/process/output/galaxymap.dat");
     strcpy(i->photo_filename, "");
     strcpy(i->output_filename, "chart");
-    strcpy(i->copyright, "Produced with StarCharter. https://github.com/dcf21/star-charter");
+    strcpy(i->copyright, "");
     strcpy(i->title, "");
 
     // ----------------------------------------
@@ -134,6 +138,7 @@ void default_config(chart_config *i) {
 }
 
 void config_init(chart_config *i) {
+    i->marg=1.12; //margin specified here
     if (i->coords == SW_COORDS_GAL) i->ra0 *= M_PI / 180; // Specify galactic longitude in degrees
     else i->ra0 *= M_PI / 12;  // Specify RA in hours
     i->dec0 *= M_PI / 180; // Specify declination and galactic latitude in degrees
@@ -142,9 +147,11 @@ void config_init(chart_config *i) {
     else if (i->projection == SW_PROJECTION_PETERS) i->wlin = i->angular_width;
     else if (i->projection == SW_PROJECTION_GNOM) i->wlin = 2 * tan(i->angular_width / 2);
     else if (i->projection == SW_PROJECTION_SPH)
-        i->wlin = 2 * sin(i->angular_width / 2) * 1.12; // margin specified here
+        i->wlin = 2 * sin(i->angular_width / 2) * i->marg;
     else if (i->projection == SW_PROJECTION_ALTAZ)
-        i->wlin = i->angular_width / (M_PI / 2) * 1.12; // margin specified here
+        i->wlin = 2*i->marg;
+	//i->wlin = i->angular_width / (M_PI / 2) * i->marg;
+	//i->wlin = M_PI / (M_PI / 2) * 1.12; // margin specified here
     i->x_min = -i->wlin / 2;
     i->x_max = i->wlin / 2;
     i->y_min = -i->wlin / 2 * i->aspect;
diff --git a/src/settings/chart_config.h b/src/settings/chart_config.h
index bdeb9f5..357ebfc 100644
--- a/src/settings/chart_config.h
+++ b/src/settings/chart_config.h
@@ -115,6 +115,12 @@ typedef struct chart_config {
     //! If true, axis labels appear as "5h" or "30 deg". If false, preceded by alpha= or delta=
     int axis_ticks_value_only;
 
+    //! If true, constant RA lines make ticks on round edge in alt_az mode
+    int ra_ticks_on_round_edge;
+
+    //! If true, constant Dec lines make ticks on round edge in alt_az mode
+    int dec_ticks_on_round_edge;
+
     //! Boolean indicating whether we draw a grid of RA/Dec lines in the background of the star chart
     int ra_dec_lines;
 
@@ -322,6 +328,9 @@ typedef struct chart_config {
     //! Colour to use when drawing a line along the equator
     colour equator_col;
 
+    //! Colour to use when drawing a line along the vernal meridian
+    colour meridian_col;
+
     //! Boolean indicating whether to draw a line along the ecliptic
     int plot_ecliptic;
 
@@ -331,6 +340,12 @@ typedef struct chart_config {
     //! Boolean indicating whether to draw a line along the equator
     int plot_equator;
 
+    //! Boolean indicating whether to draw a line along the vernal meridian
+    int plot_meridian;
+
+    //! Boolean indicating whether to label Dec lines along the vernal meridian
+    int label_meridian;
+
     //! Boolean indicating whether to label the months along the ecliptic, showing the Sun's annual progress
     int label_ecliptic;
 
@@ -400,7 +415,7 @@ typedef struct chart_config {
     int output_format;
 
     double canvas_width, canvas_height, canvas_offset_x, canvas_offset_y, dpi, pt, cm, mm, line_width_base;
-    double wlin, x_min, x_max, y_min, y_max;
+    double wlin, marg, x_min, x_max, y_min, y_max;
 
     //! Width of the right-hand column of the legend under the finder chart
     double legend_right_column_width;
diff --git a/src/vectorGraphics/cairo_page.c b/src/vectorGraphics/cairo_page.c
index 74c268d..9fe119c 100644
--- a/src/vectorGraphics/cairo_page.c
+++ b/src/vectorGraphics/cairo_page.c
@@ -177,6 +177,7 @@ void cairo_init(cairo_page *p, chart_config *s) {
     p->x2_labels = listInit();
     p->y_labels = listInit();
     p->y2_labels = listInit();
+    p->r_labels = listInit();
 
     // Create a buffer into which we write all the text labels we are to write
     // We buffer them in order that we can plot them in order of priority, not the order in which they are added to
@@ -202,6 +203,7 @@ void cairo_init(cairo_page *p, chart_config *s) {
                   (s->canvas_offset_x + s->width / 2) * s->cm,
                   (s->canvas_offset_y + s->width / 2 * s->aspect) * s->cm,
                   s->width * s->cm / s->wlin,
+		  //s->width * s-> cm /2/s->marg,
                   0, 2 * M_PI);
 
     } else {
@@ -280,6 +282,7 @@ void draw_chart_edging(cairo_page *p, chart_config *s) {
                   (s->canvas_offset_x + s->width / 2) * s->cm,
                   (s->canvas_offset_y + s->width / 2 * s->aspect) * s->cm,
                   s->width * s->cm / s->wlin,
+		  //s->width * s->cm /2/s->marg,
                   0, 2 * M_PI);
         cairo_stroke(s->cairo_draw);
 
@@ -665,7 +668,7 @@ int chart_label(cairo_page *p, chart_config *s, colour colour, const char *label
 //! \param p - A structure describing the status of the drawing surface
 //! \param s - Settings for the star chart we are drawing
 //! \param labels - The list of labels to write along this edge of the star chart
-//! \param axis - One of ("x", "y", "x2", "y2") indicating whether this is the (bottom, left, top, right) edge
+//! \param axis - One of ("x", "y", "x2", "y2", "r") indicating whether this is the (bottom, left, top, right, or round) edge
 
 void chart_ticks_draw(cairo_page *p, chart_config *s, list *labels, char *axis) {
     int N = listLen(labels);
@@ -774,7 +777,27 @@ void chart_ticks_draw(cairo_page *p, chart_config *s, list *labels, char *axis)
             cairo_move_to(s->cairo_draw, -extents.x_bearing, -extents.height / 2 - extents.y_bearing);
             cairo_show_text(s->cairo_draw, tic_text);
             cairo_restore(s->cairo_draw);
-        }
+        } else if (strcmp(axis, "r") == 0) {
+            // Calculate coordinates of this label
+	    x_canvas = (s-> canvas_offset_x + (s-> width*(1+cos(tic_pos)/s->marg))/2) *s->cm;
+	    y_canvas = (s-> canvas_offset_y + (s-> width*(1+sin(tic_pos)/s->marg))/2) *s->cm;
+
+            // Check that this label does not collide with previous labels
+            const double x_min = x_canvas-extents.width / 2;
+            const double x_max = x_canvas+extents.width / 2;
+            const double y_min = y_canvas-extents.height/2;
+            const double y_max = y_canvas+extents.height/2;
+            if (chart_check_label_exclusion(p, x_min, x_max, y_min, y_max)) continue;
+            chart_add_label_exclusion(p, s, x_min, x_max, y_min, y_max);
+
+            // Write a label on the round edge of the chart
+            cairo_save(s->cairo_draw);
+            cairo_translate(s->cairo_draw, x_canvas, y_canvas);
+            cairo_move_to(s->cairo_draw, -extents.width / 2 -extents.x_bearing +(extents.width+0.5*s->cm)/2*cos(tic_pos),
+			    -extents.height/2 -extents.y_bearing +(extents.height+0.5*s->cm)/2*sin(tic_pos)); //radial align with 0.5cm margin on each side
+            cairo_show_text(s->cairo_draw, tic_text);
+            cairo_restore(s->cairo_draw);
+	}
     }
 }
 
@@ -808,6 +831,9 @@ int chart_finish(cairo_page *p, chart_config *s) {
     chart_ticks_draw(p, s, p->y_labels, "y");
     chart_ticks_draw(p, s, p->x2_labels, "x2");
     chart_ticks_draw(p, s, p->y2_labels, "y2");
+    if (s->projection == SW_PROJECTION_ALTAZ) {
+	    chart_ticks_draw(p, s, p->r_labels, "r");
+    }
 
     // Close cairo drawing context
     cairo_destroy(s->cairo_draw);
diff --git a/src/vectorGraphics/cairo_page.h b/src/vectorGraphics/cairo_page.h
index 0c7dc7f..605bd15 100644
--- a/src/vectorGraphics/cairo_page.h
+++ b/src/vectorGraphics/cairo_page.h
@@ -64,7 +64,7 @@ typedef struct {
 } exclusion_region;
 
 typedef struct {
-    list *x_labels, *x2_labels, *y_labels, *y2_labels;
+    list *x_labels, *x2_labels, *y_labels, *y2_labels, *r_labels;
 
     label_buffer_item *labels_buffer;
     int labels_buffer_counter;
diff --git a/src/vectorGraphics/lineDraw.c b/src/vectorGraphics/lineDraw.c
index 3a99bd9..9578ec6 100644
--- a/src/vectorGraphics/lineDraw.c
+++ b/src/vectorGraphics/lineDraw.c
@@ -48,6 +48,19 @@ static void list_add_tick(list *l, double x, const char *label) {
     listAppendPtr(l, buff, FNAME_LENGTH, 0, DATATYPE_VOID);
 }
 
+//Solve second degree equation
+void solve2deg(double *sol1, double *sol2, double a, double b, double c){
+	double delta= b*b-4*a*c;
+	if(delta >= 0){
+		*sol1=(-b+sqrt(delta))/(2*a);
+		*sol2=(-b-sqrt(delta))/(2*a);
+	}
+	else{
+		*sol1=*sol2=GSL_NAN;
+	}
+
+}
+
 //! truncate_at_axis - Take a line segment which passes outside the boundary of the star chart, and truncate it at the
 //! edge of the chart. Also, if this line has a text label associated with it, then place a label on the axis where
 //! this line meets it, typically denoting the RA or the Dec being traced by this line.
@@ -125,6 +138,49 @@ void truncate_at_axis(double *xout, double *yout, double x0, double y0, double x
     *yout = y0;
 }
 
+//truncate_at_round_edge: looks for intersection with the edge of the chart in Alt_Az charts
+
+void truncate_at_round_edge(double *xout, double *yout, double x0, double y0, double x1, 
+			double y1, char *label, list *rlabels) {
+    double x=GSL_NAN, y=GSL_NAN, s1, s2, theta=GSL_NAN;
+
+    if (x1 != x0) {
+        // Look for intersection with round edge of chart
+        double m = (y1 - y0) / (x1 - x0);
+	solve2deg(&s1, &s2, 1+m*m, 2*m*(y0-m*x0), m*m*x0*x0+y0*y0-2*m*x0*y0-1);
+        if ((s1 <= gsl_max(x0, x1)) && (s1 >= gsl_min(x0, x1))){
+	    x=s1;
+	} else if ((s2 <= gsl_max(x0, x1)) && (s2 >= gsl_min(x0, x1))){
+	    x=s2;
+	}
+	y=m*(x-x0)+y0;
+    } else if (y1 != y0) {
+	    x=x0;
+	    if (sqrt(1-x0*x0)>gsl_min(y0, y1)&& sqrt(1-x0*x0)<gsl_max(y0, y1)) {
+		    y=sqrt(1-x0*x0);
+	    } else if (-sqrt(1-x0*x0)>gsl_min(y0, y1)&& -sqrt(1-x0*x0)<gsl_max(y0, y1)) {
+		    y=-sqrt(1-x0*x0);
+	    }
+    }
+    if (x >= 0) {
+            theta=asin(y);
+        } else if (y>=0){
+            theta=acos(x);
+        } else if (x<0 && y<0) {
+                theta=M_PI+acos(-x);
+    }
+    if (theta != GSL_NAN){
+        list_add_tick(rlabels, theta, label);
+	*xout = x;
+        *yout = y;
+        return;
+    }
+    // If no intersection found, then simply return the position of the start of the line
+    *xout = x0;
+    *yout = y0;
+}
+
+
 //! ld_init - Initialise this module for drawing lines on star charts
 //! \param self - The <line_drawer> structure used to hold data about this line drawing module instance.
 //! \param s - A <chart_config> structure defining the properties of the star chart to be drawn.
@@ -132,11 +188,13 @@ void truncate_at_axis(double *xout, double *yout, double x0, double y0, double x
 //! \param x2labels - The list of labels to place on the top edge of the chart
 //! \param ylabels - The list of labels to place on the left edge of the chart
 //! \param y2labels - The list of labels to place on the right edge of the chart
+//! \param rlabels - The list of labels to place on the round edge of the chart
 
-void ld_init(line_drawer *self, chart_config *s, list *xlabels, list *x2labels, list *ylabels, list *y2labels) {
+void ld_init(line_drawer *self, chart_config *s, list *xlabels, list *x2labels, list *ylabels, list *y2labels, list *rlabels) {
     self->label = NULL;
     self->label_on_x = 1;
     self->label_on_y = 1;
+    self->label_on_r =1;
     self->penup = 1;
     self->haddata = 0;
     self->xmin = s->x_min;
@@ -147,6 +205,7 @@ void ld_init(line_drawer *self, chart_config *s, list *xlabels, list *x2labels,
     self->x2labels = x2labels;
     self->ylabels = ylabels;
     self->y2labels = y2labels;
+    self->rlabels = rlabels;
     self->s = s;
     self->wlin = s->wlin;
     self->xold = GSL_NAN;
@@ -160,11 +219,14 @@ void ld_init(line_drawer *self, chart_config *s, list *xlabels, list *x2labels,
 //! \param l - The text label to be associated with the next line we draw
 //! \param label_on_x - Boolean indicating whether this label is allowed to be written on horizontal axes
 //! \param label_on_y - Boolean indicating whether this label is allowed to be written on vertical axes
+//! \param label_on_r - Boolean indicating whether this label is allowed to be written on round edge
 
-void ld_label(line_drawer *self, char *l, int label_on_x, int label_on_y) {
+void ld_label(line_drawer *self, char *l, int label_on_x, int label_on_y, int label_on_r) {
     self->label = l;
     self->label_on_x = label_on_x;
     self->label_on_y = label_on_y;
+    self->label_on_r = label_on_r;
+
 }
 
 //! ld_pen_up - Lift the pen and start drawing a new line
@@ -227,9 +289,16 @@ void ld_point(line_drawer *self, double x, double y, const char *name) {
         yp[0] = y;
         Nitems = 1;
     }
-    for (i = 0; i < Nitems; i++) {
-        if (!gsl_finite(xp[i])) ld_pen_up(self, GSL_NAN, GSL_NAN, NULL, 1);
-        else ld_point_plot(self, xp[i], yp[i], name);
+    if (self->s->projection == SW_PROJECTION_ALTAZ) {
+	for (i = 0; i < Nitems; i++) {
+            if (!gsl_finite(xp[i])) ld_pen_up(self, GSL_NAN, GSL_NAN, NULL, 1);
+            else ld_point_plot_round(self, xp[i], yp[i], name);    
+        }
+    } else {
+    	for (i = 0; i < Nitems; i++) {
+            if (!gsl_finite(xp[i])) ld_pen_up(self, GSL_NAN, GSL_NAN, NULL, 1);
+            else ld_point_plot(self, xp[i], yp[i], name);
+    	}
     }
 }
 
@@ -287,3 +356,48 @@ void ld_point_plot(line_drawer *self, double x, double y, const char *name) {
     self->xold = x;
     self->yold = y;
 }
+
+//variant for round edge
+
+void ld_point_plot_round(line_drawer *self, double x, double y, const char *name) {
+    double x_canvas, y_canvas;
+    if(x*x+y*y<1){
+        if ((gsl_finite(self->xold)) && self->penup) {
+            double xo, yo;
+            truncate_at_round_edge(&xo, &yo, self->xold, self->yold, x, y,
+                             self->label,
+                             self->label_on_r ? self->rlabels : NULL);
+
+            fetch_canvas_coordinates(&x_canvas, &y_canvas, xo, yo, self->s);
+            if (!self->haddata) {
+                cairo_new_path(self->s->cairo_draw);
+                cairo_move_to(self->s->cairo_draw, x_canvas, y_canvas);
+            } else cairo_line_to(self->s->cairo_draw, x_canvas, y_canvas);
+            self->haddata = 1;
+        }
+        fetch_canvas_coordinates(&x_canvas, &y_canvas, x, y, self->s);
+        if (!self->haddata) {
+            cairo_new_path(self->s->cairo_draw);
+            cairo_move_to(self->s->cairo_draw, x_canvas, y_canvas);
+        } else cairo_line_to(self->s->cairo_draw, x_canvas, y_canvas);
+        self->haddata = 1;
+        self->penup = 0;
+    } else {
+        if ((gsl_finite(self->xold)) && (!self->penup)) {
+            double xo, yo;
+	    truncate_at_round_edge(&xo, &yo, self->xold, self->yold, x, y,
+                             self->label,
+                             self->label_on_r ? self->rlabels : NULL);
+
+            fetch_canvas_coordinates(&x_canvas, &y_canvas, xo, yo, self->s);
+            if (!self->haddata) {
+                cairo_new_path(self->s->cairo_draw);
+                cairo_move_to(self->s->cairo_draw, x_canvas, y_canvas);
+            } else cairo_line_to(self->s->cairo_draw, x_canvas, y_canvas);
+            self->haddata = 1;
+        }
+        ld_pen_up(self, GSL_NAN, GSL_NAN, NULL, 0);
+    }
+    self->xold = x;
+    self->yold = y;
+}
diff --git a/src/vectorGraphics/lineDraw.h b/src/vectorGraphics/lineDraw.h
index 4af691e..1f96d50 100644
--- a/src/vectorGraphics/lineDraw.h
+++ b/src/vectorGraphics/lineDraw.h
@@ -31,8 +31,8 @@
 
 typedef struct ld_handle {
     char *label;
-    int label_on_x, label_on_y;
-    list *xlabels, *x2labels, *ylabels, *y2labels;
+    int label_on_x, label_on_y, label_on_r;
+    list *xlabels, *x2labels, *ylabels, *y2labels, *rlabels;
     int penup, haddata;
     double xmin, xmax, ymin, ymax, wlin;
     chart_config *s;
@@ -43,9 +43,12 @@ void truncate_at_axis(double *xout, double *yout, double x0, double y0, double x
                       double ymin, double ymax, char *label, list *xlabels, list *x2labels, list *ylabels,
                       list *y2labels);
 
-void ld_init(line_drawer *self, chart_config *s, list *xlabels, list *x2labels, list *ylabels, list *y2labels);
+void truncate_at_round_edge(double *xout, double *yout, double x0, double y0, double x1, double y1,
+		char *label, list *rlabels);
 
-void ld_label(line_drawer *self, char *l, int label_on_x, int label_on_y);
+void ld_init(line_drawer *self, chart_config *s, list *xlabels, list *x2labels, list *ylabels, list *y2labels, list *rlabels);
+
+void ld_label(line_drawer *self, char *l, int label_on_x, int label_on_y, int label_on_r);
 
 void ld_pen_up(line_drawer *self, double x, double y, const char *name, int new_line);
 
@@ -55,5 +58,7 @@ void ld_point(line_drawer *self, double x, double y, const char *name);
 
 void ld_point_plot(line_drawer *self, double x, double y, const char *name);
 
+void ld_point_plot_round(line_drawer *self, double x, double y, const char *name);
+
 #endif