Add function gswe_timestamp_get_sidereal_time()

docs/reference/swe-glib/swe-glib-sections.txt

@@ -268,6 +268,7 @@ gswe_timestamp_set_julian_day_et
 gswe_timestamp_get_julian_day_et
 gswe_timestamp_set_julian_day_ut
 gswe_timestamp_get_julian_day_ut
+gswe_timestamp_get_sidereal_time
 <SUBSECTION Standard>
 GSWE_IS_TIMESTAMP
 GSWE_IS_TIMESTAMP_CLASS

src/gswe-timestamp.c

@@ -985,6 +985,38 @@ gswe_timestamp_get_julian_day_ut(GsweTimestamp *timestamp, GError **err)
     return timestamp->priv->julian_day_ut;
 }
 
+/**
+ * gswe_timestamp_get_sidereal_time:
+ * @timestamp: a GsweTimestamp
+ * @err: a #GError
+ *
+ * Gets the sidereal time on the Greenwich Meridian.
+ *
+ * Returns: the sidereal time in hours. To get the degrees, multiply this value
+ * by 15.
+ *
+ * Since: 2.1
+ */
+gdouble
+gswe_timestamp_get_sidereal_time(GsweTimestamp *timestamp, GError **err)
+{
+    GError *local_err = NULL;
+
+    gswe_timestamp_calculate_julian(timestamp, &local_err);
+
+    if (local_err) {
+        if (err) {
+            *err = local_err;
+        } else {
+            g_error_free(local_err);
+        }
+
+        return 0.0;
+    }
+
+    return swe_sidtime(timestamp->priv->julian_day_ut);
+}
+
 /**
  * gswe_timestamp_new:
  *

src/gswe-timestamp.h

@@ -119,6 +119,7 @@ void gswe_timestamp_set_julian_day_et(GsweTimestamp *timestamp, gdouble julian_d
 gdouble gswe_timestamp_get_julian_day_et(GsweTimestamp *timestamp, GError **err);
 void gswe_timestamp_set_julian_day_ut(GsweTimestamp *timestamp, gdouble julian_day, GError **err);
 gdouble gswe_timestamp_get_julian_day_ut(GsweTimestamp *timestamp, GError **err);
+gdouble gswe_timestamp_get_sidereal_time(GsweTimestamp *timestamp, GError **err);
 
 #endif /* __SWE_GLIB_GSWE_TIMESTAMP_H__ */