   dht.begin();
   
   // **************** FOR MEMORY ****************
-  //must be left as an output or the SD library functions will not work. 
+  // must be left as an output or the SD library functions will not work. 
   pinMode(SS, OUTPUT);
+  
+  DateTime saved_time=rtc.now();
+  file_name = "obi-"+ String(saved_time.month() ) + '-' + String(saved_time.day()) +
+      ".txt";
+  
   if ( !SD.begin(CHIP_SELECT_PIN) ) 
 #ifdef DEGUB
     Serial.println("SD card initialization failed!");
 #endif
-  delay(100);
+  delay(100); // otherwise open() will fail
   // write header
-  myFile = SD.open("obidata.txt", FILE_WRITE);
+  myFile = SD.open(file_name.c_str(), FILE_WRITE);
 
 
   if (myFile) {
 #ifdef DEBUG
     Serial.println("Writing header to SD");
 #endif
-    myFile.print("lat,lon DD/MM/YYYY HH:MM:SS");
-    myFile.println("\tSharp value\tGrove value\tCO value\tHumidity\tTemp");
+    myFile.print("latitude\tlongitude\tDD/MM/YYYY HH:MM:SS");
+    myFile.println("\tSharp value\tGrove value\tCO value\tHumidity\tTemp (celsius)");
     myFile.close();
   } else {
 #ifdef DEBUG

{
  // for gps
  bool newData = false;
  unsigned long chars;
  unsigned short sentences, failed;
  
  //gps_serial.listen(); // select the GPS softserial port for listening
  
  // For one second we parse GPS data and report some key values


} //ReadSensors // ISR

