Corresponding lat and lon of Sunpy map

[Mohamed Nedal]

Hi everyone, I hope you're doing well. 

Could you please tell me how can I get the corresponding helio-latitude and --longitude on a Sunpy map which has a shape of (1440, 3600)? 

I'm drawing a rectangle over an HMI map and I would like to convert the rectangle coordinates to Heliospheric coordinates. Kindly check the attached image of the map. 

Regards, 

Mohamed