Data processing of SPHERE data:  Frequently asked questions

• I do not have OBJECT,CENTER observations - can I use the bright spot near the center of the coronagraph as object position?

Answer: The bright spot is not caused by stellar light coming through the coronagraph, but by a diffraction effect known as Arago spot or Fresnel bright spot. It does therefore not indicate the center position of the object and you should not use it as such. 

• Are there any colour transformations available for the SPHERE filters and another filter system?

Answer: SPHERE imaging data are not flux calibrated, therefore there is no conversion to other photometric systems available.