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| en:praktikum:photometrie_python [2025/04/01 11:16] – [Defining some variables] rhainich | en:praktikum:photometrie_python [2025/07/31 10:08] (current) – [Download calibration data] rhainich |
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| In the next step we can perform the actual download. For this purpose we use the function ''.query_region''. We have to pass to it the coordinates and the size of the sky region to be queried. Fortunately, both are already known. We know the coordinates from the FIT headers of the star cluster images and the radius of the region is simply the field of view, which we already calculated above. Both values can be taken from the ''V_image'' object. | In the next step we can perform the actual download. For this purpose we use the function ''.query_region''. We have to pass to it the coordinates and the size of the sky region to be queried. Fortunately, both are already known. We know the coordinates from the FIT headers of the star cluster images and the radius of the region is simply the field of view, which we already calculated above. Both values can be taken from the ''V_image'' object. |
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| calib_tbl = v.query_region(V_image.V_image.coordinates_image_center, radius=V_image.field_of_view_x*u.arcmin)[0] | calib_tbl = v.query_region(V_image.coordinates_image_center, radius=V_image.field_of_view_x*u.arcmin)[0] |
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| The table ''calib_tbl'' now comprise all objects contained in the **APASS** catalog that are in our field of view with their ''B'' and ''V'' magnitudes. | The table ''calib_tbl'' now comprise all objects contained in the **APASS** catalog that are in our field of view with their ''B'' and ''V'' magnitudes. |