The Carrington Maps are created from Level 1 XRT Al-Mesh synoptic images. The maps were created using the World Coordinate System (WCS; Thompson, 2006) code in SolarSoft. The header of the fits file should be consistent with the WCS fits header style. See for example at, Fits WCS and the standard fits header keywords defined at NASA.
The history of the map contains information about how many composite synoptic images were used to create the map and it contains the image header of the first image used in the map so users can get an idea of when the data was processed. I decided to include this information since it was valuable for me to determine why some XRT data would align well and others wouldn’t.
Please see the following table for the current definitions of the keywords in the fits header. Right now we only have Al-Mesh synoptics because it is the most comprehensive dataset but other filters will be included depending on data coverage.
v2019-01-25 Initial release
v2019-06-28 This version has additional light leak correction. The maps that required additional light leak correction are those numbered 2191 and above or after April 2017.
v2019-01-25 Initial release
|SIMPLE||0||Conforms to FITS standard|
|BITPIX||8, 16, 32,-32, -64||Number of bits per pixel|
|NAXIS||2||Number of axes in the image|
|NAXIS1||720||Full image size in x|
|NAXIS2||360||Full image size in y|
|ORIGIN||'Center for Astrophysics - Hinode/XRT'||Where the file was created|
|INSTRUME||XRT||Name of the instrument|
|DATE||'YYYY-MM-DDThh:mm:ss.sss'||Date and time of the file creation ('T' is character 'T')|
|EC_FW1||0-5||Filter wheel 1 position|
|EC_FW1_||'Open'; 'Al_poly'; 'C_poly'; 'Be_thin'; 'Be_med'; 'Al_med'||Filter wheel 1 position as name|
|EC_FW2||0-5||Filter wheel 2 position|
|EC_FW2_||'Open'; 'Al_mesh'; 'Ti_poly'; 'Gband'; 'Al_thick'; 'Be_thick'||Filter wheel 2 position as name|
|CAR_ROT||Carrington rotation number of map as string|
|CARROT||2049-9999||Carrington rotation number of map|
|WCSNAME||'Carrington Cylin-plate-carree'||Type of Cylindrical Projection|
|CTYPE1||'CRLN-CAR'||Type of units (label) of horizontal axis|
|CTYPE2||'CRLT-CAR'||Type of units (label) of vertical axis|
|CRVAL1||Location of center of map in degrees Longitude.|
|CRVAL2||Location of center of map in degrees Latitude.|
|CDELT1||0.5||Horizontal pixel size in degrees|
|CDELT2||0.5||Vertical pixel size in degrees|
|BUNIT||'DN/sec'||Pixel value units|
|Date_OBS||'YYYY-MM-DDThh:mm:ss.sss'||Date and time of start of Carrington Rotation|
|Date_START||'YYYY-MM-DDThh:mm:ss.sss'||Date and time of first image used to create map|
|Date_END||'YYYY-MM-DDThh:mm:ss.sss'||Date and time of last image used to create map|
|VER_NO||Verson number of FITS file|