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In the terminal, type:
    > convert io_bjj_0dd.tif io_bjj_0dd.jpg

• Load jpg image in Aladin as local file
Image size is 2880 x 1440
In the Frame drop menu (next to Location field), select Planet (will plot Lon-Lat coordinates, E-handed)

• Tie a coordinate frame to the image:
Click Image > Astrometrical calibration
And use parameters:
 Central pixel = 1440.0 720.0
 Pixel angular size = 7.5' (= 360/2880*60)
 Projection = CARTESIAN
 Rotation = 0°
 RA symmetry = False (default value, this is essential)

• Build a HiPS (Hierarchical Progressive Survey) from the image:
Tool > Generate a HiPS based on… > current image
It will plot after computation. Then overplot grid (Comm-G or bottom left icon), pan around, zoom in/out…
Projection is normally set to Spherical, but you can play with this also
Longitudes should be correctly set, ie increasing towards the lefteast, but may plot display as xxE and xxW in °the two hemispheres.

• Add catalogue features (but see alternative below):
Download USGS planetary nomenclature from
Extract nomenclature_all_feb2004.dbf
and convert to csv (e.g. using

Remove EOL character <NULL> from csv file in TextMate or another handy editor
Load it in TOPCAT as csv file

• Select Io features only by creating a subset:
Click on red/violet icon (subsets), add a filter (Plus icon) with parameters (name: io, expression: SA=="io")
Then select "Row subset" io in TOPCAT main window
=> 221 lines out of 8395 in io subset
Broadcast to Aladin via SAMP (Interop > Send table to…)

• Right-click the catalogue plane in Aladin, select Column Information…
Define source for coordinates carefully by clicking the Coo column and selecting a value in the drop list:
LATITUDE (col 16) => DE
LONG360 (col 18) => RA
(we're telling Aladin to handle these columns as its usual DEC and RA, respectively)

• Create a dedicated filter in Catalog > Create new filter:
Select Advanced mode, and type / copy:
# scale is 113.3 arcsec/km
draw ellipse(113.3*${DIAM}, 113.3*${DIAM}, 0) rainbow(${AD},1979,2003)
draw ${NAME} rainbow(${AD},1979,2003)