HENA instrument

The HENA instrument on the IMAGE satellite provides you with a different way of determining how much the magnetic field is disturbed. This instrument gives an idea of how strong the ring current is. The ring current is a flow of charged particles around the Earth between altitudes of 1,000 to 30,000 kilometers. They are especially intense whenever the magnetic field is disturbed.

When you click on the HENA button above, you will see a page like the one above. To use this archive, you first need to know the day-of-year (DOY). Use a calendar to calculate this. Many actually have a running tally of the days since January 1 written on them.

On the left-hand menu bar in the image, you will click the 'Browse Daily Image' spot so that the black dot appears.

Go to the bottom of this menu and enter today's year and DOY. For example, for May 7, 2003 enter '2003' and '127'. Click the 'Update' button and this image will appear:

You can use the '<<' or '>>' buttons to see if there is any more data after this DOY. Usually the HENA archive is 1-2 days behind the current DOY.

To interpret the HENA images use the following numerical scale for activity. The scale goes from blue to red. The greatest storm activity occurs when reds dominate.