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Calculate Sun Angles

This tool allows you to calculate the distance of a given RA/Dec from the Sun and Moon, at any time, to aid in planning Swift observation requests. For any observation, the target should be at least 47o from the Sun and at least 23o from the Moon. Also, a ToO is less likely to be succesful if it is between 4 and 8 hours in RA from the Sun.

In the form below please give the RA/Dec of the object (sexagesimal or decimal degrees), the initial date at which to calculate the Sun angle, for how many days it should be calculated, and whether to check visibility against ToO constraints or follow-up constraints. If the date/duration field are left blank, data will be calculated for 365 days, starting today.

Another useful tool is the Heasarc visibility calculator which checks the distance from the moon as well as the sun.

More information about ToOs

What's this?

If the save name box is selected, and a name, RA and Dec supplied, the RA and Dec will be saved in a local cache, under the name supplied. Next time someone tries to resolve that name, this cache will be searched should SIMBAD fail to return a position. Thus, if SIMBAD does not (yet) contain your object, you can select this box, to save time for future searches.