What this tool tells you
An eclipse is not the same everywhere. A lunar eclipse is the same event for everyone on the night side of the Earth, but only the people for whom the Moon is above the horizon can see it. A solar eclipse is different in a second way: the Moon’s shadow is small, so some places see a deep eclipse, some a shallow one, and some nothing at all. For Hindu observance the first question is always whether the eclipse is visible in your own place, because sutak and the other grahan rules apply only where it is. This tool answers that question for any town, and gives the times.
Pick a town or city, choose one eclipse or all nine, and press the button. For each eclipse you get whether it is seen, the time it begins, the time of the greatest eclipse and the time it ends, all in your own local time, with daylight saving. For a solar eclipse you also get the magnitude and the share of the Sun hidden. For a lunar eclipse you get the umbral magnitude, and for a total eclipse the times of totality. Choose a single eclipse and the tool lists every stage with the height of the Sun or Moon at that moment.
How the result is worked out
For a solar eclipse the tool uses the Besselian elements published by NASA for each eclipse, the numbers that describe the Moon’s shadow as it sweeps across the Earth. It places your town on the Earth, finds the moments when the edge of the shadow reaches you and leaves you, and the moment you are nearest the centre of the shadow. First and last contact are when the Moon’s edge touches and leaves the Sun’s, and the magnitude is the part of the Sun’s width that is covered at the greatest. If the Sun is below the horizon at the true greatest eclipse, the tool shows the greatest eclipse you can see, at sunrise or sunset.
For a lunar eclipse the time of greatest eclipse, the magnitudes and the lengths of the stages come from NASA’s catalogue. These do not depend on where you stand. What does depend on your place is the Moon’s height above the horizon, and the tool works that out for every stage, so it can tell you that you see the eclipse from moonrise, or until moonset, or the whole of it.
We checked the method against timeanddate.com for at least six cities for each of the nine eclipses. First and last contacts agreed to within a minute, magnitudes to within 0.005, and moonrise and moonset to within two minutes. The same code produces the 49 city tables on each page of the grahan section.
Reading the sutak time
By tradition sutak starts twelve hours before first contact of a solar eclipse and nine hours before the dark shadow first touches the Moon in a lunar eclipse, and it ends when the eclipse ends. It is kept only where the eclipse is visible. A penumbral lunar eclipse, a faint shading in which the Moon never enters the dark shadow, is generally not counted as a grahan, so the tool shows no sutak for it. Where only a small part of an eclipse is seen, for example at moonrise, practice varies, and the tool shows the time anyway, so that you can follow your own custom.
Where traditions differ
The twelve and nine hours are the most common rule, but some traditions and temples count the sutak differently, for example from a fixed hour of the day, and some give a shorter period for the unwell, the old and children. The tool gives the standard figures and leaves the rest to your family or temple. The positions of the Sun and Moon in the sky, in sign and nakshatra, are on each eclipse page, using the Lahiri ayanamsa.
Safety
Never look at a solar eclipse directly, even when most of the Sun is covered. The safety note under the tool says how to watch with eclipse glasses or a pinhole projector. A lunar eclipse is safe to look at.
Frequently asked questions
↳ How do I know if an eclipse is visible in my city?
Pick your town above. The tool checks whether the Sun, for a solar eclipse, or the Moon, for a lunar one, is above your horizon during the eclipse, and says so in the Seen column. Where it is only partly visible it tells you whether you see it from sunrise or moonrise, or until sunset or moonset.
↳ What is the difference between magnitude and how much of the Sun is covered?
Magnitude is the share of the Sun's width that the Moon covers. The share of the Sun's disc that is hidden, shown as a percentage, is smaller at low magnitudes, because the disc is a circle. A magnitude of 0.5 hides about 39 per cent of the disc.
↳ Why does the tool show a time that is not the true maximum?
If the Sun or Moon is still below the horizon when the eclipse is at its greatest, you cannot see that moment. The tool then shows the greatest eclipse you can see, at sunrise, sunset, moonrise or moonset, and marks it.
↳ Does a penumbral lunar eclipse have sutak?
In most Indian almanacs it does not, because the Moon is not touched by the dark shadow. The tool therefore shows no sutak for the penumbral eclipses of 2027 and for the faint one in July, which is not visible at all.
↳ Is my place sent anywhere?
No. The calculation runs in your browser. Only the place search, which asks OpenStreetMap for the town, leaves the page.