The 2021 eclipse in Potosi, Wisconsin, USA

In this table, we’ve listed the following information:

Location identifier and latitude/longitude

The times in the table have been calculated based on this exact location. Times can shift by several seconds as you get several miles/km away from the location shown.

Notes

Here, we give you one of the following notes to tell you what is most likely to happen given "typical" refraction:

• All eclipse above horizon
  You should see all of the eclipse!
• All of annular phase may be visible
  Refraction might be enough to allow you to see all of the annular phase.
• All of annular phase should be visible
  Refraction should be enough to allow you to see all of the annular phase.
• Annular phase most likely below horizon
  Refraction will most likely not be enough to allow you to see any of the annular phase.
• Eclipse almost certainly not visible
  Refraction will most likely not be enough to allow you to see any of the eclipse.
• Eclipse very unlikely to be visible
  Refraction will probably not be enough to allow you to see any of the eclipse.
• Good chance to see small amount of eclipse
  Refraction will probably be enough to just barely allow you to see some of the partial phase of the eclipse.
• Should see very small amount of eclipse
  Refraction should definitely be enough to just barely allow you to see some of the partial phase of the eclipse.
• Sun may touch horizon during eclipse
  A very special case, where the eclipse will begin with the Sun above the horizon - then the Sun will dip down to the horizon before lifting up again.
• Sun rises during eclipse
  The Sun should rise during the eclipse, but you will most likely only see the partial phase.
• Sun rises during eclipse - annular phase may be visible
  The Sun should rise during the eclipse, and refraction might be enough to allow you to see some of the annular phase.
• Sun will likely rise during annular phase
  The Sun should rise during the eclipse, and refraction should be enough to allow you to see some of the annular phase.
• Very small chance of seeing some eclipse
  Refraction will probably be enough to allow you to see some of the partial phase of the eclipse.

C1 Through C4

For all eclipses, you will see the contact times for C1, Mid, and C4, in the time zone you've selected. If the eclipse is annular, you will also see rows for C2 and C3.

These times are defined as follows:

• C1
  This is the start of the partial phase of the eclipse - the beginning of the eclipse.
• C2
  (If applicable) This is the start of the annular phase of the eclipse.
• MID
  The mid-point of the eclipse, when the maximum amount of Sun is covered by the Moon.
• C3
  (If applicable) This is the end of the annular phase of the eclipse.
• C4
  This is the end of the partial phase of the eclipse - the end of the eclipse.

You will also see degree measures for an Altitude and Azimuth for each contact time. These will let you know where the Sun will be in the sky at that time, so you can check to make sure that trees, buildings or mountains won’t be in your way. (You can also go outside to your planned viewing location on the day before the eclipse at eclipse time and check it out yourself. The Sun’s location in the sky at that time won’t change enough in one day for you to notice the difference.)

• Altitude is given in degrees. The horizon is at 0°, and straight up is 90°. So 45° would be exactly halfway up, 30° would be 1/3 of the way up, and 60° would be 2/3 of the way up. Anything in between is, well, in between!
  These values do NOT take atmospheric refraction into account, so you have to rely more on the animation above to show you what will likely be visible.
• PLEASE NOTE that if you see a negative altitude, that means that part of the eclipse is happening BELOW the horizon. Again, this is without taking refraction into account, but the animation and notes will help you visualize things.
• Azimuth is given as an angle so you can tell exactly where the Sun will be, and here are some references: 90° is due east, 180° is due south, and 270° is due west. So, if you see 200°, that’s a bit less than 1/3 of the way from due south to due west. 135° would be straight southeast.

A word about "Atmospheric Refraction"

Refraction plays a very important role in the 2021 eclipse, because it applies to objects like the Sun and Moon when they are very close to the horizon. The effect serves to make the Sun and Moon appear slightly higher in the sky than they otherwise would. This means they will appear to rise earlier than what the math might suggest. This is normally no big deal, because it happens every day. But when an eclipse is happening while the Sun is rising, it means that you'll be able to see more of the eclipse than the math formulas tell us. But HOW MUCH more of the eclipse?

That's the problem, because the exact amount of refraction depends completely on the temperature and pressure values that exist in the atmosphere that the Sun's light is passing through. These values cannot be predicted in advance, and so we don't know EXACTLY (to the fraction of a second) what time the Sun will appear to rise in any given location! We do know when the eclipse will be happening, but we don't know EXACTLY where the Sun will be (with respect to the horizon) when the important milestones of the eclipse are happening.

We know the usual values for refraction, and we can give pretty good estimates based on what the weather forecasts are. But if you're wanting to know EXACT values and times for sunrise, you're going to be disappointed; sunrise is NEVER predicted to an accuracy at the level of seconds, for just this reason.

In the animation on each city page, we've given you a slider that lets you play with the refraction values. You can leave the slider as is, and this will be an "average" value for refraction that approximates what you most likely will see. Or, you can move the slider left or right to make the refraction values more or less aggressive. This is the best we can do by way of predicting what you'll exactly see.

As a general guide, we can tell you that refraction will increase if the barometric pressure increases, and the refraction will decrease if the temperature goes down. If you're using this tool to plan your eclipse-day activities, you'll want to explore a range of possible values when making your decision as to where to locate yourself on eclipse morning. Part of the fun and excitement of a sunrise or sunset eclipse is not really knowing in advance what you'll see, and knowing that you are enjoying a very unique and special view of the eclipse. We hope you have a wonderful eclipse experience!