Giving better looks for the stacked images

There is no denying it - stacked and unsharp masked halo image can be rather ugly. Ground objects are blurred and horizon is coated with blue glow.

But the looks can be improved by taking the ground from single untreated frame. That's what is done in the upper right image. It is the same image as the upper left except for the ground.

Near the horizon the clouds from the single frame dominate the sky, but in this case it has no significance as the halos are anyway blurred at the horizon. This technique works best with high sun displays where halos are far from ground objects.

The display was seen in Lahti on June 9. The upper image pair is stacked (using Registax) from 72 frames taken during 15 minutes. The lower is 60 frames /12 minutes stack. It shows lower 24 plate arc on the right and perhaps some 24 halo on the left. Jukka Ruoskanen also photographed the display some 40 kilometres from Lahti. Another example of the ground adding is here.

46° halo in Czech Republic

The April 21st 2007 was undoubtely one of the best halo days in this year. Observers from all over the Czech Republic enjoyed very bright 22° halo with tangent arcs and infralateral arcs.

We probably observed Wegener arcs and 120° parhelia, but this cannot be proven, because even fotos from Registax didn’t help us to clearly identify them. Anyway, Martin Popek saw that day very nice 46° halo and he took these pictures which were stacked from 40 images in Registax.

As the Sun was setting down, more halos appeared. In the second picture you can see parhelion with a part of parhelic circle (parhelic tail), 22° halo, circumzenithal arc and probably supralateral arc.

Edit: It isn’t supralateral arc in the second photo, but 46° halo because there is no upper tangent arc. That signifies absence of horizontal oriented columns, which are necessary in order to make supralateral arc.

9° column arcs in Prague

Today Ondrej Vlach seen nice Lunar display in Prague, Czech. Halo, upper tangent arc and rare 9 column arcs. Ondrej say: "Left side of 9 halo was very bright and I was took some photos at 22:40 UT. I use Registax for photo stacking."