New filmclip

[jan lameer]

Hi all!

I've edited a new filmclip of the 2001 March 20 morning event. It was already on my site as a GIF animation but this DivX clip is better and color- and contrast corrected.

In this clip green aurora is also visible, with an upper edge of about four degrees above the horizon (just below the three goats in Auriga). My table of distances isn't here so I cannot give the distance, but as I remember the upper limit of green aurora is at about 150 km height. I'd like to find out how far this substorm was. Since the stars above Auriga are only the dimn stars in Camelopardalis, checking how high the blue sunlit Nitrogen went is hard, I'll do that later. I figure 600 km high or so and that the display was at a distance of 1000 - 1500 kilometers.

This clip, by the way is an in between result. A next and even better clip will be posted when the seven negatives are rescanned. Making clips like these is getting faster now I've learned a few tricks.

Can someone check whether the clips plays in good order? At first it didn't work so I re-encoded it and uploaded it again.

The clip can be seen through my site, click on the upper left image, then go to the bottom of thet 2001march20 page.

Thanx, JanL

[Ulrich Rieth]

Hi Jan!
Do you really think that you see a green aurora in your sequence?
I am not quite sure. Maybe it is "only" a color transition due to dust in the lower atmosphere. The green parts seem to follow exactly the movements of the nice blueish aurora. So I would expect them to be at the same distance and within the same auroral curtain. But as you said, the blue should be rather far away (1000 - 1500km) and from such a distant aurora you cannot see the lower green parts.
Anyway, the clip is running nice and smoothly.
I am awaiting more of these great documents in the future.
Have fun editing them.
Best regards

Ulrich

[jan lameer]

Hi Ulrich!

Thanks for bouncing that my clip is on-line.
Is it the right color, i really do not know. What I know is that it has the intenisty of what I felt. Seeing real aurora locally is special. And yes, we need more persons seeing what aurora is......

[Ulrich Rieth]

Hi Jan!

> Is it the right color, i really do not know.

Good question. I don't know. I have never seen one of these blue displays so far. But I can imagine, that each kind of film gives a slight color shift. So I would say, the color is right for the film used to record the display.

> What I know is that it has the intenisty of what I felt.

Ok, so if the intensity is right, the most important fact is correct. I think the color does not play a big role in these weak events, as one sees only white beams or whitish glow with his very own eyes.
Have fun

Ulrich

[jan lameer]

> Hi Ulrich!

Eh, there was green in the display, at least, if I view the clip in green only, I see green aurora low over the horizon. I haven't seen blue aurora ever myself but the film records it every time in late spring and early fall when the sun is in the right position. Film is very sensitive to blue and near UV light, that is why it records blue aurora very good. By the way, videocameras are sensitive to near UV also, but that is off topic.

I remember the 2001 March 20 morning event very well, it was extremely bright with very thin and sharp white rays. The same was noticed from Schotland. Also what was remarkable was that the rays appeared suddenly, it was an intense substorm. If I watch the display, I can almost see the disturbance travel southward. I hope I can film a display like this with 3200 Iso and a 50/1.4 lens. I think an exposure time of 4 seconds will be enough then.

Greetings, JanL