Unknown traces in subs - Forums

Topic starter

Oct 30, 2021

Hello,
on two of my photographs there are line traces, which are different from the usual traces of satellites and airplanes. Maybe someone of you knows what can be seen there.

Recording data:
TS Photoline with 0.65x reducer, FL 520 mm.
ASI294MM Pro, Gain 120, -10 °C
Object: NGC 7635 (Bubble Nebula) lower left, Sh2-157 (Lobster Claw Nebula) right of image

The images are untreated subs. No stretching, no curves, just resized and converted to jpg. The tracks can only be seen on one sub.

Image 1: 2021-10-27, 21:31:51
H alpha
Exposure time: 300 s
The trace is faint on the left, becomes stronger towards the middle and ends abruptly.

Image 2: 2021-10-28, 21:21:58
SII
Exposure time: 300 s
This track is thin at both ends and thicker in the middle.

Can anyone tell me what phenomena are seen here?

Thank you very much!
Clear skies!
Olaf

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andrea tasselli

Frequent contributor

Oct 30, 2021

It is a spinning artificial satellite. Simple as that. One side is reflecting light and the other isn't so the time period showing peak and through is recorded as a fading-peaking-fading streak.

Olaf Fritsche

Topic starter

Oct 30, 2021

Thank you, Andrea!

With the second picture the explanation makes sense to me. What kind of satellite is rotating?

In the first picture, however, I'm surprised that the right end is so abrupt. Do you think that is also a satellite having fun spinning?

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andrea tasselli

Frequent contributor

Oct 30, 2021 · Edited: Oct 30, 2021

A number of comunication satellites are rotating although I do not have a break-down in percentage over total. The abrupt end of one of the traces might be due to the end of the exposure altough it is also possible it entered the earth shadow.

Bob Lockwood

Oct 30, 2021

Hear are two examples in the same shot, to the left is a shooting star, lower center is a rapidly spinning satellite.
I intentionally left both in the final image.

Olaf Fritsche

Topic starter

Oct 31, 2021

Thank you, Andrea and Bob!

So, I have spied a satellite. The satellite tracks I knew so far were always so long that they went through the whole picture. These rotating satellites are new to me. I have learned something again.

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Olaf Fritsche

Topic starter

Nov 5, 2021

Thanks for pointing that out, Thibault. My French is just enough to ask for directions and buy cheese (for the French cheese, it's worth the trip across the border). I'll see how much I understand from the tutorial.
I know most of the tracks by now. I had irritated in the first picture only that the track is broken off so suddenly. Therefore I had suspected, it could be perhaps a meteoride.