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 What is this!!!? This hobby always provides us with interesting intellectual challenges! I got this image last night when imaging the Cave Nebula in NB. This is a 600s SII shot (Tak 130, APMach2Pro,QHY600). Notice (how can you not) the wiggly and curved trajectory. Here is what went thru my mind when I saw it  :- A very small, dying light bug, on my lens - A satellite sent of track by a meteor (does not explain the curved trajectory - An Alien craft in serious trouble Any ideas? Finally I came up with, maybe, a more logical explanation (but who knows): In this season in NY state the Milky Way is directly above us, at this time of the night (almost midnight  ) the cave nebula is close to the zenith. My telescope is almost vertical and my filter wheel or its cable touched the pier, tracking was stopped, the mount either vibrated or tried to bounce back slightly. As a result the straight satellite trail changed into a curved and wiggly one and stars started to trail.This still does not explain the explosion like ending of the trail. All in all I think I prefer the « Alien craft in trouble » hypothesis, don’t you?  Thanks for watching and let me know if you come up with a better explanation  .
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Philippe Lemaitre: That is when it starts, not when it ends. |
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I do not think so, the scope never recovered and the stars kept drifting on the following pictures. The satellite was going straight at the beginning of the trail. Unless this starship came out of an hyperspace disruption, thus the glow. Who knows! |
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| If you stretch the image you'll notice there are multiple trails following the same pattern. |
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| You are right. They are very faint and look like startrails. Why is the main one so bright on only a portion of its length? |
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Philippe Lemaitre: You didn't mentioned that in the first post, tricksy! |
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Could that be a drone from your neighbour's kids. Some "light paintings" I saw looked similar🤔 Just my two cents |
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| There are definitely more parallel trails visible, although much fainter. Can you rule out a meridian flip? The slight wobble could be caused by the periodic error of either axis. |
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I think I was about 30 min from meridian flip, the Nina DIY meridian flip instruction was not triggered. I do not see how 1 trail only would be affected by the wobbling. Absolute encoder AP mounts do not have periodic errors. Why is this one trail suddently brighter? I am still sticking to my « Alien craft in distress » as the main theory that best cover all the observations  |
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| Kids should not play with drones at midnight. I will talk to my neighbors. |
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| I don't think your AP mount's encoders will be able to eliminate the PE, or even try to do so while slewing, since there is no need to. Although maybe there is now? 😄. Most probably the aliens flattened the other star trails. Or you might see them (the wobbling trails, not aliens) too when stretching your image a little more. |
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Please make clear: This is one subframe, not stacked. Then it look really like an object (three objects). That is the strangest picture I've ever seen. Mostly you will find a normal explanation. I do not have one. |
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| Yes it is only one 600s SII subframe. |
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Is it possible that this occurred during a meridian flip, that the imaging program would have continued imaging during this? Really very strange, especially that bright curve. I would also ask the AP user group: https://ap-gto.groups.io/g/main/topics |
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| Phd2 deciding to track a satellite? |
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| Looks to me like you had an exposure going while it was still slewing, and with an Sll filter you would possibly only see the bright star. Then with a 600 sec exposure everything starts to show up. Also, an AP mount will not do a meridian flip while it doing an exposure unless the program you use over rides it and flips the mount when it sees the counterweight in an up position. |
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But if the tracking fails, why are there only three trails. Then all the other stars must have trails too?? Ahh, sorry didn't read the prepost. The filter could be a good explanation. |
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If you look at the image you will see that the trail start as a straight line, like a satellite would do, then it breaks into a very bright wiggly one. I do not see how an SII filter would enable that. Also there are other brighter stars that do not seem to be affected in the same way, if they trail their trail is extremely faint not brighter. I use Nina with: Pause before meridian flip: 3min Minutes after meridian: 5 min Max min after meridian: 10min I have a camera in my dome and it didn’t register a flip. The filter box did touch the pier and the mount stopped. On the following images you do see the expected startrails. |
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There have been many times when I've visually seen small bright objects move strangely. One time I saw a constellation, everything was very still, and then, all of a sudden one of the supposed stars starts slowly moving elsewhere; I was like, "huh". Another night I believe I saw one of these moving bright objects take a right angle turn through my binoculars. Another time, I saw what looked like a small meteor shower (or shower of something), but going sideways, like in a close orbit; they were small bright objects that resembled satellites, and they were moving SLOWLY and in sync; they quickly appeared and disappeared. Everything is so weird  |
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Jaggy wiggly line in the arc could possibly be cause by electric motor motion of the mount. I like the hypothesis that scope was pointed at zenith and something rubbed on the mount or tripod, and stalled for a bit. 2 axis makes the jaggies and curve An Aircraft possibly flew by Then maybe the exposure was taken during this slewing. Oh - but how does the star field remain without trails.... hmmmm. Maybe the aircraft was brighter? Did I miss out how long the exposure might have been? Meridian flip at the end of a 3 minute exposure and a plane flies by - maybe with afterburners, chasing a UFO possibly.  Fun puzzle! |
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| 600s |
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Hi, There clearly are visible short arcs from star trails in the upper left and lower right. It looks like a possible cable snag (or other, a slip?) somehow caused your camera rotate in place perhaps for the last few seconds of a frame capture. This would explain the rotation about the center of the image (it looks a little offset from the center actually, is the image cropped?). If the mount slewed while an exposure was active, it is unlikely the rotation would be about the center of the frame, rather long straight lines from star trails would be observable. Edited again: The bright arc not being centered around the center of the frame may be caused by a satellite moving and the relative position of it when a possible camera rotation occurred. |
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Not a bad assumption but how do we explain: - the increased brightness in the satellite trail only - the wiggle in the satellite trail - why the satellite trail is actually 3 trails - the light "explosion" at the end of the trail The image is not cropped. |
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| Well, the bright trail could be a satellite that was increasing in brightness like an Iridium flare or other. The other trails are most likely other satellites. They are relatively faint. If there was a cable snag, that might account for the sawtooth pattern in the bright trail. The mount or guiding could be fighting. |
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| Actually the bright trail is 3 trails intermingled. I think you might be very close from what happened but there are still a couple of « ?? » |
