Two halves of a Perseid or not?

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    Two 15s exposures, one immediately after the other. Obviously the same object but is it a Perseid meteor or just a satellite with a brightness "flare"? Passing through Pegasus, next to my observatory dome.

    What do you think? Looks like a meteor to me but must be quite slow moving. Inset shows the two images overlayed to show they are the same object with a gap in the middle between exposures.

    1. horstm42 5 months ago | reply

      If you knew the dead time between exposures (tough question), that would immediately give the duration of the flare. Knowing the length of the trail in degrees might help, also whether the direction roughly points back at the radiant; Peg is a good place to see Perseids. With deg per sec and an assumed distance of 50 to 100 km, the real speed can be estimated; a meteor should have tens of km/s, the Earth moving at 30 km/s around the Sun.

    2. markarianuk 5 months ago | reply

      horstm42 Timestamp for images are: 22:56:22 and 22:56:41 Exposures are 15s. Gives a 4s dead time - which is too long! Don't know how accurate those times are as there will be in-camera save / download / processing time in there. I'm reasonably sure I was starting the next exposure immediately after the previous, so those times are probably unhelpful..
      From planetarium software, direction makes it seem likely it's a Perseid. And it has the appearance of a meteor more than a satellite, but could just as easily be a satellite flare.

    3. markarianuk 5 months ago | reply

      horstm42 And length of train is similar to the distance between the top 2 stars of the square of Pegasus, which is approx. 14 degrees.

    4. horstm42 5 months ago | reply

      Ah, it IS Pegasus, wider field than I imagined.
      If the gap is 4s, the visible track is about 10 s, the speed is 0.025 rad/s. At 100 km distance that is 2.5 km/s, too slow for a meteor. At 1000 km distance it would be about 25 km/s, too fast compared to the 7 km/s circular orbit speed of a low satellite. But at 10 km the speed would be 900 km/h, which could be a plane.

    5. markarianuk 5 months ago | reply

      horstm42 Seems a more likely explanation, thanks. Although when I've caught planes before they look quite different, which is why I didn't consider it this time. And the track does lead back to Perseus.

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