Joe, The whole sky rotates at the same rate. It rotates very close to 1 hour of right ascension per hour of mean solar time, as measured by your watch. The angle between the radiant and the galaxy will not change, neglecting the movement of the radiant itself. (That movement happens over days, not minutes.) Both of those traces cannot be due to Perseid meteors because of the angle formed by the two traces. One of them MAY be, but the other is certainly not. How does the the line from the radiant intersect NGC 6946 as seen on your digital planetarium? Does it pass through at the same angle as one of the traces? If not, then both are either sporadic or not meteors at all. Brent ________________________________ From: Joe Bauman <josephmbauman@yahoo.com> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Sent: Friday, August 16, 2013 6:09 PM Subject: Re: [Utah-astronomy] Galaxy NGC 6946 through smoke and meteriors Looking at my computerized planetarium, it's certainly possible to draw a radiant from Perseus to NGC 6946 at the time I took the views, about 3:14 and 3:44 a.m., respectively, on Wednesday morning. I haven't had time to figure it out formally yet, but by running my planetarium program from the first to the second time it looks like NGC 6946 revolves about the same amount as the difference in the lines in the two subs. Because they are in different sections of the sky, the galaxy and the constellation revolve at different rates. So unless someone wants to be a lot more scientific about calculating these things and proves me wrong, I will continue to believe they are both Perseids. -- Joe ________________________________ From: Chuck Hards <chuck.hards@gmail.com> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Sent: Friday, August 16, 2013 4:40 PM Subject: Re: [Utah-astronomy] Galaxy NGC 6946 through smoke and meteriors For the meteors to be considered Perseids, they must have radiated from the Perseid radiant. They can appear anywhere in the sky, and at any angle relative to the observer, but in order to be a member of a given shower, if you extend their path backwards across the sky, it must intersect the radiant. If it doesn't, it's a sporadic, or a member of a different shower. Some showers do overlap their times of activity. All members of a given shower hit the earth's atmosphere at the same angle. They are traveling parallel in space. It just looks different to a ground-based observer. Imagine the radiant as a sort of "vanishing point" in the sky. On Fri, Aug 16, 2013 at 2:25 PM, Joe Bauman <josephmbauman@yahoo.com> wrote:
I did consult a star atlas ant I think they could be perseids -- meteorites seem to show up at various parts of the sky, not necessarily heading from Perseus directly. It is a wide stream of cometary dust that yge Earth passes through and I reckon that the atmosphere may hit the dust grains at various angles. Also saying the tracks look too uniform isn't a good way to judge them when you consider the field of view is tiny -- in a larger field they may have been less regular over s lmgrt stretch of their entry path. Well, that's my story and I'm stickin' with if! -- Thanks, Joe
------------------------------ On Fri, Aug 16, 2013 9:48 AM MDT Brent Watson wrote:
Joe,
They can't both be Perseids. They are coming from different directions. I am not sure where the Perseid radiant is with respect to your photograph, but in fact neither may be a Perseid. Please check the direction of travel. The tracks also look pretty uniform. In fact, almost too uniform to be meteors. Are they instead, satellites?
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