Strange objects in sky - Can you identify?

[RobinSchouten]

They kept returning in my pictures. What are they? They seem to follow a different route than the surrounding stars.

http://i48.tinypic.com/x1yl5e.png

This image is just for showing you these objects :P

Thanks :)

Edit: sorry for the large image, new one uploaded :)

[Celestron]

The biggest and brightest are stars . The purple circle around them is CA (Chromatic Abberation) caused by the lens optics quality . They are longated because of the length of time you exposed the image and therefore causes star trailing . The little spots below each star is probably some type of internal reflection or movement of the lens in some way . Hope this helps some . Others probably have different explainations tho so keep headsup :D !

[Adrena1in]

The little spots below each star is probably some type of internal reflection or movement of the lens in some way .

Agreed, I've sometimes had very similar effects, but only on the absolute brightest stars in my image. Expose for a bit longer and you'll notice every star will cause this effect.

[Lowner]

Odd how this thread is very similar to a question I have. With my apologies to the OP, I hope you don't mind my tagging along here.

Last night while hanging around waiting for the light show (I did see one trail in 2 hours), I took a series of 15 shots of Orions belt, and attempted to stack them together as an exercise. I quickly learnt that I don't have a clue what to do once I've got everything in register, so any links to a tutorial would be gratefully received, but thats not my question.

Have a look at the cropped final image here. Orions Belt and other stars are stacked, so exhibit no trail, but a very few random "stars" (or whatever they are) show a very distinct anticlockwise curve as they move against the background. I hope the lower res crop I've prepared shows this, because in the original it is very clear. If its difficult to spot, they are a series of dots. The whole series took me no more than 10 minutes to shoot.

[WMS]

Is it possible that you have captured the images of larger/lower satellites? I'm not an Astro-photographer but am old enough to remember seeing the echo orbital balloons as a kid.

Wayne

[Adrena1in]

Very strange, Lowner. 15 shots you say? I can see the strange curve of 5 or 6 dots several times on the image, all with the same curve-shape and layout. One thing I'd get you to check is are these strings of dots visible on every image, or does each image definitely show a single dot moving a little each time? How far apart was each image taken?

[DonR]

a very few random "stars" (or whatever they are) show a very distinct anticlockwise curve as they move against the background.

Hi Lowner,

What you see are hot pixels. Your telescope was tracking the stars but the hot pixels are in a fixed location on the sensor, so after registration and stacking they appear to be moving. Notice that one of the trails is red and another is blue - that's a clue! Hot pixels always have one of the three primary colors as each pixel in the camera is designed to capture either red, green or blue light. It's not unusual though for hot pixels to end up white ater the raw image is processed in the camera and in the software you use to decode the raw images, and it looks like you have captured one of those too.

Shooting dark frames with the same exposure time and ISO as your light frames, and at about the same temperature, will show those same hot pixels, but as single points of illumination. Subtracting the dark frames from the light frames before registering and stacking them will eliminate the hot pixels.

Don

[Lowner]

Don,

Thank you. I had a sneaking suspicion that is what they were. Never noticed them in normal use.

Adrena1in: They are on every layer, but my very basic stacking obviously is not what it should be, because the lower the layer in the stack the less it contributes to the final image. A whole host of new skills to aquire I suspect.