I have been photographing the night skies.

I debated on what section to post this. I ended up posting here because I really am not 100% sure of what I captured.

I have been setting up my Canon 7D, on clear nights, to make timelapse videos of the stars. I usually shoot about 200-300 frames per hour. I typically scroll through all the frames manually before making the video. Everytime I scan the shots, I see things like streaks, flashes, colors, that appear in just one single frame. Each frame is typically a 15 second shot. Satellites will usually cross in three or four frames. Meteors will be only in a single frame. I am working on consolidating some of the stranger things, versus the things I can ID with reasonable certainty.

Here is a short clip of me scanning some frames from a couple of weeks ago. Sorry if it's a long and boring video. It's not intended for entertainment.


These are probably space debris, or manmade satellites catching the sunlight. Towards the end of the video, I highlight three or four red objects which are actually camera anomalies called hot pixels. They are always there.

You MUST watch this video FULL SCREEN and MAX resolution to really see the anomalies.
www.youtube.com...


There is more to come.

reply to post by zayonara


I'm going to guess and say: Satellites.
If I'm wrong, I'll come back and edit this.

Okay, so I guess you're not freaking out over satellites.
All I see, however, is someone moving around a mouse pointer on a screen seemingly stupidfied over the fact that stars are in the sky and that they happen to be shaped funny when photographed on a really low shutter speed.

I would suggest taking an actual chart of stars in the night sky, line it up with your photo experiment, and see what lines up where so you know what you're looking at.

I'd suggest trying to do something more like this:

You probably don't have the resolution or monitor setup to see properly. There are "anomalies" that appear/disappear from frame to frame. When I spot one, I zoom in on it.

I know what stars look like and have star charts. Stars usually don't usually appear and disappear within the hour, make tiny colorful specs and streaks. I also know what camera sensor anomalies look like. If you want FULL resolution stills, I can make them available.


Here is a zoom from a few nights ago. Probably a satellite spinning, seen only in a single 15 second sequential frame.





That's a pretty video, but what you don't see is the pre-processing. In the pre-processing, if you scan frame to frame, 1 by 1, you will see things that pop up and dissappear. They usually don't come through in a timelapse film because they are captured in only ONE frame. In a timelapes film, ONE frame passes by your eye in about 0.02 seconds or so.

reply to post by Druscilla


Hi - you obviously do not understand what the OP is saying, or understand what he is showing you. It's ok though you cant know or understand everything, maybe go away and do some learning before commenting.

To help you understand, the OP is taking long exposure shots of the night sky (this is when you keep the shutter open for a long period of time, allowing more light to hit the sensor, so good for night shots), 15 seconds i believe, so a slow moving object like a satellite would appear as a streak, a fast moving object like a shooting star would appear as a longer streak. Those little white dots that appear are neither of the above, obviously...

OP i get what your showing us, it's interesting how some of those stars disappear from one exposure to the next, i have no idea why they do or what they are... maybe atmospheric disturbance... who knows! hopefully someone can come along and add something constructive!

reply to post by zayonara


Good for you for taking the time to do this

I don't know if you saw them, but I recently posted a couple of threads that might help you with identifying some of the objects that you imaged:

How to view, track, and identify satellites

Flashes and Star-like objects that move strangely in the sky explained

Originally posted by doubledutch
OP i get what your showing us, it's interesting how some of those stars disappear from one exposure to the next, i have no idea why they do or what they are... maybe atmospheric disturbance... who knows! hopefully someone can come along and add something constructive!

There are a few obvious possibilities:

1/ Brief flares or flashes from satellites in ordinary orbits.
2/ Brief flares or flashes from satellites in geostationary orbits.
3/ Point meteors (meteors that head directly towards an observer).

Originally posted by doubledutch
reply to post by Druscilla

 

Hi - you obviously do not understand what the OP is saying, or understand what he is showing you. It's ok though you cant know or understand everything, maybe go away and do some learning before commenting.

Wow - can you be any more condescending? Just because someone takes a guess at something that you don't agree with doesn't mean you have to display your arrogant superiority complex here, sheesh.

Maybe you should go away and relax a little and come back a little less rudely. Even if you are the worlds foremost expert on night sky photo anomolies you can still be polite, can't you?

Now I have absolutely no formal expertise on astronomy, satellite trajectories or night time photography so please excuse me if this comes across as an idiotic question - but is it possible that these anomolies are something mundane such as bugs flying in front of the camera? Granted that this would not explain all of the anomolies, but is is a possible explanation for some of them?

Originally posted by doubledutch
reply to post by Druscilla

 

Hi - you obviously do not understand what the OP is saying, or understand what he is showing you. It's ok though you cant know or understand everything, maybe go away and do some learning before commenting.

To help you understand, the OP is taking long exposure shots of the night sky (this is when you keep the shutter open for a long period of time, allowing more light to hit the sensor, so good for night shots), 15 seconds i believe, so a slow moving object like a satellite would appear as a streak, a fast moving object like a shooting star would appear as a longer streak. Those little white dots that appear are neither of the above, obviously...

OP i get what your showing us, it's interesting how some of those stars disappear from one exposure to the next, i have no idea why they do or what they are... maybe atmospheric disturbance... who knows! hopefully someone can come along and add something constructive!

Actually, I understand completely that the OP has no clue what they are looking at.
Otherwise they would not be wallowing about, floundering lost, pointing out 'things' they label as "anomalies".

The OP doesn't know what they are looking at.
By definition, that's what an 'anomaly' is. 'Anomaly' is a statement of "I don't know"; a statement of ignorance.

Obviously, your 'obvious' detector' is broken, since you use the word 'Obvious', when in fact, I'm quite certain the OP, as stated above, is parading their ignorance about dots they think are interesting before us.

OP also claims to know about hot pixels and sensor errors, yet, OP goes out of their way to point them out as 'anomalies'.

Whatever the case, as an open public forum, regardless of how much you may disagree with my posts, so long as I'm on topic, I'm entirely entitled to make statement regarding said topic; even so especially if you disagree.

Wow. Really D.?

Fireball, I read your link about the satellites when you posted it. I thought it was a great post. I was also thinking about creating a thread that shows photos and videos of KNOWN things that are often confused for other-worldly things.

I am merely showing what the sky showed my camera. No more, no less. I pointed out hot pixels in my video to show that the OTHER things were not hot-pixels. Different shapes and textures than the hot-pixels.


BTW: An anomaly is not a statement of ignorance, at least not in science.

reply to post by zayonara


Glad to see you are taking an interest in astrophotography, something that I've been doing myself since 1997, using both film SLR cameras and digital cameras, both wide field and through the telescope.

Here are some things to consider:

As you said, each frame is at 15 seconds of exposure. In the frames where we have motion (IE meteorite or satellite), we can see this motion against the fixed back ground of stars as a streak.

Each anomaly that you have shown does not appear to have that streak, which would suggest there is no motion by it (unless it appears only in the very last second of your exposure, and for that to happen every single frame, I would highly doubt).

So what could these things be?

Well, each one that you have shown, appears to be very dim (extremely low magnitude), which would make it visible to the camera during long exposures, but not our eyes of course. It's possible that you may have captured very faint object that are not close to Earth (IE space junk, satellites, etc), but are faint an far away (small asteroids or comets that are far from the sun, so no tail yet). The motions of these will not be very apparent as you would need to photograph the same spot in the sky at the same time for several nights. If the objects are not on any star charts, and appear to move against the background stars (over the course of several nights), that may have been what you are capturing on the camera.

Or:

The night's "seeing" for the air could be affecting things. "Seeing" is how much turbulence is in the upper atmosphere, and is what makes stars "twinkle". Really good "seeing" makes the stars appear mostly steady (only a little bit of twinkle) and most seem to have a steady magnitude. Really bad "seeing" can make even the planets seem to twinkle sometimes.
The point about this is, that some stars are so far and faint, that you can only see them with a camera, or by using a telescope with a large reflecting mirror (helps concentrate the light for your eyes). If stars are far and faint enough, and the "seeing" that night is bad enough, the stars magnitude can appear to be affected.
This means it would appear to wink on and off in your photo frame.
Brighter stars will not do that, but they will seem to 'twinkle" more.

Or:

You may be capturing very faint Variable Stars who's magnitude (brightness) can fluctuate. However, most of these stars have a cycle that is measured in days or years. It might be possible that you are catching them right when they enter a brighter cycle (but that would be highly unlikely for it to happen that many times for you. Would be like winning the lottery every day).

Or:

Thermal noise on your CCD chip of your camera:

Thermal noise and cosmic rays may alter the pixels in the CCD array. To counter such effects, astronomers take several exposures with the CCD shutter closed and opened. The average of images taken with the shutter closed is necessary to lower the random noise. Once developed, the dark frame average image is then subtracted from the open-shutter image to remove the dark current and other systematic defects (dead pixels, hot pixels, etc.) in the CCD.

CCD Chips and Astronomy

Just some ideas as to what could be in your photos.

Have fun!

Originally posted by Druscilla

Originally posted by doubledutch
reply to post by Druscilla

 

The OP doesn't know what they are looking at.
By definition, that's what an 'anomaly' is. 'Anomaly' is a statement of "I don't know"; a statement of ignorance.

OFFS:
No...No and NO
Just to state the OBVIOUS: OBVIOUS
Anomaly has NOTHING WHAT SO EVER to do with "dont know" or "Ignorance"..

So as a prevoius poster said...Go back, learn. Then come back and ask nicely if
you can post.

As for OP, nice work. Keep it coming..Maybe you get that shot that will change
ppl´s minds(read attitude)...

Thanks, I have done images using darks, flats, and lights, stacked with DSS so I know what to look for. I do have some experience with this. I have just never compared frame to frame to frame, so closely to see that the sky has so many "on-offs" and things making streaks in one frame and not the next. Some of the streaks are more like someone threw paint splatter; non-linear, blotchy colored and random.

I don't know what a cosmic ray hit looks like on a CCD but I will research it. Thanks for the encouragment.

I really do enjoy shooting into space.

Here is a video I found from someone, calling these cosmic ray hits. Looks similar.

www.youtube.com...

Here a nice video about Cosmic Rays from our friends at NASA.

Originally posted by doubledutch
reply to post by Druscilla

 

Hi - you obviously do not understand what the OP is saying, or understand what he is showing you. It's ok though you cant know or understand everything, maybe go away and do some learning before commenting.

To help you understand, the OP is taking long exposure shots of the night sky (this is when you keep the shutter open for a long period of time, allowing more light to hit the sensor, so good for night shots), 15 seconds i believe, so a slow moving object like a satellite would appear as a streak, a fast moving object like a shooting star would appear as a longer streak. Those little white dots that appear are neither of the above, obviously...

OP i get what your showing us, it's interesting how some of those stars disappear from one exposure to the next, i have no idea why they do or what they are... maybe atmospheric disturbance... who knows! hopefully someone can come along and add something constructive!

You are talking about the only anomaly I have ever seen in the night sky hat I can't understand.
On a few occasions all in the last few years, I have looked up at the sky and dot of light blinks out.

On a couple of occasions the light blinks out then blinks again maybe 10 seconds later in s slightly different position. I know what satellites are and i see them every night.. very curious.

reply to post by Druscilla


bahahahaha. Now that is a statement of ignorance if ever I read one!

I see you post a lot, are all your posts as bad as the ones in this thread?


Ok so back on point. i guess space junk is possible, but wouldn't that just look like a satellite?

Point meteors sounds best to me so far, although if im honest I just want them to be ufo's... don't we all?

oh and of course the cosmic ray hits, could well be that

reply to post by zayonara


Just confirming you are shooting in RAW correct? I find I get a lot of "noise" with my 7D if I don't shoot in RAW on long night exposures.

I shoot RAW+JPG. But the video in the OP was made from JPG's. The anomalies show up in the RAW files too.

Off topic. Try shooting in the 160/320/640...ISO settings with exposure one or two ticks to the right. It seems to really help reduce noise, espcially when you correct the exposure downwards in the RAW file later. Also the new firmware release for the 7D seems to clean up the image noise a bit.

Originally posted by zayonara
I shoot RAW+JPG. But the video in the OP was made from JPG's. The anomalies show up in the RAW files too.

Off topic. Try shooting in the 160/320/640...ISO settings with exposure one or two ticks to the right. It seems to really help reduce noise, espcially when you correct the exposure downwards in the RAW file later. Also the new firmware release for the 7D seems to clean up the image noise a bit.

Here's another idea:

Set the 7D aside.

Get like an old Olympus SLR. Load it with ISO 800 film and take your shots (same amount of time, 15 seconds). Finish the roll.
Then you have to wait until the next day to take the roll some place and get the pictures developed, making sure to explain that they are star shots, and that you need ALL frames processed.
If you're lucky, you only have to wait a few hours.....or in the really old days, wait for several days, to finally take a look at your shots!

Then....using scanner, you can scan the picture, and zoom in.....then instead of wondering if it's thermal noise or a hot pixel.......you can instead wonder if it's the grain of the film!

Here's a couple examples of exactly what I just described, taken with an old Cannon AE1:

...or noise introduced by the scanner. Will film even pickup ray hits?

Originally posted by zayonara
Thanks, I have done images using darks, flats, and lights, stacked with DSS so I know what to look for. I do have some experience with this. I have just never compared frame to frame to frame, so closely to see that the sky has so many "on-offs" and things making streaks in one frame and not the next. Some of the streaks are more like someone threw paint splatter; non-linear, blotchy colored and random.

I don't know what a cosmic ray hit looks like on a CCD but I will research it. Thanks for the encouragment.

I really do enjoy shooting into space.

Here is a video I found from someone, calling these cosmic ray hits. Looks similar.

www.youtube.com...

Those do look like cosmic ray hits in the video. The Hubble deals with actual cosmic ray hits (mostly protons), but here on the ground we see the after-effects of the collision with the atmosphere which is a shower of particles, which can look like paint splatter as you describe it and as that video shows.

Which stacking software do you use?
ATSer NGChunter mentioned this free software, and I think he uses it: Deepskystacker
I expect some of those stacking algorithms will work better than others at filtering out the cosmic ray images.

Here's an interesting paper:
Cosmic Rays and other Nonsense in Astronomical CCD imagers
That's probably referring to imagers more sophisticated than yours but it may give you some ideas.