Asteroides or what?!

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carlwagle
Posts: 73
Joined: Thu Mar 07, 2019 6:58 am

Asteroides or what?!

#1

Post by carlwagle »

My telescope is a Celestron SkyProdogy 130 Telescope on a computer directed mount.

On this April first (no April Fools Joke here) I took two stacks (about 20 pictures each) of M-44, the Beehive Cluster. It was about a week later that I got the software to see the fits Liberator stacked picture. When I saw the pictures I was surprised to see two similar groups of small bright dots that I thought might be two separate asteroids. Each group's total number of individual dots closely agreed with the number of pictures making up the stack. Variations in gain or "shutter speed" did not aprieciably change the brightness of the dots. It took a lot of magnification to see them, otherwise they looked like a small smudgy star.

For the past two weeks I have spent a lot of time trying to isolate what is the problem since I did not think it likely that this "newbie" found what appeared to be a field of asteroids moving faster than normally observed! But I was taking the worse case seriously.

Here is what I have concluded after looking at over 20 pictures taken on separate nights:
1, If I twist the camera 90 degrees the stacked image I see on my computer from from Fits Liberator has the star field rotated 90 degrees but the artifacts are very close to the same X Y coordinates they were measured at before this camera rotation, like seen in previous pictures.
2, The artifacts show up as being very much in focus when the stars may not be.
3, the groupings they show up in can vary between a curving stretched out line, to a loose oval cluster, to such a tight grouping that they look like a nearly in focus star, lots of variation.
4, All the available choices for the image file I want to use produce these artifacts, but to a small degree differently. Mono 8 seems the least upset by these things.
5, No artifacts seen if I press SAVE AS SEEN which puts it all into a PNG file. Those pictures look very different from what I see from FITS L.. Less but but good focused stars are seen but I can't indentify the pattern.
6,removing a "city light" filter has no effect on seeing artifacts.

I am wondering if I'm having trouble with my camera (ZWO ASI 178MC) or is the problem in the FITS Liberator somehow.

I will try to send as attachments 2 of the first pictures along with the Camera Settings in the next posting I make. I fear at this time if I try to combine THIS with THEM I will loouse what I have written so far. Carl
carlwagle
Posts: 73
Joined: Thu Mar 07, 2019 6:58 am

Re: Asteroides or what?!

#2

Post by carlwagle »

My third try to send the first picture taken on April 1rst.. I will have to make another posting to include the "Camera Settings". Can't seem to get them all together.
Look for artifacts at :
X 1790
Y1920

X 2345
Y 945

X 1301 very faint
Y 166

X2287 very faint
Y 1411
Attachments
Notice the apparent motion between the two pictures.
Notice the apparent motion between the two pictures.
Stack_16bits_53frames_98s first of two pics showing anomolies.jpg (527.81 KiB) Viewed 2275 times
carlwagle
Posts: 73
Joined: Thu Mar 07, 2019 6:58 am

Re: Asteroides or what?!

#3

Post by carlwagle »

This is the Camera Settings For the First picture:


[ZWO ASI178MC]
Debayer Preview=On
Pan=0
Tilt=0
Output Format=PNG files (*.png)
Binning=1
Capture Area=3096x2080
Colour Space=RAW16
Temperature=11.6
Hardware Binning=Off
High Speed Mode=Off
Turbo USB=40
Flip=None
Frame Rate Limit=15 fps
Gain=380
Exposure=4.641689
Timestamp Frames=Off
White Bal (B)=46
White Bal (R)=46
Brightness=82
Auto Exp Max Gain=130
Auto Exp Max Exp M S=13631
Auto Exp Target Brightness=106
Mono Bin=Off
Banding Threshold=35
Banding Suppression=0
Apply Flat=None
Subtract Dark=None
#Black Point
Display Black Point=0
#MidTone Point
Display MidTone Point=0.5
#White Point
Display White Point=1
TimeStamp=2019-04-01T04:42:01.5397398Z
SharpCapVersion=3.2.5949.0
TotalExposure(s)=278.50134
StackedFrames=60
carlwagle
Posts: 73
Joined: Thu Mar 07, 2019 6:58 am

Re: Asteroides or what?!

#4

Post by carlwagle »

Second picture of artifacts. In the Camera settings notice that I have done nothing to improve color. I have not adjusted a histogram yet. I have been happy to just capture some stars or perhaps a field of asteroids.

What deep sky objects will be just coming up that will be good things to practice on for developing color techniques for the next few months. M-44 will be getting low on the horizon pretty soon. Carl
Attachments
Stack_16bits_60frames_279s    Second pic taken about 30 min. latter.jpg
Stack_16bits_60frames_279s Second pic taken about 30 min. latter.jpg (600.83 KiB) Viewed 2272 times
carlwagle
Posts: 73
Joined: Thu Mar 07, 2019 6:58 am

Re: Asteroides or what?!

#5

Post by carlwagle »

Camera Settings for second picture taken on April 1rst 2019

[ZWO ASI178MC]
Debayer Preview=On
Pan=0
Tilt=0
Output Format=PNG files (*.png)
Binning=1
Capture Area=3096x2080
Colour Space=RAW16
Temperature=11.6
Hardware Binning=Off
High Speed Mode=Off
Turbo USB=40
Flip=None
Frame Rate Limit=15 fps
Gain=380
Exposure=4.641689
Timestamp Frames=Off
White Bal (B)=46
White Bal (R)=46
Brightness=82
Auto Exp Max Gain=130
Auto Exp Max Exp M S=13631
Auto Exp Target Brightness=106
Mono Bin=Off
Banding Threshold=35
Banding Suppression=0
Apply Flat=None
Subtract Dark=None
#Black Point
Display Black Point=0
#MidTone Point
Display MidTone Point=0.5
#White Point
Display White Point=1
TimeStamp=2019-04-01T04:42:01.5397398Z
SharpCapVersion=3.2.5949.0
TotalExposure(s)=278.50134
StackedFrames=60
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admin
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Re: Asteroides or what?!

#6

Post by admin »

Hi,

I hate to disappoint you, but I think the most likely explanation is that the lean points of light are hot pixels on your camera sensor (pixels that wrongly give a high reading even when they are not being illuminated by a significant amount of light). They appear as little worm trails in the stacked image because they stay still on the frame while the stars drift around a little due to imperfect tracking. Then when the images stacked, the stacking software aligns the stars and ends up making a trail out of the hot pixels.

The best way to remove these from future images is to use dark subtraction (using a dark frame taken at the same temperature and other camera settings as your light frames).

Cheers, Robin
carlwagle
Posts: 73
Joined: Thu Mar 07, 2019 6:58 am

Re: Asteroides or what?!

#7

Post by carlwagle »

Thanks Robin. I am not disappointed but relieved to hear that you think I don't have a underperforming or Broken camera.
In my pictures (at least 30) the hot pixels always show up in the same place. If they are repeated those XY coordinate places are generally repeated. As the night temperatures rises it seems that this repetition of artifact images is getting much worse although 99 percent or more of them are getting so weak that the images show up looking more like noise. Is this the same experience you have had with hot pixels?

The pictures I sent you seemed to have been flipped over. Is that to be expected?

I will get busy rereading SharpCap and learn how to apply the black and flat frames.

Tomorrow I will ask you a few questions about capturing Color. Carl
Rojoyinc
Posts: 5
Joined: Sat Apr 21, 2018 11:26 pm

Re: Asteroides or what?!

#8

Post by Rojoyinc »

hot pixels (noise). trailing. Generally from lack of calibration frames.
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