NGC7741 Imaging: Should I Stack Images Through IRAF?

In summary, the user is taking images of NGC 7741 at school and is almost 100% sure that their galaxy will show up once they stack their images. PixInsight says that you need six stars to stack through the software. The user tried stacking through IRAF and found that there are only around three stars that show up. The user is not familiar with Dave's software, but he recommends DeepSkyStacker (64 bit) as an alternative software that does not require stars to stack. After doing some post processing, the user is still not sure if their galaxy is in the images.
  • #1
starstruck_
185
8
Hey!

So, I took images of NGC 7741 at school using CCD Soft. The field view looked exactly how I would expect when aligning to my galaxy, so I'm almost 100% my galaxy will show up once I stack my images ( I took a set of 20 with 1min exposure). I tried to check by stacking through PixInsight, however, there are unfortunately only around 3 stars that showed up on my images, PixInsight says you need 6 in order to stack.

Should I just go through with the assumption that my galaxy is there (although I can't see it) and start my data reduction and stack the images through IRAF?
Is there another way I can stack?
 
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  • #2
starstruck_ said:
Is there another way I can stack?

I'm not familiar with your software, but there is other software that requires fewer stars to stack or let's you manually stack.

starstruck_ said:
Should I just go through with the assumption that my galaxy is there (although I can't see it) and start my data reduction and stack the images through IRAF?

What is IRAF?
 
  • #3
Drakkith said:
I'm not familiar with your software, but there is other software that requires fewer stars to stack or let's you manually stack.
What is IRAF?

There’s software that uses fewer stars? Do you happen to know any?

we do our data reduction stuff through Xming/PuTty and it involves doing stuff in an IRAF and a Linux terminal.

I don’t really know how to explain it :// I’m in second year so don’t have extensive experience with data reduction
 
  • #4
starstruck_ said:
There’s software that uses fewer stars? Do you happen to know any?

I use AIP4Win, but it's not free. CCDOPS will let you manually stack, but it's rather tedious for anything but a handful of images.
You can probably download a trial version of MaxIm DL Pro and use that.
 
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  • #5
Registax can use as few as 1.
 
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  • #6
IRAF is the pro Unix based software. It is very powerful but very old and command line driven.
 
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  • #8
BrushyCanyon said:
Try DeepSkyStacker (64 bit). Free and very versatile.

http://deepskystacker.free.fr/english/download.htm

BC
Yup …. I have used it for some years now … but I, like many, only do the stacking in DSS
we do the editing in lightroom, photoshop or whatever you other fav image processing app isDave
 
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  • #9
BrushyCanyon said:
Try DeepSkyStacker (64 bit). Free and very versatile.

http://deepskystacker.free.fr/english/download.htm

BC

This was helpful! Tried stacking, didn’t see the galaxy :(( there was a light leak when we were take photos of my galaxy(+11.25 mag) guess I’m using my friend’s images for data reduction, he didn’t have light leaks when he took the images of the galaxy later in the night:((

Although two professors told me that my field of view was perfectly fine and my galaxy SHOULD be there. Gosh darn it
 
  • #10
starstruck_ said:
This was helpful! Tried stacking, didn’t see the galaxy :(( there was a light leak when we were take photos of my galaxy(+11.25 mag) guess I’m using my friend’s images for data reduction, he didn’t have light leaks when he took the images of the galaxy later in the night:((

Although two professors told me that my field of view was perfectly fine and my galaxy SHOULD be there. Gosh darn it
Did you do any post processing? Can you upload a sample? Often, the signal needs a lot of amplification to be visible.
 
  • #11
Do you use any plate solving programs, like Astrotortilla? This will let you precisely place your subs by matching your field with with referenced images.
 
  • #12
starstruck_ said:
Tried stacking, didn’t see the galaxy :((

in DSS ?

As @russ_watters hinted at, even after stacking in DSS, you will have to do significant post processing to bring out the object
Only with bright objects will you see anything of them after doing the stacking ( but before processing)
starstruck_ said:
there was a light leak when we were take photos of my galaxy(+11.25 mag)

well that would probably destroy any faint objects and M11 or more is very faintDave
 
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  • #13
davenn said:
in DSS ?well that would probably destroy any faint objects and M11 or more is very faintDave

But this should show up after I do my reduction right? I’m hoping the light leak would somewhat be subtracted but idk. I’m worried now, definitely don’t want to have to go back and take images again.
 
  • #14
starstruck_ said:
I’m hoping the light leak would somewhat be subtracted but idk

if the light leak is on every frame, then no it won't be subtracted

if it is only on a couple of images, then remove those images from the ones to be stacked
 
  • #15
davenn said:
if the light leak is on every frame, then no it won't be subtracted

if it is only on a couple of images, then remove those images from the ones to be stacked

Ah darn, looks like I’m retaking my images then ;-; (or not, my prof knows what happened and he said he’ll let me use my partner’s images for the reduction instead)

Do want my own set of images though, the galaxy is gorgeousEDIT: We did move the field of view as far away from the light leak as possible though (the field of view matched exactly so all of the galaxy is supposed to be in the darker area) guess I’m still screwed :((
 
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  • #16
First, are you properly 'stretching' your image? Images can sometimes be much darker than regular photos. In Pixinsight, use the 'nuke' button for auto screen transfer function.
Second, if you can't see the object after 'stretching' your image on a single frame, than stacking is not going to make it magically appear. Stacking will reduce noise.
Third, proper calibration images (bias, dark and flat) can help fix light leaks - to some extent.
 
  • #17
M Augustyn said:
First, are you properly 'stretching' your image? Images can sometimes be much darker than regular photos. In Pixinsight, use the 'nuke' button for auto screen transfer function.
Second, if you can't see the object after 'stretching' your image on a single frame, than stacking is not going to make it magically appear. Stacking will reduce noise.
Third, proper calibration images (bias, dark and flat) can help fix light leaks - to some extent.

The images I saved and worked with were black for some reason so I did stretch them, after stretching them, they looked like what I saw on the computer while using the CCD(my galaxy wasn’t there when I was taking images with the CCD - but my prof had said that we shouldn’t expect them to show up while we’re taking images, only after reducing)

But now there’s this amazing light leak I also need to deal with :))
 
  • #18
starstruck_ said:
But now there’s this amazing light leak I also need to deal with :))

Welcome to astrophotography and image processing. :wink:
 
  • #19
PIxinsight: in Star alignment go to Star Detection and try these settings:- Detection scales try 8
Log Sensitivity try -3
All the rest in star detection leave at default
 
  • #20

1. What is IRAF and how does it relate to NGC7741 imaging?

IRAF (Image Reduction and Analysis Facility) is a software package commonly used in astronomy for image processing and analysis. It can be used to stack multiple images of NGC7741, which is a spiral galaxy in the constellation Pegasus.

2. Why is stacking images through IRAF recommended for NGC7741 imaging?

Stacking images through IRAF can improve the quality and clarity of the final image. This is because it combines multiple images, reducing noise and enhancing details that may have been missed in individual images.

3. How many images should be stacked through IRAF for NGC7741 imaging?

The number of images to stack through IRAF depends on various factors such as the quality of the individual images, the desired final image resolution, and the level of noise present in the images. Generally, a minimum of 10-15 images is recommended for a good quality final image.

4. Can IRAF be used for other types of astrophotography?

Yes, IRAF can be used for various types of astrophotography, including imaging of other galaxies, nebulae, and star clusters. It is a versatile software package that can be used for different types of astronomical data.

5. Is IRAF difficult to use for stacking images of NGC7741?

IRAF can be a complex software package for beginners, but there are many tutorials and resources available online to help with the process. With some practice and patience, the process of stacking images through IRAF for NGC7741 imaging can be mastered.

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