If at first you don't succeed, you try and try again.

[wimvb]

A month ago, I tried to image a faint Andromeda dwarf satellite galaxy, And XXX / Cass II. This galaxy was discovered as late as 2013 during a deep sky survey of the Andromeda galaxy region. At the time that I posted my attempt, I had collected 40 minutes of Luminance data that showed no trace of this small companion to M31.

One month and 30 imaging hours later, I may have caught something.

And XXX / Cass II is the thirtiest satellite galaxy to M31. It has diameter of only approximately 1600 ly (540 pc). The galaxy was discovered and characterised based on only 8 of its member stars. Although the galaxy has an absolute magnitude of -8, its surface brightness is only 26 mag/arcsec2, making it almost impossible to detect.

I believe that this image is the first obtained by an amateur astronomer.

Technical data:

Equipment: SW 190MN and ZWO ASI294MM camera with Optolong LRGB filters

Exposures: 483 x 3 minutes L frames (24 hrs in total), and 71 x 5 minutes (almost 6 hours) RGB

Processed in PixInsight

You don't see it?

It's there allright, hiding in plain sight:

[geoflewis]

Amazing work

[wimvb]

11 minutes ago, geoflewis said:

Amazing work

Thanks, Geof. This is the faintest object I have ever tried to capture. I was surprised to discover that it has a surface brightness of only 26 Mag/arcsec2. I would never have expected that I could get this deep from my location. My best sky darkness so far was 20.4 Mag/arcsec2, and that was during mid winter.

[geeklee]

9 hours ago, wimvb said:

I believe that this image is the first obtained by an amateur astronomer.

Superb, well done Wim.  Great perseverance to keep collecting data on this and see the end result.  Did the IFN (?) only start to show much later in the data collection?

[wimvb]

1 hour ago, geeklee said:

Superb, well done Wim.  Great perseverance to keep collecting data on this and see the end result.  Did the IFN (?) only start to show much later in the data collection?

Thanks, Lee. The ifn is actually a lot brighter than the galaxy, and normally you wouldn't be able to discern one from the other. It is the combination of the slightest increase in brightness over the background and identification of those 8 individual stars that allowed this to be identified as a galaxy. This truely is a faint fuzzie.

[tomato]

Outstanding work. To borrow from JTK,  you’ve boldly gone where no amateur imager has gone before.👍

[wimvb]

1 hour ago, tomato said:

Outstanding work. To borrow from JTK,  you’ve boldly gone where no amateur imager has gone before.👍

Thanks! And now I'm chasing the very faint tidal stream that supposedly exists around ngc147. I don't know if I'm bold or just foolish, because no one has imaged that before. And it may be even fainter than And XXX.

https://ui.adsabs.harvard.edu/abs/2013ApJ...776...80M/abstract

[Rodd]

It is amazing.  I am afraid it would be completely beyond my ability. I can’t even get the IFN. I got a dark site 

[wimvb]

On 04/11/2022 at 07:25, Rodd said:

It is amazing.  I am afraid it would be completely beyond my ability. I can’t even get the IFN. I got a dark site 

Thank you, Rodd. How dark is your site? According to Clear Outside, the sky quality where I live is supposed to be 19.4 Magnitude, or Bortle 6. But at best it is closer to 20.4 Magnitude, Bortle 5.

Edited November 5, 2022 by wimvb

[wimvb]

On 04/11/2022 at 01:26, wimvb said:

Thanks! And now I'm chasing the very faint tidal stream that supposedly exists around ngc147. I don't know if I'm bold or just foolish, because no one has imaged that before. And it may be even fainter than And XXX.

https://ui.adsabs.harvard.edu/abs/2013ApJ...776...80M/abstract

Well, that turned out to be a dud. I spent an unexpected clear night on ngc 147 and couldn't even reveal the box-like outer regions of the galaxy that show in the wide field image of my previous post. There's no way I could ever come close to catching the tidal stream itself.

[Rodd]

3 hours ago, wimvb said:

Thank you, Rodd. How dark is your site? According to Clear Outside, the sky quality where I live is supposed to be 19.4 Magnitude, or Bortle 6. But at best it is closer to 20.4 Magnitude, Bortle 5.

I think I mis wrote--I should have said I got to have a dark site.  No, my site is poor.  Bortle 6.  But the Jetstream is overhead and transparency is usually muck.  Unless a target is very bright (like a galaxy), RGB is a waste of time.

[MarsG76]

Awesome work.. that crazy good and some serious exposure time dedication.

[Rodd]

35 minutes ago, MarsG76 said:

Awesome work.. that crazy good and some serious exposure time dedication.

 

Edited November 5, 2022 by Rodd

[Xilman]

On 02/11/2022 at 23:20, wimvb said:

A month ago, I tried to image a faint Andromeda dwarf satellite galaxy, And XXX / Cass II. This galaxy was discovered as late as 2013 during a deep sky survey of the Andromeda galaxy region. At the time that I posted my attempt, I had collected 40 minutes of Luminance data that showed no trace of this small companion to M31.

One month and 30 imaging hours later, I may have caught something.

And XXX / Cass II is the thirtiest satellite galaxy to M31. It has diameter of only approximately 1600 ly (540 pc). The galaxy was discovered and characterised based on only 8 of its member stars. Although the galaxy has an absolute magnitude of -8, its surface brightness is only 26 mag/arcsec2, making it almost impossible to detect.

I believe that this image is the first obtained by an amateur astronomer.

Amazing work!  If only you had chosen a different title or tagged it with "local group" I would have referenced it from my local group thread here:

 but I didn't get to see it in time. WLM is trivial by comparison!

Now VERY tempted to see whether I can become the second amateur to take an image. To help set my expectations, how bright are those eight stars? My kit can manage V=22 or so in about 3 hours integration.

Perhaps I should put in a cross-reference.

 

Paul

 

[wimvb]

5 hours ago, Xilman said:

Amazing work!  If only you had chosen a different title or tagged it with "local group" I would have referenced it from my local group thread here:

 but I didn't get to see it in time. WLM is trivial by comparison!

Now VERY tempted to see whether I can become the second amateur to take an image. To help set my expectations, how bright are those eight stars? My kit can manage V=22 or so in about 3 hours integration.

Perhaps I should put in a cross-reference.

 

Paul

 

Interesting target, the WLM galaxy. Unfortunately it’s a bit too low for me. At 60 degrees north, the galaxy clears the horizon by 15 degrees at best. I have a forest across a field to the south, so it would clear those trees by maybe 10 degrees. My view is also a bit limited by trees on my own property, which means a clear view only about 2-3 hours at best per night. I generally avoid imaging objects which have a declination less than zero.

Andromeda XXX has a surface ”brightness” of 26 Mag/arcsec2, well below my sky quality. The stars are brighter but very small. They didn’t show up until after 8-9 hours of total integration time. You can find more information here

https://aladin.unistra.fr/AladinLite/?target=00 36 34.901%2B49 38 48.00&fov=0.28&survey=P%2FDSS2%2Fcolor

[wimvb]

An update on imaging this very faint galaxy. PixInsight has several useful tools for data and image analysis. One of these is the 2DPlot script (Scripts -> Utilities). This script allows one to create an intensity profile along a line, either horizontal, vertical or diagonal  in a monochrome image. I used a linear stretch  on a copy of my luminance master, meaning that I brought in the black point and white point, without touching the  mid point slider. This means that between the clipping points, the data is still linear. This is what the script came up with.

The right hand side shows a zoomed in section of the luminance image, with the position of And XXX marked with an ellipse. The horizontal line is where the intensities were measured, and the panel on the left shows the pixel intensities across this line. Not that the profile is for the whole image width, not just the zoomed in section. The position of the galaxy is marked by a red line. This line covers the same section as the ellipse in the image panel. There is a very slight increase in intensity where the galaxy is supposed to be. But since the surface magnitude of And XXX is 26 Mag/arcsec2 or fainter, this hardly clears the background level and noise floor.

This project was never intended to result in a pretty picture. Rather I wanted to know if it is possible to image faint dwarf galaxies with moderate amateur equipment. I also wanted to show some of the cool physics that is going on in what is essentially our backyard of the universe.

[symmetal]

I unfortunately missed this one when it was first posted so a belated Wow Wim. 😊 Your patience paid off.

Alan