Jump to content


NGC2903 - last one of the season

Recommended Posts

In the first half of April we had a few nights with clear skies, so I aimed my rig at the galaxy that Messier missed ...

60 x 80 and 120 second light frames (total integration time approximately 90 minutes), bias frames and flats

Imaged over 2 nights; 2/3 of the frames ended up being permanently archived ...

Equipment as per my signature. As always, unguided.

Processed entirely in Pixinsight.

This is still a WIP, TGVDenoise mottled the background and I'm still trying to find the right mix of edge protection and local support.


... and solved with Pixinsight. Note that the image solver in Pixinsight marks the galaxies that should be there, not just the ones you can actually see.


Comments / suggestions welcome

  • Like 5
Link to post
Share on other sites

Noise is always an issue. Try ACDNR with a gentle deconvolution or multiscalemediantransform but I'm sure you know this- more to help the uninitiated in these matters. I find that the only way to really deal with noise is more signal- lots of signal!

Link to post
Share on other sites

Thank you, Laudropb and pyrasanth.

More data is always the right answer, but unfortunately my current setup doesn't allow long exposures. Will try to remedy that after the summer.:headbang:

Multiscale noise reduction would also work, the trick is to preserve detail in the galaxy.

I already got better results simply by not pushing the intensity and saturation as much. It's all about subtle improvements and proper masking.

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    No registered users viewing this page.

  • Similar Content

    • By jackrussell0232
      Who knew renovating a house could take so long - and it's still a long way from being finished (maybe I shouldn't have tried to tackle it all myself...)
      But having finally uncovered some of the boxes containing my kit, and with a bit more free time than normal, I decided to have another go, starting with one of the top targets this time of year. (I am working from home, honestly).
      I felt like I was learning again from scratch.  But at least I've discovered the masked stretch.  This image might be over-saturated for some tastes, but what can I say, it's the first time I've managed to get any colour in my
      stars! 🙂
      20x10 mins L
      10x300s RGB
      Altair Astro Wave 115 refractor, SBIG STF8300M, GM1000HPS (never managed to get it to track unguided, but at least it can be guided now)

    • By The-MathMog
      Hey there

      I was out with my scope for the first time this years and was imaging the galaxy NGC2903 in LRGB. When I was stacking the RGB images, I noticed that one of the stars didn't properly align, and can now see that it is a very slowly moving object.
      I am not sure how I can identify what object it is?
      I can't find anything in Stellarium that shows up in that period, so anyone of you that can help? Loosely comparing it to other stars, it appears to be like +14 magnitude ⭐

      It was imaged from around CET 01:43 to 02:28 in this GIF:

      It probably also appeared in the light frames that I took previously to this, but I haven't been able to check that yet - Any inputs would be very welcome and interesting! 😁

      (If there is a better forum for this kinda post, please let me know too).

      Imaged with:
      Celestron AVX Mount
      Skywatcher 150PDS
      ZWO ASI183MM-Pro
      Baader RGB Filters
    • By stevewanstall
      Celestron 9.25 at f6.3, SW EQ6R pro, Canon 550 D modded
      The galaxy group Hickson 44 in Leo. This is based on 29 x 240 s, plus bias and flats.

      Hickson 44 in Leo:

      There are some other galaxies near by, some of which are names in this overlay from Astrometry.net:

      Overlay from Astrometry, naming the other objects:

      The main ones are NGC 3190, NGC 3185, NGC 3187 and NGC 3193. NGC 3190 has a well defined dust lane. NGC 3187 is a barred spiral galaxy with two arms. NGC 3193 is an elliptical galaxy.
      The light captured by my camera last night left these galaxies just after the extinction event killed the dinosaurs on Earth.
      From APOD: Galaxies, like stars, frequently form groups. A group of galaxies is a system containing more than two galaxies but less than the tens or hundreds typically found in a cluster of galaxies. A most notable example is the Local Group of Galaxies, which houses over 30 galaxies including our Milky Way, Andromeda, and the Magellanic Clouds. Pictured above is nearby compact group Hickson 44. This group is located about 60 million light-years away toward the constellation of Leo. Also known as the NGC 3190 Group, Hickson 44 contains several bright spiral galaxies and one bright elliptical galaxy on the upper right. The bright source on the upper left is a foreground star. Many galaxies in Hickson 44 and other compact groups are either slowly merging or gravitationally pulling each other apart.
      Abell 1367
      This image is based on 19 x 300 s , plus flats and bias. It shows a LOT of galaxies, in a grouping called Abell 1367. In this image you are looking at part of one of the biggest structures in the Universe, the Great Wall.

      The Leo Cluster (Abell 1367) is a galaxy cluster about 330 million light-years distant (z = 0.022) in the constellation Leo, with at least 70 major galaxies. The galaxy known as NGC 3842 is the brightest member of this cluster. Along with the Coma Cluster, it is one of the two major clusters comprising the Coma Supercluster, which in turn is part of the CfA2 Great Wall, which is hundreds of millions light years long and is one of the largest known structures in the universe.
      The overlay from Astrometry gives some of the galaxies visible in the image.

    • By gorann
      I took Olly @ollypenrice seriously when he claimed that 6" refractors are great galaxy hunters, so I let my EdgheHD scopes rest in the cupboard and put the Esprit 150 at work. These images summarizes the few clear night I had in February and March. RGB was collected with ASI071 (OSC) in most cases supplemented with additional lum from ASI 1600 MM (sometimes sitting on the Esprit 100).
      Top left: NGC2903
      Top middle: NGC4712, 4725, 4747
      Top right: NGC3718 and 3729
      Bottom: M96 and M96
      Yes, I have already posted the images separately, so excuse the spamming but I thought it was nice to see them together. It also gives an idea of their relative sizes as all imgaes are on the same scale.
      Comments welcome, including if I should put the 11" EdgeHD on the mount instead.....

    • By gorann
      I recently had my first light with my new Mesu mount and aimed the Esprit 150 at NGC2903. Combined with the he ASI 071MC with its APS-C sized chip this gave me a rather large FOV and therefore a rather small galaxy.

      I kind of like the small galaxy in a large space, but still I started playing with ways to crop the image, realizing that there are indeed many different ways to do this.
      I first made a rather standard crop keeping approximately the same image dimensions and  the galaxy in the centre:

      Then it struck me that it could look nice in a more panoramic view:

      And finally, I started to think about the possibility to use the famous Golden Ratio (https://en.wikipedia.org/wiki/Golden_ratio) used by artists since Leonardo da Vinci. I first tried it in its simplest form by just placing the galaxy in the one-dimensional golden ratio position along the length of the image:

      But this could also be done in two dimensions using the Fibonacci spiral, and to get it there I felt it benifited from a 180° rotation of the image:

      Any more suggestions? What looks best, if any? Feel free to play with different ways to crop my image.
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.