Cookie consent

AstroBin saves small pieces of text information (cookies) on your device in order to deliver better content and for statistical purposes. You can disable the usage of cookies by changing the settings of your browser. By browsing AstroBin without changing the browser settings, you grant us permission to store that information on your device.

I agree
Contains:  M 33, NGC 598, Triangulum galaxy
Getting plate-solving status, please wait...
Triangulum galaxy M33/NGC598 (c-lrgbhos), 


            Ram Samudrala
Triangulum galaxy M33/NGC598 (c-lrgbhos)
Powered byPixInsight

Technical card

Dates:Sept. 25, 2017July 29, 2019

Astrodon Ha 1.25 5nm: 13x300" (gain: 350.00) -20C bin 1x1
Astrodon OIII 1.25 3nm: 8x300" (gain: 350.00) -20C bin 1x1
Astrodon SII 31mm 3nm: 8x300" (gain: 350.00) -20C bin 1x1
Orion Skyglow 1.25" Imaging Filter: 10x120" (gain: 350.00) -20C bin 1x1
Orion Skyglow 1.25" Imaging Filter: 139x60" (gain: 350.00) -20C bin 1x1
Baader Planetarium UV/IR Cut: 77x120" (gain: 0.50) -15C bin 1x1

Integration: 7.6 hours

Darks: ~13

Avg. Moon age: 15.81 days

Avg. Moon phase: 17.84%

Bortle Dark-Sky Scale: 3.00

Mean FWHM: 3.10

Temperature: 15.00

Basic astrometry details job: 2830355

RA center: 1h 33' 47"

DEC center: +30° 38' 27"

Pixel scale: 0.992 arcsec/pixel

Orientation: 238.011 degrees

Field radius: 0.649 degrees

Resolution: 3941x2580

Locations: Ram Samudrala, Youngstown, NY, United States

Data source: Backyard


Triangulum is yet another member of our local group of galaxies, about three million light years away and is the third largest behind our own Milky Way and Andromeda, one of the distant permanent objects that can be seen with just your naked eye under the right conditions.

Imaging this galaxy ended up being a complicated process. I collected all the data that went into one of the final images over a couple of years. I had earlier collected the luminance and narrowband data on my Takahashi FS128N with the mono QHY163M camera in 2017 but I decided to redo this one in OSC with the colour QHY247C camera and the FC100DF tube. I then went about creating an image that combined all of the collected data by first creating a synthetic luminance channel which combined the luminance data from both the colour and mono cameras, then created a new LRGB image combining this with the separated red, blue and green channels and then added the Ha, O3, and S2 data to this image at a 80:20 ratio using PixelMath.

The great but sometimes frustrating aspect of astrophotography is that there are so many ways to produce a "final" image. I find the variant without the narrowband data and just only with mono (L) data just as aesthetically pleasing (and it is interesting to observe the differences). In addition I tried out different weightings for the channel combinations and also different approaches for combination including PixInsight's NBRGB combination script. At this point, this is just one of the few choices among what I considered aesthetically pleasing and also reasonably accurate in terms of representing the data. Short of combining all the respective channels, I ended up doing little post processing for now.

Normally I've been tending towards combining RGB channels in linear form and then processing them further but this time I created the final "look" of each channel as I wanted it and just combined them which locks you in with earlier choices. This can be both good and bad, since as I write above, there are many branch points and they largely seem to produce interesting results. To this end, I also put up the synthetic LRGB only image (containing all the luminance and OSC data) and also the complete luminance image for comparison. As always, thanks for looking!



Ram Samudrala
License: Attribution Creative Commons


  • Final
    Triangulum galaxy M33/NGC598 (c-lrgbhos), 


            Ram Samudrala
  • Triangulum galaxy M33/NGC598 (c-lrgbhos), 


            Ram Samudrala
  • Triangulum galaxy M33/NGC598 (c-lrgbhos), 


            Ram Samudrala


Description: This contains only the LRGB data (excluding narrowband).


Description: Only the luminance data.

Sky plot

Sky plot


Triangulum galaxy M33/NGC598 (c-lrgbhos), 


            Ram Samudrala