NGC2903 in LRGB

[AMcD]

I have finally managed to complete an image for galaxy season, despite the inclement weather.  This is an LRGB image of NGC2903 taken with a QHY268M and Antlia Pro V LRGB filters through a TS130 Photoline APO mounted on a Paramount MyT and guided with an OAG and ZWO 174MM.  I continue to be very pleased with the performance of the MyT.  The total integration time was 16 hours, comprising 4 hours of 120s integrations each in L, R, G and B under Bortle 5 skies.  The data was acquired using SGPro and processed in PixInsight.  As can be seen from the annotated version, the area is rich in galaxies, including an interesting cluster along the bottom edge of the image.  I have also included a closer crop of the image which reveals quite a lot of detail in NGC2903.  I hope to add some Ha to the image in due course.  Constructive criticism always welcome.

 

Cropped Version:

 

Annotated Version:

 

Edited May 4 by AMcD
Uploaded correct versions

[Adreneline]

Great image and very interesting plate solve - so much to look at.

I was drawn to PGC1650398 because it looks like two interacting galaxies, so I took a closer look in Simbad which appears to confirm just that:

I couldn't seem to find how far away this is though - needs an expert!

You could spend hours investigating this lot!

Thanks for sharing.

 

[ollypenrice]

Wow, that's really well resolved and the colour is convincing as well. An exceptional image.

Olly

[AMcD]

39 minutes ago, Adreneline said:

Great image and very interesting plate solve - so much to look at.

I was drawn to PGC1650398 because it looks like two interacting galaxies, so I took a closer look in Simbad which appears to confirm just that:

I couldn't seem to find how far away this is though - needs an expert!

You could spend hours investigating this lot!

Thanks for sharing.

 

Fascinating.  There is a real temptation in this hobby to move on to the next image once the last one has been posted, but I too have been dwelling on the abundance of objects in this one.

[AMcD]

24 minutes ago, ollypenrice said:

Wow, that's really well resolved and the colour is convincing as well. An exceptional image.

Olly

Thank you for your generous words Olly.  I am very pleased with how it turned out.  Persevering with this hobby through the weather is still worth it!

[wimvb]

10 hours ago, Adreneline said:

Great image and very interesting plate solve - so much to look at.

I was drawn to PGC1650398 because it looks like two interacting galaxies, so I took a closer look in Simbad which appears to confirm just that:

I couldn't seem to find how far away this is though - needs an expert!

You could spend hours investigating this lot!

Thanks for sharing.

 

About 1 billion light years according to its redshift. But this is with quite a large uncertainty, since the redshift was measured photometrically (with filters rather than a spectrometer).

At the very bottom of the image is a group of galaxies. These have redshifts between 0.034 and 0.276, which puts them at distances between (roughly) 460 million and 3.8 billion light years. In the same direction there is even a galaxy with a redshift larger than 0.4 (5.6 billion light years distant), but that falls just outside the image.

Edited May 4 by wimvb

[Adreneline]

1 hour ago, wimvb said:

About 1 billion light years according to its redshift. But this is with quite a large uncertainty, since the redshift was measured photometrically (with filters rather than a spectrometer).

My knowledge does not go as far as calculating distance from redshift.

How do you do the calculation ( accepting the uncertainty)?

LEDA 1650398 -- Galaxy
Other object types:    G (2016RAA,LEDA), Opt (LAMOST,SDSS)
ICRS coord. (ep=J2000) :    142.67269037 +21.45612886 (Optical) [ ] C 2020ApJS..249....3A
FK4 coord. (ep=B1950 eq=1950) :    09 27 51.56168 +21 40 35.1496 [ ]
Gal coord. (ep=J2000) :    208.62660025 +44.19877366 [ ]
Radial velocity / Redshift / cz :    V(km/s) 20955 [~] / z(spectroscopic) 0.072523 [~] / cz 21741.85 [~]; (Opt) E 2018MNRAS.474.1873W

 

[PhotoGav]

Redshift (z) is the fraction of the speed of light that the galaxy is moving away from us, in this case:

0.072523 x 300,000 km/s = 21,757 km/s

Plug that into the equation:

v = Ho d

where v is the radial velocity, Ho is the Hubble Constant and d is the distance. Rearrange to get

d = v / Ho

Let’s use a value of 70 km/s/Mpc for Ho (debatable what value to use here depending on your preference for working it out! So I’ve gone for a middling value). Plug in the values and you get:

d = 21,757 km/s / 70 km/s/Mpc = 311 Mpc

1 Mpc = 3,260,000 light years, so the distance is 1.01x10^9 ly, which is just over a billion light years. Far, far away…!

[wimvb]

42 minutes ago, Adreneline said:

z(spectroscopic) 0.072523

 

1 hour ago, wimvb said:

redshift was measured photometrically (with filters rather than a spectrometer).

I stand corrected (for this one at least). But there are other uncertainties.

[PhotoGav]

I meant to add: great image! Well done on acquiring sufficient data to create an image… tricky so far this galaxy season. I like the wider field of view, which puts the galaxy into context.

[wimvb]

46 minutes ago, Adreneline said:

How do you do the calculation ( accepting the uncertainty)?

The short version of @PhotoGav:

Multiply z by 14 000 to get the distance in millions of lightyears

[Adreneline]

Thanks @wimvb and @PhotoGav . I had found formulae but was not confident in their use. All noted for future reference. 🙏

[AMcD]

8 hours ago, PhotoGav said:

I meant to add: great image! Well done on acquiring sufficient data to create an image… tricky so far this galaxy season. I like the wider field of view, which puts the galaxy into context.

Thank you @PhotoGav.  Looking back at my files, I captured the first integrations at the beginning of March.  So only two months of searching for gaps in the cloud to get enough for the final result!