18 replies to this topic

[Dan_I]

  Hi,

 

NGC3718 is a barred spiral galaxy in Ursa Major (distance 57 millions l.y.), well-known for its distorted shape due to its gravitational interaction with nearby NGC3729. The galaxy group Hickson 56 at its feet is much further away (about 400 millions l.y.)

 

I had a small window of clear weather on Monday night to shoot about 5h30min of luminance in good seeing conditions (1.83" median FWHM after stacking), that I combined with RGB data from last year. This is a rather difficult object from my light-polluted backyard.

 

 

Link to the full-resolution: https://www.webastro...25f0d7472db.jpg

 

Link to the annotated luminance: https://www.webastro...04e12850d83.jpg

 

One can see a quasar at z=4.8 which is my new record!

 

Thanks for looking and clear skies,

 

Dan

 

Technical details

200/800 custom Newtonian astrograph with Romano Zen optics and carbon fiber tube
AP900 CP4 mount on Losmandy HD tripod

ASI183mm (0.66"/pix)
TS 2.5" Riccardi-Wynne corrector
ZWO LRGB filters
Guiding : ZWO OAG + ASI120mm mini + AsiairV1
Luminance : 330 *60sec
Chrominance : 80*60sec for R and G filter, 150*60sec for B filter
Conditions : Bortle 7/8 skies in Paris' suburbs (20km from the Eiffel tower), rather good seeing, average transparency
Processing with Pixinsight

Edited by Dan_I, 21 March 2023 - 11:09 AM.

[Dynan]

Very nicely done! 

 

(But it's NGC3718. [Trois-mille-sept-cent-dix-huit] Those darned numbers make a difference. )

Edited by Dynan, 21 March 2023 - 04:23 AM.

[Dan_I]

Very nicely done! 

 

(But it's NGC3718. [Trois-mille-sept-cent-dix-huit] Those darned numbers make a difference. )

Thanks! Corrected

[Dynan]

Can't seem to find the quasar. Can you point it out please?

[Dan_I]

Can't seem to find the quasar. Can you point it out please?

It is near NGC 3729. Here's an inverted annotated image

 

[Dynan]

Thanks 

 

What program/site did you use for the annotation?

Edited by Dynan, 21 March 2023 - 05:12 AM.

[Steve OK]

A very beautiful image of a tough target!

 

Steve

[Dan_I]

Thanks 

 

What program/site did you use for the annotation?

I used the AnnotateImage script in Pixinsight. You need to select the Milliquas catalog to display the quasars.

[Dan_I]

A very beautiful image of a tough target!

 

Steve

Thanks a lot Steve!

[Dynan]

Thanks, Dan. This'll be very handy to see what crept into our images.

[Mert]

That's a great image of a difficult galaxy!
What is the total amount of integration time?
I did an attempt of the same field with 24h total but under strong LP ( Bortle 8+ ) balcony skies

Edited by Mert, 23 March 2023 - 07:19 AM.

[dhkaiser]

Z=4.8, how many light years is that?

[Dan_I]

That's a great image of a difficult galaxy!
What is the total amount of integration time?
I did an attempt of the same field with 24h total but under strong LP ( Bortle 8+ ) balcony skies

 

Thanks Mert ! The total integration time with the L filter was 5h30min. The conditions were rather good (not in absolute terms, but for my place).

 

Z=4.8, how many light years is that?

 

The photons that hit the sensor were emitted 12,6 billions years ago.....

Edited by Dan_I, 23 March 2023 - 05:22 PM.

[PeteM]

Nicely done Dan! Tons of galaxy scattered throughout. It was fun to explore that high-res.

[Dan_I]

Thanks a lot Pete!

 

clear skies,

 

Dan

[Startex]

Absolutely nuts!!

[Dan_I]

Absolutely nuts!!

 

Thanks!

 

clear skies,

 

Dan

[Jim Thommes]

Excellent image! Well done.

[Dan_I]

Thanks a lot Jim!

 

Clear skies,

 

Dan