Jump to content

sgl_imaging_challenge_2021_annual.thumb.jpg.3fc34f695a81b16210333189a3162ac7.jpg

Quasar CTA 102 - seriously deep sky!


Recommended Posts

Hi folks,

This, surely, is seriously deep sky.

Has anyone else been looking at this amazing quasar in Pegasus, which is undergoing a massive outburst. I read about it on the Sky and telescope website.

It's normally at around mag 16/17 but occasionally has outbursts to around mag 12 every other year or so. However, it's currently having a massive burst, and my measurements on Astrometrica make it currently at mag 11.2. Relatively easy visually, for an object allegedly 8 billion light-years distant.

Can that really be true? That's a point source over 20 times more distant than the entire galaxy NGC7305 nearby, and brightening by truly unbelieveable levels in a short time.  I thought that, at such a phenomenal distance and moving away at huge speed, its redshift would at least make it appear red, however in my image it's distinctly blue. Does my head in.

Just 30 x 60s luminance, 200mm f/5 Newt, ATIK 428EX, plus 20 x 60s R & B, sythesised G.

 

31157171753_f014ed46ef_b.jpg

 

31818762372_7ea82f9267_b.jpg


Anyways, whatever it is, I'm a big fan of the Byrds, who wrote about it when it was discovered in the 60s and its radio waves were thought to be messages from aliens:

Year over year receiving you
Signals tell us that you're there
We can hear them loud and clear

We just want to let you know
That we're ready for to go
Out into the universe
We don't care who's been there first

On a radio telescope
Science tells us that there's hope
Life on other planets might exist

  • Like 18
Link to post
Share on other sites

Its good to see a colour shot of this incredible object that is confounding all expectations (apparently getting brighter in fits and starts).

Coincidentally, I was looking at it for the first time tonight in mono (image posted on CN thread). If I get the chance I'll try for an RGB version next time out. I haven't tried Astrometrica but I'd estimate around 11.6. I imagine this is bright enough to take a spectrum with amateur kit too.

Martin

Link to post
Share on other sites
1 hour ago, Martin Meredith said:

Its good to see a colour shot of this incredible object that is confounding all expectations (apparently getting brighter in fits and starts).

Coincidentally, I was looking at it for the first time tonight in mono (image posted on CN thread). If I get the chance I'll try for an RGB version next time out. I haven't tried Astrometrica but I'd estimate around 11.6. I imagine this is bright enough to take a spectrum with amateur kit too.

Martin

11.6?  Makes it brighter than 3C 273 at 12.8.  Challenge accepted although I am a beginner armed only with a SA100!

Link to post
Share on other sites

Great story, thanks for sharing!

Yes, it should be red, should it not, unless it is not moving fast away even if it is far away. Or, maybe its original light is around UV and shifted to blue?

Edited by gorann
Link to post
Share on other sites
21 hours ago, gorann said:

Great story, thanks for sharing!

Yes, it should be red, should it not, unless

O r, maybe its original light is around UV and shifted to blue?

Yep you got it !

The term "red shift" is wrt to doppler of the whole spectrum,  but more usually applied (as a specific measure) to the shift of the Hydrogen line(s) towards the red or where it (relative otherwise) should be if all was at rest.

In other words, the whole spectrum gets shifted towards the red, but that includes all (if any) Blue, UV, X and Gamma ,, all go downwards towards the blue -> red, IR and radio. But the shift of the Hydrogen line(s) as a "red shift" as a cosmological quasar thingumy does not prescribe a visual colour

 

 

Edited by SilverAstro
  • Like 2
Link to post
Share on other sites

Hi all,

I had another look at this quasar tonight, and my Astrometrica measurements show that it's now magnitude 12.3. That means that it's now over a magnitude fainter than it was a few days ago. That's mindblowing (to me anyway!) for a strange, unfathomly luminous, object 8 Billion light years away.

Here's my latest image. Just 5 x 60 seconds exposures between clouds. That's it, bang in the centre.

31956538302_f3d7fd3b79_k.jpg

 

  • Like 2
Link to post
Share on other sites

A group of us gathered to do visual on this with my C9.25".  It was great to get a buzz from 8 Billion Year old photons hitting your retina.  I am actually waiting right now to get an image when the clouds go.  We observed on the 2nd when it dipped below mag 13.  However, as suggested we came back to it an hour later and it had improved (subjectively). The AAVSO daily obs concurred with our subjective assessments.  It has brightened a bit since then to around 12.5.

Edited by Owmuchonomy
Link to post
Share on other sites

I finally found a window of opportunity to capture an image of CTA 102 last night.  This is the result using my C9.25" SCT at f/10 with my Canon 5D.  The black circle is the FOV using the same scope and a 14mm 82' ES EP.  AAVSO had this at just under Mag 12 last night which is a whole step brighter than when we did visual on it on the 2nd January.  It brightened to Mag 11 on the 8th. I need to read up more but it seems this object is actually classed as a Blazar partly associated with its very bright spectral emission lines outside the visual range.

CTA 102.jpg

  • Like 1
Link to post
Share on other sites

If anyone is interested in tracking down Quasars I can recommend forum member Martin Meredith's Pretty Deep Maps. It's a set of PDF charts plotting stars down to mag 18 and galaxies to mag 20, and includes a list of Quasar which is sortable by apparent magnitude and constellation. It's likely there are a few lurking in the backgrounds of peoples' galaxy images.

My own distance record is about 8 billion light years - I'm pretty sure I picked up a mag 19.6 Quasar in Draco in this image. This was just with a 200mm lens and DSLR.

 

  • Like 1
Link to post
Share on other sites
  • 2 months later...

There's a common misconception that a cosmological "redshift" automatically makes the object red - it doesn't!  A redshifted object can appear "blue" if there is dominate radiation in far-UV etc shifted into the visible range ! 

Conversely at extreme range and redshift, where there is no significant radiation in the far UV etc, it can appear "red".  Look at some of the remotest "red" galaxies in the Hubble Deep Field.   Converting redshift to a visual concept is challenging  :)

Nytecam

  • Like 1
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.

×
×
  • 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.