Object of the Week November 6th, 2016 - Arp 284 and a mind bending quasar.

[Howard B]

Arp 284 = NGC 7714 and NGC 7715 (magnitudes 12.5 and 14.5 respectively)
Quasar 2333+019 (magnitude 18.0)

The two interacting galaxies of Arp 284 are, by chance, right next to a magnitude 5.7 star, 16 Psc, making them particularity easy to find but also somewhat difficult to observe. I've observed it three times, with the last two times with my 28 inch scope in August and last week with Jimi's 48 inch, and it's interesting to compare the two observations, especially because of the unexpected bonus that made this an incredible observation in the 48 inch.

28 inch
"The bright star is 16 Psc and I had it outside the 408x fov while observing - it's a bright one! Anyway, both galaxies are immediately obvious and the tidal tails pop out with averted vision in 7715. 7714 is brighter with a small star-like core (7715 has a much fainter star-like core). The tidal arms don't point exactly at 7714's central area giving the galaxies a nice asymmetry. 21.72 SQM."

2336 2337

Last week, when we got the pair in Jimi's 48 inch he noticed on MegaStar that there is a high z quasar in the same field of view - with a z of 1.871, which equates to a 10 billion year light travel time! We (Jimi, Steve Gottlieb and myself) were bowled over that it was as easy to see as it was, even though MegaStar listed it at 18th magnitude. It really was the most memorable view of the night, and is one of those rare observations that made the back of my neck tingle in awe.

48 inch
The best and most memorable view of the night. Wow, a quasar who's light has taken 10 billion years to get here - and I could hold its stellar image steady with averted vision. Holy Moly...

NGC 7714 and 7715 were astonishing too, and much more detailed than I saw in the 28 inch at the OSP in August. 812x, 21.45 SQM."

2338 2339

...and the MegaStar image:

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There's an incredible depth of field here - 16 Psc is in our Milky Way galaxy, about 101 light years distant. NGC 7714 and 7715 are about 100 million light years away - amazing enough - while the quasar's light has taken 10 billion years to get here, about 71% the age of the universe. Oh man, the back of my neck is tingling again...

Give it a go and let us know!

[wvreeven]

My notes with my 20" from SQM 21.5 skies on September 8 this year:

NGC 7714: At 427x stellar nucleus with north north west a condensation surrounded by a halo. Towards NGC 7715 I sometimes see that the halo is a ring. A dark region lies due west of the nucleus.
NGC 7715: At 427x elongated, oval central region with very faint outer regions.

I didn't know about the quasar because the settings for SkyTools Pro 3 were such that it didn't display the quasar labels but I have fixed that now. According to SkyTools the quasar is called PB 5468 or Q2333+0019 by the way.


Clear skies, Wouter

[Uwe Glahn]

Interesting combination Howard and another pair of interacting galaxies and a discordant redshift object - Arp knows why.

I just try to find out the exact magnitude. You and NED write ~18vmag. NOMAD says 16,7vmag (17,35bmag) for this stellar source. And you wrote "steady". Perhaps near to the 17vmag and so perhaps a goal for smaller telescopes like 30"+?

My old observation is without the quasar but with some nice structures. NGC 7714 showed a shifted center brightening and NGC 7715 showed slightly bend extensions towards NGC 7714.

16", 360x, fst 6m5+
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[Howard B]

Hi Uwe,

I want to try the quasar in my 28 inch if I get a quality clear sky later this month because it just might be in reach. It was steady with averted vision in Jimi's 48 inch, and I've seen other objects this faint in my scope so who knows. To have any chance it will certainly require steady seeing.

[Steve Gottlieb]

Uwe, the magnitude certainly may be brighter - as you mentioned, NOMAD (http://vizier.u-strasbg.fr/viz-bin/VizieR-5?-ref=VIZ58212a04464b&-out.add=.&-source=I/297/out&NOMAD1===0921-0787962) gives Vmag = 16.7.

The earliest magnitude I could find is the 1993 "Revised and Updated Catalog of Quasi-stellar Objects (http://vizier.u-strasbg.fr/viz-bin/VizieR-5?-ref=VIZ582124140e23&-out.add=.&-source=VII/158/table1&recno=21981)", which lists Vmag = 18.0. More recently the 2010 version of the Quasars and Active Galactic Nuclei (http://vizier.u-strasbg.fr/viz-bin/VizieR-5?-ref=VIZ58212a04464b&-out.add=.&-source=VII/258/vv10&recno=131442) catalogue (13th Ed.) by Veron et al gives a Vmag = 18.3. That's quite a range from 16.7 - 18.3. Perhaps somewhere in between?

[Howard B]

Whatever Q2333+019 actual Vmag is - faint magnitudes are slippery things - it wasn't at the 48 inch scope's limit. On a great night many of us here may have a chance to see it with our own scopes, but the only the way to know for sure is, of course, to give it a go. Having the chance to see 10 billion year old photons is so worth the effort.

As a related comment, one thing I have to be mindful of when attempting a difficult observation like this is to disengage my mind from the effort of trying to see something so faint and to remember what I'm seeing at that moment. It's too easy for me to get caught up in the effort, make a sketch and write my notes without savoring the moments at the eyepiece when the actual photons are trickling into my eye. When I do remember - which is easier when I'm not in a hurry - the experience of observing becomes so much more meaningful. It seems odd that I have to constantly remind myself to slow down and smell the roses when it's always so wonderful when I do. Does anyone else struggle with this?

[Uwe Glahn]

Howard and Steve, you are right, to give it a try is the best way to know if it is visible or not. The praxis is more honest than any theory.


It seems odd that I have to constantly remind myself to slow down and smell the roses when it's always so wonderful when I do. Does anyone else struggle with this? I think I know what you are talking about. Basically it is not the time itself what makes the night meaningful. For myself and because of sketching I rarely manage to visit more than 15 objects per night. But is is more the reminder what we are generally doing and observing. As experienced observers we all have our plans, our projects, our list to work on. And we are able to work efficiently. And I believe that is often the problem. Although we operate good we have to take a deep breath during our observing session. For example not to fight with 2MASS 02224186+4222417 with high power only but to shift a lower gear and to enjoy the simply beauty of the magnificent whole object.

[kisspeter]

I finished my NGC 7714-15 sketch a bit more than a week ago. But the final drawing will need to wait (I have about 50 sketches to be processed).

I was surprised to see quite many details with a 16" scope (220x-294x).
NGC 7714:
Bright with a bright stellar core. Core slightly offset to the North. Bar visible with the start of both arms.
NGC 7715:
Faint, elongated, straight, no core.

I wasn't aware of the quasar. I can imagine that it really gives perspective to the observation. But I think 16" will be far too small.

I think I understand what you are saying, Howard. I can get lost during the search for details while drawing as well. I concentrate only on the details: is it visible / is it not? is it elongated? which direction? etc. It's easy to forget that it's actually a pair of distant galaxies in a violent collision for example. Not just an image but the galaxy itself.
On the same night I drew NGC 7714-15 we took a look at OJ 287 as well. If I understand it correctly the "smaller" black hole is passing through the accretion disk of the bigger one right now. So it's quite interesting. The next event will be 12 years from now. And after estimating the brightness I still had to force myself to relax a bit and think about what that little starlike dot really is.

[Howard B]

Hi Peter,

I agree, a 16 inch scope probably won't pick up Q2333+019, but I'll bet you can (or already have) seen Markarian 679 in Bootes which is nearly as far away with a light travel time of 9.3 billion years.

These numbers are so staggeringly gigantic that I have no hope of really comprehending them, but that adds to my excitement when I remember what I'm looking at. This also points out two of the enormous advantages we enjoy as visual observers over our predecessors - not only do we have better equipment than visual observers 100 years ago, but given the work of many brilliant minds in that time we now have the chance to appreciate what these faint objects actually are in real time.

By the way, I wasn't aware of OJ 287 so I'm glad you used it as an example in your post. For others who aren't familiar with this object check out:

https://en.wikipedia.org/wiki/OJ_287
and
http://www.skyandtelescope.com/astronomy-news/monster-black-holes-soon-to-collide/

This just went to the top of my Spring observing list - and according to the Sky & Telescope link the last outburst was in 2007 so the next one will be in 2019.

[Steve Gottlieb]

Howard and Steve, you are right, to give it a try is the best way to know if it is visible or not. The praxis is more honest than any theory.

I think I know what you are talking about. Basically it is not the time itself what makes the night meaningful. For myself and because of sketching I rarely manage to visit more than 15 objects per night. But is is more the reminder what we are generally doing and observing. As experienced observers we all have our plans, our projects, our list to work on. And we are able to work efficiently. And I believe that is often the problem. Although we operate good we have to take a deep breath during our observing session. For example not to fight with 2MASS 02224186+4222417 with high power only but to shift a lower gear and to enjoy the simply beauty of the magnificent whole object.

Good words to observe by, but I had to chuckle about your comment regarding 2MASS 02224186+4222417 (one of the difficult companions of NGC 891). Howard, Jimi and I spent some time observing NGC 253 at high power two weeks. Well not exactly NGC 253 -- we were looking at the small (background?) galaxies surrounding NGC 253 like 2MASX J00472496-2521253!