25 replies to this topic

[SNH]

I know it’s possible that some of you might read the title of my thread and quickly think, “Hey, wait a minute, how can seeing 2 billion light-years in a 10-inch telescope be a record when I’ve seen the quasar 3C 273 at 2.45 billion light-years in a 4-inch reflector?” Well, I’m referring to seeing the light from a entire galaxy as opposed to just the nuclei of one – which is what a quasar is.

It’s been noticeably cloudy this month, so just yesterday morning I went out to observe since I was going to have three full hours of total darkness after the Moon set. As it turned out, the temperature was just below freezing with minimal frost, the naked-eye scintillation was really good, the telescopic scintillation was excellent, and my SQM-L reading at the zenith was 21.5 – which tied my record for best reading yet.

Of the various 'exotic' objects I had plans to try for, one was the galaxy LEDA 1561869 (2MASX J09562806+1831023) in western Leo. In a thread I started a year ago after seeing a spiral galaxy that's over a billion light-years distant, the ever helpful Donald Pensack (@Starman1) posted a list of distant galaxies he planned to try for with his 12.5-inch telescope. I eagerly looked it over, hoping to find one that broke the 2 billion light-year barrier and would be just bright enough for me to catch sight of in my modest-sized telescope.

He had LEDA 1561869 listed right at 2 billion light-years and magnitude +15.8. So first I checked the NED website and surely enough, it was listed at 2.083 Gyr. Then I looked at a 15’ wide DSS image of it and was glad to see that it had a strong appearance.

With 264x (my main high magnification) on my classic 10-inch Meade SCT, I was thrilled to find that after looking at its field for 20 minutes I came away with nearly a dozen glimpses of it. I was blown away by how I was getting ‘hits’ from it without straining myself. Until this observation, my previous record was set nearly two years ago by PGC 37477 in Leo at a distance of 1.8 billion light-years.

 

 

I’ve seen IC 1101 in Virgo at a distance of 1 billion light-years and have to say that I haven’t seen a galaxy that breaks the 1 billion light-year barrier and is brighter. So I’d say that LEDA 1561869 is probably the brightest that breaks the 2 billion light-year barrier. As for the 3 billion light-year barrier, I don’t have anything to say on that for now except that I’ll be taking a crack at it in the next couple years when I plan to acquire a 16-inch telescope!

 

 

Scott

 

P.S. I hope that you find this report encouraging. I do hesitate to post it in case it could be found otherwise since sadly not everyone's skies are as good as mine.

[TOMDEY]

Excellent! "Remote Little Galaxies" are my favorite targets. My typical SQM here is 21.35-ish. I kept getting bigger and bigger telescopes, so I could see more and more of them. They kinda go on forever...    Tom

[GUS.K]

Thanks for sharing this observation Scott, an enjoyable read.

[Bob4BVM]

Awesome work Scott !  Thx for sharing this, it's exciting stuff.

I'm hoping i can take up such challenges again myself once i get my 2-eyed machine running.  Doing it one-eyed at my age is getting tougher all the time

Bob

[Redbetter]

Good work with a 10".  These get tougher as they become more distant, because they are so much redder and weaker in the wavelengths we see at night.  It quickly snowballs at 3 billion light years and beyond because they not only are smaller/dimmer, but their surface brightness has been reduced by the reddening as well.  The other thing in play is seeing as aperture increases and the targets become smaller.  

 

While the total numbers of distant galaxies detectable visually continue to increase rapidly with aperture, the numbers added at increasing distance begin to decline and start heading toward zero at some point.  There is likely some distance at perhaps 4+ billion light years or perhaps 5+ where no more galaxies are within visual reach with any reasonable aperture.

[Franta]

Great observation in a 10 inch! Thanks for sharing. I have also a 10 inch (yet a dobsonian), and IC 1101 is the most distant galaxy I have successfully seen.

 

Before you resign in pushing your envelope in your 10 inch, perhaps you might give a try to galaxy cluster Abell 1689. This is at a distance of 2.3 billion light years. This is in my list, but I have never tried this. I suspect that it is beyond my ability to see this galaxy cluster in a 10 inch, but someone else might have a better trained eye than me.

[Sheol]

                    Who said you couldn't do that in a 10 inch telescope? Very inspiring, thank you for the report!

 

                    Matt.

[Pcbessa]

Excellent observation SNH,

What is the magnitude of that galaxy?
I gave seen PGC 37477 last year. It is faintly mag 15 but doable with my 10" under Bortle 2 dark skies.

Abell 1689 sounds like a good suggestion.

There are two 1 billion ly galaxy clusters where I can see about 5 faint galaxies in them with good dark skies. These are Abell 2065 in Corona Borealis and Abell (can't remember number) in Orion near Bellatrix.

[SNH]

Excellent observation SNH,
<...snip...>

Well, in private communication with Starman1, he has told me that it is visual magnitude +14.6 - though I actually agreed with his former magnitude of +15.8 for it.

 

I just looked at a 15' DSS image of Abell 1689 and I'd say that I could probably see the "clump" of galaxies in the middle, but they are too close for me to pick out an individual one.

 

Scott

[Redbetter]

I don't know that a V mag of 14.6 is correct for PGC 37477 (MCG+04-28-097), it seems optimistic.  The Simbad listed g and r values (from 2016 based on SDSS III images I suppose) are 15.62 and 14.52 respectively.   This works out to ~15.0 V mag, which sounds about right compared to the old 15.57 B mag listed from 2000--this was probably based on DSS2 plates. 

 

The actual scotopic magnitude (real threshold visual at night) will be somewhere between the V mag and the g mag.  I don't have a formula for that at the moment.   

[SNH]

I don't know that a V mag of 14.6 is correct for PGC 37477 (MCG+04-28-097), it seems optimistic.  The Simbad listed g and r values (from 2016 based on SDSS III images I suppose) are 15.62 and 14.52 respectively.   This works out to ~15.0 V mag, which sounds about right compared to the old 15.57 B mag listed from 2000--this was probably based on DSS2 plates. 

 

The actual scotopic magnitude (real threshold visual at night) will be somewhere between the V mag and the g mag.  I don't have a formula for that at the moment.   

Umm, Redbetter - Pcbessa wrote "I have seen PGC 37477 last year. It is faintly mag 15 but doable with my 10" under Bortle 2 dark skies." So you are only agreeing with that statement with your work.

 

So when you (Redbetter) say "I don't know that a V mag of 14.6 is correct for PGC 37477, it seems optimistic.", you must be getting something mixed up because Pcbessa said "Excellent observation [of LEDA 1561869] SNH, what is the magnitude of that galaxy?" and I responded that Starman1 had told me it was +15.8 but is now thinking he had that wrong and it is actually +14.6 - which I'm disagreeing with.

 

Scott

Edited by SNH, 27 January 2021 - 11:46 PM.

[Bill Barlow]

SNH, how dark are your skies to see galaxy IC 1101 in a 10” Meade?  I have searched for this galaxy several times using SCT’s from 10” to 12” but haven’t seen it yet.  I typically go down to a site that is in a yellow/tan light pollution zone.

 

Bill

[SNH]

SNH, how dark are your skies to see galaxy IC 1101 in a 10” Meade?  I have searched for this galaxy several times using SCT’s from 10” to 12” but haven’t seen it yet.  I typically go down to a site that is in a yellow/tan light pollution zone.

 

Bill

Hi Bill!

I'd say that I'm on the border between Bortle Class 2 - 3. My SQM-L usually reads between 21.1 and 21.5 mpsas. I know where Overland Park is and you'd have to get out of there for sure to have any chance of seeing IC 1101. For me I know I could see it in an 8-inch for and possibly in a 6-inch. I have a 5.1-inch, so I plan to try! Good luck.

 

Scott

[Pcbessa]

Hi Bill, I live in Bortle 4. With my 10 inch I can barely detect IC1101 with averted vision The galaxy becomes much more easily seen when I drive to a Bortle 2 location, still faint but much better.

[Starman1]

I don't know that a V mag of 14.6 is correct for PGC 37477 (MCG+04-28-097), it seems optimistic.  The Simbad listed g and r values (from 2016 based on SDSS III images I suppose) are 15.62 and 14.52 respectively.   This works out to ~15.0 V mag, which sounds about right compared to the old 15.57 B mag listed from 2000--this was probably based on DSS2 plates. 

 

The actual scotopic magnitude (real threshold visual at night) will be somewhere between the V mag and the g mag.  I don't have a formula for that at the moment.   

I use V = 0.42g + 0.58r on those distant galaxies.

g = 15.62

r = 14.52

V = 14.98

 

NED has V = 13.92  for PGC 37477 From viewing it, this is obviously wrong.

 

I think it's safe to use 15.0

Edited by Starman1, 05 February 2021 - 06:53 PM.

[Starman1]

I thought 14.64 applied to IC1101

My list has PGC 37477 at 15.5

It's 2MASX J09562806+1831023 that is on my list at 2bly and mag.15.8, though I think that is too faint.

3 different galaxies being confused here.

Edited by Starman1, 05 February 2021 - 06:53 PM.

[Starman1]

NED has 2MASX J16394598+4609058 at 3.56bly and V magnitude 15.705.

I haven't seen it.  It's in Hercules.

[Redbetter]

NED has 2MASX J16394598+4609058 at 3.56bly and V magnitude 15.705.

I haven't seen it.  It's in Hercules.

That is an interesting find.  Hyperleda shows it as also being listed as PGC 2276277 (not that Wikisky will find it this way.)  The magnitudes appear to be far dimmer:  17.92 g, 16.54 r.  That would yield a V mag of 17.1, but that is likely too optimistic with respect to scotopic vision because of the heavy red shift of the galaxy.  It might be closer to 17.5 effective (scotopic.)   

 

Far more problematic is the listed mean surface brightness:  24.77 MPSAS, but that is likely based on the B mag of 18.15.  From Wikisky, it looks like visually it is just short of 30 arc seconds long and about 8-9 arc seconds thick. If I use my 17.5 scotopic estimate and dimensions I arrive at ~23.3 MPSAS.  That is low surface brightness, particularly for what would already be threshold limiting total magnitude.

[Starman1]

I can see that obtaining V magnitudes for these distant galaxies is fraught with discrepancies.

If NED is in error, how reliable are the magnitudes in SIMBAD?

[Redbetter]

I can see that obtaining V magnitudes for these distant galaxies is fraught with discrepancies.

If NED is in error, how reliable are the magnitudes in SIMBAD?

Every once in awhile NED has a crazy unexplained value for magnitude.  We are lucky for this particular galaxy as it is in the SDSS-III data set, which features u, g, r, i, and z mags.   I usually check with Hyperleda and use the magnitudes tab.  That worked for this one.

 

Sometimes the LEDA and SIMBAD info are linked and will display the SDSS-III data, and sometimes not.  This one is a not.  The PGC/LEDA number doesn't work in SIMBAD and using the 2MASX number doesn't show the identifier there.   I imagine these will be updated eventually.

[Pcbessa]

We have been talking about 4 different targets, and I will add a few more.

My reports are done with a 10" Dob in excellent skies (Bortle 2) and much patience. So far I did not exceed the 2 billion light years barrier.

Past the 1 billion light years:
IC1101 in Virgo, mag around 14.5-15.0
Abell 1377 in Ursa Major, mag around 15-15.5 (3 galaxies seen)

Past the 1.5 billion light years:
Abell 1783 in Ursa Major, mag 15-15.5 (1 galaxy seen)
Abell 655 in Lynx, mag 15-15.5 (1 galaxy seen)
PGC 37477 in Leo, mag around 15-15.5 (1 galaxy seen)

Past the 2 billion light years: (I haven't tried these)
Abell 1689 in Virgo, unknown magnitude 
LEDA 1561869 (2MASX J09562806+1831023) in western Leo, unconfirmed magnitude around 15.5-16.0

 

Past the 3lby?

2MASX J16394598+4609058 in Hercules, unconfirmed magnitude around 15.5-16.0

I sincerely do not expect to be able to see these last three with a 10" Dob!

Edited by Pcbessa, 08 February 2021 - 07:42 PM.

[Redbetter]

Past the 2 billion light years: (I haven't tried these)
Abell 1689 in Virgo, unknown magnitude 
LEDA 1561869 (2MASX J09562806+1831023) in western Leo, unconfirmed magnitude around 15.5-16.0

 

Circling back around to this one (LEDA 15618690, Hyperleda lists its magnitude data from SSDS III as g 16.49, r 15.34 which calculates out to about 15.8 V.  The effective scotopic magnitude is probably somewhere between 15.8 and 16.0. I calculate the mean surface brightness as about 22.6 MPSAS based on V mag, but it has good brightening to the center, so it should appear to have reasonably good surface brightness.  This is in line with what Scott described.

 

Abell 1689 looks tough for a 10" to me, but I don't believe I have observed it in the 20".   The SIMBAD designations/magnitudes are rather mixed on this one and leave me scratching my head about the individual galaxy magnitudes.  The central galaxy (Biggest in Cluster or BiC) 2MASX J13112952-0120280 is nominally listed as 16.48 V mag, with 16.9g and 15.7r mag.  This BiC's likely visually detectable regions appear to be about 15x10 arc seconds.  There are several other notable galaxies nearby, but they range from the 17's to 18's, so I don't know if they present enough overall brightness to help define this central region, which is maybe 40 arc seconds across.  There is a 15.6 mag star on the ENE edge of the core group.  Three other of the most prominent members further NE run from 17.0 to 17.7 V with the SDSS III g magnitudes running much dimmer than that and sizes of about 10 arc seconds.  I am not sure if I could identify much past the BiC with the 20".     

Edited by Redbetter, 09 February 2021 - 04:42 AM.

[happylimpet]

Good work with a 10".  These get tougher as they become more distant, because they are so much redder and weaker in the wavelengths we see at night.  It quickly snowballs at 3 billion light years and beyond because they not only are smaller/dimmer, but their surface brightness has been reduced by the reddening as well.  The other thing in play is seeing as aperture increases and the targets become smaller.  

 

While the total numbers of distant galaxies detectable visually continue to increase rapidly with aperture, the numbers added at increasing distance begin to decline and start heading toward zero at some point.  There is likely some distance at perhaps 4+ billion light years or perhaps 5+ where no more galaxies are within visual reach with any reasonable aperture.

Agreed. Its very noticeable when I image using R+IR(G)Lum as R(G)B that when it comes to the myriad faint galaxies in a field, there are vastly more visible in the R+IR (610 longpass) image than in the luminosity (400-700nm) image. Faint galaxies are red.

[Pcbessa]

Can someone please provide me with a chart to locate that LEDA galaxy in Leo?

I have located the region near TYC 1414-0140-1 near NGC3040 but I need a more detailed chart

[SNH]

Can someone please provide me with a chart to locate that LEDA galaxy in Leo?

I have located the region near TYC 1414-0140-1 near NGC3040 but I need a more detailed chart

Here are the charts that I made up last month when I went after 2Gyr away LEDA 1561869: