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nirvanix
Carpal Tunnel


Reged: 06/07/07

Loc: Saskatoon, SK
Re: My tale of Trapezium F - finally new [Re: Messyone]
      #5707782 - 03/01/13 08:55 PM

Quote:

I found the f star last night for the first time with my 6" f8 achro and a Pentax XW 7mm. Jumping for joy as I also got the 'pup' for the first time with a 5mm XW
Matt
Had to use a green filter on the pup






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CelestronDaddy
scholastic sledgehammer
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Reged: 08/22/09

Re: My tale of Trapezium F - finally new [Re: Messyone]
      #5708531 - 03/02/13 10:48 AM

Hot dang, WTG

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Messyone
sage


Reged: 05/02/12

Loc: Down Under
Re: My tale of Trapezium F - finally new [Re: CelestronDaddy]
      #5709177 - 03/02/13 05:25 PM

Just to prove to myself it wasn't a fluke I did it again tonight! This time the pup was easy to see, no surprises there but now I'm wondering why it took so long in the first place Spent the best part of 4 months looking for this one. On to the trap and now hoping to see some of the others in there....not likely but worth a try. I love my scope.
Matt


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WRAK
scholastic sledgehammer


Reged: 02/18/12

Re: My tale of Trapezium F - finally new [Re: Tamiji Homma]
      #5711913 - 03/04/13 04:04 AM

Quote:

... A-E was not so difficult but F isn't easy with small aperture...Tammy




If the current WDS data is correct, then the C-F pair has as separation of 4.5" with magnitudes +5.06/11.5mag - this is certainly a double very hard to split with an aperture below 150mm even under perfect conditions means ignoring the fact that there is also a nebula to consider.
Is +11.5mag not already at the telescope magnitude limit of a 60mm scope?
Wilfried


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Bonco
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Reged: 04/17/06

Loc: Florida
Re: My tale of Trapezium F - finally new [Re: WRAK]
      #5712807 - 03/04/13 04:06 PM

I've found the F member is doable in a 100mm. Actually I think I've viewed it in my 75mm but to be sure I'd have to search my unorganized notes.
Bill


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WRAK
scholastic sledgehammer


Reged: 02/18/12

Re: My tale of Trapezium F - finally new [Re: Bonco]
      #5713829 - 03/05/13 03:49 AM

Wow, sounds good. If you ever do a session in UMa could you please try WDS11593+3310 BU919 RA 11h 59m 18s Dec +33:10:01 +5,96/12mag 4,7" - should be a very similar challenge.
Wilfried


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nirvanix
Carpal Tunnel


Reged: 06/07/07

Loc: Saskatoon, SK
Re: My tale of Trapezium F - finally new [Re: Bonco]
      #5714232 - 03/05/13 11:19 AM

Quote:

I've found the F member is doable in a 100mm. Actually I think I've viewed it in my 75mm but to be sure I'd have to search my unorganized notes.
Bill




I've tried for F in a 100mm in my light-polluted backyard, but never found it. I suspect that it could be found with that scope in darker skies.


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Bonco
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Reged: 04/17/06

Loc: Florida
Re: My tale of Trapezium F - finally new [Re: nirvanix]
      #5714729 - 03/05/13 03:47 PM

Nirvanix,
I too have very light polluted skies. Your main disadvantage compared to my home site is Latitude.
Bill


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nirvanix
Carpal Tunnel


Reged: 06/07/07

Loc: Saskatoon, SK
Re: My tale of Trapezium F - finally new [Re: Bonco]
      #5714998 - 03/05/13 06:02 PM

Quote:

Nirvanix,
I too have very light polluted skies. Your main disadvantage compared to my home site is Latitude.
Bill




Well that's a good point Bonco. I forget how good M42 must look for you folks way down there. It's always a bit in the soup for me.


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WRAK
scholastic sledgehammer


Reged: 02/18/12

Re: My tale of Trapezium F - finally new [Re: nirvanix]
      #5715812 - 03/06/13 03:50 AM

Light pollution is not such a topic concerning resolution of double stars - it may add a few mm to the required aperture for a split but usually less than 10 even for heavy light pollution. Given stable air without any turbulences (Pickering 7 or better - this certainly excludes altitudes below 35) and high transparency (no haze or air pollution for example by air traffic) you can more or less ignore light pollution. The exception are very faint companions near the telescope magnitude limit as LP takes some tribute here. This is why I am a bit sceptic about small telescopes below 150mm for resolving F especially given the surface brightness of the M42 nebula adding some haze even in the best of conditions.
Wilfried


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Kon Dealer
professor emeritus


Reged: 01/05/11

Loc: Cambridge UK
Re: My tale of Trapezium F - finally new [Re: WRAK]
      #5715839 - 03/06/13 05:01 AM

Did "E" abd "F" with my 8SE for the first time last night.
I can see "E" quite easily with my 4" 'frac and 6SE.
Never seen "F" in either and they are out alot more than the "8".


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HCR32
sage


Reged: 08/27/10

Loc: Australia
Re: My tale of Trapezium F - finally new [Re: Kon Dealer]
      #5715850 - 03/06/13 05:31 AM

I see them no problems with a 6" APO at 125x.

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Bonco
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Reged: 04/17/06

Loc: Florida
Re: My tale of Trapezium F - finally new [Re: WRAK]
      #5716661 - 03/06/13 03:30 PM

Quote:

Light pollution is not such a topic concerning resolution of double stars - it may add a few mm to the required aperture for a split but usually less than 10 even for heavy light pollution. Given stable air without any turbulences (Pickering 7 or better - this certainly excludes altitudes below 35) and high transparency (no haze or air pollution for example by air traffic) you can more or less ignore light pollution. The exception are very faint companions near the telescope magnitude limit as LP takes some tribute here. This is why I am a bit sceptic about small telescopes below 150mm for resolving F especially given the surface brightness of the M42 nebula adding some haze even in the best of conditions.
Wilfried



I have documented observations of F with my 4 inch f/5. It is very doable in the right conditions. I've observered it many times in a 10 inch but I've also not been able to see it or E in the bigger scope. It's fickle. I checked my notes concerning my 75mm. Notes reflect positive observations of E but questionable views of F. So I won't say the 75mm viewed F, but I can guarantee you the 4 inch has revealed it.
Bill

Edited by Bonco (03/06/13 04:01 PM)


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cpsTN
Carpal Tunnel
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Reged: 04/26/07

Loc: Rutherford Co, TN
Re: My tale of Trapezium F - finally new [Re: Messyone]
      #5717863 - 03/07/13 07:58 AM Attachment (21 downloads)

That's great. With the seeing we have here in Middle Tennessee, I have to work a little to see star E and have never seen star F. ...and that is with the 12" dob. I included a diagram to help people.

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bhuloka
super member


Reged: 03/06/12

Loc: Maryland, USA
Re: My tale of Trapezium F - finally new [Re: Bonco]
      #5717952 - 03/07/13 09:11 AM

Last November, under better-than-average seeing, red zone, I set up my 8" edge HD and my 16" Hubble optics dob, as a test of the 16" mirror, since I knew the 8" was very good. The 8" showed F star faintly and only intermittently. The 16" showed it clearly and steadily, very easy. So aperture does play a big role here. BTW, I used a variety of magnifications.

On other days, when seeing was not as good, neither scope revealed F. E was usually there in the 16" even under mediocre seeing. Light pollution didn't seem to be a major factor.


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nirvanix
Carpal Tunnel


Reged: 06/07/07

Loc: Saskatoon, SK
Re: My tale of Trapezium F - finally new [Re: bhuloka]
      #5718032 - 03/07/13 10:06 AM

I find in my backyard the theoretical limiting magnitude of my scopes cannot be reached - I'm assuming it's light pollution. E and F are magnitude 11 which is a stretch for my 4" refractor in the city. In fact I find the 10" dob can only reach about magnitude 12 from the yard. Under good seeing, it's not the separation of the doubles that presents the problem with the trapezium. I've split tougher doubles that are brighter using the 4" in town, Porrima for example.

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WRAK
scholastic sledgehammer


Reged: 02/18/12

Re: My tale of Trapezium F - finally new [Re: nirvanix]
      #5718752 - 03/07/13 04:21 PM

Surprise - after a cloudy day a clear sky in the evening. NEML about +3mag and Pickering 6-7. M42 about 33 altitude so I gave STF748 AE and CF a try with a 140mm refractor. With x140 magnification I could barely make out the faint spot of E with a magnitude of +11.1mag but I could not resolve F with +11.5mag. This is my telescope magnitude limit with this degree of light pollution (without it would be about +13.4mag). Now and then there was a flicker in the diffraction pattern in the right position but then - there were also flickers in wrong positions, so no resolution.
Wilfried


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azure1961p
Postmaster
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Reged: 01/17/09

Loc: USA
Re: My tale of Trapezium F - finally [Re: cpsTN]
      #5719951 - 03/08/13 07:45 AM

Quote:

That's great. With the seeing we have here in Middle Tennessee, I have to work a little to see star E and have never seen star F. ...and that is with the 12" dob. I included a diagram to help people.




Charles,

F can be a frustrating object for me in common seeing in winter from Connecticut. I will say though , if you haven't done it, running a small 5" DC fan rated 12v off a boxy 6v flashlight battery purrs along with no vibration for me and significantly less flaring in star patterns. My 5" is the typical computer type DC fan of the variety like the more common 3 or 4" had at RadioShack. I wouldn't rule out running two 4" DC fans behind that large a glass.

If you already are doing something similar than its probably seeing/collimation related.

In 7/10 its nicely shown for me, but in 3-4 its basically invisible and 5/10 barely there.

Pete


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nirvanix
Carpal Tunnel


Reged: 06/07/07

Loc: Saskatoon, SK
Re: My tale of Trapezium F - finally [Re: azure1961p]
      #5720295 - 03/08/13 11:06 AM

Good idea Pete. Right now I have a little 50mm fan at the back of my 10" dob and I don't run it during observing because of vibration. The 120mm fan will move much more air and do it with less vibration.

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fred1871
professor emeritus


Reged: 03/22/09

Loc: Australia
Re: My tale of Trapezium F - finally [Re: WRAK]
      #5721178 - 03/08/13 08:49 PM

My experience with E and F is similar to many others' experience - E is much easier to see than F, and is less likely to disappear when seeing gets unsteady.

Nights I've seen both with 140mm refractor there's a big difference in the look of E and F - E pretty easy, F a tiny pinpoint of light.

These days, with both AE and CF being a little wider than the earliest measures, the AE and CF separations are near enough identical - 4.6" for AE, 4.5" for CF. Not enough to account for the difference.

The big factor is the magnitudes of A and C - A is listed at 6.55, C at 5.06. So you're looking at an 11th magnitude star not far from a much brighter one in each case - but C is ~4 times as bright as A. That by itself makes a big difference. Comparisons with brighter, closer, near-even pairs (such as Porrima) are meaningless - there's a totally different factor set involved.

The other thing that might make a small difference is the brightness level of the nebulous background - is it the same, to the eye, in both cases? I don't know, but in marginal cases a difference could affect visibility.

For smaller telescopes a further factor is that m11.5 is closer to the magnitude limit than m11.1 - especially when the other factors (above) are also in play.

So I'm surprised when F is seen with less than about 100mm aperture - even at 100mm it's doing very well. I'd expect it to take very good conditions and very good eyesight with 70-80mm telescopes. Exceptional in fact. It doesn't mean it can't happen, but it won't be the standard experience, as the many and varied comments in this thread show.


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