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WRAK
scholastic sledgehammer


Reged: 02/18/12

Re: Ever observed COU1900? new [Re: Bill Boublitz]
      #5917319 - 06/12/13 04:37 PM

Bill - basically I agree but not to full content.
It seems that COU1900 is dubious but the data for BU1074 is as far as I can see very solid - so the double negative report from Mark makes me cautious. A positive on BU1074 and a negative on COU1900 would have been more convincing.
Alternatives for COU1900 are scarce. BU1074 would be one but seems already a bit on the faint side compared with the other Haas project objects.
Other possibilities are all a bit fainter than COU1900 (and I have found no brighter doubles with ~2.5" sep and delta_m of 4mag):
WDS ID Name RA DEC M1 M2 Sep Con Notes
WDS23243+8625 HO200, IDS23244+8552, BDS12403, ADS16759, BD+85 00399 23h 24m 21s +86:25:04 6,65 10,61 2,4 Cep RA PM:-23, Dec PM:16, AB. First: 1885|138deg|1.7. Last: 1991|152deg|2.4. #Obs: 9. Note Code: D.
WDS16408-7218 HDO255, IDS16292-7206, CP-72 01971 16h 40m 47s -72:17:59 6,67 10,6 2,4 Aps RA PM:20, Dec PM:30, AB. First: 1897|235deg|2.8. Last: 1991|253deg|2.4. #Obs: 5. Note Code: D.
WDS12223-7330 FIN198, IDS12165-7257, CP-72 01240 12h 22m 15s -73:30:13 6,76 10,8 2,5 Mus RA PM:-58, Dec PM:-12, AB. First: 1933|108deg|2.1. Last: 1991|102deg|2.5. #Obs: 4. Note Code: D.
WDS16523-2536 SEE291, IDS16461-2526, BDS7773, ADS10232, CD-25 11743 16h 52m 16s -25:36:02 6,9 11 2,5 Sco RA PM:22, Dec PM:-10, AB. First: 1897|7deg|2.6. Last: 1961|359deg|2.5. #Obs: 5.
Wilfried


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Nucleophile
super member


Reged: 05/24/13

Loc: United States
Re: Ever observed COU1900? new [Re: Bill Boublitz]
      #5917517 - 06/12/13 06:45 PM

Quote:

Perhaps someone could suggest another to take it's place in the table?




I nominate STT 344. It is located in HER (near the border with Draco) and is currently viewable for many of us.

This binary has had 27 observations with a 2009 measurement being the most recent. Here are more stats:

mag1=6.5
mag2=10.3
delta mag = 3.8 (not 4 but pretty close)
sep=2.3"

Also, here is an image of this double by Florent Losse--so at least we know the secondary is there to be seen:

http://www.astrosurf.com/hfosaf/ids/stt344.jpg


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Nucleophile
super member


Reged: 05/24/13

Loc: United States
Re: Ever observed COU1900? new [Re: WRAK]
      #5917539 - 06/12/13 07:04 PM

Quote:

It seems that COU1900 is dubious but the data for BU1074 is as far as I can see very solid - so the double negative report from Mark makes me cautious. A positive on BU1074 and a negative on COU1900 would have been more convincing.





Considering how easy it was for me to view STT 344 with my 15" reflector and how similar this is to both BU1074 and COU1900, I am really surprised I cannot detect the secondary for BU 1074. I imaged STT 344; if I get a night of no wind, I will also try to image BU 1074 for more data to consider.

There exists the small possibility that the sky is not dark enough during the narrow window of opportunity I have to observse BU 1074 (close to after twilight) before it becomes occluded by my house. Also, I dont like looking at objects above my roof because of heat waves.

All that being said, last night was one of those classic hazy, still nights where the seeing was excellent and high powers gave crisp images (without the shaking due to wind). To the best of my ability all I detected was maybe a very faint secondary quite close to primary of a similar orange/red color---it at least appeared to have the correct position angle. What I saw was at best separated by 1 arcsecond.

I will keep looking.


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fred1871
professor emeritus


Reged: 03/22/09

Loc: Australia
Re: Ever observed COU1900? new [Re: Nucleophile]
      #5917729 - 06/12/13 09:07 PM

Mark, I'm curious about the nature of this "artifact" that gave you a false positive in observing COU 1900. And whether it might occur in other angles than around PA 300.

I've come across other reports of this happening, including a report of seeing the companion of Procyon (an extraordinarily difficult object) with a 9-inch telescope - the observer used a filter that gave internal reflection, producing a dim reproduction of the primary star so it appeared to have a companion. Moving the primary around the field changed the position of the reflection.

Regarding BU 1074, I don't think there's any reason to doubt its existence as a double. It's rather a pity there are no measures after 1923 recorded, but the five measures obtasined suggest a pair virtually unchanging (or changing very slowly) in that period, as Aitken had a measure of 2.5" in 1899, the same as 1923, though a little wider than Burnham's discovery number. The one doubtful matter with BU 1074 is the magnitude of the secondary star, for which there appears to be no recent high-accuracy photometry; so the mag 11.2 might be old eye estimates.

In terms of change in separation, the Hipparcos parallax for the primary star suggests a large distance (slightly over 500 light years) so this is a system on a large scale, which can't be expected to change quickly. Hipparcos/Tycho did not pick up the secondary star, but that's not unusual around mag 11 and dimmer.

There are a couple of positive sightings of BU 1074 as a double in this thread, in addition to the old observations by Burnham and Aitken, so I don't think there's any good reason to doubt its existence as a double. The difficulty of seeing the companion, sometimes even with a 15-inch telescope, might be informative about the vagaries of seeing very uneven and quite close pairs. In particular, local seeing conditions, telescope thermals, and sometimes other factors can make such companions obscure or invisible.


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Nucleophile
super member


Reged: 05/24/13

Loc: United States
Re: Ever observed COU1900? new [Re: fred1871]
      #5917754 - 06/12/13 09:21 PM

Quote:


There are a couple of positive sightings of BU 1074 as a double in this thread, in addition to the old observations by Burnham and Aitken, so I don't think there's any good reason to doubt its existence as a double. The difficulty of seeing the companion, sometimes even with a 15-inch telescope, might be informative about the vagaries of seeing very uneven and quite close pairs. In particular, local seeing conditions, telescope thermals, and sometimes other factors can make such companions obscure or invisible.




Yes, and it also might be I was so tired the other night due to lack of sleep night after night I looked at the wrong star!
I dont know that this happened but I am thinking it may have.


One thing I know--it was a no go with the 8 inch the first time around---I had never hopped to that area so I am always careful to confirm the eyepiece view matches the cartes du ciel reflector view for that FOV before I star observing--that is why I am certain I had not seen it with that scope. But the other night I was hurrying and hopping based on memory of the prior hop---problem is there is another orange star about mag 6 in the vicinity and I may have just stopped there.

Naturally, there are clouds tonight. I am encouraged by the others positives to keep looking at BU1074. The negative for COU is firm though---that is a star hop ingrained into my head and no question I could not see a companion with the 15 inch.

The artefact appears in the same place each time and most of the time I am looking in the same area of the sky so I dont think it interfered with other observations---but it is something to be aware of---I am pretty happy this mass produced Orion mirror is as good as it is--and has travelled so well all these years. Someday a Zambuto will supplant it though.


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fred1871
professor emeritus


Reged: 03/22/09

Loc: Australia
Re: Ever observed COU1900? new [Re: WRAK]
      #5917952 - 06/12/13 11:06 PM

Wilfried, that's a useful list of doubles to try for comparison. One of them (in Cepheus) is out of my sky always, but the other three are possible, and I've found I already have observing notes for two of them.

HDO 255 in Apus (16 40.8, -72 18) I looked at way back in 1996 with a C14 on a night of about 7/10 seeing. My notes: very close faint companion suspected 110x, glimpsed in steadier moments 160x, clear at 240x. I can try it again, with smaller telescopes (140mm, 235mm) when I get some clear sky.

FIN 198 in Musca (12 22.3, -73 30) I observed a couple of years ago with my current 140mm refractor; the air steadiness was not great that night, but I saw the companion flickering into view at 230x after hints of it at 160x. I'll try this one again as well.

SEE 291 in Scorpius - not observed yet; I'll put it on my list to do soon.

A bonus pair - A 524 in Monoceros (07 14.2, -03 54), I looked at 2 months ago - mags 6.14 and 10.17, separation 2.7" in PA 152 1991 (spec M1). I used the 140mm refractor, companion seen at 230x, steady in the best moments - seeing 7/10, best moments 8/10. That's a delta-m of 4.0, and a separation slightly larger, with the data suggesting a pair that's not changing much (1903-1991) though perhaps a tiny bit closer now, though the measures are within probable errors of each other (2.9" and 2.7" - perhaps 2.8" both times).


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WRAK
scholastic sledgehammer


Reged: 02/18/12

Re: Ever observed COU1900? new [Re: fred1871]
      #5918181 - 06/13/13 03:28 AM

Yesterday I had the for me rare experience of a clear if somewhat bright sky - SQM showed around +17mag for the sky background and NEML was ~2.5mag. Seeing with 140mm and Polaris was ~6-7 Pickering but got worse due to a rather quick drop in temperature resulting in air turbulences.
Tried COU1900 again with my 140mm refractor (Bill assumed 4" aperture sufficient for this one but this seems a bit on the optimistic side to me. My RoT model suggests 138mm aperture for a fair 50% chance for a split and in this aperture range I trust my model meanwhile fully) but COU1900 is with ~35 altitude meanwhile already a bit low in the sky for me so I had anyway not a real chance regardless if wrong data or not. I then tried again BU1074 with negative result - my model here suggests 164mm and the companion is with +11.2mag already rather close to my NEML reduced TML of about +11.8mag or may be even a bit less.
A524 sounds good, proposed aperture 130mm refractor. Separation 2.7" may be already a bit too large to fill in the required place in Sissy's matrix.
Detto FIN198, proposed aperture 150mm refractor. Seems to look fine to fill in.
STT344 seems also quite interesting (proposed aperture 141mm refractor) but is in my opinion already a bit away in terms of separation and delta-m - but for me certainly an object of interest to check the validity of my RoT model.
I can suggest these candidates to Sissy (will may be look again for somewhat brighter candidates if a wider variation in sep (2.3-2.7") and delt_m (+3.8-4.2mag) is accepted.
But this is certainly the decision of Sissy Haas and as there are still several empty places in her matrix may be this slot can also remain empty.
I for my part have to quit on COU1900 even with larger apertures (still struggling to come to terms with my C9.25) as this one gets already too low in the sky for me for resolving even under else very good conditions.
Wilfried


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Nucleophile
super member


Reged: 05/24/13

Loc: United States
Re: Ever observed COU1900? new [Re: fred1871]
      #5918297 - 06/13/13 07:42 AM

Quote:

SEE 291 in Scorpius - not observed yet; I'll put it on my list to do soon.




I should be able to tackle this one as well soon enough.


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WRAK
scholastic sledgehammer


Reged: 02/18/12

Re: Ever observed COU1900? new [Re: Nucleophile]
      #5918373 - 06/13/13 08:59 AM

Did not find any brighter doubles with the required combination of separation and delta_m.
Found another one with similar parameters like COU1900:
KU1 WDS16431+7731 2.6" +6.06/10.2mag in UMi with 19 observations according to WDS.
Wilfried


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7331Peg
Sirius Observer
*****

Reged: 09/01/08

Loc: North coast of Oregon
Re: Ever observed COU1900? new [Re: WRAK]
      #5918893 - 06/13/13 02:18 PM

I've been back to Cou 1900 a few more times, Wilfried, and still am not quite satisfied I saw the secondary. I thought I had it one night in a six inch f/10 refractor, but I lost it quickly and never did get another good glimpse of it. Altogether I believe I've got about three hours of time invested in trying to catch the secondary.

It's too low in the sky for me now, also, so it'll have to wait until it rotates into view in the eastern sky later this year.

I'm of the opinion the secondary is really there, but it would be great if someone could come up with a photo of it in order to confirm it. This one has to be one of the toughest doubles I've come across.


John


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Nucleophile
super member


Reged: 05/24/13

Loc: United States
Re: Ever observed COU1900? new [Re: 7331Peg]
      #5919080 - 06/13/13 04:16 PM

Quote:


I'm of the opinion the secondary is really there, but it would be great if someone could come up with a photo of it in order to confirm it.




That is my plan when conditions cooperate.


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WRAK
scholastic sledgehammer


Reged: 02/18/12

Re: Ever observed COU1900? new [Re: Nucleophile]
      #5920014 - 06/14/13 05:01 AM

Mark and John, thanks for putting this much effort into attempts for resolving COU1900, interesting topic anyway.
I hope we come any conclusive result here. To some degree I suspect that while COU1900 may exist the magnitude of the companion is muche fainter than +10mag - the number suggests only an estimation and not a precise measurement and as both observations were done with huge refractors the "real" magnitude of the companion might be so faint that we don't have a real chance with amateur scopes.
I hope this assumption is wrong.
Wilfried


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Bill Boublitz
super member


Reged: 05/04/13

Re: Ever observed COU1900? new [Re: WRAK]
      #5922308 - 06/15/13 01:36 PM

Finally had an hour and twenty minutes to spend on Cou 1900 with 178 mm last night.

NELM 5.0, seeing; very good with calm lasting 10 seconds or more. Moon; day 6, lunation 1119, in Leo.

At x44, red "fringes" were noticed in PA 310, evidence of some type of refracting phenomenon. Examined x200, x300, x600 and x685... (higher than I typically employ). Primary blue-white, typical for type A2V. Observed some evidence of a possible deeper blue companion, in PA 310, (close to the 304 listed position). In terms of brightness, the appearance would be consistent with what would be expected on a pair with this magnitude difference. One positive thing I can say; whatever I was seeing; it never changed position. Whatever I was seeing also appeared 1.0" or less away from the primary. At no time was there any evidence of anything at 2.4" separation. An additional oddity; slight de-focusing revealed two "knots" in the diffraction ring 180 apart. One at PA 310, the other at PA 170. Typically, with a single point source, de-focusing simply shrinks the diameter of the Airy disk and throws more light into the diffraction ring equally, in all directions. Knots usually suggest the presence of multiple objects. At no time did I observe elongation in the primary itself.

That's about as honest as I can state it. While there might be some evidence for a multiple object, nothing was resolved. Yet, I wouldn't dismiss it as singular because it didn't appear/behave like a single point source of light. Cou 1900 demands greater aperture and hopefully some unbiased electronic means of documenting what is actually there.

Ironically, as I began writing this, the two week update came in from Sissy. It includes a positive resolution report on Cou 1900 using 550 mm. She made known some reservations, but instructed me to log it into the database for now. I don't think she's received my (somewhat ambiguous) report yet. Cheers! ~ Bill


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Nucleophile
super member


Reged: 05/24/13

Loc: United States
Re: Ever observed COU1900? new [Re: Bill Boublitz]
      #5922475 - 06/15/13 03:48 PM

Thanks for the report, Bill.

I am hoping to get some clearing tonight to collect and report more data on this one (and others). My very first impressions of this with the 15" were also that there was duplicity hinted at---but higher powers showed nothing.

Sure hope I can generate a pic before the moon conspires against me.


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Nucleophile
super member


Reged: 05/24/13

Loc: United States
Re: Ever observed COU1900? new [Re: Bill Boublitz]
      #5922477 - 06/15/13 03:51 PM

Quote:

An additional oddity; slight de-focusing revealed two "knots" in the diffraction ring 180 apart. One at PA 310, the other at PA 170. Typically, with a single point source, de-focusing simply shrinks the diameter of the Airy disk and throws more light into the diffraction ring equally, in all directions. Knots usually suggest the presence of multiple objects. At no time did I observe elongation in the primary itself.




I like this--will also try this once I am able to view the object again. (waiting, waiting, ...sigh)


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fred1871
professor emeritus


Reged: 03/22/09

Loc: Australia
Re: Ever observed COU1900? new [Re: Bill Boublitz]
      #5922885 - 06/15/13 09:35 PM

Interesting report, Bill. Pretty certainly it can't be regarded as a positive sighting of the double. There's no reason to think the separation has suddenly dropped from 2.4" to 1" or less.

Your description of 'red "fringes"' and other details (bilateral knots in the diffraction ring) makes me wonder if there are optical issues of some kind with the telescope. That what you were seeing "never changed position" would fit for a telescope issue rather than a seeing conditions issue.

You mention "knots" in the diffraction ring 180 deg apart, but the PAs you give are 140 apart. Assuming one at 310, 180 offset gives PA 130, not PA 170. Think I'm asking for clarification

Good to hear someone with 550mm has tried it. Any details possible on what they reported seeing, given Sissy's "reservations" about it?

Incidentally - my guess in a previous note re Couteau finding COU 1900 with the Nice Observatory 30-inch refractor was wrong (based on late date for his discovery program); Wilfried has made available the full data list from WDS as a download, and it was the Nice 20-inch refractor Couteau used - about 510mm aperture.

The full data list also shows no result from Hipparcos (secondary too faint?) and no result from McAlister with speckle interferometry - delta-m too large is the likely cause, which is also consistent with a secondary fainter than the listed 10.0mag. The 2010 measure was, like McAlister, with a very large telescope, but not using speckle - adaptive optics in this case.


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Bill Boublitz
super member


Reged: 05/04/13

Re: Ever observed COU1900? new [Re: fred1871]
      #5923246 - 06/16/13 04:59 AM

Thanks, Fred.

It shouldn't be regarded as a positive sighting; it wasn't.

There are most certainly "optical issues" with my telescope. A telescope is little more than a set of "optical issues."

PA clarification: opposite. Very sorry about the math. It was 4 am local. PA 130 accepted, My original estimate was only approximate. It may have been 309... that would make it, what (?) 129 degrees. Just for the record, of course.

Yes, good to hear about the 550 mm observation. No details available. You can always e-mail Sissy directly with your concerns.

Agreed on no result from Hipparcos, McAlister, etc. Often wondered why we're chasing this object in the first place. For the fun of it, I suppose.

Hope you get a look.


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WRAK
scholastic sledgehammer


Reged: 02/18/12

Re: Ever observed COU1900? new [Re: Bill Boublitz]
      #5923273 - 06/16/13 06:04 AM

Quote:

... Often wondered why we're chasing this object in the first place. For the fun of it, I suppose...



"Chasing" is already the answer - it is a difficult object and therefore an interesting challenge. And even negative results from reliable amateur observers are while of no value for the Haas project certainly of interest for the maintenance of the WDS catalogue - enough errors to weed out.
Wilfried


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fred1871
professor emeritus


Reged: 03/22/09

Loc: Australia
Re: Ever observed COU1900? new [Re: Bill Boublitz]
      #5924759 - 06/17/13 01:25 AM

My comments about no data from Hipparcos and McAlister were meant as an indication that this suggests a large delta-m (McAlister); fainter companion (Hipparcos); in other words, it's likely the companion is fainter than magnitude 10.0 as listed. Perhaps mag 11.0 or even fainter. It was simply the application of logic to data to give a probable result (probable, not certain, because there are assumptions, though I'd suggest reasonable ones, re the data).

On the suggestion that "A telescope is little more than a set of "optical issues."" - well, yes, but that tells us nothing. Your description of the red fringes and knots in the diffraction ring suggested a possibility of the kinds of "optical issues" that might give rise to spurious image effects. You'll notice, earlier in this thread, that Mark (nucleophile) ran into exactly this ype of problem with his 8-inch telescope, and consequently withdrew some observations that he therefore came to see as needing "retraction" because the telescope produced an "artifact" that simulated a star.

I've seen this happen with various telescopes, including some with good optics when they were out of adjustment, or had some other issue. It's usually fixable by adjustment or minor modification. So, my thought was, that perhaps your scope had an issue of adjustment or collimation or ???
One scope I owned used to develop astigmatism on cold nights because of pinching of an optical element as a cell contracted; adjustment solved that. I've also seen a cell pinch optics in a way that produced spurious star effects - such as bilateral brighter spots in the diffraction ring, similar to what you've noted. Hence my wondering about "optical issues".

Re the 550mm observation - I was merely wondering if Sissy had said why she had "some reservations" (your words).


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Bill Boublitz
super member


Reged: 05/04/13

Re: Ever observed COU1900? new [Re: fred1871]
      #5925687 - 06/17/13 02:43 PM

From a technical point of view, I look at it this way;

The theoretical Dawes for 178 mm is 0.65". The best human eyesight typically resolves details as fine as 1 arc-minute apart. Therefore, 60 arc-seconds/0.65 arc-seconds = x92.3 (!) Theoretically speaking, (assuming good calibration), at x92.3, the 178 mm is already revealing all it is capable of resolving. The rest is eye and air.

In practice, for my eyes, x200 reveals 90% of what scope is able to resolve. x300 is often useful, but here the atmosphere begins to affect the image to a higher degree. On rare occasion, I've found x400 profitable to clarify what I've already seen at x300. At x400, the images are never that good. I don't mean distorted, just not crisp. So I've concentrated my time on learning to see more at lower magnifications. I've never had anything "pop out" at x400. If I first see it at that power, backing down to x300 always reveals it was there all along.

From what I gather, 100x per inch is often profitable with refractors. Indeed my first split of Antares with 4" was achieved at x400.

I would not expect any kind of text book image from the 7" Mak at x600-x685. I'm pushing it well beyond it's design limits. While it may hold up on a test bench, in the field (and down here near sea level), the atmosphere will never allow it.

Not to preclude the possibility, but at this point I'm not seeing any evidence of optical issues with this scope. "The red fringing" was only observed at low power (x44). The target was fairly high and the atmosphere moisture laden. Experience writes it off to atmospheric refraction. x200-x300 the image was clean, crisp, clear - no artifacts or distortions; no companion. Artifacts/distortions only appeared at x600/x685. My claim; there may be some evidence of duplicity.... That leaves a lot open.

Another reason why I would not yet begin to suspect my scope; the closet pair on the Haas table is 0.7". I have not yet failed to see anything on the list with more than x200-x300. The only pair that requires more careful revue is our beloved Gamma Equ...

As for the 550 mm log; she "didn't think it would hold up, but enter it for the time being." I act in a supporting role; receiving a set of apertures and numbers to enter and have no privilege to reports. (Thankfully.)

BTW, after hopefully completing the table early this summer, I will be taking the 178 mm in for routine servicing (every three years). If it's totally out of whack, I'll go back and do the table again... next year.

Okay, that's enough out of me....


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