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Asbytec
Guy in a furry hat
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Reged: 08/08/07

Loc: La Union, PI
Some Doubles in Tau and a bonus new
      #5607971 - 01/06/13 09:47 AM

6 Jan 2013 1230 to 1400UT, Seeing 9/10, trans mag 5. Most observations 163x (12mm UO HD Ortho) 262x (12mm UO HD Ortho 1.6x Barlow) and 320x (6mm TMB II.)

STF562: Unequal pair at 262x held faint companion fairly steady at ~PA 275 just outside the first ring. Cleanly split and easier at 163x. Fleeting glimpses at 320x. I got a possible hint of ruddy hue. Unsure. (PA 135 listed is incorrect.) Striking pair, much like BU 87. Estimate sep about the same as BU 87: 1.2"< sep <2.0" (Not very good at estimating it, yet.)

BOV28 and STT78: unable to locate on mag 8.5 chart.

STT95: Closely matched pair cleanly split at 163x, PA ~300. Dark space seen at 163x and 262x. NW component is a little dimmer. Very close pair, rings did not appear pinched. Would estimate sep at <1.2" (inside first ring.)

42 Ori: Best night with 42 Oir to date. The companion was readily visible at 262x and 320x. Often times it was a brighter section of the ring PA ~200 or so, and on a few occasions a fleeting, distinct Airy disc.

80 Tau: Difficult unequal pair at 163x, easy at 262x. Companion held steady outside the first ring at ~PA 015. Estimate the split to be ~ 1.5" arc. Primary appeared a yellow white, nor color apparent for the companion.

STF749 AB: A fine equal magnitude pair cleanly split at 163x and easier at 262x. Black space seen at 163x, better at 262x. Both components appeared to be white with no pinched rings. I estimate the sep to be < 1.2", maybe less than 1" arc. Companion was inside the first ring. A few field stars noted west, north, and east.

Honorable mention goes to Zeta Ori. A bright pair with a bright, but dimmer companion easily split at 163x. Each component's first ring seemed clearly defined and touching. Estimate sep about 2.5" arc and PA was south pointing. (I did not estimate the PA, forgot. Just enjoyed the view.) Also, the fainter C component north was easily seen.

It was a great night, too bad I was unprepared with more observations and had reasons to call it a night. Could have done an all nighter under these nearly perfect conditions.

May add a few sketches tomorrow. Thanks, enjoy!


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CelestronDaddy
scholastic sledgehammer
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Reged: 08/22/09

Re: Some Doubles in Tau and a bonus new [Re: Asbytec]
      #5608269 - 01/06/13 12:34 PM

Asbytec - Sounds like a good list of Doubles! Your sky conditions were much better than mine I had maybe a 5-6 / 10 and mod light at my site. I've been wanting to get back to viewing doubles with my 6SE but conditions have just not been favorable. I had a hard time at 150X and even 136X. I had to stick with lower power of around 60 to 75X. Sky conditions are supposed to be better tonight so maybe I'll have better luck. I did get a decent view of the Trapezium but of course all I got was the main A thru D group. Still a nice view though. Not sure if I could split some of your list even on a good night due to the lights of Austin. Thanks for the report and might I ask what atlas or software you use when planning an observation? Thanks, Tony

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Ed D
Carpal Tunnel
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Reged: 04/30/10

Loc: Sunny South Florida
Re: Some Doubles in Tau and a bonus new [Re: CelestronDaddy]
      #5608339 - 01/06/13 01:08 PM

Norme, I've been so into observing planets that I have been ignoring doubles since before the Mars opposition! I'll give the ones you listed a try.

Ed D

ADDED: I just looked in my DS log and I can't believe how badly I have ignored Taurus - Chi Tauri and 118 Tauri, that's it! This needs to be seriously rectified. At least I have HR 1370 and another one I observed the other night that I have to ID and log. I have also observed Zeta, your 'honorable mention' in Orion.

Ed D

Edited by Ed D (01/06/13 01:20 PM)


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WRAK
Pooh-Bah


Reged: 02/18/12

Loc: Vienna, Austria, Europe
Re: Some Doubles in Tau and a bonus new [Re: Ed D]
      #5608537 - 01/06/13 02:34 PM

Norme, thanks for the report. You failed on A117 or did not try it?
For STF554 and STF749 I have advertised values from the WDS catalogue different from your list:
STF554 1.5" 5.70 8.12 -> req. Ap 111
STF749 1.1" 6.54 6.55 -> req. Ap 113
BOV28 seems to be a bogus double listed in the WDS catalogue with only one observation - sorry that I did not check this before posting my list.
STT78 should exist as there are 26 observations listed in the WDS catalogue and the Tycho catalogue lists in this position TYC2371-01437-1 with +7.82mag.
I would be glad if you could try some of the objects from my list with a required aperture greater 150 as not only success would be of interest but also if and when you failed with your 150mm reflector.
Wilfried


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azure1961p
Postmaster
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Reged: 01/17/09

Loc: USA
Re: Some Doubles in Tau and a bonus new [Re: WRAK]
      #5608638 - 01/06/13 03:29 PM

It's a Maksutov actually Wil, not a reflector.

Pere


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fred1871
scholastic sledgehammer


Reged: 03/22/09

Loc: Australia
Re: Some Doubles in Tau and a bonus new [Re: azure1961p]
      #5609001 - 01/06/13 06:29 PM

Interesting notes, Norme - your observation of STF 562 is similar to mine. Unfortunately I didn't run through a full set of eyepieces on it to see what was the minimum magnification for seeing the secondary; I found the field with low power, then tried 285x, which gave a neat uneven double, the secondary star clear and plain (140mm refractor). Think I'll have to go back to looking at pairs step-by-step in magnification terms.

Incidentally, the listed numbers of Wilfried's list on the far right are not PA numbers, but estimated apertures based on a particular formulation of the rule of thumb.

42 Ori - the better of the two nights I observed it the companion was steady at 320x. Didn't try 285x or 250x that night.

The other doubles you mention are easier.

Very steady nights make such a difference with difficult, and even moderately difficult, pairs. Seeing 9/10 - one dreams...

Your Mak is not a reflector?


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Asbytec
Guy in a furry hat
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Reged: 08/08/07

Loc: La Union, PI
Re: Some Doubles in Tau and a bonus new [Re: fred1871]
      #5609181 - 01/06/13 08:27 PM

Wow, lot of comments. Thanks.

Daddy, on these, seems seeing will help. I could not imagine seeing most of them in turbulent air. I hope you get one of those "rare nights," as we call them. The tropics are more prone to better seeing, so I get lucky pretty often.

Ed, yea, you know maybe surveying doubles by constellation is easier. Tau has a few good ones. In retirement, I am spending time getting caught up on planets, lunar and doubles, areas I gave up pursuing deep sky previously. Turns out, there is a lot to see in all three.

Wilfred, I guess I did not attempt A117. Not sure why, but I will along with others on your list. It interesting to see how Haas rule of thumb and maybe your own apply to the discussion in Fred's thread and elsewhere. Since I am learning doubles, I'd be happy to report those on your list over the coming days. I am particularly interested in unequal pairs at or near the first ring.

Maybe STT78 might be too dim for my charts. It looks like a challenging one, I'll find another source to star hop to it.

Pete, well, it's both. Its not a dioptric nor catoptric, it's a catadioptric, ergo, both.

Fred, I think I am beginning to see some differences in eyepiece design. Throughput matters, it seems. It's interesting that some doubles appear to be more steady at lower power, for some reason that was the impression of STF 562 and maybe one other.

Okay, I misread his listing. Thanks. Normally, when I observe, I try to go into the observation as blind as possible. If course, I know something of the reported separation because that's how I chose them. But, PA is the big unknown making me find and confirm it. I really need a better method of estimating both aspects.

It's interesting, and consistent I think, that you held 42 Ori steady. The first ring on mine is relatively bright making it definitely challenging. I don't know how to estimate the apparent magnitude of the first ring (apparent intensity spread over some surface area), but if the companion has a higher intensity it should be seen. Still mulling that over, along with the idea there might be a soft gradient of decreasing light intensity from the central disc making such observations difficult. Plus, I just like to know what my scope and I are capable of, love a good challenge. And doubles seem to provide it.

Thank you all for commenting.


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azure1961p
Postmaster
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Reged: 01/17/09

Loc: USA
Re: Some Doubles in Tau and a bonus new [Re: Asbytec]
      #5609685 - 01/07/13 07:04 AM

Norme ,

Well written report. I enjoyed your descriptions. Tonight I'm off if weather holds I'd like to hit these.

C-Daddy, I can sympathize with your sky conditions hemming in your magnification envelope as its been no better than 5/10 here in Connecticut since thanksgiving week. It's dispiriting though in the same token there is aesthetic beauty in 5" doubles for example at 70x. I'm really looking forward to you getting at least 7/10 seeing or better so than scope can show u it's stuff.

Well here's to hoping for clear sky's tonight - weather looks promising.

Pete


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fred1871
scholastic sledgehammer


Reged: 03/22/09

Loc: Australia
Re: Some Doubles in Tau and a bonus new [Re: Asbytec]
      #5618258 - 01/12/13 12:02 AM

Here are brief notes on two more of the Taurus doubles that Wilfried listed in another thread. I found I had recent notes on these two. Both were easier than the suggested apertures in Wilfried's list.

Both of these were observed with my 140mm refractor. Two separate nights; good but not great seeing conditions both nights.
BU 1040 mags 7.8 and 11.5 at 3.5"- companion glimpsed with 160x, clear and definite tiny speck (separated) at 285x.
[listed for 154mm]

BU 91 mags 8.1 and 10.6, at 1.5" - companion suspected 160x, seen at 230x and 285x.
[listed for 161mm]

In the case of BU 1040 I think the dim magnitude of the companion made it more difficult. BU 91, though closer, had both a smaller delta-m and a brighter companion.

Added note - I should have mentioned, no moon in the sky when I observed these; so less of the natural light pollution, and a quite dark sky for a suburban site. Mag 5.0 naked eye, at least - maybe a little better than that.

Edited by fred1871 (01/12/13 11:41 PM)


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WRAK
Pooh-Bah


Reged: 02/18/12

Loc: Vienna, Austria, Europe
Re: Some Doubles in Tau and a bonus new [Re: fred1871]
      #5618441 - 01/12/13 04:12 AM

Fred, thanks - will add these observations do my data set of limit observations. I assume NEML near 6 as especially the BU 1040 observations suggests. +11.5mag would be for me with my ever present light pollution already too dim for resolution, even BU 91 with the +10.6mag companion would be rather hard for me.
The current RoT model is probably biased by my light pollution situation and therefore a bit too pessimistic. This suspicion is substantiated by the fact that it adds rather too few mm to the required aperture for a quite bad NEML value - this made me curious already earlier when I checked the model for all significant different parameter values. Will have to give greater weight to light pollution.
Additional observations will be greatly appreciated. I can make similar lists for other constellations also for any given aperture between 1-6" scopes.
Wilfried


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Asbytec
Guy in a furry hat
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Reged: 08/08/07

Loc: La Union, PI
Re: Some Doubles in Tau and a bonus new [Re: fred1871]
      #5618470 - 01/12/13 05:14 AM

Fred, thank you for the notes. Both of those are on my short list. Maybe tomorrow night, weather permitting.

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fred1871
scholastic sledgehammer


Reged: 03/22/09

Loc: Australia
Re: Some Doubles in Tau and a bonus new [Re: WRAK]
      #5620034 - 01/12/13 11:48 PM

Wilfried, I've been working my way through Taurus and Orion in recent weeks - if you want to offer an Orion list similar to the Taurus list you've already given us, I can see which pairs I've already observed, and then add others from your list to my observing program.

It'd also be a useful list for Norme, and anyone else who wants to try the difficult pairs for 10-18cm telescopes, and it'll add data points for the RoT projects (plural) that are now happening.


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Asbytec
Guy in a furry hat
*****

Reged: 08/08/07

Loc: La Union, PI
Re: Some Doubles in Tau and a bonus new [Re: fred1871]
      #5620129 - 01/13/13 02:13 AM

I'd love to try some of them, Fred.

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WRAK
Pooh-Bah


Reged: 02/18/12

Loc: Vienna, Austria, Europe
Re: Some Doubles in Tau and a bonus new [Re: Asbytec]
      #5620676 - 01/13/13 12:24 PM Attachment (40 downloads)

I have uploaded a spreadsheet with about 150 Orion doubles with requ. apertures from 100 to 210mm with the known light pollution bias means overly pessimistic with very faint companions. I have not checked the advertised data, there are for example several Jonkheere doubles listed to be handled with caution.
Wilfried

Edited by WRAK (01/13/13 12:29 PM)


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Asbytec
Guy in a furry hat
*****

Reged: 08/08/07

Loc: La Union, PI
Re: Some Doubles in Tau and a bonus new [Re: WRAK]
      #5620910 - 01/13/13 02:23 PM

Got it, Thank you. Weather cleared well after midnight. Should be on for tomorrow to get a few more on your Tau list, first.

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fred1871
scholastic sledgehammer


Reged: 03/22/09

Loc: Australia
Re: Some Doubles in Tau and a bonus new [Re: WRAK]
      #5621389 - 01/13/13 06:25 PM

Thanks for the Orion list, Wilfried. It does look very useful. I'll start by checking to see if I already have some of these doubles observed.

One small matter - the magnitudes listed are given, via my Excel Viewer, to two decimal places - but they have only one significant decimal of information.

For example, STF 728 comes up as mags 4.40 and 5.80 - where the current WDS lists 4.44 and 5.75. So, I'll assume the Excel Viewer is giving me a meaningless second decimal, and your spreadsheet has mags rounded to the nearest single digit.

Rounding introduces an occasional (trivial) difference in Delta-m, as here, from 1.3 (WDS) to 1.4 mags on the spreadsheet - as well, since WDS 2-decimal place mags are usually Tycho mags, we no longer can see where there's a modern magnitude versus a possible old, maybe eye-estimated, magnitude, as with a lot of the Jonckheere doubles.

I thought I should mention these minor points that need to be noticed. Overall, it won't affect the usefulness of your list, which is excellent for those of us working on telescope limits.


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fred1871
scholastic sledgehammer


Reged: 03/22/09

Loc: Australia
Re: Some Doubles in Tau and a bonus new [Re: WRAK]
      #5621835 - 01/13/13 10:28 PM

Wilfried, notes I have already on some of the Orion doubles you've listed I'll now post in the Orion doubles thread.

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WRAK
Pooh-Bah


Reged: 02/18/12

Loc: Vienna, Austria, Europe
Re: Some Doubles in Tau and a bonus new [Re: fred1871]
      #5622210 - 01/14/13 07:35 AM

Quote:

...One small matter - the magnitudes listed are given, via my Excel Viewer, to two decimal places - but they have only one significant decimal of information.

For example, STF 728 comes up as mags 4.40 and 5.80 - where the current WDS lists 4.44 and 5.75. So, I'll assume the Excel Viewer is giving me a meaningless second decimal, and your spreadsheet has mags rounded to the nearest single digit.

Rounding introduces an occasional (trivial) difference in Delta-m, as here, from 1.3 (WDS) to 1.4 mags on the spreadsheet - as well, since WDS 2-decimal place mags are usually Tycho mags...




Fred, thanks for this hint - this seems to be a shortcoming of AstroPlanner I use for selecting doubles out of the WDS catalogue by constellation, magnitude and separation range etc. I will inform Paul Rodman.
Wilfried


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WRAK
Pooh-Bah


Reged: 02/18/12

Loc: Vienna, Austria, Europe
Re: Some Doubles in Tau and a bonus [Re: WRAK]
      #5623814 - 01/15/13 04:10 AM

Quote:

... this seems to be a shortcoming of AstroPlanner I use for selecting doubles out of the WDS catalogue ...



Fast answer from Paul - needed only changing the settings for the number of decimals in the mag columns. Just another feature of AstroPlanner I did not know.
Wilfried


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