257 replies to this topic

[Nucleophile]

Fred:

 

In the following statement regarding STT 51 [post #244], did you mean to say pre-Gaia instead of pre-Hipparcos?

 

"The matter of genuine binaries being included and supposed optical pairs being excluded is probably the biggest wrong decision made in CDSA 2nd Ed. The data at the time (pre-Hipparcos) was in many cases not adequate to decide if a pair was gravitational or line of sight. In the case of STT 51 it appears simply to be overlooked - no bar, despite PM numbers in the WDS suggesting very clearly gravitational rather than chance line-up. There are quite a few like this I've come across."

 

The 2nd Ed. of CDSA came out in 2015 and the Hipparcos data that I routinely examine whilst searching the 4th Int Catalog is all listed as circa 1991.

 

 

On the matter of optical versus physical double stars, I will reserve my (rather strong) opinions on the matter for the appropriate time.

[fred1871]

Yep, correct, my mind is drifting (again)... pre-Gaia, with HIP available but not for everything; and, as we know, even Gaia does not find some secondary stars, and some others that are found don't have PM data.

 

Keeping us in suspense, Mark, re views on "optical vs physical" double stars?

Will look forward to the "appropriate time".

[John Miele]

31 Tauri...my new record and it was easy! Two tiny little points with definite black space between both stars and I could hold it for several seconds at a time at 390X. The nearly equal mags helped a lot.

 

Sky Safari listed it as 0.8" sep and mags 6.55 and 5.69.

 

Seeing was excellent tonight and the Starmaster 14.5 was collimated very well. I don't do a lot of doubles. I'm surprised at how much concentration it takes to do these. Of course my eyes are also nearly 63 YO...lol!

 

cs...John

[Ihtegla Sar]

Where I live under the Jetstream, it is rare to have seeing good enough for sub-arcsecond doubles, but last night the Jetstream moved south and seeing was excellent. Based on what I was seeing in my TEC 140, I would say it was Pickering 6 or 7, which is about as good as it ever gets here. So I was scanning around in Sky Safari to see what double I should look at after spending about an hour on Mars and I found STF 1037. It is actually a triple star with a mag 12.8 companion at about 14 arcseconds from the A/B pair. The A/B pair are mag 7.24/7.27 according to Stelle Doppie, which is about as close to equal magnitude as you can get. Sky Safari reports the separation as 0.7" in one place and 0.9" in another, so I didn't know what to expect when I first pointed the TEC 140 FL at it, using a 4mm TOE.

It quite appeared clearly as two stars, just touching, like tangent circles. Increasing magnification with my set of Vixen HRs, starting with the 2.4mm and eventually going up to the 1.6mm showed the same.

Then I switched to my 10" GSO Classical Cassegrain. In the past this scope had given me trouble with close doubles, possibly due to thermal issues but temperatures were rather stable last night dropping only a 3 or 4 degrees over a few hours from about 29 degrees at 11:15 pm to about 25 or 26 degrees at 2:45 am when I packed it in. I could immediately see A/B as separate stars with black space in between. Best view was with the 6mm TPL (500x, 0.5mm exit pupil). I could easily see separation between A/B and the C component was intermittently visible in averted vision in my light polluted (18.5 SQML) skies.

Checking Stelle Doppie, it looks like STF 1037 changes separation every year and only 14 years ago was over an arcsecond in separation. But the 2025 separation is listed at 0.704". I was pretty happy to have finally split a sub-arcsecond double with the 10" Classical Cassegrain.

Edited by Ihtegla Sar, 28 January 2025 - 05:09 PM.

[C. Evangelista]

52 Orionis (STF 795): 5.99m/6.03m, sep. 0.96".

 

A hair black line split with my TMB/LZOS 130/780 at 312x, last Saturday night, Pickering 9.

Peanut, but no black line split at 260x.

 

https://www.stelledo...?iddoppia=21652

[JoeFaz]

Last night I got my 10" dob out for the first time in several months, and split some tight doubles. I was expecting to do more DSO than anything, so I hadn't jotted down all that many doubles to try for, but when I realized how great the seeing was last night I wished I had marked some more down, and maybe a couple closer to 0.5"...

 

STF 412 ABC - Taurus (7 Tauri)
6.6/6.86/9.92

Sep 0.78″/22.4

PA 350°/53°

Clean split @ 417x. A and B white, C looked chalky blue to me.

 

HO 22 - Orion

8.5/8.64

Sep 0.93″

PA 208°

Clean Split @ 313x. No colors seen.

 

STF 1037 AB - Gemini

7.24/7.27

Sep 0.76″

PA 300°

Later in the evening. Seeing was still quite good, but no longer "near perfect." Cleanly split in moments of steady seeing (313x), and occasionally stars bridge the gap and "touch." No colors seen.

 

It's not a sub-arcsecond double, but last night I started out with my first 100% definite observation of Sirius B. This was my first time trying with my (fairly new) 10" and had only made "I think so" kinds of observations with my 6" under less-than-perfect conditions. Lucky me, we don't get seeing so rocksteady in the Maryland Appalachians very often...

[Rustler46]

I don't know if I've posted this before, but here is one of the few times I've split a double with less than 1 arc-second separation - Omega Leonis.

• 2021-April-5, Ocean Observatory, Coos Bay, Oregon
• Celestron-8, f/10 using 2-1/2X Powermate and 11mm T6 Nagler
• No clouds, good to very good seeing, good transparency, 1 day before full  Moon
• Double star, 2 Leonis, STF 1356 - 5.7/7.3 magnitudes @ 0.9 arc-second, @ 461X amazingly that one is split, separate with a bit of dark sky between 'em, they're not the same brightness, how cool is this, look at that guy, I haven't used this high magnification for years, interestingly my eye has significant astigmatism even though the exit pupil is only 0.44 mm, that even helped a bit in resolving this close pair in that the narrow part of the astigmatic star images are oriented so as to increase the amount of dark sky between 'em, I'm not using the Dioptrx astigmatism correction accessory on this Televue 11mm Nagler eyepiece, this is the highlight of the night, what a neat way to end the observing session

Best Regards,

Russ

[Rustler46]

Been a little bit since my last post, so this covers five different nights in the last three weeks of December (separated by spaces). 

 

• BU 84 - 0.98", mags 6.4, 7.9

• STT 119 - 0.69", mags 8.1, 8.9
• A 2724 - 0.85", mags 8.4, 9.2  notes: "close, moderately uneven" (though given some of the other doubles listed, you can tell I'm super consistent with my notes and impressions)

• A 816 - 0.90" mags 7.5, 7.8
• HU 1030 - 0.80" mags 8.9, 9.0
• STT 6 - 0.66" mags 7.5, 8.8 - Together these form the primary of STF26, whose companion is a mag 9.9 star 13.1" away.

• BU 1030 - 0.8" mags 7.8, 9.7

I was confused for a bit, because it seemed like I was struggling to make any of the usual splits, despite relative steadiness.  I eventually noticed that my mirror support had lost a fair number of the nylon(?) contact points and was kinda just catawampus with one of the whiffle supports basically not engaged at all.  Some creative fixes later and I come out with this that night:

• BU 98 - 0.63" mags 8.3, 8.4
• STF 1074 - 0.8" mags 7.4, 7.8
• STF 1126 - 0.8" mags 6.6, 7.0
• STT 182 - 0.92" mags 7.8, 7.9
• HO 245 - 0.67" mags 7.9, 8.7
• STF 1157 - 0.67" mags 7.9, 7.9
• A 539 - 0.66" mags 8.8, 9.5
• STF 787 - 0.63" mags 8.3, 8.8
• STF 849 - 0.94" mags 9.2, 9.5

I still need to address the cracked weld in the edge support, but it doesn't seem that that was causing any issues (yet) at least. 

I've observe one of these with my GSO 10-inch Dob:

 

• STF 1126
• 2022-Mar-06, Ocean Observatory, Coos Bay, Oregon, cold (in high 30s), very clear, seeing ended up being pretty good for splitting fairly close pairs (<1 arc-sec.), no clouds, crescent Moon
• Double star - 6.6/7.0/12.0 magnitudes @ 0.81/43.1 arc-seconds (Stelle Doppie), very close to Procyon, the C-component is quickly seen, there are two other 10th magnitude field stars beyond in the same direction maybe twice as distant, @318X the A-B pairing is suspected, @499X with careful focusing and enduring uncorrected astigmatism in my eye it split down into a double image of  the pair (like a "double-double"), the PA of each image is the same, and it matches the PA versus that of the C-component as shown in SkySafari with a much zoomed-in iPad view, one component is a little bit brighter, there's a little bit of dark sky between 'em (about the same as the primary's Airy disc diameter), with all this I'm convinced I'm seeing the A-B split, a little bit of brightness contrast, at best focus there's an astigmatic image with those "doubles" in there, a most interesting triple, I don't see any color

Here's another close pair from 57 years ago, using my home made 8-inch RFT reflector:

• A 1110, WDS 14497+0759
• 1968-Mar-25, near Eureka, CA on Fickle Hill, good transparency, excellent seeing, temperature 17°F !!
• Double split, 7.7/7.9 mag, 0.7"; one star seems brighter; in Bootes

For such a close pair, it is a bit odd that it has shown no apparent change in PA or separation in the last 20 years. From StelleDoppie:

 

 

In 1905 when discovered by R.G. Aitken it had a separation of 0.2 arc-seconds with a different PA. Anyone know more about this one?

 

Since Aitken was later (in 1930) director of Lick observatory, I assume he used its 36 inch refractor for that discovery observation.

 

Clear Skies,

Russ

Edited by Rustler46, 20 March 2025 - 01:21 AM.