Moonlit Doubles & Superb Seeing

[SuburbanMak]

Thursday January 13th was one of the those rare days in Winchester where an azure blue sky persists to the horizon. As dusk fell the moon was tantalisingly crisp naked eye but I hadn't got my hopes up as thick fog was forecast from 7pm with a Met Office weather warning. After supper Kathy (spouse) suggested I go out as she 'd noticed the sky was still crystal clear (very thoughtful & she has a good book on the go obviously...) so I put the Mak out to cool.  By the time I started at around 9pm, seeing looked very steady in all but the last 10 degrees or so above the rooftops to the S & SE.    It was around freezing and dropping fast and it got better all the time. Transparency was initially good and only started to worsen after midnight as the threatened fog began to build, thankfully five hours late. 

After some detailed Messier hunting in the last couple of sessions I was happy to align the GoTo (Procyon & Sirius, the latter in that low zone and flashing away like a Christmas tree, back there later...)  & linked the SynScan app to SkySafari on my phone to work through the Orion area stars in the app's  "Best Doubles" list for a lazier un-prepped tour.  Reading on SGL made me keen to visit some of the Orion doubles I'd either missed or only picked out the obvious in last winter. 

Rigel,  Beta Or (Mag 0.1 & 6.7, Sep 9", PA 203°) - always start here to benchmark seeing and tonight despite being still quite low down the pale white dot of the secondary popped out immediately, going to be a good night! 

Alnitak, Zeta Or (Mag 2 & 3.7, Sep 2.2", PA 167°) - the Eastern most belt star, have never actually tried to split this one as a double star before and was a main target having read about it on SGL.  Was showing elongation at 100x & a clean split close white pair at 224x. Lovely view! 

Mintaka, Delta Or (Mag 2.3 & 6.8, Sep 52.5", PA 0° - the Western most belt star, easy split at 100x, secondary is faint but the wide separation makes it easy - White & Blue white. 

Saiph al Jabbar,  Eta Or, (Mag 3.3, 4.7, Sep 1.7", PA 77° - love the arabic star names, this one means "sword of the giant" apparently although its not now considered part of Orion's sword being further West, a quarter of the way between belt-star  Mintaka & Rigel.  This yielded a clean split at 224x with a nice black separation between, slightly yellow white compared to the hot blues so far & lovely overlapping diffraction rings on both. Spent a good while on this view and will be back. 

Na'ir al Saif - Iota Or (Mag 2.9 & 7, Sep 10.8", PA 138) -  "The Jewel in the Sword".  Having enjoyed some spectacular view of M42 under dark skies earlier in the month I was able to pass over the moon-washed nebula where I often get sidetracked and downward to focus on the job in hand.  White primary and pale blueish secondary looked great at both 100x & 224x.  Popped the 32mm in to enjoy a lovely field with Struve 747 & 745 to the SW, three doubles for the price of one and a stunning view. There's another Struve star, 754 off to the SE but I didn't register this. Read later that Iota has a C star too which I wasn't looking for - Mag 9.7 at 49" separation, as if I needed a reason to go back.

Sigma Or - (Mag 4.2, 6.6, 6.6 & 9 Sep AB-C 11", AB -D 12", AB-E 42").   Below and West of Alnitak, I've looked at this almost every time I observe Orion and only noted it as a triple, reading on SGL there's a faint C I was keen to tease it out, and sure enough a pale dot emerged at 224x just outside the first diffraction ring of the AB star (B being wayyy beyond my 121mm of effective aperture at 0.25" distant from A).  An amazing system this - (always like to imagine what the sky would be like from a planet orbiting one of those stars) creating a dog-leg line starting with C then the bright AB and on to D and E.  

The Trapezium - Theta Or. Didn't spend too long in the heart of the Orion Nebula as I look at this so often & was enjoying my voyage of discovery. Checked in to verify seeing and was getting five stars reliably at 100x and the sixth winking slowly in and out of direct vision at 224x. 

Meissa - Lambda Or (Mag 3.4 & 5.5, Sep 4.2", PA 44°) "The Head of Orion" forming the tip of a broad triangle between Betelgeuse and Belatrix. Nice bright pair to my eye yellowish, close but not difficult, lovely rings at 224x - again have looked at this rich cluster, Collinder 69, many times at low power & with binoculars but never put the power on it to split. I subsequently read that its a quintuple system with other elements down around 9th / 10th magnitude, so yet another where there's more to come back and see. 

Beta Mononceros - (Mag 4.6, 5 & 5.4, Sep AB - 7.25" AC 2.8", PA 132° & 109°). Hopped South West from Orion to neighbouring Monoceros for the stunning triple. Went up to 250x to maximise the separation and enjoyed the view of 3 fairly even in brightness white discs with steady rings.  

32 Eridani  - (Mag4.8 & 5.9, Sep 7", PA 347°) Off to the West of Orion in an area I don't often look at is 32 Eridani. After all those shades of blue & white in Orion this is a stunning colour contrast of golden yellow and sea green, a real gem and one I'll often visit.  Tried for 55 Eridani but behind a tree! 

Keid, Omicron/40 Eri  - (Mag 4.51 & 9.7, Sep 82.4, PA 102°).  Swept quite quickly over this one, a dim wide spaced secondary.  Apparently in Star Trek, Vulcan orbits 40 Eri & there are further dim components that should be in reach of the Mak so maybe I have a reason to go back and spend more time here sometime in search of Spock.  By this time I was getting cold. 

After a spell inside to de-ice my fingers and toes I came back out, now a  heavy frost and still rock-steady seeing, spent some time on the moon (Gruithissen Domes & Rilles in Gassendi courtesy of tips from @Nik271) then the seeing lured me back to the doubles for a tour of some favourites & nemeses...

55 Eridani - (Mag 6.7 & 6.8, Sep 9"). Out from the trees now & a relatively easy split of an even pair, doesn't stand out so much in the memory.

Castor - Alpha Gem  (Mag 1.93, 3 & 9.3, Sep AB 5.4", AC 71", PA 62° & 164°).  The first double I split with the Mak, Castor was blazing away, I'd read on here about the dim C star and was delighted to pick it up glimmering away to the South at 100x. 

Sirius - Alpha Ca Ma. (Mag -ve 1.46, 8.4 , Sep 11" PA 70°) by now high in the sky & steady I glanced at Sirius. Have spent many hours on this one and after a quick look in case the Pup was immediately & dramatically more obvious (it wasn't) The A star  was so bright with a large apparent disc and bright rings, but steadier than I've seen. I have noticed that when I get a hint of the pup star its often in the first few seconds when I put my eye to the eyepiece - wonder if this is something to do with receptors in the eye - tonight though the longer I looked, the less I saw so I moved on. 

Theta Aurigae - (Mag 2.6, 7.2, 10.6 & 10.1, Sep AB: AB: 4.0”  AC: 55.2” AD: 135.3”.   PA AB: 304°, AC: 300°, AD: 351°.   Having seen the B star once in my f15 80mm Towa 339, then quite easliy, I've found this one a bit of a nemesis since. The faint C & D stars can be found easily but for me with small apertures, B has needed the best nights. Tonight it sat with very obvious separation in the Mak at 224x , a white dot on the first diffraction ring. Satisfying & a good test of seeing. 

Achird -  Eta Cass (Mag 3.5, 7.4, Sep 13.3", PA 322°). Returning to a favourite, a lovely White/Orange pair. There are apparently more faint companions to tease out so will be back for a closer search. 

Iota Cass - (Mag 4.6, 6.9  9.0, Sep AB: 2.6″, AC: 7.1″   PA  AB: 229°,   AC: 116°).  Often check out this lovely triple after recommendation from @John a few months back, super view tonight rock steady off-set L shape.  I read there's a faint D star a little way off so will be back soon to track that down. 

Tegmine - Zeta Cancri (Mag 5.6, 6 & 6.3, Sep 1.1" & 6.3", PA 80° & 70°).  It was gone midnight now and signs of the forecast fog were building, halo round the moon but seeing still close to perfect. Cancer had risen to the ESE and I was able to pick Tegmine out of the mist in the finder. At 224x I got the best view of this I've had - it sits right on the optical limits for the Mak 127 at 1.1." separation for the close pair and they appeared as a steady figure of eight with a clean black line between, the C star still close in at 6.3" making a spectacular trio with nice rings. I've only fully split this once before and normally see it as a "notched" pair, one night with my son (19) he could see the separation where I only had it as notched, tonight though was definitive. 

Elated with both telescope performing at diffraction limits, a good night for the observer and with freezing fog finally building, I looked at one final star before a brew & bed...

Algieba - Gamma Leonis (Mag 2.2, 3.5. Sep 4.4", PA 127°).  Along with Castor a favourite from my first tries at double stars, Algieba's golden orbs shining through a circular halo of mist looked like an owl's eyes peering back at me. Lovely way to end a great session. 

A note on equipment:  I'd taken out my set of Baader Classic Orthoscopics -18mm, 10mm & 6mm, a Televue 15mm Plossl plus the Badder 2.25 Barlow that is built for the Hyperion Zoom.   I found myself gravitating to the TV 15mm to start giving 100x & barlowing it down to 6.67mm to give 224x for the closer pairs, occasionally dropping in the BCO 6mm to give 250x to confirm the closest splits.   The TV+ Barlow combination was working superbly - nice and bright and better ergononmics than the BCOs in the Mak. I wear contacts so am ok with close eye relief but the TV + Barlow combo was more comfortable from both this perspective and the longer tube made viewing easier on the Mak with less headbanging against the finderscope & Telrad and consequent time spent waiting for vibration to settle. 

A session to remember.  

[ScouseSpaceCadet]

A great read, thanks for posting. 👍

[Stu]

What an excellent session, some great ones in there. Nice write up 👍👍

[Mr Spock]

Quite a selection there. Sounds like a great night.

[Captain Scarlet]

Very nicely written. List totally stolen, for convenience when hopefully soon, I’m next out.

Magnus

[JeremyS]

That’s quite a haul 👍🏻

[Nik271]

That's a superb session and report, thank you! You must have been frozen by the end of it. The 127 Mak is such a great grab and go scope for doubles and much more. I should try Tegmine with mine, as you said it is a good test of its diffraction limit (and observer skill!)

[SuburbanMak]

1 hour ago, Nik271 said:

That's a superb session and report, thank you! You must have been frozen by the end of it. The 127 Mak is such a great grab and go scope for doubles and much more. I should try Tegmine with mine, as you said it is a good test of its diffraction limit (and observer skill!)

Thanks Nik - I was in full winter mountaineering garb so mainly fingers & feet that signalled the end of the session. Tegmine is at 1.1” I believe - and it showed as a good clean line, I reckon it would go a shade closer with an equal pair. Need to find a candidate at exactly 1 arc sec separation for a test. 

As for skill, you’re very kind but honestly think it’s a testament to the extraordinarily good seeing. More of that please  

Edited January 15, 2022 by SuburbanMak

[chiltonstar]

Superb post! There are some superb doubles in Orion and the 127 Mak a lovely scope (I have had one for 12 years).

Chris

[Nik271]

10 hours ago, SuburbanMak said:

 Need to find a candidate at exactly 1 arc sec separation for a test. 

52 Orionis is currently at  0.99'' separation and the two components are exactly equal at magnitude 6. It should make an excellent challenge for the 127 Mak or indeed any 5 inch scope. This is  a simulation what the double should look like. I entered 120mm aperture and 30% obstruction in aberrator: 

 

I've only tried it with my 180 Skymax and in good seeing it is easily split with it.

Edited January 16, 2022 by Nik271
added a picture from aberrator

[Stu]

Looking back at my previous posts, I see I got both these (32 and 52 Orionis) in the Mewlon 210 I had a while back, handled them quite easily at x193 with a Docter 12.5mm.

I seem to have had consistent results with a 4” too ie success with 32 but only elongation/peanut/snowman, call it what you will. That’s both with FC100DC and Vixen FL102S. Aperture counts on the tighter ones. The LZOS should get there with 52 I would hope.

[SuburbanMak]

1 hour ago, Nik271 said:

52 Orionis is currently at  0.99'' separation and the two components are exactly equal at magnitude 6. It should make an excellent challenge for the 127 Mak or indeed any 5 inch scope. This is  a simulation what the double should look like. I entered 120mm aperture and 30% obstruction in aberrator: 

 

I've only tried it with my 180 Skymax and in good seeing it is easily split with it.

Thanks Nik - looks the perfect test subject, I’ll definitely track that down next time seeing allows! 

[JDF]

I really enjoyed reading that, thanks for posting. Gives me something to work on with my own 127.

[Graham Darke]

Really nice report. This is why I love observing double stars so much. No matter what the Moon phase, time of year or light pollution, there is always something to look at. 

[domstar]

That's a great report of an excellent session. I really enjoyed it- thanks.