Southern Sky Doubles for small telescopes

Here's the place for any sights you wish to remark on

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RMSteele
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Southern Sky Doubles for small telescopes

Post by RMSteele »

Acamar - Theta Eridani. 2017 November 22, 11.00 UT.
Roughly two thirds of the way from Rigel (Beta Orionis) to Achernar (Alpha Eridani), Acamar is one of the brighter stars among the dim straggling suns of Eridanus. Between the 2nd and 3rd magnitudes, Acamar splits clearly into a pair of 3rd and 4th magnitude, white “A” stars, separated by about 8 arcsecs at x40 in my 102mm MAK. At x80 they are a handsome pair of starry siblings with first and second order diffraction arcs twirling around them like moths on this warm and mosquito ridden evening in Melbourne, Australia. Maybe someone can tell me who discovered the pair, which some say is reminiscent of Theta Aquilae.
Last edited by RMSteele on Wed Nov 29, 2017 3:26 am, edited 1 time in total.
Brian
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Re: Southern Sky Doubles for small telescopes

Post by Brian »

Well....... the info I found in SkyMap Pro is as follows:


<<WDS Catalog Data

Washington Double Star Catalog, 2001. (Brian D. Mason, Gary L. Wycoff, William I. Hartkopf, Geoffrey G. Douglass, and Charles E. Worley, Astrometry Department, U.S. Naval Observatory, 3450 Massachusetts Ave, NW, Washington, DC 20392, USA)

Discoverer's reference: PZ 2
Observer: Piazzi, G.

RA (J2000.0): 02h 58.3m
Dec (J2000.0): -40° 18'

Number of measurements: 67

Date of first observation: 1835
Position angle: 82°
Separation: 8.7"

Date of last observation: 1997
Position angle: 90°
Separation: 8.3"

Magnitude of first component: 2.88
Magnitude of second component: 3.97
Spectrum: A4III A1V

Proper motion in RA: -0.045 "/year
Proper motion in dec: 0.019 "/year

Catalog number: CD -40 771

Notes:

Theta Eri. A is a spectroscopic binary. Proper motion of B -017 -006.

Delta Magnitude given. >>

Hope this helps :)
Brian
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RMSteele
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Re: Southern Sky Doubles for small telescopes

Post by RMSteele »

Zeta Phoenicis - 2017 November 27, 12.15 UT
An interesting “double” simply because the brighter member is an eclipsing Algol type variable (ranging between mags 3.9 and 4.4). A check with 8x40 binoculars indicated that no primary eclipse was in progress, by comparing it with kappa Phoenicis (mag 3.9). Actually zeta was quite difficult to locate in the 102 MAK’s 6x30 finder due to strong moonlight even though it makes a convenient triangle with Achernar and alpha Phoenicis. Nobody would admit to switching on the fairy lights that also lit the garden like a midnight barbecue party! There are at least 4 stars in this group since, in addition to the eclipsing system, there are two fainter visual companions. “B” at mag 7.2 is less than one arcsec from the primary and thus undetectable in the small MAK. However “C” at mag 8.2 and about 6 arcsecs distant showed up at x130 as the tiniest pip of light beyond the strong diffraction pattern of the primary. Although well within the grasp of a 102mm scope, I count this as a very satisfying observation given the strong moonlight and artificial illumination. I finished the session by half heartedly swinging the telescope down onto alpha Centauri, low over Melbourne’s southerly summer horizon. Expecting little more than a blur of poor seeing at x130, I was astounded to see twin suns blazing like flecks in a black fire opal, iridescent vermillion to green surrounded by rioting mobs of diffraction. I’ll never forget that. The starry night still takes me by surprise even after sixty years of looking. PS thanks for the info Brian. Kind thoughts to you.
David Frydman
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Re: Southern Sky Doubles for small telescopes

Post by David Frydman »

Hi Bob,
Apparently it was 35C today in Melbourne and very humid. It felt like 40C in the town centre and even hotter in the trams.

What with crocodiles, great whites, although maybe not in the trams, and spiders I think I prefer the 4C here today.

Regards,
David
RMSteele
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Re: Southern Sky Doubles for small telescopes

Post by RMSteele »

Yes David, temperatures are torrid at the moment here. It's going to change to torrential rain and flash flooding at the weekend, but I shall be on a boat to Vanuatu by then. Back in two weeks: my son's house is in a flood zone so hope it will be ok. I shall continue to chase some southern doubles when I get back. The mystery of the fairy lights is solved and the culprit unmasked. It was the possum who lives in the garage. He shins up the sun porch and clicks the light switch with his claws! Kind thoughts, Bob
RMSteele
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Re: Southern Sky Doubles for small telescopes

Post by RMSteele »

Binocular doubles somehow don't often have the same snappy attraction of telescopic pairs, but sweeping the area of the "false cross" at 12.30 pm UT, Melbourne, Aus, revealed 4 widely spaced pairs of binocular doubles. 2 pairs of 5th mag lie within the "cross" and 2 pairs of 6th mag easily picked out in the vicinity of iota carinae. A tight little group of three 4th, 5th and 6th mag lie within the field of delta velorum and make the narrow base of an iscosceles triangle with another 4th mag star that altogether appear to be the brighter members of the cluster I2391. The whole area is an interesting mix with epsilon carinae showing a spark of orange; and in the same field is the misty spangle of the large binocular cluster I2516. All mags here are approximate (eye estimates). Bob
jeff.stevens
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Re: Southern Sky Doubles for small telescopes

Post by jeff.stevens »

Hi Bob, I was having a quick look at the area in Starry Night, looks an interesting view. I've never seen southern skies. I'm guessing Melbourne must suffer heavily from light pollution. Will you be having any opportunities to observe outside of the Melbourne area?

Best wishes, Jeff.
RMSteele
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Re: Southern Sky Doubles for small telescopes

Post by RMSteele »

Binocular doubles in Vela and Puppis.

Yes Jeff, we’ll get away to the eastern countryside for a few days in January, I think. The Melbourne sky suffers the same uncouth intrusions by lighting as our northern conurbations. Stars are easily visible only down to mag 3. There are, however, more urban park areas, like Wattle Grove, just behind the house here, if you need a broader sky view. So, the LP problem is similar. For a northern visitor the night scene is made other-worldly by the frequent appearances of staring possums crawling along the fences with the gleam of strange lights in their eyes. The strangeness is enhanced by the fact that you can see familiar constellations such as Orion, rising in the east now but with The Sword, like a buttoned bodice uppermost and lower, alpha like a trailing flamenco hem. Silver limned Sirius leads to the right and farther right, Canopus and Achernar, upper right at the end of the muddy old sky river. Northern views of the stars strike me as more sombre somehow, while the southern sky is like a long Spanish street after dark, chattering with life and light and clusters of society. Maybe it's that chorus of bright stars from Orion round to the south; those lively bands of southern OB Associations. Anyway I digress. The following binocular observations were made on 2017 December 21.

Gamma Velorum. 11.45 UT. A bright 2nd mag primary and a 4th mag companion, so close that you have to hold the 8x40s against a wall to steady them sufficiently to see the pair. Gamma’s primary is a spectroscopic double comprising our brightest Wolf-Rayet star and a more massive O type. The fainter member is a tiny speck about 40 arcsecs distant that seems fainter than it's stated brightness. Gamma sits in a field sprinkled with 5 mag stars. A prince among binocular doubles.

Pi Puppis. 11.55 UT. At 3rd mag, one of the brightest stars in Puppis, a K type giant with a close telescopic companion that cannot be seen in binocs. It sits among the stars of the sparse grouping Collinder 135 and I include it simply because there is a neat pair of white 5th mag stars close by the orange supergiant.

Xi Puppis. 12.00 UT. A dull orange primary at the fainter end of the 3rd mag with a well separated 5th mag companion (actually it looks more like mag 6 to me). I have seen the companion described as orange but to me it looks white in the 8x40s.

Regards, Bob
brian livesey
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Re: Southern Sky Doubles for small telescopes

Post by brian livesey »

Back to Eridanus Bob. Take a look at Omicron 2 Eridani. This is a triple system with an orange K-type primary, accompanied by white dwarf 40 Eridani ( the easiest white dwarf in the sky they say) and a red dwarf. I've seen the white dwarf in a 60mm refractor.
It's an interesting system because all three stars are at different stages of stellar evolution. A cubic centimetre of matter from 40 Eridani would weigh as much as a battle tank or thereabouts.
brian
RMSteele
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Re: Southern Sky Doubles for small telescopes

Post by RMSteele »

Brian, the conditions were far too poor to try for omicron2 Eridani this evening. A view of 32 Eridani in our 102mm MAK was most unimpressive. Some binocular pairs were examined, as follows: 2017 December 22, 8x40 binoculars, Melbourne, Aus. Very poor sky transparency and diffuse artificial illumination adversely affected definition and contrast in the 8x40s.

Zeta Reticuli, 12.20 UT. At 5th magnitude and reasonably close in binoculars to make a handsome enough pairing. Otherwise an unremarkable duo of sol-like stars.

Pi Hydri, 12.24 UT. A neat pair of 5th mag unrelated red giants. Although no colour was visible in the poor conditions, this pair is a real showpiece in binoculars. They are a close duo nestling in the curve of a beautiful arc of four 3rd and 4th mag stars, comprising zeta, epsilon, delta and eta2 Hydri.

Eta1 and Eta2 pictoris, 12.27 UT. Too wide to be impressive in binoculars. A unaided eye pair.

Regards, Bob
RMSteele
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Re: Southern Sky Doubles for small telescopes

Post by RMSteele »

Beta Tucanae. 2017 December 24, 11.10 UT.
Just time for a double on Christmas Eve night! It's 22.10 local time here in Melbourne. Beta Tucanae is a fairly eye catching double in 8x40 bins with easily spaced 4th and 5th mag stars. At x40 in the 102 MAK, the 4th mag star splits into two very evenly bright 5th mag components. At x130 all 3 form a diamond white triple spanning a field that is well worth seeking out.
Merry Christmas, Bob
RMSteele
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Re: Southern Sky Doubles for small telescopes

Post by RMSteele »

Upsilon Carinae. 2018 January 03, 11.40 UT. X130 with 102mm MAK. A third mag white primary and a 6th mag bluish white companion. The companion was surprisingly elusive. The separation is 5 arcsecs, not difficult in itself, but the bright white primary casts strong a strong diffraction pattern (I estimate the seeing at an indifferent Pickering 5) that makes the companion more tricky to pick out than I expected. An interesting observation.
Nearby is the "Southern Pleiades", IC 2602, so I next panned the telescope onto the cluster at x40. It resembles the Pleiades not at all. Yes, it's an unaided eye object with a bright 3rd mag star (theta carinae) and its best seen in binocs but to my mind it's looser and it has none of the appealing pattern of the northern group.
Hope you are all well. Happy new year! Bob
RMSteele
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Re: Southern Sky Doubles for small telescopes

Post by RMSteele »

A bit of a cheat tonight. Eta Carinae is not a visual double, but my excuse is that it has been shown recently to be a titanic system comprising a 90 solar mass primary and a 30 sol mass secondary. Eta has proved spectacularly variable over the past couple of hundred years, culminating in the great outburst of the 1830s that lasted two decades with the star rising to second only in brightness to Sirius. Observed at 1130 UT today (2017 Jan 04) in 8x40 binoculars, the star seemed to me to have a slight (burnt) orange tinge. It sits in a fascinating field of 3rd mag and fainter stars that is sprinkled with clusters and faint tinges of nebulosity - easily visible even through the urban light pollution that limits the unaided eye to about 3rd mag. IC2581 is a tiny sprinkling of light in the left field, while IC3532 is a larger, fainter smear to the lower right. Eta is flanked by tiny smudges of nebulosity and by comparison with nearby stars of mags 4.6 and 4.7 I make Eta tonight to be mag 4.5.
Kind thoughts, Bob
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Re: Southern Sky Doubles for small telescopes

Post by jeff.stevens »

Happy New Year to you too, Bob. It's very interesting to read your observations. I had a quick look at the "Southern Pleiades" in some planetarium software - not the same as being there, but I'd never heard of it before and I was curious.

Best wishes, Jeff.
RMSteele
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Re: Southern Sky Doubles for small telescopes

Post by RMSteele »

Thanks Jeff, at this time of year you can compare the "southern Pleiades" with the real Pleiades in the evening here - they are almost opposite each other and at similar altitudes in the southern and northern parts of the sky. The Pleiades is clearly a brighter and more striking group by an order of magnitude, literally (in my opinion at least).
And now for something a bit different. There's a great wattle tree in the park, right over the fence from where I observe here at almost 38 degrees south. The Sun and Moon appear to rise up though it's spans of leaves. At night Sirius shines on the right like a lamp, as Orion rises from its canopy. The wattle tree raises a more civilised Orion than our northern hunter. He appears sword first here, looking like he is wearing a buttoned shirt instead of savage skins. The wattle seems to push the whole sky around from where I am in the garden: a shame to see some vandalism on the tree trunk when I walk in the park. Here is a "Star Story" about this mover of mind and universe. Sonnet No. 11. The Wattle Tree.

(31/12/17 rev). RM Steele
Last edited by RMSteele on Fri Apr 13, 2018 12:10 pm, edited 2 times in total.
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