Southern Sky Doubles for small telescopes

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

Moderators: joe, Brian, Guy Fennimore

RMSteele
Posts: 569
Joined: Thu Jun 02, 2016 11:32 am
Location: New Farnley, Leeds lat 53.8N long 1.6W
Contact:

Re: Southern Sky Doubles for small telescopes

Post by RMSteele »

2018 January 10, 1140 UT. The tiny constellation of Crux Australis fits entirely in the field of my 8x40 binoculars with room to spare. The Jewel Box cluster glitters to the right of beta (Mimosa) and gamma (Gacrux) is the orange odd-star-out at lower left field. Actually it is our closest red giant at only 88 ly distant. The rest of the stars are white. The Coal Sack dark nebula reveals itself indirectly even under the glare of Melbourne's lights. I centre alpha (Acrux) at the top of the field, count the stars in the field left of alpha and roughly down to delta and then count the stars in the field right of alpha roughly down to beta. There are about 4 times as many stars visible in the left field than in the right field containing the coal sack!
Now onto Acrux with the 102mm MAK. The seeing is not great, about Pickering 4 and at x40 all I see is the the combined light of apha's components and the the dull 5th mag companion. At x130 alpha 1 and 2 split into a white pair whose diffraction rings are in contact. It's actually a grand sight, these bright, white near equals. And therein is a slight mystery. The brightness difference between them is generally given as 0.5 magnitude, but they are so close (4arcsec) and bright that their individual magnitudes are hard to measure. In the past they have been estimated as much closer in brightness and that is how I see them - with only maybe 0.3 of a mag between them. Acrux is the most southerly of all the first mag stars by the way. Kind thoughts Bob
RMSteele
Posts: 569
Joined: Thu Jun 02, 2016 11:32 am
Location: New Farnley, Leeds lat 53.8N long 1.6W
Contact:

Re: Southern Sky Doubles for small telescopes

Post by RMSteele »

Melbourne, Aus. 2018 January 14, 10.15 UT. 102mm MAK x130. Seeing Pickering 9. Rigel, though visible in northerly latitudes, is technically a "southern" sky double as its declination is -8 degrees. Rated as mag 0.12 Rigel has a 7th mag companion over 9 arcsec distant. Now a small confession; in 50 or so years of desultory attempts with telescopes ranging from 5cm to 30cm I have never spied the companion. But in the deep dusk tonight, in the 10mm eyepiece, keeping my head still..... there it is, Job's blue spark hovering above the shrivelling diffraction rings of Rigel's bright, burning lamp. There is only one musical composition that can accompany the supernal thrill of finally seeing such a small thing as Rigel B.
Blink 182...All The Small Things.
Say it ain't so
I will not go
Turn the lights off
Carry me home
Keep your head still
I'll be your thrill
The night will go on
The night will go on
Na na na na na na na na na na
Na na na na na na na na na na

I'm sixteen again, Carpe noctem, Bob
Last edited by RMSteele on Sun Jan 14, 2018 10:44 pm, edited 2 times in total.
jeff.stevens
Posts: 2552
Joined: Fri Dec 03, 2004 12:51 pm
Location: Stoke-on-Trent
Contact:

Re: Southern Sky Doubles for small telescopes

Post by jeff.stevens »

Sounds good Bob. I don't think I've ever seen Rigel B. Did you have Blink-182 playing as you were observing?

Best wishes, Jeff.
Brian
Posts: 3691
Joined: Fri Dec 03, 2004 9:58 pm
Location: Wellingborough
Contact:

Re: Southern Sky Doubles for small telescopes

Post by Brian »

Bob, did you mean the date of your Jan 14 observations to be 2018, not 2017 as posted?

regards,
Brian
52.3N 0.6W
Wellingborough UK.

254mm LX90 on Superwedge, WO ZS66SD, Helios 102mm f5 on EQ1, Hunter 11x80, Pentax 10x50
ASI120MC Toucam Pros 740k/840k/900nc mono, Pentax K110D
Ro-Ro roof shed
RMSteele
Posts: 569
Joined: Thu Jun 02, 2016 11:32 am
Location: New Farnley, Leeds lat 53.8N long 1.6W
Contact:

Re: Southern Sky Doubles for small telescopes

Post by RMSteele »

Thanks Jeff, the music was playing in my head! And thanks for pointing out the date error Brian, I must have "Blinked" and gone back a year in my excitement. Corrected. Actually it was 1969 when I was sixteen. Rigel is 50 per cent higher in the sky here and the seeing was brilliant. Cheers chaps, old Job here is still chuffed the morning after. Kind thoughts, Bob
brian livesey
Posts: 5442
Joined: Mon Jan 09, 2006 11:05 am
Location: Lancashire
Contact:

Re: Southern Sky Doubles for small telescopes

Post by brian livesey »

I've seen Rigel B in the 8-inch Newtonian, but it wasn't easy because of the glare from the primary. You seem to have done well to spot it with a small Mak.
brian
RMSteele
Posts: 569
Joined: Thu Jun 02, 2016 11:32 am
Location: New Farnley, Leeds lat 53.8N long 1.6W
Contact:

Re: Southern Sky Doubles for small telescopes

Post by RMSteele »

Hello Brian, the state of the atmosphere (seeing conditions) is the only factor that matters imho. After that almost any old telescope and (old) observer will do - within reason. At home in Leeds, I have always observed Rigel at moderate altitudes over convecting town rooftops in winter. Here in Melbourne it is higher in the sky and seen over parkland, thus in steadier air.
Kind thoughts, Bob
brian livesey
Posts: 5442
Joined: Mon Jan 09, 2006 11:05 am
Location: Lancashire
Contact:

Re: Southern Sky Doubles for small telescopes

Post by brian livesey »

The Rigel system actually consists of four stellar members ( one source says five ), so it's a complex system.
brian
RMSteele
Posts: 569
Joined: Thu Jun 02, 2016 11:32 am
Location: New Farnley, Leeds lat 53.8N long 1.6W
Contact:

Re: Southern Sky Doubles for small telescopes

Post by RMSteele »

Melbourne, Aus. 2018 January 28. Sky slightly hazy and gibbous Moon. 8x40 binoculars.
With daytime temperatures approaching 40c the stars were too twinkly this evening for the telescope, so 8x40 bins it is.

Beta Tucanae was observed on Christmas Eve last, but just out of curiosity I looked again at 10.50 UT this evening (which of course is morning in the UK!). A wide and unmissable double at first glance in the binoculars but, holding them steady, propped on a broom handle, I can just make out that the brighter star (beta) is discernibly double. A good result with the small “bins”.

Delta Chamaeleontis. 11.00 UT. These form an unequal pair (4th and 5th mag), reasonably close so as to appear properly double. The fainter star has a touch of orange to it.

Mu Crucis. 11.05 UT. Mu itself is a telescopic double but the binocular view reveals a startling white 4th mag star accompanied by a rather lack-lustre bluish looking 5th mag associate.

Delta 1 and 2 Apodis. 11.10 UT. A neat, dull, orange pair of 5th magnitude siblings. They make one apex of a narrow right angled triangle in the binocular field with two pristine, white 3rd and 4th mag stars.

Kind thoughts Bob
jeff.stevens
Posts: 2552
Joined: Fri Dec 03, 2004 12:51 pm
Location: Stoke-on-Trent
Contact:

Re: Southern Sky Doubles for small telescopes

Post by jeff.stevens »

Bob, that's an impressive observation on Beta Tucanae, well done. Good to read your observations too. I like the idea of the broom handle stabiliser. I've often thought about making something similar, or purchasing a monopod for mine.

As for 40 degrees Celsius, wow, that's warm.

Best wishes, Jeff.
RMSteele
Posts: 569
Joined: Thu Jun 02, 2016 11:32 am
Location: New Farnley, Leeds lat 53.8N long 1.6W
Contact:

Re: Southern Sky Doubles for small telescopes

Post by RMSteele »

2018 Jan 31, 02.00 - 02.10. Melbourne, Aus. Adhara (epsilon Canis Majoris). 102mm MAK x260. Seeing Pickering 8-9. Companion at first suspected then glimpsed repeatedly throughout 10 minutes careful observation, with one brief interruption to check the PA. Extremely difficult because the primary is bright and the very faint speck of the companion lay on the edge of the second or third diffraction ring, maybe 7 or 8 arcsecs distant. Rigel B used to get correct focus before swinging to Adhara. Observation made during totality of the lunar eclipse visible here in Melbourne. Eclipse estimated at between 2 and 3 on the Danjon scale and the Moon maybe a couple of magnitudes brighter than Sirius (comparison made without spectacles, myopia defocussed images). Regards, Bob
RMSteele
Posts: 569
Joined: Thu Jun 02, 2016 11:32 am
Location: New Farnley, Leeds lat 53.8N long 1.6W
Contact:

Re: Southern Sky Doubles for small telescopes

Post by RMSteele »

Hello, just a quick round up on this straggly thread. Most of these objects objects are easily visible in 8x40 binoculars or a 100mm telescope. A couple, such as Rigel and Adhara are a bit more challenging in these instruments. Thus, on my own 0 to 10 scale of double stars I rate Beta 1&2 Tucanae (the brighter component) as "3-requires attention, discernible in fair seeing"
in the binoculars. In the 100mm telescope Rigel would be "5-visible in good seeing" and Adhara "7-challenging, glimpsed at intervals in good seeing". Some of these stars have fascinating stories of their own when you look into them, for example Adhara is the brightest UV star in the sky and a few million years ago it was much closer and the brightest star of that epoch, shining at mag -4.0. Jim Kaler calls it the "last of the 1st mag stars (mag 1.50). Kind thoughts to all, Bob
RMSteele
Posts: 569
Joined: Thu Jun 02, 2016 11:32 am
Location: New Farnley, Leeds lat 53.8N long 1.6W
Contact:

Re: Southern Sky Doubles for small telescopes

Post by RMSteele »

Sorry, a postscript that I meant to add earlier. Whenever I was able to see the companion to Rigel, I also tried for Sirius B in the 102 Mak, but it was not to be. Sirius was always at a good altitude at culmination (almost 70 degrees) where the seeing was usually good to excellent, nevertheless "the pup" was always swamped by the glare. Really, my test of the seeing should be the visibility of Adhara; it seems that Sirius B must be a bit more difficult than that pair. I shall resume the contest next time I am downunder. Bob
jeff.stevens
Posts: 2552
Joined: Fri Dec 03, 2004 12:51 pm
Location: Stoke-on-Trent
Contact:

Re: Southern Sky Doubles for small telescopes

Post by jeff.stevens »

Bob, it has been very interesting to follow your posts on the southern sky. I’ve just been having a read about Adhara - very enlightening.

Best wishes, Jeff.
Post Reply