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Caught the Pup for the First Time

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#1 Sarkikos

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Posted 15 January 2013 - 11:54 AM

Last week I took my 10" f/4.8 Dob to a yellow zone dark site to finish up the Herschel 400's. A couple of my observing buddies were there, also. One has a 15" Dob, the other a 12". The transparency and seeing were both decent that night.

While I began to star hop through the H400 galaxies in Ursa Major, I could hear the two other observers as they split the Pup from the Dog Star. I went over to their scopes and took a look. Both showed a good split. Fortunately, the Pup was situated almost exactly between two diffraction spikes and was nearly due east. I thought, "Well, I've never done that. The seeing is pretty good and Sirius is high enough. I'll give it a go."

First I put my BGO 7mm in the focuser. This gave me 171x. Nope, not good enough for the Pup. Next I tried the BGO 6mm at 200x. Nada. The Pup was still lost in Sirius' glare.

Then I put in my XO 5.1mm. Success! There was the Pup showing timidly between two spikes of light. The split was good, but at 235x, it was not as pretty as I like. So I replaced the XO 5.1 with the XO 2.5. Now that was nice! A clean and pretty split at 465x. No blinking in and out, but a steady appearance with good clarity and color.

The image of the Pup in the XO 2.5 was distinct, completely beyond the glare of Sirius, and the color was clear and bright. The Pup star appeared to have a slightly light-blue tinge to my eyes. It also seemed to have this cast in the other two Dobs.

I finally popped the Pup! :jump:

I regret, though, that I did not try other eyepieces that I had in the case. I wonder how my XW 3.5, UO Ortho 4 or Radian 4mm would have performed? Maybe next time.

Mike

#2 Erik Bakker

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Posted 15 January 2013 - 03:21 PM

Nice one Mike!

#3 Ed D

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Posted 15 January 2013 - 03:43 PM

:waytogo:

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#4 Bonco

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Posted 15 January 2013 - 03:47 PM

Nice report. Similar to my experience with my 10 inch f4.8 a few years ago. Most solid views were at high magnification. Congrats!
Bill

#5 Sarkikos

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Posted 15 January 2013 - 04:59 PM

How have others seen the Pup's color? Sirius B is supposed to be a white dwarf. To me, it looked white with a definite tinge of light-blue. This was in all three telescopes and with all the eyepieces that would split it from Sirius.

Mike

#6 rookie

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Posted 15 January 2013 - 11:54 PM

great observation, congratulations!

#7 Sarkikos

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Posted 16 January 2013 - 06:50 AM

Has anyone else seen Sirius B as white with a tinge of light-blue? Or is this just some sort of contrast effect?

Mike

#8 Achernar

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Posted 16 January 2013 - 09:32 AM

You just hit upon the keys to successfully seeing Sirius B, steady seeing, and high mangification. I ahve seen the Pup with both my 10 and 15-inch Dob, and if a steady night comes along soon, I'm going to try it with my 6-inch too. But yes, I see it too as an ice blue dim star that lies nearly due east of the primary star which shines 10,000 times brighter.

Taras

#9 ziridava

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Posted 16 January 2013 - 02:47 PM

Mike,congratulation!


''... the primary star which shines 10,000 times brighter.

Taras


Taras,good point.It reminds me of something and make me ask the following question:how hard is to see the Pup/companion of Sirius compared to see the companion of Antares?
I saw more times the companion of Antares in my 125mm F/7 Dobsonian but never the companion of Sirius.
There are differences between this two systems but there are also strong similarities.
Mircea

#10 Bonco

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Posted 16 January 2013 - 03:21 PM

For me Antares is way easier than the pup. I've clearly viewed it on several occasions with my 4 inch telescopes. The pup took dozens of attempts and so far has only yielded to my 10" Dob.
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#11 Achernar

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Posted 16 January 2013 - 07:58 PM

It's much harder to see the Pup than Antares B for two reasons. One is the apparent orbit of Sirius B is very elliptical, ranging from 3 to about 12 arc seconds from Sirius A, When it's anywhere near periapsis in it's orbit, it vanishes from sight even in large telescopes. This extreme proximity is the main reason why this star is hard to see, if it were on it's own or distantly orbiting Sirius A, it would be an easy find in binoculars at a magnitude of 8.7! Right now it is getting easier to see as it coasts out to apoapsis in 2022 or 2023, before it starts closing in with Sirius A again. The orbit itself is just under 50 years and the average distance between the stars is 19 or 20 A.U., about 2 billion miles. The other reason is the extreme difference in brightness between the two stars. The glare from Sirius A is also extreme, and diffraction spikes in many telescopes can also hide it. It's very demanding of seeing conditions, steady seeing, good, well collimated optics, and high magnifications is what it takes to bag this elusive object. You need high quality optics and eyepieces that suffer from as little scattered light as possible, that is enough to hide this Earth sized but Solar mass stellar corpse. I have noticed that my ES 82 degree eyepieces have a significant edge over my Orion Stratus and TMB Planetary eyepieces in this regard, the white dwarf shows up in the ES eyepieces, and is invisible or much harder to see through the others. I see Antares B often with my 6-inch Dob, whenever the seeing is good at 200X and it is much easier than Sirius B. Rigel's binary companion is even easier to spot, though it's binary nature is only detectable through a spectrograph. Siris A and B are about the most disparate stars in terms of brightness I have ever seen, Antares and Rigel B are about five and six and a half magnitudes dimmer than their primaries respectively. Sirius B is ten magnitudes dimmer than it's primary, and five magnitudes is a factor of exactly 100 times when it comes to stellar brightness. Your telescope will have a better chance of seeing it for the next decade, look for very steady seeing and use 250 or 300X. For the next twenty years or so, it will not be any easier to spot, then it will be hidden in Sirius's glare until after 2050 when it pulls away again. Collimate your optics carefully too, this is one tough object to spot. It was first spotted by an American astronomer testing a new telescope in 1862. He at first though there was something wrong with the telescope he had nearly completed. Then he realized he has seen Sirius B for the first time after many other astronomers failed to find it. Alvan Clark confirmed Frederich Bessel's detection of Sirius by by it's gravitational tugs on Sirius A. Good luck in your hunt.

Sirius and Antares are not similar star systems, Sirius was once a binary star where Sirius B was born with five solar masses. Then it expanded into a red giant before finally turning into a white dwarf 120 million years ago. That is why it is very massive, small, dense and searingly hot for a white dwarf with a surface temperature of 25,000 degrees C. Antares is a red supergiant with a mass of 15 or 20 Suns with a peculiar blue sub-dwarf that has a luminosity of some 50 Suns. It's is rich in iron and other heavy elements, but only hydrogen can be detected in Sirius B's high pressure and density atmopshere. So no, these systems are not that alike, except one star aged and died first, and transfered somehow a lot of their outer envelopes to their companions. That increased their mass, luminosity and sped up their evolution towards the planetary nebula and or supernova stage. Both star systems will be the site of a supernova in the future, fortunately at a safe distance from Earth.

Taras

#12 Sarkikos

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Posted 16 January 2013 - 09:12 PM

Thanks to all for the congratulations on my popping the Pup! At 465x through the XO 2.5, Sirius B was a beautiful sight: a sharp, light-steel-blue point between two sparkling spikes of Sirius.

This really brought home to me the importance of high magnification for double star observation. A crystal clear image at about 47x per inch! I don't usually go that high for planet, lunar or DSO viewing. But I always collimate my 10" Dob very carefully with a Cheshire/sight tube followed by an autocollimator. And I have a fan blowing beneath the primary mirror. I'm sure these measures helped.

I don't recall ever seeing the companion of Antares. I'm not sure if I ever made the attempt. Antares is way easier than the Pup? I'm definitely giving it a try this summer!

Mike

#13 Ed D

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Posted 17 January 2013 - 05:57 AM

The PUP is definitely a pale blue color - it's a tough one.

Ed D

#14 Sarkikos

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Posted 17 January 2013 - 07:50 AM

But she is a pretty little Pup! Well worth the effort.

It was also an opportune time to split Sirius. The seeing was good, the separation is wide now (about 9'' I believe), and Sirius B was situated right between two of my spider vanes. If the Pup was behind one of Sirius' spikes, I probably couldn't have seen it. My 10" Dob's OTA can rotate, but that is a PITA to do in the dark.

Mike

#15 Achernar

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Posted 17 January 2013 - 09:00 AM

Antares B is much easier than Sirius B, and moreover, it actually looks green too. In reality, its true color is blue. It is due west of Antares A three arc seconds from it.

Taras

#16 Sarkikos

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Posted 17 January 2013 - 09:30 AM

Yes, I've heard that. There are a few stars that appear green, through a contrast effect, but of course none of them really are. Due west of Antares should make it easy for me to spot B between the spider spikes.

Mike

#17 ziridava

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Posted 17 January 2013 - 03:20 PM

Thank you very much for your replies,it will help me to better prepare to see the Pup.
Thank you also for all the interesting data.
When I mentioned similarities between the Pup and the companion of Antares, it was strictly from observational point of view:bright main star and close, dim companion.
It still puzzle me that I had more opportunities to see the companion of Antares,which is much lower in the sky than Sirius.
The season when each cross the meridian in the evening it have probably something to do with it.

Mircea

#18 RobDob

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Posted 21 January 2013 - 09:56 PM

Two nights ago (1/19/13), I had a spectacular clear and steady evening. Turned my Z12 w/6mm Z-planetary (250X) towards Sirius. The Pup was a nice clean split despite Sirius's glare trying to grab it away from me. It seemed to be as wide as Rigel's split. It was steadily observable without a doubt a pinpoint little dot following the big dog through the field of view :).

I think that I observed it intermittantly last year but was convinced my imagination played a part. This year - Booyah!

Rob

#19 nirvanix

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Posted 01 February 2013 - 12:47 AM

How have others seen the Pup's color? Sirius B is supposed to be a white dwarf. To me, it looked white with a definite tinge of light-blue. This was in all three telescopes and with all the eyepieces that would split it from Sirius.

Mike


I agree with your color observation - a hint of blue in the white. Congrats on the split. I split it 3 years ago with a 10" dob, magnification about 220x. Requires very steady skies.

#20 Sarkikos

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Posted 01 February 2013 - 07:05 AM

The magnification that you needed to split Sirius in your 10" was close to what my 10" required: 220x vs 235x. At 200x, I could not see the Pup with my BGO 6mm. I needed the XO 5.1 at 235x.

Mike

#21 Achernar

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Posted 01 February 2013 - 10:18 AM

Sirius B always had an ice blue color to me like the hue glacial ice takes on, especially in big telescopes.

Taras

#22 rookie

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Posted 01 February 2013 - 04:33 PM

The Pup is grey-blue to my eyes too. Antares companion is green.

#23 David Knisely

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Posted 02 February 2013 - 02:29 AM

How have others seen the Pup's color? Sirius B is supposed to be a white dwarf. To me, it looked white with a definite tinge of light-blue. This was in all three telescopes and with all the eyepieces that would split it from Sirius.

Mike


Well, the term "white dwarf" refers to the type of star (an ancient collapsed one no longer producing energy by nuclear fusion) and not necessarily its color. White dwarfs can have color indices from nearly -1 (bluish) to around +1.4 (yellowish-orange), so they aren't exactly all "white". Sirius-B has a color index of -0.12, so it would definitely be a bluish-white color similar to that of Regulus or Lambda Tauri-A. Clear skies to you.

#24 FlorinAndrei

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Posted 08 February 2013 - 01:42 AM

The Pup star appeared to have a slightly light-blue tinge to my eyes. It also seemed to have this cast in the other two Dobs.


That seems normal, given its temperature of 25,000K.

BTW, I'm pretty sure I nabbed the Pup in the 6" newtonian - just for the challenge. Seeing was good but not outstanding, so I only had a few moments when I could see it appear out of nothing, faint but unmistakably round and at the correct distance from the primary, due east. The diffraction rings from the primary were quite steady when the Pup showed up, so I'm pretty sure the observation is legit.

I used 255x and 340x magnification that night, but I can't remember which one I was actually using when the Pup was peeking out from behind the veil of turbulence. Either way, the diffraction pattern was looking sharp at either magnification - to the extent allowed by turbulence.

I'm going to keep trying with the little scope until I catch a longer sequence of excellent seeing.

#25 Sarkikos

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Posted 08 February 2013 - 08:23 AM

I recently tried to see the Pup star with my C6 here at home in a red zone. This was first light for the telescope. I had just star tested it and saw it has tight collimation and very good optics (no SA visible, smooth). But the seeing was only about 7/10 and we have a lot of ambient glare, so my expectations were not high for seeing the Pup. I did not spend much time on it. Though I did tease out the E and F Trapezium stars with no problem that night and saw about six bands on Jupiter.

I have the feeling that you might have better luck seeing the Pup with your 6" Newt - as long as the spider vanes are out of the way, and depending on the f/number - than with my 6" SCT. But this is my first SCT and I'm still finding out what I can expect from it.

Mike






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