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6 doubles in Leo - 6 May 2021

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#1 flt158

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Posted 07 May 2021 - 06:14 PM

After some cloudy periods I eventually had a very clear night on Thursday 6th May 2021.

I had set up my William Optics 158 mm F/7 apochromatic refractor on its Berlebach Planet alt-az mount in the back garden before evening dinner.

My time of observing went from 21.15 pm until midnight.

Sunset occurred at 21.03 Irish Summer Time.

The wind never died down completely. At its max it was 15 km/h.

It was very cold. The air temperature plummeted from +5˚ to exactly 0˚ Celsius.
Yours truly had 6 layers on although I never did shiver at all.

 

www.stelledoppie.it provide all the important figures regarding these doubles.

 

1. While I was waiting to see the first star appear, I thought I ought to check out Polaris (Alpha Ursae Minoris) or STF (Struve) 93 and see if I could see the secondary at a minimum magnification. It is a true binary with magnitudes: A = 2. B = 9.1. Sep = 18.4”. PA = 236˚. What is particularly fun is to see where B is at any time of the night. As we all know, our Earth is spinning on its axis once every 24 hours. Therefore Polaris B is also doing the very same. I managed to find A at 11X in my small apo at 21.19 pm. At 40X there was no sign of B in the main scope. But at 112X - hey presto, I had B straight down below A.

 

2. Over I go to Leo yet again. And the 1st double I wish to tell you about is STF 1417 which is near Gamma Leonis (Algieba). Rugby, here on Cloudy Nights, had informed me he thought STF 1417 are very similar to STF 1413. I had observed the latter on Friday 30th April. And I have to fully agree with Rugby. The magnitudes of STF 1417 are: A = 9.2. B = 9.3. Sep = 1.8”. PA = 270˚. Whereas the magnitudes of STF 1413 are: A = 9.8. B = 9.8. Sep = 2.4”. PA = 78˚. I find both doubles a delight to split at 112X. Both doubles’ primaries are even that little bit yellow. And so I thank you, Rugby, for encouraging me to notice the similarities of both systems. waytogo.gif 

 

3. HJ 476 is a true binary near Gamma Leonis too. Magnitudes: A = 7.6. B = 11.7. Sep = 24.3”. PA = 49˚. Even though the separation is good and wide, the secondary is seriously dim. To see it directly I required a full 225X. crazyeyes.gif  Even then I wasn’t seeing it all the time. I found myself wondering what size the stars are of HJ 476. Could A be a giant and B a dwarf star? I shall leave that question to the experts. Stelle Doppie states the system is about 1450 light years from us. The primary has a spectral class of G5. And I did indeed saw its yellow colour. HJ stands for John Herschel.

 

4. And so the time came for yours truly to re-observe BU 603 once again. Let’s start with the summary. BU 603 is s true binary with magnitudes: A = 6. B = 8.5. Sep = 1”. PA = 327˚. The question is at what magnification would the diffraction ring (DR) appear. And if so, would it prevent me from seeing the elusive secondary. Well at 225X there was the dreaded DR. However at 280X I could see the dim star that little bit brighter than the DR. Further success was to be had at 320X. I feel truly blessed and privileged to now confirm to you all this observation. Hallelujah! jawdrop.gif. BU stands for Sherborne Burnham.

 

5. STF 1511 is true binary some distance from Iota Leonis. Its magnitudes are: A = 9.3. B = 9.5. Sep = 7.6. PA = 287˚.  Please notice these 2 stars are that little bit fainter than Polaris B. And with my 2” 28 mm eyepiece which delivers 40X, I did wonder would I see the 2 stars split at that power beforehand. However there was definitely no problem at all! I had the loveliest of black gaps in between. Once again I had 2 separated eyes looking at me. At 112X I could see the primary had an orange hue. Its spectral class is K0 after all.

 

6. And so finally, Chris from Cloudy Nights invited me to check out a double-double which is very near STF 1511. STF 1503 is a true binary. Magnitudes: A = 9.4. B = 11.1. Sep = 11.6”. PA = 271˚. A’s spectral class is F8. HJ 172 is also a true binary. Magnitudes: A = 10.2. B = 10.3. Sep = 13.6”. PA = 94˚. The 2 systems are a mere 9 arc minutes apart. What sheer delight I had when I saw both doubles split at 40X in the same fov. They were nice and tight at that point. However I was soon to discover both doubles were “buried” behind a very large tree which I do not own. Therefore the next clear night I get I will go after these 2 systems straight away and see what colours I see. But I very much have to thank Chris for informing not just me of this truly remarkable double-double. waytogo.gif

 

Comments and corrections are very welcome. 

 

And on that note I wish you all clear skies from Aubrey.


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#2 R Botero

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Posted 08 May 2021 - 02:37 AM

Great report Aubrey! You are having so much fun waytogo.gif

 

Roberto


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#3 Carbstone

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Posted 08 May 2021 - 05:02 AM

I have already written the duo STF 1503 & HJ172 into my bucket list.

 

Regards,

Dirk


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#4 flt158

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Posted 08 May 2021 - 12:41 PM

Thank you, Roberto, Dirk and all the "likes" from Mark, Jeremiah, Dan, Van Jan, Rugby and Rich. 

Yes, Roberto, I was having great fun on Thursday night. 

 

Good man Dirk!

Maybe you could do one of your superb sketches of STF 1503 & HJ 172. 

 

Best regards from Aubrey. 


Edited by flt158, 08 May 2021 - 01:26 PM.

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#5 VanJan

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Posted 08 May 2021 - 02:29 PM

Fun and interesting report, Aubrey. applause.gif  Some observations with my 90mm F/10 refractor:

 

STF 1511 - White, bluish.  130X   30 April 2018     I'm thinking not enough aperture to show the true color in the primary like you detected.

 

HJ 476 - Orange, no color. B star is 11thmv, not 10.3 as listed in Sky Cat 2000.0.   130X    23 April 2016     Bit of a mystery re: the magnitude of the B star. SC2 says 10.3. I say 11th. Stelle Doppie lists 11.7. Your observation suggests even fainter than that. Variable? shrug.gif

 

No new observations from me lately because of clouds, clouds with high winds, clouds with soaking rains, and clouds with absolutely no consideration of my desires. shameonyou.gif Not tonight, they say. Tomorrow night, I pray.praying.gif Repeat till relief.whew.gif

 

   


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#6 flt158

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Posted 09 May 2021 - 11:36 AM

Thank you, Van Jan, for your great comments! 

 

You seem to have plenty of experience in separating doubles in Leo. waytogo.gif

And I'm of the opinion STF 1511 is a secret little treasure just waiting to be observed.  

I've no idea whether the secondary of HJ 476 is variable or not. 

Maybe our expert Fred from Australia could shed some light on that issue. 

 

And, like you, Van Jan, I don't know when the clear skies will return to my little island. frown.gif

But I can always ask God to keep me patient. 

Anyway, I'm not free either Monday or Tuesday coming. 

 

Very best regards from Aubrey.  


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#7 fred1871

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Posted 10 May 2021 - 09:15 AM

HJ 476 is one of John Herschel's many discoveries. Rather wide, as so many of his earlier finds were. The magnitudes reported for it vary somewhat over time, and the 11.7 for star B has only recently made it into the WDS, from which stelle doppie obtains its data. Looking through older versions of WDS I find that it had the dimmer magnitude, 11.7, by June 2013. In February 2013 it still had mag 10.3 for B, the same as WDS in 1996 and in 1984 from which the Sky Catalogue 2000 gets its data.

 

Further back - not much point in checking the numbers for 1827, which WDS gives as the first measure date. Back then, the Pogson magnitude scale was not yet in use, though one can estimate equivalents in modern magnitudes from those by Struve, Herschel, etc.

 

I found no mention of HJ 476 in Smyth or Webb; however SW Burnham lists it in his General Catalog of Double Stars (1906) with magnitudes of 7 and 11.

 

Gaia Gmagnitudes, not quite the same as Visual magnitudes, we have from DR2 magnitudes of 7.04 and 11.97 (to two decimal places). It reinforces the dimmer recent WDS magnitude being more accurate. That both the older magnitude at 10.3 and the newer one at 11.7 are quoted to one decimal place only, suggests strongly that neither is a modern photoelectric magnitude: those are usually to two decimal places (Gaia even goes to 4 places). Therefore they're likely an estimate of some kind.

 

I don't have the full WDS data file, so I can't check through the older observations to see what magnitudes were given by which astronomers at which dates. That could at least tie down the basis of the differing numbers, where 10.3 came from, and who changed it to 11.7. On the face of it, there's no strong evidence of a variable, but nothing definite to exclude the possibility either. Unless someone wants to do photometry of the stars over a period of time we may not find out.


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#8 c2m2t

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Posted 11 May 2021 - 10:02 AM

Hi Aubrey!

Nicely done...another fine report!! I have only two systems to present here...most were too tight for my setup. As with Rich's last report, both of you had selected systems that needed processing. The two systems that I present here are HJ 476 and STF 1511. Enjoy!!

 

Cheers, Chris.

Attached Thumbnails

  • HJ 476-1903-pt-ns-ID.jpg
  • STF 1511-9899-pt-ns-ID.jpg

Edited by c2m2t, 11 May 2021 - 10:02 AM.

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#9 flt158

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Posted 11 May 2021 - 12:53 PM

I fully accept Fred's comments here on HJ 476. 

 

I thank you for them, Fred.  

 

Excellent images, Chris. 

Your image of HJ 476 proves the secondary of HJ 476 is seriously faint 

But you sure got it!! applause.gif dalek12.gif

And it looks superb, Chris!

 

Clear skies from Aubrey. 


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