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  #1  
Old 28-05-2018, 02:41 PM
Tropo-Bob (Bob)
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Join Date: Sep 2013
Location: Cairns
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Corona Borealis- The Grand Tour

This main stars in the 'Northern Crown' form an obvious arc, wherein, Alpha to Epsilon are appear close together in the sky. Indeed, it is probably only in the 'Southern Crown' where the first five stars appear more closely associated.

Corona Borealis is somewhat of a "Moonlight Constellation". There are no DSOs to view here and indeed the faintest star here is normally only at Mag 10.


Below are the subjects in Corona Borealis that I wish to view:-

The Main Stars:

Alpha Coronae Borealis. A binary star with a period of around 17 days. An unusual star in the sense of being hydrogen deficient. Alpha is thought to have been two-white-drawf stars that have previously merged.
https://en.wikipedia.org/wiki/Alpha_Coronae_Borealis
https://en.wikipedia.org/wiki/Corona_Borealis

Beta Coronae Borealis. Another binary star with a 10 year period and a seperation of 0.25 arc seconds, which is way-too-small a gap for my equipement to resolve.
https://en.wikipedia.org/wiki/Beta_Coronae_Borealis

Gamma Coronae Borealis. This consellation is full on binaries! Gamma has a 90 year period and a separation of less than 1 arc second.
https://en.wikipedia.org/wiki/Gamma_Coronae_Borealis

Delta Coronae Borealis. This star is in the process of transitioning to be a giant. Delta is also known for having magenitic variations similiar to those of our Sun.
https://en.wikipedia.org/wiki/Delta_Coronae_Borealis
http://stars.astro.illinois.edu/sow/deltacrb.html

Epsilon Coronae Borealis. Epsilon is an orange giant with an orange dwarf companion, whose orbit takes 900 years.
https://en.wikipedia.org/wiki/Epsilon_Coronae_Borealis


Other objects of interest:

T Coronae Borealis (The Blaze Star). This famous star has featured two seperate nova outbursts some 80 years appart. The last was in 1946, so another could be due any time now! The star can be seen shining at 10th magnitude in its normally quiet state. It may go supernova at some stage and if so, it could appear with the brightness of a crescent Moon.
https://en.wikipedia.org/wiki/T_Coronae_Borealis

Zeta Coronae Borealis. An easy double for small telescopes.
https://en.wikipedia.org/wiki/Zeta_Coronae_Borealis

Sigma Coronae Borealis. Another fine double where the main star is similiar to our Sun.
https://en.wikipedia.org/wiki/Sigma_Coronae_Borealis

Nu Coronae Borealis. A double said to be visible to the unaided eye. The two components are unrelated and are approximately 60 lightyears from each other.
https://en.wikipedia.org/wiki/Nu_Coronae_Borealis
https://en.wikipedia.org/wiki/Nu1_Coronae_Borealis
https://en.wikipedia.org/wiki/Nu2_Coronae_Borealis

R Coronae Borealis. (A reverse nova). This star is normally around magnitude 6, but can drop to around mag 15.
https://en.wikipedia.org/wiki/R_Coronae_Borealis

Last edited by Tropo-Bob; 05-06-2018 at 11:45 AM.
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  #2  
Old 06-06-2018, 09:45 AM
Tropo-Bob (Bob)
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Location: Cairns
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My observations

I observed Corona Borealis with my Tak 100mm last night. The weather was similar to the previous evening when I reported on Bo÷tes. It was very clear, but the seeing was lacking.
Fortunately again, my targets were not challenging objects to view, so I was able to proceed.


Objects of interest:

T Coronae Borealis (The Blaze Star). This famous star has featured two seperate nova outbursts some 80 years appart. The last was in 1946:
Using 50x and my Uranometria 2000 star atlas, I found this to be an easy star hop out from Epsilon. The star appeared to be around 9th magnitude, when I compared it to nearby stars marked in the atlas.

Zeta Coronae Borealis. An easy double for small telescopes:
Zeta was just visible to my eye. It appeared as a pair of white stars, one more than half a magnitude fainter than the other. They were easily split at 50x, using a 15mm Delite.

Sigma Coronae Borealis. Another fine double where the main star is similiar to our Sun:
Sigma was easily split with 50x into an off-white pair thats brightness were about a magnitude apart.

Nu Coronae Borealis. A double said to be visible to the unaided eye:
Though visible to my eye, I could not resolve them into seperate stars. However, they were easily resolved in binoculars (7x35).
At 30x, they appeared as a golden pair of stars. I was pleasantly surprised by these. They are well worth looking at and serve as a useful signpost when star hoping to Sigma.

R Coronae Borealis. (A reverse nova). This star is normally around magnitude 6, but can drop to around mag 15:
I star hoped out from Delta to find this one. It is currently around mag 6, which is lucky, because it has been much fainter during the better part of the last decade. Now that I have it located, it would be great to see it go fainter.


The Main Stars:

All five of these stars were visible to the eye.

Alpha Coronae Borealis... An unusual star in the sense of being hydrogen deficient. Alpha is thought to have been two-white-drawf stars that have previously merged:
Alpha is the easily the brightest star in the constellation. It appeared to be white as Antarctic ice.

Beta Coronae Borealis:
Beta appeared as a creamy white and it really was the second brightest star in the consellation.

Gamma Coronae Borealis... Gamma has a 90 year period and a separation of less than 1 arc second:
Using 148x, I could not split this. When estimating its colour, I was undecided between white and creamy white.

Delta Coronae Borealis. This star is in the process of transitioning to be a giant:
The colour appeared to be either a deep yellow, or a golden yellow.

Epsilon Coronae Borealis. Epsilon is an orange giant:
Fortunately, it appeared as orange to me as well.
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