Variable: U Orionis

[SilverAstro]

In this topic on 8 March '16 :- https://stargazerslounge.com/topic/264914-thanks-bino-sky-newsletter/?do=findComment&comment=2901107 I reported that U Ori was not observed in 10x50 bino

I am now pleased to be able to report that this evening I got my first sight of U Ori ( HIP 28041 in Stellarium )

At approx m6.5 it is an easy target in 10x50

-- a good  BAA chart is available here : http://www.britastro.org/vss/xchartcat/u-ori-5d.html     where F at 6.7 and D at 5.9 are nicely placed for comparison, and it confirms the Stellarium magnitudes of surrounding stars.

[JeremyS]

Congratulations on this observation of U Ori - I hope you will submit it to the BAA to help keep up our long term coverage.

It is one the the longest observed variables in the BAA Variable Star Section database. There is a light curve here: 

This "only" goes back to 1893, but in fact we have data back to 1885 when it was discovered by the BAA VSS's first Director, John Ellard Gore, from his home town of Dublin. 

I should point out that he wasn't actually Director at the time of the discovery as the VSS was formed until 1890 (the same year as the BAA itself).

Jeremy

[SilverAstro]

Thanks Jeremy, very interesting.

I have been doing some digging on the interwebby and came back to make an addendum ! :

a ) that it has been observed for about ~120y so it isnt going to spring any surprises (?! who knows !) yet it seems to be an interesting subject for the bino user. (thanks Steve @BinocularSky)

b ) that the max is usually in the 6.something region but from time to time it manages 4.8 which would make it an NE candidate !  And having figured out just now how to generate a plot on AAVSO it seems to be still on its upward trend? at ~6.5 so may be worth watching to see if it manages a bit more this time round.

c ) the BAA chart was easy to use in conjunction/confirmation with Stellarium; I still have not tamed the AAVSO charting device

As for submitting ! thanks for the invitation but 'unaccustomed as I am' etc lol! I wouldnt know how, but am happy to describe * how I arrived at ~6.5 from the 5.9 <> 6.7 interval and then please feel free to submit pp.'bloke on Stargazers'

Edit * ok erewego : I thought it ever so slightly brighter than F but not near D so taking the interval (6.7 - 5.9)/2 = 0.4 , then halfway is 5.9+0.4 = 6.3 and I decided that it was closer to F than it was to D so it is betwixt 6.3 and 6.6 QED ! But if I had said it was 6.4 - 6.5 would have implied that I could determine mag to 0.1, a deffo unwarranted assumption,,, hence ~6.5 Howzat?

 

 

[JeremyS]

Glad to hear you like the BAA charts, SilverAstro. They are carefully drawn with the visual observer in mind.

Yes, U Ori does seem to be reasonably well behaved. Other Long Period variables have changed their behaviour quite markedly over the course of a few decades, so its worth continuing the observational record. In fact I would argue it's even more important now for visual observers to continue to watch these stars as there are increasingly few visual observers out there (by contrast CCD observations are increasing). So please keep up the good work started by our forbears more than 120 years ago.

Jeremy

[JeremyS]

By the way, U Ori was the BAA Variable Star of the Year in 2008. There is an article about it here, which is well worth a read: http://www.britastro.org/vss/VSOTY_uori_2008.pdf

Jeremy