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Gamma Leo - Algieba

Posted: Fri May 07, 2021 7:53 pm
by SkyBrowser
Last night (Thu 6th May) was an incredibly clear night, though very cold. Anyway, I couldn't pass up the opportunity, so here's a short extract from my observing notes.

2218UT : Algieba (mag 2.0). LE12.5 (x83, 0.63°). Happened on this by chance, though it was on my list of things to look for. Very nice, even in the slightly wobbly seeing. It was well split at this magnification with concentric diffraction rings evident. Algieba and its companion (3.1) looked about the same colour to me, orangey in fact. A rough guesstimate (have no other way of doing it!) put the position angle at 135°. I think the official value is 125°. Separation is 4.5".

Two other stars form a right-angle triangle with it, one due south of Algieba, the other due east of the former. Algieba to the star at the right-angle-corner of the triangle is just over half the FOV of the LE12.5, so 0.4° or so, the other one is closer to the corner. I think these must be 40 Leo at mag 4.8 and 1423-256 at mag 8.1.

2224UT : LE5 (x208, 0.25°). Diffraction rings even more evident, but wobbling about a bit. Colour was less noticeable, both stars now looking white. On the west of the FOV are a pair on north-south-aligned semi-bright stars that I didn't notice before. It turns out that these are two fainter companions of Algieba, mags 9.6 and 10.0 at about 6 arcminutes away from the primary. Position angles around 300°. Official figures are 9.6/288°/341" and 10.6/302°/371".

2227UT : Pan41 (x25, 2.5°). Algieba elongated, but not split. But it's back to looking orange!