Saturday, January 30, 2021

collected photons from a little arrow (Bradford)

Improved the polar alignment then flipped to the other side of the meridian to catch Sirius crossing over. While I waited I aimed at the small and intriguing σ (sigma) Orionis cluster aka OCL 516.1. It contains the σ Orionis double star... Rotated the camera body about 90 degrees to nicely frame the little celestial pointer. Refocused.

sigma Ori cluster in colour

Celestron 8, Vixen Super Polaris-IDEA GoToStar, William Optics external focuser, manually focused, Canon 40D (unmodified), Tele Vue PowerMate 2x, Canon EOS Utility, IOGEAR USB-ethernet extension, 8 seconds, ISO 1600, RAW, daylight white balance. Minor adjustments in Canon Digital Photo Professional 4.

Note! North to bottom-left; east to bottom-right. The camera was almost upside-down.

sigma Ori rendering in SkyTools

Screen snapshot from SkyTools 3 Pro, Context Viewer.

Good correspondence.

The circle from the software is for the cluster...

Look at those interesting blue-white hot stars!

So, the double star system is front and centre.

The A star is the obvious, bright star. B is a fraction of a degree from A so lost in the glare.

The C star is above. That's south-west. Very dim. aka Σ762 (Struve, STF).

D and E are below. D is east while E and north-east. Equal in brightness? Maybe E is a tiny bit brighter.

Now, the stars to the left or north-west, that's a completely different double star! STF 761. The primary star is the lower one. B and C are above and nearly equal. B is to the right and C left. B is a tiny bit brighter and C.

SkyTools ays there is a D companion, left or NW from A. Do you see it? It's there! But it's right at the limit...

Huh. I see a very faint star below... similar to D!

The bright star to the far right, the tip of the wedge, that's solitary HD 37525.

sigma Ori, the star: Also known as 48 Ori, β 1032 (Burnham, BU), HR 1931, HD 37468, SAO 132406, PPM 188303, and HIP 26549.

STF 761: aka HD 294271, SAO 132401, and PPM 188298.

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