Monday, February 10, 2020

things spotted in Ori-Tau photo

I kept seeing interesting things in the stacked Orion-Taurus photo. So, I thought I'd do a deep dive.

As much as possible, I'm going to do a clockwise, from centre.

We'll start with the obvious big things... This photograph centres on the constellations of Orion and Taurus but also shows portions of Aries, Cetus, Eridanus, Lepus, Monoceros, and Gemini. Constellations are official the boundaries but we see the ancient figures like Orion the Hunter. 

Orion is sometimes shown as holding a clubbed lion or a shield but in my photo I really do get a strong sense of the bow and not a simple curved arcing bow but one with an opposing arch in the middle, like a traditional Mongolian bow. I don't capture all of Taurus in my framing but I easily caught the big "flying-V" at the centre of the figure of the Bull, which in artwork is the head of the raging steer. I also include half of the unicorn, the head and unusual solitary horn.

At this scale, which is approximately 60 by 35 degrees, only large and bright deep sky objects are visible. Still, there are a lot. 

There's the Hyades cluster, the various bright and dim stars in the aforementioned V in Taurus. This big open cluster is also known as Collinder 50, Melotte 25, OCL 456, and Caldwell 41. Easily spotted naked eye. SkyTools 3 Professional shows it centred near 71 Tauri with a radius (over 2½ degrees of arc) that includes orange Aldebaran.

It goes without saying, at the top-right, the Pleiades. Well known as the Seven Sisters, this suggests people can see seven stars. I think you need perfect vision or better than 20-20. Rhonda says she can see more stars. In the photo, I easily count 15 to 20 stars. This is an object in the famous catalogue by Charles Messier, entry number 45 (M45). aka The Subaru. Did you know that Subaru in Japanese meaning "unite." I'm for that.

Messier also catalogued item 42, the Great Orion Nebula, is his list of non-moving, comet-like objects. I like how in my image the large diffuse reflection nebula shows within the sword region of Orion. A very large "fuzzy" star.

The open cluster from the New General Catalog, NGC 1981, is visible above M42. Six or seven stars are clearly visible. Compact.

Many know the Belt stars of Orion, Alnilam, Alnitak, and Mintaka, equidistant, equal in brightness and colour, and in a nearly straight line. SkyTools notes this as a cluster, formally. I did not know that was a thing. It's officially Collinder 70 or OCL 503. And I've never really noticed it before but there is a conglomeration of stars huddled around The Belt.

At the head or neck area of Orion, between Betelgeuse and Bellatrix, we have Meissa. Actually, that's a specific star. The backwards L-shape of stars is Collinder 69, a small open cluster, with Meissa as a single star within. I once thought I saw something unusual and uncharted here but it turned out to be nothing. Look close! There's a straight line of faint, tight stars inside. Wow.

The Rosette Nebula is far too faint and diffuse to see. But the open cluster in the heart of the big nebula is easily spotted. That's NGC 2244.

There's lots going on in Monoceros according to my favourite planning software but there's nothing obvious in the picture. Zooming in, look at the top-left corner of the photograph, I wanna say I can see the Cone Nebula. The bright star of 15 Mon is easily tagged.

The last open cluster to share is Collinder 65 aka OCL 474. I must admit, if it weren't for ST3P, I wouldn't know about this. It is a very large open loose collection, inline from M42, through The Belt, and Cr 69. There are two bright stars at the top with 119 Tau.

Finally, one more clockwise sweep, down to stars this time.

The photo is nearly centred on Tabit, aka pi 3 Orionis or 1 Ori. It's near the bottom of Orion's interesting bow.

Within the Hyades there are a number of wide double stars. σ (sigma) Tauri is south-west of Aldebaran. Two nearly equal stars oriented nearly north-south. The northern star is a touch brighter. aka STF A 11. Over 400 arc-seconds apart. South-west of the lucida, we have the similar pair of 81-80 Tau, about 480" apart. This pairing is not official, not found in the WDS, but is interesting nonetheless in photos, in binoculars. Each star however is a recognised double. Finally we have the obvious pairing of θ (theta) 1 and 2 in the middle of the V. Brighter than the aforementioned pairs, at nearly a 90 degree angle to 80-81, STF A 10 is tighter. 337" according to ST3P.

Curious how they all are approximately the same distance apart.

Lots going on. Fun for the eye, with binoculars, and with the telescope.

North of the Hyades is a pair of stars, similar in separation to the others. Struve 541 is actually a multi-star system but κ (kappa) 1 and 2 are the brightest elements.

Between Hyades and the Pleiades is a very wide apparent double with 37 and 39 Tau. Each of these stars are telescope double stars.

South-west of Hyades is 10 Tauri. At this scale, there seems to be an unequal companion to the north but that's V711 Tau.

Comet 114P/Wiseman-Skiff was south of Pleiades. Not visible in the image unfortunately.

North-west of pi 1 is a tiny cluster. Really it is telescopic. But it shows in the photo as a smudged collection of grey stars. NGC 1662, Collinder 55, OCL 470.

Orangle Menkar is tangled in the tree branches...

Below centre of the image is the intriguing little triangle of unequal stars with μ (mu) Eri.

Bottom-centre in the image is the equally intriguing triangle of 46 Eri. Nearly the exact same pattern!

To the right or west of Rigel is a tantalising dim star. It's not related, HR 1704.

There's a nearly equilateral triangle north of Rigel. Ah. It includes Cursa. Good. Good to know.

The bright stars at the bottom-left of ζ (zeta) and η (eta) Leporis. I think they are the back of the bunny.

South of the great nebula in Orion's sword at the bright stars of ι (iota) and HR 1887. In the telescope ocular, these reveal themselves as fantastic double and multi-star systems.

I think I can see the naked eye double 42-45 just above M42.

It'd be cool to see individual elements of σ Orionis but there's not enough resolution to pull that off.

Star of show... Well. OK, maybe, one of the most interesting things in this, is alpha Orionis, aka Betelgeuse. Talk of the town of late. So, what do you think? Compare the brightness of Betelgeuse to Bellatrix (magnitude 1.64) or any of The Belt stars (1.77, 1.69, and 2.14). Or Saiph (2.06)! The lucida of the constellation is heading toward an all-time low in magnitude...

The stars that are to make up the horn of the unicorn are not bright...

Don't forget we're looking through the plane of the galaxy. But outward, away from the central bulge. In an outer spur.

§

Imaged on 29 Jan.
Satisfactorily stacked on 9 Feb.

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