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Scooting into Northern Scutum: H VI 50, Σ 2391 (STF 2391), and Delta Scuti

Scutum, as in SKOO-tum.   What kind of a name is that?  You probably wouldn’t name your dog or cat that, and certainly not a child, I hope.  So who would name a constellation something like that?  And why?

Johannes Hevelius, that’s who, and as it turns out, he did have his reasons.  He named this area of the sky in honor of his king, John III Sobieski, King of Poland, who was responsible for defeating the Turks when they laid siege to Vienna in 1683.  Scutum means shield, so you can see how the name makes some sense.  Actually, Hevelius’ first choice for a name was Scutum Sobiescianum.  Fortunately, Flamsteed shortened it to Scutum in the 18th century, no doubt concerned with how to fit a name larger than the constellation on a map of the heavens.  Credit for this illuminating information goes to the Night Sky Observer’s Guide.

Stellarium screen image with labels added. Click on the image for a larger view.

I’ve had plans to take a look at this area for the past two months, but most of July and the first part of August were plagued by clouds and fog that blanketed the sky about 110% of the time.  When the skies finally cleared, a bright moon was sitting a few degrees above Scutum, so I spent those nights exploring Cepeheus and Cassiopeia.  Finally, the evening of September 2nd arrived with clear and dark skies, so I scooted up a chair and sat down to take a look into the northern reaches of Scutum.

Both of our first two double stars, along with the Wild Duck Cluster, can be seen in a single field of view. (Stellarium screen image with labels added, click for a better view).

H VI 50          HIP: 92391    SAO: 142661
RA: 18h 49.7m   Dec: -05 55′
Magnitudes: 6.2, 8.2
Separation:  110.6″
Position Angle: 171°  (WDS 2011)
Distance: 1489 Light Years
Spectral Classification: K1

Σ 2391  (STF 2391)      HIP: 92296    SAO: 142640
RA: 18h 48.7m   Dec: -06 00′
Magnitudes: 6.5, 9.6
Separation:  38.4″
Position Angle: 332°  (WDS 2006)
Distance: 527 Light Years
Spectral Classification: A2

The first two stars on the list are within a degree or so of the beautiful open cluster M11, also known as the Wild Duck Cluster.  Both of these can be seen in the same field with the cluster in a wide field eyepiece.  You don’t need much magnification, so  I used a 40mm Plössl (38x) in my six inch refractor and positioned Σ 2391 at the upper left corner of the eypiece (which was northwest), H VI 50 in the middle, and M11 at the lower right side (southeast), all of which, when combined with the a fairly dense star field, made for a very rewarding sight.

Image as seen in the eyepiece of a refractor with a diagonal. Note that east and west have swapped positions.  (Stellarium screen image with labels added, click for a larger view).

In my six inch, H VI 50 is reddish yellow (or yellowish-red, take your pick), while the secondary is too faint for detecting color.  Haas describes the primary as “grapefruit orange,” which actually is pretty much what I saw.  Σ 2391 is white, or as Haas describes it, “lemony white,” and again the secondary is too faint for color.

In my 60mm f/15, each component of H VI 50 was easy to see.  The secondary of Σ 2391 was more difficult, though – I needed averted vision to see it with a 20mm TV Plössl (45x).  But I found it much easier to pick out with a 15mm version of the TV Plössl (60x).

As for views, in the 60mm the view was essentially one of two doubles in the same field — M11 just did not resolve well in the 60mm scope, so it became an unfocused blob of light.  However, I was looking into some haze in that portion of the sky, so I suspect a 60mm will do much better under more transparent skies.  In the six inch, the wide angle view which included M11 was by far the best.  The two companions are interesting in that they’re almost a mirror image of each other with regard to PA.

Actually, I wasn’t impressed in the least when I first looked at these stars in the six inch.  That was because my attention was drawn immediately to H VI 50.  After a few minutes, I realized that Σ 2391 was in the same field.  As I shifted the scope a bit to the east and brought M11 into the scene, I realized this was something special.  The longer I looked at this view of the two doubles and M11, the more I liked it.  I spent about thirty minutes admiring the three objects against the background of a fairly dense star field.   If the transparency had been better here, I’m sure the view in the six inch would have been really spectacular.

Delta (δ)  (H V 36)       HIP: 91276    SAO: 142515
RA: 18h 42m   Dec: -09 03′
Magnitudes   AB: 4.7, 12.2    AC: 4.7, 10.6
Separation    AB: 14.4″          AC: 51.1″
Position Angles   AB: 45°  (WDS 1999)     AC: 131°  (WDS 2007)
Distance: 187 Light Years
Spectral Classification   A: F2     B: K8    C: G7

South of this area, and on the east side of Scutum, is the triple star Delta (δ) Scuti.  The primary is a bright white — the other two are too faint to call anything but pale white.  All three were quickly picked out in the six inch with a 20mm eyepiece (76x).  In the 60mm f/15, “A” and “B” area were easy to see, but I needed to use an 11mm TV Plössl (82x) and averted vision to detect “C.”  I also tried to pick it out with direct vision in a 7mm UO Ortho (129x), but I couldn’t do it without averting my vision.  By this time, Scutum was about halfway between the meridian and the western horizon, so I was looking through quite a bit of haze.

There are several more potentially interesting doubles in this dense region of the Milky Way, but positioning in the sky is working against me now thanks to the loss of observing time in July and August.  This may be a project to be continued in the early hours of a mid-winter morning.  At the least,  the cold temperatures will be softened somewhat by the impact of gazing at the summer constellations.

But it sure is a lot more comfortable in July!   😎


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