Another nearby star: Lalande 21185

 The six nearest stars, in order, are: Alpha Centauri system (3 stars), Barnard's Star, Wolf 359, and Lalande 21185.  This list omits* three known brown dwarfs that slot in between Barnard's Star and Wolf 359.

*(The brown dwarfs are omitted not because they are insignificant, but because they are not stars - they do not fuse hydrogen.  Also, they mostly radiate in deep infrared wavelengths invisible to the human eye.) 

Lalande 21185 is a red dwarf 8.3 ly away with an apparent magnitude of 7.5.  This makes it visually accessible to both binoculars and small telescopes.  It is in the constellation Ursa Major, approximately halfway between the Big Dipper and the constellation Leo.

With the help of a star chart, Lalande 21185 was easily found with a 10x50 binocular. It was likewise an easy sight in a 60mm f/6 refractor.  It is currently high in the sky after twilight ends.   

credit: SkySafariAstronomy.com

Lalande 21185 is circled.  Samyang AF 35mm f/1.8, softon filter.

Olympus 75mm f/1.8, softon filter.

Lalande 21185

I also made another attempt at seeing Barnard's Star with binoculars, but could never be sure I had it.  With the 60mm telescope, however, it was an easy target at 18x with a 20mm eyepiece.

There were some passing clouds near the horizon.  The measured sky brightness was sqml=21.45.

Barnard's Star

The second-closest star to our sun is Barnard's Star, just under 6 ly distant.  Technically, it is the fourth closest star because the nearer Alpha Centauri  system consists of three stars.

The closest member of the Alpha Centauri trio is Proxima. At a distance of 4.25 ly, it has a visual magnitude ranging between 10.3 and 11.1.  Barnard's Star has a visual magnitude of 9.5, which makes it 2.3 times brighter than Proxima, and an easy target in a small telescope if you know where to look.

Barnard's Star is located in the constellation Ophiuchus.  At this time of year this constellation is rising in the east after twilight.

Ophiuchus rising over Snowshoe Mountain.

 This photo was taken with a Sony A7iii camera and a Samyang AF 35mm f/1.8 lens and Hoya Softon filter.  There are very strong bands of purple and green airglow present.  The bright star near top center is Rasalhague, Alpha Ophiuchi.  The location of Barnard's star is very near the center of this image.

A closer look is provided with an Olympus E-M1iii + 75mm f/1.8 lens (and softon filter).

Barnard's Star is circled.  The bright star top center is Cebalrai, Beta Ophiuchi.

 An even closer look:

 The open star cluster (top center) to the left of Beta Ophiuchi is IC 4665.

Although I have photographed Barnard's Star many times, last night was one of the few times (maybe the first?) that I have used a telescope to see it with my own eyes.  A Celestron C8 Schmidt-Cassegrain and a Pentax XW 40mm eyepiece (50x) provided an excellent view.  I also tried to pick it out with a 10x50 binocular, but the view was too shaky free-handed. 

 

Scorpius rising over Snowshoe Mtn.  Samyang AF 35mm f/1.8, softon filter.

Antares rising.  Olympus 75mm f/1.8, softon filter.

 

Omega Centauri.  Olympus 75mm f/1.8.

I was wrong about not being able to see Omega Centauri from the back yard.  However, the time is very short between when it emerges from behind the cabin on the hill and then sets behind the distant ridgeline.

In spite of the strong airglow visible near the horizon, the measured sky brightness overhead at midnight was sqml=21.65, which is very respectable.

The progression of twilight

 There are three defined stages of twilight:  Civil Twilight ends when the sun is 6° below the horizon, Nautical Twilight ends when the sun is 12° below the horizon, and Astronomical Twilight ends when the sun sinks to 18° below the horizon.  The significance of Astronomical Twilight is that the sky is finally dark enough to begin observing faint objects (supposedly).

The following four images were taken with a Sony A7iii camera , Sony 20mm f/1.8 lens,  and a Sparkle-6 filter .  The first two were obtained about 20 min before the end of Astronomical Twilight, and the second set very close to twilight's end. 

Leo, Mars, and Gemini setting over Bristol Head (SW view).

Gemini (Castor and Pollux) and Auriga (Capella) setting over Bristol Head (NW view).

Twenty minutes later, at twilight's end:

 

 One feature of interest in these images are the bands of green and purple airglow.  This airglow is never easily visible to the eye but is always picked up by the camera sensor.  Until I started photographing the night sky I had no idea how much color was present in the seemingly dark sky, just below the level of perception.

The sky brightness measured over an hour after the end of Astronomical Twilight was sqml=21.45.  This is about 0.2 mpsas brighter than earlier in the week.  The likely explanation is the airglow illustrated above, but there was also some haze in the air this morning, so distant wildfires might be contributing to the decrease in darkness. 

Looking toward the southern horizon, the giant globular cluster Omega Centauri was just emerging from behind the flank of Snowshoe Mountain:

Olympus E-M1iii + Sigma 56mm f/1.4 lens. ISO 1600, 30 s, softon filter.

 Some obtrusive cabin lights have been blacked out in the lower left corner.  These lights are unfortunately just below the line-of-sight to the cluster.

Looking almost straight up, the constellation Coma Berenices is dominated by the star cluster cataloged as Melotte 111.  This cluster is one of the nearest open star clusters, about 300 light years distant.

The Coma Star Cluster, Mel 111.  Sigma 56mm + softon filter.

 

Four constellations and three double stars

The measured sky brightness Thursday night was sqml=21.58, which is about 0.1 mpsas brighter than the two preceding nights.  There is a hint of green and purple airglow in the unprocessed wide-angle images, so that probably explains it. 

The constellation shots that follow were obtained with a Samyang AF 35mm f/1.8 lens and Hoya Softon filter, mounted on a Sony A7iii camera, ISO 1600, 30 s.  On a star-tracker mount, of course.

The Big Dipper, the most prominent part of Ursa Major.

 

The constellation Boötes, and Arcturus.

Arcturus is the fourth brightest star in the night sky.  This portion of Boötes forms an asterism known as "the Kite".

 

credit: IAU

The constellation Virgo, and its brightest star, Spica.

credit: IAU

The constellation Leo and Mars (lower right).

Mars is currently about 1.3 times brighter than Regulus, the brightest star in Leo.

The Celestron C8 telescope was already set up on the outside mount, which provided an easy opportunity to photograph some famous double stars.

Polaris and its companion. Stack of 3 images. ISO 400, 1 s.

 The North Star, Polaris, is a very tricky double star in small telescopes.  I spent a long time staring at it with a 60mm refractor on Wednesday night and was unsuccessful in seeing the magnitude-8.7 companion star.  With the 8-inch SCT it was relatively easy, but did take a few moments to become apparent.  The angular separation is 18.2 arcsec.

Castor.  Celestron C8 + 2x Barlow.  Stack of 3 images, ISO 800, 1/10 s.

 Castor, Alpha Geminorum, is actually a sextuple-star system.  The two stars seen here are both unresolved doubles.  A third, much fainter companion star (not seen here) is also a double.

Porrima.  Celestron C8 + 2x Barlow. Stack of 3 images, ISO 800, 1/10 s.

 Porrima, Gamma Virginis, consists of two stars orbiting each other with a 169 year period.  It is currently resolvable in moderate-size scopes. 

Some dark-sky views

 At this time of year astronomical twilight ends (sun 18° below horizon) just after 10pm MDT.  Pictures taken before that will still show some blue in the sky, even though it appears dark to the eye.

This image was taken at 9:33 pm with a fish-eye lens:

E-M1iii + Rokinon 7.5mm f/3.5 fish-eye.  ISO 1600, 60 s.

 The Big Dipper stands high near top center in this view.  This image was a prelude to a 1-hour star-trail exposure that was half in twilight and half in dark sky:

E-M1iii live composite, 1 hour.

 It is impossible anymore to take long-exposure views of the sky without being photobombed by planes and satellites.  Here is a crop from the above image that shows the passage of a satellite swarm (bottom center):

 When twilight ends the sky has been remarkably dark.  The last two nights at 11pm MDT the sky brightness has measured sqml=21.67 mpsas.  The summer crowd has not yet showed up to leave porch lights blazing all night, so this is a great time to enjoy stargazing.  It won't last long.  I can already hear the buzz of ATVs doing laps around the neighborhood.

Corona Borealis.  Sony A7 + Samyang AF 85mm f/1.4 + Softon filter.

 The constellation Corona Borealis is the location of a recurrent nova that is expected  to erupt "very soon now".   Also known as the "Blaze Star" the location of this variable star is shown in the chart below.  When it erupts it will likely be as bright as Alphecca, the brightest star in this constellation.

credit: SkySafariAstronomy.com

The constellation Lyra is the location of Vega, the fifth brightest star in the night sky, and an iconic double star, Epsilon Lyrae, also known as the "double double".

Lyra.  Sony A7iii + Samyang AF 85mm f/1.4 + Softon filter.

 

credit: SkySafariAstronomy.com

The two main components of Epsilon Lyrae, known as ε¹ and ε², are separated by 208 arcsec and are easy to see in small scopes. 

Epsilon Lyrae.  Astro-Tech 102mm ED telescope, Olympus E-M5iii.

Each of the two main components is also a double star (hence the name "Double Double") and can be resolved with larger scopes.  The separations are only 2.6 arcsec and 2.2 arcsec, so high magnification is required.  I tried to capture them photographically with a Celestron C8 telescope and was only moderately successful.  Splitting these components requires a steady atmosphere, and the star was only about 30 deg above the horizon.

Epsilon Lyrae.  Celestron C8.  ISO 400, 1/10 s. stack of two images.

I tried viewing at 200x and had a hard time separating the stars visually.  It is surprising that the images turned out as well as they did.  This will require another attempt when the stars are higher in the sky.

Vega is the fifth brightest star and is an A-type star with strong hydrogen absorption lines in its spectrum:

 

Vega was the first star to be photographed, on silver-plated copper, in 1850.  It was also the first star to have its spectrum photographed, in 1872.  Sky & Telescope magazine has a nice article by Bob King here.
 

Ursa Minor

 There was only a brief look at the sky after astronomical twilight ended (about 10pm MDT), then the clouds took over.  There was just enough time to get a picture of the "LIttle Dipper", the prominent part of the constellation Ursa Minor.  

The LIttle Dipper.  Sony A7iii + Samyang AF 85mm f/1.4 @ f/2. Softon filter.

credit: SkySafariAstronomy.com

Saturday morning. 19.2-d moon.  Vivitar Series 1 135mm.

Rising and setting over the mountain ridges

 There was a large cloud looming over Bristol Head Friday night as Jupiter sank toward the mountain ridge.

Jupiter setting over the Bristol Head ridgeline.

 The four Galilean moons are visible in the original image.  Here is a close crop magnified by 3:

credit: SkySafariAstronomy.com

The lens used here, and in the following images, was a Vivitar Series 1 135mm f/2.3 with a Minolta mount, attached via adapter to a Sony A7iii camera.  This lens was first marketed in 1975.  At that time, 50 years ago, the Series 1 lenses were considered to be top-tier.  They are still pretty good, but fall short of modern designs that utilize newer glass types and aspherical surfaces. 

After twilight faded the clouds disappeared and the sky was nicely dark at sqml=21.53. There was some green airglow visible in the long exposure (30 s) images.

 

Capella (R) and Menkalinan (Beta Aurigae) setting over Bristol Head. Softon filter.

The constellation Corvus.  Softon filter.

When the distinctive quadrilateral asterism of Corvus has passed the meridian it is time to look near the southern horizon for Omega Centauri:

 

Omega Centauri (below center).  Centaurus A near top center.

Antares and Scorpius rising above the flank of Snowshoe Mountain. Softon filter.

Pollux (L) and Castor (R) setting over Bristol Head.  Softon filter.

Vivitar Series 1 135mm mounted on Sony A7iii

Omega Centauri

 Back in Creede!  It snowed briefly on Thursday (15 May) afternoon, but the clear-sky forecasts correctly predicted that there would be an open sky between 10pm and midnight.  

This is the best time of year for viewing the giant globular cluster Omega Centauri.  The cluster transits about 11 pm MDT on this date and is only about 4° above the horizon when viewed from Creede.  This low elevation requires a carefully selected viewing location.  I can see it from the front yard when it clears the southern flank of Snowshoe Mountain, but the view is always blocked from the back yard.

 There was a light breeze while setting up the Seestar S50 in the front driveway, but it tapered off.  The temperature was 34 deg F and the sky brightness was an excellent sqml=21.71.  This is two magnitudes darker than my home location in Santa Fe.  Two magnitudes is 6.3 times darker.

 

Omega Centauri.  Seestar S50, 5 min, AI Denoise.

About 4.5° higher in the sky is the radio galaxy Centaurus A (NGC 5128).  This galaxy was one of the first identified extra-galactic radio sources and is the 5th brightest galaxy in the sky, or 3rd brightest excluding the Magellanic Clouds.   Some clouds started moving in during this exposure, so it had to be ended after 8 min.

Centaurus A radio galaxy.  Seestar S50, 8 min, AI Denoise.

 These objects are most easily located by first finding the star Spica (Alpha Virginis) as it transits and then following a line downward to the horizon.

credit: SkySafariAstronomy.com

 The next morning:

18.3-d waning gibbous moon.  Vivitar Series 1 135mm f/2.3, Sony A7iii.