August star fields

Clear moonless nights have been rare so far this month. Last night over half the sky was still covered by clouds during early twilight. Later in the evening it was clear and calm with a measured sky brightness of sqml=21.49.  

Arcturus is the brightest star in the western sky in the late evening, hanging low over Bristol Head. Above Arcturus is the constellation Corona Borealis. This semi-circle of stars is the location of the recurrent nova T Coronae Borealis, also known as T CrB or the "Blaze Star". Based on its behavior prior to previous outbursts in 1866 and 1946, this nova is expected to erupt "any time now" (roughly, every 80 years). Current predictions are for November of this year or June of 2026.  In its normal state the star requires a small telescope to be seen. When it erupts it will likely be similar in brightness to Alphecca, the brightest star in Corona Borealis. 

The following images were obtained with an Olympus E-M1iii + Sigma 56mm f/1.4 lens + Hoya Softon filter.

Corona Borealis.  T CrB is circled. 

 

The constellation Cepheus lies on the edge of the northern Milky Way and is the location of a star of cosmological importance: Delta Cephei.  This star was one of the first identified of the class of variable stars now known as "Cepheids".  The pulsation periods of these stars are directly related to their intrinsic brightness, and the distance to this type of star can thus be inferred simply by measuring its period.  Observations of these stars provided the first measurements of the distance to other galaxies and helped establish our knowledge of the scale of the universe.

Delta Cephei is circled.

 The orange star top center in this image is Mu Cephei, also known as the "Garnet Star".  It is one of the largest and most luminous stars in our galaxy.

 Another significant Cepheid variable is Eta Aquilae.  It was first recognized as a variable star about the same time as Delta Cephei.  Both of these stars are nearly the same distance from us at about 900 ly.

Eta Aquilae is circled.  Altair (Alpha Aquilae) is the bright star top left.

The Small Sagittarius Star Cloud (top center).  The Lagoon Nebula (M8), bottom.

The heart of the Milky Way.

The tail of Scorpius, with star clusters M7 and M6 near center image.

Sturgeon Moon

 A traditional name for the full moon of August is "Sturgeon Moon".  The exact time of the full moon was 1:56 am MDT on Saturday 09 August.  These photos were taken on the same date, but 20 hours later with the moon still 99% illuminated.  Equipment: AT60ED f/6 refractor + Olympus E-M5iii.

There was thick wildfire smoke on Saturday, and this colored the rising moon Saturday night.  There are several nearby (within 60 miles or so) wildfires, but Canadian smoke is apparently also a factor. 

Color-balanced to mitigate the smoke tinge: 

 Daylight color balance ("true color", sort of):

 

The moon through distant trees

The moon was not so much rising as it was sliding along the distant (about 1 mi) ridgetop.  The full Sturgeon Moon occurs on Saturday.  The current moon age is 12.6 days.

 

 

Smoky moon

 We are currently experiencing an influx of wildfire smoke, most likely from the Middle Mesa fire just south of the Colorado border near Navajo Reservoir. That fire is about 60 miles distant.  The campfire-like smell was obvious during a mountain-bike ride this morning, although the air clarity was still pretty good.  It became thicker and more obvious later in the day.  The rising moon this evening was colored a deep golden hue by the smoky haze.

 

Quarter-plus moon last night

After a very windy afternoon the evening was calm, with just a few clouds floating by.  The moon was just past first quarter, at 8.8 days.  

Celestron C8 + Sony A7iii.

 

Clavius is the crater at bottom left with the dark floor and two interior craters.