The Monthly Sky

By Tom Lugar

SEPTEMBER 

Prominent Constellations

 Triangulum, Andromeda, Pisces, Pegasus rising in the east; Cygnus,Vulpecula, Delphinus, Lyra, Aquila, Scutum, Sagittarius, Capricornus in the south; Draco, Cepheus, Cassiopeia in the north; Bootes, Hercules, Ophiuchus, Scorpious, Libra in the west.

September Star Chart – Click on the link to the left for a star chart by Sky Maps. On the site, scroll down and click on the Month Star Chart listed under Northern Hemisphere. The chart is in a PDF format and prints well. Note that it is two pages and use zoom at 125x or 150x for better resolution.

Planets

      Evening Sky          Midnight          Morning Sky
 Saturn  - west        Jupiter - southeast         Jupiter - west
 Mars      - west        Uranus - southeast         Uranus - west
 Venus    - southwest      Neptune - south       Mercury - east   
 Jupiter  - east         

Mercury: Best dawn apparition of the year; becomes visible in binoculars during the second week of September.  By September 13, visible to the naked eye a half hour before sunrise 8 degrees above the eastern horizon. By September 16, Mercury will be +0.2 magnitude; on September 19, -0.4 magnitude and 7.2″ disk, half lit. 

Venus:  Reaches peak brightness late in the month, -4.8 magnitude; Venus’s crescent phase lengthens and thins throughout the month.  However, Venus will be very low in the west southwest shortly after sunset and atmospheric turbulence will blurr the crescent phase as observed with a telescope.

Mars:  Magnitude +1.5, disk 4.2″; Mars is a little higher and sets a little later than Venus after sunset and is hard to view without binoculars.

Jupiter:  Jupiter reaches opposition on September 20; magnitude -2.9 and located south of the Great Square of Pegasus; disk is 49″.  This is Jupiter’s closest approach to Earth between 1963 and 2022.  Uranus is <1.5 degrees north of Jupiter all month; minimum separation of 0.8 degrees on September 18.

Saturn:  Visible in binoculars low in the west far to the right of Venus after sunset.  By mid-month, Saturn is too close to the Sun to observe.

Uranus: <1.5 degrees north of Jupiter all month and only 0.8 degrees from Jupiter on September 18; magnitude 5.7 and 3.7″ disk and a pale greenish-blue color.

Neptune:  Well above the horizon at dusk in the northeastern corner of Capricornus; high in the south by late evening; +7.8 magnitude, 2.3″ disk.

Pluto:  In Sagittarius, needs at least an 10″ scope  and very dark skies to spot; 14 magnitude, 0.1″ disk.  For a finder chart go to www.skyandtelescope.com/pluto.

Comets

Comet 103P/Hartly:  Passes through Cassiopeia; expected to reach 10th magnitude by late September.  A finder chart is in Astronomy Magazine, September issue, p. 42.

 

Events

Sept. 1:  Alpha Aurigids Meteor Shower peaks before dawn; last quarter moon will interfere; 6 per hour.

Sept. 7: Moon at Perigee, closest approach, 221,948 miles.

Sept. 21: Moon at apogee, farthest distance, 252,379 miles.

Sept. 22:  Autumnal Equinox, fall begins.

  

Jupiter Shadow Transits

Observing Evening, pm to am              Moon ShadowTransit Times, EDT

                9/3 to 9/4                                     Europa:    3:32 am start, 6:17 am end

               9/6 to 9/7                                                Io:  12:52 am start, 3:07 am end

               9/10 to 9/11                           Ganymede:    7:53 pm start, 10:59 pm end

               9/13 to 9/14                                             Io:    2:47 am start,  5:02 am end

               9/14 to 9/15                                  Callisto:    2:58 am start,  4:03 am end

                9/15 to 9/16                                            Io:     9:15 pm start, 11:30 pm end

              9/17 to 9/18                            Ganymede:     11:55 pm start, 3:00 am end

               9/21 to 9/22                                  Europa:    10:00 pm start, 12:45 am end

               9/22 to 9/23                                            Io:    11:10 pm start,  1:25 am end

             9/28 to 9/29                                    Europa:     12:36 am start,  3:20 am end                                                 

               9/29 to 9/30                                            Io:       1:06 am start,  3:21 am end

  

  
CURRENT MOON

CURRENT MOON

Lunar phases

Full - 9/23, Last Quarter - 9/30, New Moon - 9/8, First Quarter - 9/15

 

Deep Sky Objects

Best Nights to Observe: September 1 – 13.

NGC 2276:  Galaxy in Cepheus, multiple arm spiral, 11.4 magnitude, 2.5’ x 2’ halo.

NGC 7510:  Open Cluster in Cepheus, 7.9 magnitude, 4’, triangular arrangement of 25 stars most between 10 and 12 magnitude; 6,800 l.y.

NGC 7023:  Reflection Nebula in Cepheus, “The Iris Nebula”, consists of countless dust grains each only aq few thousandths of a micrometer across that reflect the light of a 7 magnitude star at tye nebula’s center; 10’ halo seen with a large aperture scope; 1’ halo in smaller apertures.  Since it is a reflection  nebula, OIII and UHC filters will not enhance.  At a dark site and with a 12”+ scope, bright and dark lanes can be seen.

NGC 7142:  Open Cluster in Cepheus, 9.3 magnitude, made up of faint stars from 12 magnitude and fainter; 6,000 l.y. distant; 4.3’ wide field.  A 10” scope will show 35 stars across a background glow of fainter stars; 60 total stars; 12’ expanse in a larger aperture scope.

NGC 7139:  Planetary in Cepheus, 13.3 magnitude, 78” ghostly disk; appears circular with a diffuse edge; central star is 19 magnitude; an OIII or UHC filter will enhance.

NGC 6939:  Open cluster in Cepheus, 7.8 magnitude, 100 stars of 12 magnitude and fainter in a 10’ area; 40’ NW of NGC 6946; fan shaped grouping; use 130x for better resolution of cluster components; 4,000 l.y. distant.

NGC 7510:  Open Cluster in Cepheus, 7.9 magnitude, 4’ wide triangular arrangement of 25 stars most between 10 and 12 magnitude; two parallel rows of the cluster’s brightest stars dominate the grouping; 6,800 l.y. distant.

IC 1396:  Open cluster and faint emission nebula in Cepheus; 5 deep sky objects within a single field <1.5 degrees wide. The grouping includes a stunning red star (μ Garnet Star), double Σ 2819, triple star Struve 2816 and large open cluster IC 1396 set against a glow of a large faint nebula.  The entire grouping can be seen in a 4” scope with a low power eyepiece at a dark sky site.  A UHC filter will enhance the nebula.  The group is also called Trumpler 37 (from a photo taken at Lick Observatory; 2,600 l.y. distant.

NGC 40:  Planetary in Cepheus, 12.4 magnitude, 40” x 30”l; high surface brightness allows higher magnifications to be applied depending on seeing conditions; 11.0 magnitude central star; responds well to a OIII or UHC filter; oval disk with bright central star; interior appears mottled, bluish-green color.

M52:  Open Cluster in Cepheus, 6.9 magnitude, dim and small, 200 stars; 5,000 l.y. distant.

NGC 6946:  Galaxy in Cepheus, spiral, slightly oval, 8.8 magnitude, 11’ x 10’, tiny nucleus, several broad knotty arms; 19 million l.y. distant.

IC 1470:  Emission nebula in Cepheus, 12 magnitude, belongs to our galaxy’s Perseus spiral arm, 11,000 l.y. distant; 1.2’ x 0.8’.  With a large aperture scope at 200x, the nebula appears bright, 0.5’ across with a fainter extension to the SE; comet shaped; needs a dark sky site and at least an 8” scope to view.

NGC 7380:  Open cluster in Cepheus, 30 stars, 7.2 magnitude, 12’ wide, 7,200 l.y. distant.  The cluster is embedded in a very faint emission nebula (Sharpless 2-142); an OIII filter will slightly enhance the nebulosity; stars are mostly 9 and 10 magnitudes; ‘V’ shaped grouping; nebula is 20’ wide.

NGC 6811:  Open Cluster in Cygnus, 6.8 magnitude, 75 stars in a 20’ area; curving chains of stars resembling a human figure or Greek letter omega; 4,000 l.y. distant; stars 10 magnitude and fainter; relatively large and faint and without a central concentration of stars.

NGC 6834:  Open Cluster in Cygnus, 7.8 magnitude, 60 stars in a 7’ area; faint; straight line of 5 stars oriented east-west with many additional faint stars appearing behind this group as seen in large aperture scopes.

NGC 6894:  Planetary in Cygnus, “The Diamond Ring Nebula”, 12.3 magnitude, 42”; When using an OIII filter with a large aperture scope, a ring structure can be seen; scopes smaller than 8” show only a hazy disk with a diffuse edge.  With a 12” scope, the dark 20” center appears.  With a 16”+ scope, a faint star NW of the ring’s center appears; 3,400 l.y. distant; smokey-gray disk, wide ring and patchy.

Barnard 145:  Dark Nebula in Cygnus, elongated anf triangular, just west of NGC 6888; stands out well in the star field.

NGC 7000:  “North America Nebula” in Cygnus, use a UHC filter with the naked eye to observe from a dark site; spans more than 2o which gives small aperture, wide field scopes an advantage when viewing; magnitude 4.0; an OIII or UHC filter works well at moderately light polluted skies; at a very dark site, a filter will not be necessary. 

NGC 6826:  ‘The Blinking Planetary ’in Cygnus, 8.8 magnitude, 27’x24’, 5,100 l.y. distant, 10 magnitude central star.  Using 150x, if you look straight at the central star, the surrounding nebula will seem to fade.  But if you use averted vision and glance a bit to one side, the nebula will brighten again.  Switching your gaze back & forth creates the impression of blinking (the soft light of the nebula is falling upon areas of the eye’s retina with different sensitivities to light).  An OIII filter reveals a faint outer region of nebulosity beyond the bright greenish disk.

M29:  Open Cluster in Cygnus, 6.6 visual magnitude, 6’, 3,700 l.y. distant. Looks like a miniature dipper or tiny Pleiades, compact grouping, one of the least impressive open clusters in the Messier Catalog.

NGC 6994/995/6960: Veil Nebula in Cygnus, beautiful, ghostly tendril arcs in three areas, supernova remnant of a 30,000 years ago explosion, 1,800 l.y. distant, 2.9 degree expanse, you need a dark site, an OIII filter and a low power wide angle eyepiece to view this object at its best.  One of the arcs, NGC 6960, harbors a naked eye star, 52 Cygni. The star is a foreground object at 150 l.y. and thus not associated with the emission nebula.  The delicate wisps take on an almost ghostly surrealistic appearance in a 16” or larger scope with an OIII filter and dark site.

M39:  Open Cluster in Cygnus, 4.6 magnitude, 31’.  Since the cluster spans ½ degree, it requires a low power view to fully appreciate, around 25 stars of magnitudes 6 to 10 and many fainter stars, 800 l.y. away.

NGC 6819:  Open Cluster in Cygnus, a butter-fly-shaped group of faint stars with a double star on the lower right (mag. 7.3), 100 stars 11.5 to 15 magnitude in a 5’ area, 7,500 l.y. distant.

NGC 6888:  ‘Crescent Nebula’ in Cygnus, a shell of gas and dust pushed away from v1770 Cygni, a hot mag. 7.5 Wolf-Rayet star.  A OIII or UHC filter will enhance the nebula, difficult to see in a small aperture scope, faint, large and irregular, to bring out the crescent shape, use a 16” scope or greater and an OIII filter, 18”x13”, 5,000 l.y. distant, magnitude 8.

NGC 7008:  Planetary in Cygnus, 10.7 magnitude, 86”, fat tightly curved arc opening towards the SE. It has brighter patches NE and SSW; the northern patch being more intense.  The central star is visible and another star is embedded in the arc East-NE of center, an OIII filter shows more nebula in the oval but the filter also hinders the view of fainter stars.  The central star is a close binary with components of roughly equal brightness.  The double is 9.3 and 10.2 magnitude at 18” separation.

NGC 7062:  Open Cluster in Cygnus, 8.3 magnitude, 30 stars of 12 to 15 magnitudes.  The group is a 5’ oblong running East-SE to West-NW, 30 stars can be seen in a 10” at 165x but only a faint glow is seen in small apertures.

NGC 6866:  Open Cluster in Cygnus, 7.6 magnitude, 10’, 4,700 l.y. distant, 30 stars can be seen at 90x, faint to very faint stars, 80 stars are visible in a large scope (10” or greater), more than half the stars are between 10 and 14 magnitude.

NGC 7606:  Galaxy in Aquarius, 10.8 magnitude, 4.4’ x 2.0’, spiral.

NGC 7293:  Planetary in Aquarius, ‘Helix Nebula”, 7.3 magnitude; among the nearest planetaries; needs an OIII filter to observe; very faint, 15’ x 12’.  The planetary is large and spread out and thus has a low surface brightness making it difficult to see without an OIII or UHC filter.  With a 4” scope, a filter will reveal its ring structure; a 10” scope will bring out the slightly brighter concentrations on the north and south edges.

NGC 7492:  Globular in Aquarius, very faint and sparse, 11.4 magnitude, 4’ wide; needs at least an 8” scope to spot; a 12” scope can bring out a half dozen of the brightest members against a pale glow; all members are fainter than 15 magnitude.

NGC 7392:  Galaxy in Aquarius, 11.8 magnitude, 1,5’ x 1’, faint, just south of NGC 7184 in the same medium power field.

NGC 7135:  Galaxy in Aquarius, 11.3 magnitude, 3.0’ x 2.1’, faint, round, has some central core brightening.

NGC 7130:  Galaxy in Aquarius; in same medium power field to the west of NGC 7135; faint haze, smaller than 7135.

NGC 7009:  Planetary in Aquarius, ‘Saturn Nebula’, magnificent sight through any size scope, 8.3 magnitude, 40” x 30”.  At 250x, the central star at 11.7 magnitude is visible; use a UHC filter to enhance.  The planetary resembles Saturn because it has thin extensions at either end of its disk which resemble Saturn’s rings.  The wings extend 15” from the ends of the oval disk which itself is 25” long; bluish-green tint.  An 18” scope at high power will reveal a small, hollow disk placed inside the fainter shell of the main disk.  The planetary is 1.5 degrees west of 4.5 magnitude Nu (μ).

NGC 7172, 73,74,76:  Quartet of galaxies in Aquarius also known as Hickson 90.  7172 is 11.8 magnitude and 2.8’ x 1.4’, small and moderately bright and elongated east-west.  The system lies at a distance of 90 million l.y. The other three galaxies are clumped into a region 2’ across and faintly visible in a 13” scope.

M2:  Globular cluster in Aquarius, 6.4 magnitude, brilliant, 8’ diameter halo, core is well compressed and the star count drops off quickly outside the bright center, in a 10” scope numerous 13 and 14 magnitude stars come into view and the cluster’s size grows to 7’, 35,000 l.y. away.

M72:  Globular Cluster in Aquarius, 9.3 magnitude, in a 12” scope  it is 4’ across and reveals a faint haze of stars that are broadly concentrated but difficult to resolve, 53,000 l.y. distant, M72 is one of the 5 retrograde clusters that orbits the Milky way Galaxy against its direction of rotation.

M73:  Actually an asterism of 4 stars in Aquarius and not an open cluster; an equilateral triangle of three 10 and 12 magnitude stars with a fainter companion to the west packed into an area only 1’ across.

NGC 7180:  Galaxy in Aquarius, 12.6 magnitude, 1.5’x 0.75’, located just south of NGC 7184 in the same medium power field.

NGC 7184:  Galaxy in Aquarius, 11.2 magnitude, 6.5’x1.4’, the center is sharply concentrated and slightly brighter than the surrounding glow.  In a 16” scope, arms become apparent especially to the east of the core, two much fainter galaxies (NGC 7180 and 7185) are to the north in the same medium power field.

NGC 7103:  Galaxy in Capricornus, brightest member of a galaxy group that lie in a chain to the north of 7103, faint, 12.6 magnitude, 1.4’ x 1.2’, lightly concentrated core.

Palomar 12:  Globular cluster in Capricornus, 2 degree NE of NGC 7103, very faint, 11.7 magnitude, 2.9’; 60,000 l.y. distant.  A 13” scope will bring out a faint uniform haze just over 1’ across.

M30:  Globular Cluster in Capricornus, bright, 7.3 magnitude, stars as bright as 12 magnitude, a 6” scope resolves the core, a 12” scope shows a swarm of hundreds of star out to a diameter of 8’ with a broadly concentrated center, stars are 12 – 16 magnitude.

NGC 6907:  Galaxy in Capricornus, 11.1 magnitude, 1.75’ x 1.25’, faint, appears as a one-armed spiral in small apertures, exhibits a barred-spiral structure in a 12” or greater scope, bar is oriented East-West.

NGC 6903:  Galaxy in Capricornus, 11.9 magnitude, 1.5’ diameter halo.

NGC 7245:  Open Cluster in Lacerta, 9.0 magnitude, 7’ extent.  In a 10” scope at 115x, this cluster is very rich in aint stars; 70 stars, 12.5 magnitude and fainter; use 150 to 200x.

IC 1442:  Open Cluster in Lacerta, 9.1 magnitude, 5’; 22’ SE of NGC 7245.  In a 10” scope at 115x, about 30 stars can be seen of 11.0 magnitude and fainter.

NGC 7296:  Open Cluster in Lacerta, 9.7 magnitude, 36 stars of 12-13 magnitude in a 4’ area; 1o east of β.

NGC 7209:  Open Cluster in Lacerta, 6.7 magnitude, 24’ wide, In a 10” scope 100 stars 11 to 12 magnitude can be seen.  Many stars are arrayed in meandering chains; 3,000 l.y. distant.

NGC 7243:  Open Cluster in Lacerta, 6.4 magnitude, 21’, in a 10” scope, 75 stars can be seen in a very irregular grouping with patches and gaps.  Stars are 9 magnitude and fainter; 2,800 l.y. distant.

IC 5217:  Planetary in Lacerta, 11.3 magnitude, 8” x 6”, stellar looking, use an OIII filter; in a 10” scope at 170x it appears as a tiny, slightly oval disk with a robin’s egg blue color; 14.0 magnitude central star.

NGC 7223:  Galaxy in Lacerta, 12.2 magnitude, 1.5’ x 1.0’.

IC 1434:  Open Cluster in Lacerta, 9.0 magnitude, 7’; in a 10” at 115x, this cluster is very rich in faint stars.  The cluster contains 70 stars of 12.5 magnitude and fainter; use 150 to 200x.

NGC 6950:  Open Cluster in Delphinus, 14’ across, sparse cluster of 18 stars in the shape of an open umbrella with a cane-like handle; this may not be a true cluster.

Poskus 1:  Asterism in Delphinus, “The Flyswatter” or “Mandolin”; stars of magnitude 11.5 to 12.8; shows up nicely in a 10” scope at 70x; 6.5’ long; 4 stars make up the handle; 15’ NW of γ (Gamma); pointed out to Sue French by Bernie Poskus.

NGC 6928:  Galaxy in Delphinus, 12.6 magnitude, spindle 1’ long and 0.3’ wide; very faint, a little mottled and brighter in the center.  There are two very faint companions nearby: NGC 6930 at 13 magnitude, elongated, 4’ SSE of 6928 and NGC 6927: 13 magnitude and 3’ to the west of 6928.

NGC 6891:  Planetary in Delphinus, 10.5 magnitude, bluish-green 15” disk, tiny but has a high surface brightness, 12.4 magnitude central star.  Large aperture scope (>12”) may show glimpses of the faint, 74” diameter, outer halo and the bluish color of the central disk; 7,200 l.y. distant..

NGC 6905:  Planetary in Delphinus, magnitude 11.1, ‘Blue Flash Nebula’, 40” x 35” disk.  The central star twinkles in and out of resolution depending on seeing conditions.  A 10” scope is needed to spot the14 magnitude central star as well as the bluish color.

NGC 7006:  Globular Cluster in Delphinus, 10.5 magnitude, 1.75’ halo, the most distant globular known, fuzzy spot in a small aperture; mottling starts to show up in 12”+ apertures, 113,000 l.y. distant..

NGC 6934:  Globular Cluster in Delphinus, 4’ halo, 8.7 magnitude; in an 8” scope and high magnification, the cluster appears small, round and slightly mottled around the edges.  A 12”+ aperture shows it to be oval shaped and partially resolves some of the stars.

 

Double stars

δ Cepheus:  Variable double star, 4.4-3.5 and 6.3 magnitudes at 41” separation, gold and blue, similar to Albireo.

ξ Cepheus:  4.4 and 6.5 magnitudes at 7.9” separation, both white.

μ Cepheus:  Herchel’s ‘Garnet Star’, carbon star, deeply colored; it will look yellowish-orange in a large scope and deep blood red in smaller apertures.

ο Cepheus:  5.0 and 7.3 magnitudes at 3.3” separation, topaz, gold

β Cepheus:  3.2 and 7.9 magnitudes at 13.3” separation, white, blue.

Σ 2903 Cepheus:  7.1 and 7.8 magnitudes at 4.2” separation, both reddish-orange.and 19.9” separations.

Struve 2816 Cepheus:  Triple, 5.8, 7.7, 7.8 magnitudes at 11.7’ 

Kappa (κ) Delphinus:  Triple, 5.1 and 11.7 magnitudes at 28.8” separation primary pair, yellow, yellow and reddish.5.

Gamma (γ) Delphinus:  4.3 and 5.1 magnitudes at 9.6” separation, yellow, greenish.

Alpha Capricornus:  Wide double-double, 3.6 and 4.2 magnitudes at 378” separation and each of these primary stars is a double: 3.6 and 9.5 at 154.6” and 4.2 and 9.0 at 45.4” separation, primaries are yellow, yellow.

Beta Capricornus:  3.4 and 6.2 at 205” separation, orange-yellow, blue.

Sigma (σ) Capricornus:  5.5 and 9.0 magnitudes at 55.9” separation, yellow, pale blue.

RT Capricornus:  Carbon Star, 4 degrees SW of Omicron (ο), variable, 7-11 magnitude.

Omicron (ο) Capricornus:  5.9 and 6.7 magnitudes at 22” separation, bluish-white, blue.

Zeta (ζ) Aquarius:  4.3 and 4.5 magnitudes at 2.1”, needs at least 200x to split, both white.

(ψ) Aquarius:  4.5 and 10.8 magnitudes at 49.6” separation, pair of orange stars with a greenish field star that looks like Uranus.

41 Aquarius:  7.1 and 7.1 magnitudes at 5.0” separation, gold, blue.

4 Aquarius:  5.0 and 7.0 magnitudes at 13” separation, white, yellow-blue.

β) Cygnus:  Albireo, beautiful, 3.1 and 5.5 magnitudes at 34.3” separation, golden yellow, blue.

Delta (δ) Cygnus:  2.9 and 6.3 magnitudes at 2.5” separation, both bluish-white, use 200x to split.

61 Cygni:  5.2 and 6.1 at 30.3” separation, orange, orange. This system holds a special place in the history of Astronomy because it was the first star to have its distance measured in 1838 by Friedrich Bessel using the Parallax Method.  He measured the distance as 10.3 l.y. with the modern value at 11.4 l.y.

Omicron (ο) Cygnus:  Triple: 3.8, 4.8 and 7.0 magnitudes, yellow, light blue, light blue, primary pair at 337.8” and third star at 106.8” from primary pair.

16 Cygnus:  6.0 and 6.2 magnitudes at 40” separation, both yellow; resembles a distant pair of car headlights.