Late Summer Skies

Galaxies and Nebulae

On the clear night of September 12th most of my neighbors' troublesome lights were turned off. The sky was slightly hazy, but cloud free conditions are so rare this time of year that I decided to try some Seestar imaging.

Galaxy NGC7331 in Pegasus and other nearby galaxies were good candidates for Seestar's mosaic mode. The following 25-minute exposure successfully captured nine galaxies, but all besides NGC7331 at top left were too small to show internal detail. These small galaxies only show up as fuzzy smudges in Seestar's wide field of view. View the next image at full size by clicking on it. In the enlarged image notice three small fuzzy spots to the left of NGC7331 at top left. Notice also the group of small fuzzies on the lower right. These are the five galaxies of Stephan's Quintet. (It's difficult to see any of these small galaxies unless the image is viewed at full size.)

The next labeled image identifies previously mentioned galaxies. In the Stephan's Quintet group on lower right the presence of two foreground stars is distracting. Only the small fuzzy things are galaxies. One of the galaxies has a double nucleus. Four of these galaxies are gravitationally interacting. 

Sky and Telescope magazine's October issue featured an article about visually observing a pair of dark nebulas called Barnard's E in the constellation Aquila. These clouds of gas and dust block starlight coming from behind and appear black against background stars. I usually have no hope of seeing these visually through an eyepiece, but Seestar reveals what my eye can't see. The next 15-minute exposure shows c-shaped dark nebula Barnard 143. The c-shape is the top of Barnard's E.

In order to capture the entire E, I used mosaic mode to widen the field. In the next 21-minute exposure dark nebula Barnard 142 now appears below Barnard 143 and completes the E.

The E-shape is more apparent in a reduced view below.

The September 12th observing session ended when a rising Moon brightened the hazy sky.

Six days later on September 18th the cloud free sky was once again hazy. Some temporary ground fog was also present. Two nebulae high above diminishing ground fog looked like good targets. I began with the Heart Nebula, IC1805, in Cassiopeia. With light pollution filter engaged and mosaic mode employed I was able to fit the entire heart shape within the field of view in the following 60-minute exposure. The heart-shaped outline is definitely visible, but somewhat dim. The heart shape's visibility varies depending on what screen the image is displayed upon. In the heart's center, accompanied by a bright nebular patch, is the star cluster that powers the heart's emission. In the upper right is another nebula, NGC896, sometimes called the Fish Head Nebula. 

My final target was the North America Nebula, NGC7000, in Cygnus. It was well after midnight when I began the following mosaic mode 66-minute exposure with light pollution filter engaged. I was able to catch some sleep while Seestar successfully kept running. "Mexico", the "Gulf of Mexico", and "Florida" are clearly visible, but the "Midwest" is missing.

I'm continually amazed at what little Seestar can produce!

Outer Planet Surprise

Unexpected Results

In the predawn hours of August 23rd, just out of curiosity, I decided to point Seestar at Neptune. Expectation was low because Seestar isn't designed to produce spectacular detailed planetary images. The 2-minute exposure I took at 4:02am EDT showed an overexposed blob. Upon closer inspection, however, I noticed a definite spherical bump on one side of the blob. Could this be one of Neptune's moons? The situation is shown in the next picture, a cropped image enlarged to three times normal size.

The spherical bump was, indeed, the Neptunian moon, Triton! At the time this image was captured Triton was only 16.3 arc seconds from Neptune - far enough away to escape the overexposed Neptunian blob. A better optical system and exposure might have produced something like the following idealized picture from planetarium program Sky Safari 6.

You can see how Triton in my Seestar image is in the correct orientation relative to Neptune. Amazing! I actually detected a moon of Neptune! The angular diameter of Neptune this day was 2.4 arc seconds, so the approximate 16.3 arc second radius of the overexposed blob was much bigger than Neptune's true size. Triton shines at magnitude 13.7. Another Neptunian moon, Nereid, at magnitude 19.3 was too dim to detect. 

Almost three weeks later at 10:18pm EDT on the evening of September 12th I took another 2-minute Neptune exposure. This time Neptune's overexposed blob seemed slightly less spread out, as you can see in the next cropped image enlarged three times.

By September 12th Triton's orbital motion had clearly brought it to a new position relative to Neptune. This was confirmed by the idealized Sky Safari 6 image below.

After capturing Neptune before sunrise on August 23rd I also imaged Uranus at 5:13am EDT with a 15-minute exposure. Once again, I was amazed to see two possible Uranian moons near the overexposed Uranus blob. The next picture, enlarged two times, clearly shows possible moons to the right of Uranus.

I wondered if these objects were really moons. Perhaps they were two background stars that happened to be near Uranus. So, I checked Sky Safari which reproduced the following arrangement of moons near Uranus at 5:13am on August 23rd. Titania and Oberon on the right seemed to have the correct orientation, but Ariel and Umbriel also had the correct orientation.

To resolve the ambiguity, I checked angular separations from Uranus. Titania was 30.2 arc seconds from the planet and Oberon was 41 arc seconds away. Ariel was only 13.2 arc seconds away and Umbriel was 18.1 arc seconds away. It seems like Titania was almost at the outer edge of the overexposed planetary blob because Umbriel at magnitude 15 would be too dim to see. Therefore, I think the situation is accurately represented by the following picture.

The area within the red circle (including the wide red boundary) is the overexposed planetary blob. Uranus' actual angular diameter this night was 3.6 arc seconds, and the blob's radius was approximately 27 arc seconds. Three Uranian moons are apparently hidden within the blob. Therefore, Titania and Oberon are the moons captured in my Seestar image. 

Almost a month later on September 19th I took a 4-minute exposure of Uranus at 1:11am EDT. Once again, two moons appear to the planet's right, as you can see in the next cropped image enlarged twice. The arrangement is slightly different from the situation on August 23rd.

Sky Safari reveals that Titania now appears below Oberon as shown in the next picture. (The other three moons, as before, are invisible within the overexposed blob.) Titania has an 8.71-day orbital period and Oberon has a 13.46-day orbital period. Between August 23rd and September 19th slower Oberon had gone around Uranus twice, while faster Titania had gone around slightly more than three times appearing now below Oberon. Titania and Oberon both shine at near 14.0 magnitude. Between August 23rd and September 19th Titania's separation from Uranus went from 30.2 to 31.5 arc seconds., and Oberon's separation went from 41 to 41.8 arc seconds.

Honestly, I'm rather astounded that little Seestar could reveal these distant planetary moons! 

Conjunction Near Dawn

Beautiful Morning Scene

Sometimes I get lucky! There were no clouds near the northeastern horizon before sunrise on September 19th, and no trees blocked the view. A conjunction of the crescent Moon, Venus, and the star Regulus was clearly visible from my back patio. Just before twilight began the next pictures show the scene. (Click on images to view at full size.)

 

At this time Venus was just 42 arc minutes from the Moon and 34 arc minutes from Regulus. (Regulus is the brightest star in the constellation Leo.) These three were nearly along the same line of sight from Earth but, of course, the Moon is closer than Venus and Venus is closer than Regulus. The Moon was 1.29 light seconds away, Venus was 12.08 light minutes away, and Regulus was 79.3 light years away. Although Regulus is intrinsically much, much brighter than either the Moon or Venus, the star is so far away its closer companions outshine it.

As twilight deepened foreground trees added to the scene. 

I struggled with dew formation on my camera lens because I waited too long to install a dew heater. Nevertheless, I did manage to salvage a couple good pictures of this magnificent event.

 

Sunspot Outburst

Pleasant Observing Conditions

Pleasant and comfortable observing conditions existed on the morning of August 27th. Blue sky held no clouds, temperature ranged from 71 to 73 degrees, and only light breezes puffed from time to time. In addition, the Sun exhibited an attractive collection of sunspots!

Sunspots were mostly concentrated in the southeastern solar quadrant as shown in the next 9-panel disc mosaic. (Click on these images to enlarge for the best view.)

The large dark umbra of sunspot 4191 is near center. Others will be described below.

A few prominences around the limb can also be seen in the following enhanced disc mosaic.

The sunspot cluster in the Sun's southeastern quadrant was quite dramatic. The complex array can be seen in the following 2-panel mosaic.  

Closest to the top is the dual umbra of sunspot 4195. The lower 4195 umbra is split. White areas are regions of energetic emissions including a minor flare to the upper left of 4195. Nearest to the limb below are two umbras that seem to be fenced in by a curved dark filament. The upper umbra is sunspot 4202 and the lower one is 4204. All other complex structure to the upper right of the 4202/4204 filament "corral" is active area 4197. (Enlarge the image to see more detail.) Area 4197 is quite amazing! It features a curved arc with 5 separate umbras, two more umbras to the lower left of the curve, magnetic arcs connecting the two umbra arrays, and some white high energy emissions. Quite a showpiece! 

In addition to the nice sunspot array, the southeastern quadrant also featured a prominence and a "filaprom". The transition from prominence to filament showed up nicely near bottom of the next image.

Finally, examine the neighborhood of large sunspot 4191 at full size below. Magnetic arcs seem to swirl around the major umbra like a whirlpool! A smaller split umbra accompanies the larger one on the left. Magnetic arcs connect the two small umbras of sunspot 4200 near the image bottom. 

This observing session was happily productive!

August Seestar

Summer Celestial Scenes From My Backyard

Although cloudless sky was a little hazy on August 16th, none of my neighbors had turned on glaring spotlights. It seemed like a good opportunity to use Seestar, even if conditions were imperfect.

In spite of haziness, I was able to capture a nice mosaic image of galaxy NGC6946 and open cluster NGC6939 together in the same field of view. These objects in the constellation Cepheus are separated by only 39 arc minutes (0.65 degrees). The following image is a 45-minute exposure with detail good enough to be viewed at full size. The star cluster, only about 5,900 light years away, is a member of our own Milky Way galaxy. On the other hand, galaxy NGC6946, about 22 million light years away, is far beyond the Milky Way. These objects just happen to be nearly along the same line of sight from our point of view.

I next tried to image nebulosity in Sagittarius. After engaging the light pollution filter I could only manage the following 30-minute exposure before increasing haziness made the sky milky white. At that point it was time to quit this August 16th session.

There are at least four named nebulae in the next picture. The most prominent red emission nebula just above center is IC1284. The dim red glow just to the upper right of IC1284 is another emission nebula, IC1283. The silvery white glow surrounding two stars in the center is reflection nebula NGC6595. Enlarge the image to see the faint presence of a tiny dark nebula within NGC6595's white glow. Another small white reflection nebula, NGC6589, is located to the upper right of NGC6595. Diffuse red Milky Way glow spreads across the bottom of the frame. As always, I'm disappointed by the dull red color produced by Seestar.  

A new Moon and clear sky beckoned on August 22nd. I began by targeting the Cave Nebula, Caldwell 9, in Cepheus using mosaic mode and the light pollution filter. Although I was able to get a 70-minute exposure, the nebula seemed dim. It might have been better to try the Cave Nebula alone without mosaic mode. The dark cave entrance does show up, but surrounding nebulosity is very faint.

Mosaic mode allows a field of view large enough to include the entire Andromeda Galaxy, M31, in Pegasus. My previous images of M31 included only segments which I unsuccessfully tried to blend together in a panorama. Mosaic mode allowed the whole galaxy to appear at once in the following 68-minute exposure. During this exposure a powerful neighbor light was suddenly turned on. I rushed inside to get a card table which can be set up to block the glaring light from hitting Seestar. Looks like the offending light didn't ruin this image of M31 and its two satellite galaxies.

Clear sky lasted well after midnight. I plugged a power cord into Seestar to recharge the nearly depleted battery and moved to a new target, the Pelican Nebula, IC5070, in Cygnus. The pelican's head and long beak extend diagonally downward from right to left in the following 60-minute exposure with light pollution filter. Bright blue star 57 Cygni sits to the left of the pelican's upper beak. Another bright star, 56 Cygni, is on the pelican's right side. The dull red nebula color is, again, disappointing.

With a few hours remaining before dawn I took a few images of planets Neptune and Uranus. A future post will describe the surprising details I saw!
 

 

Venus and Jupiter Dance

Conjunction Before Dawn

The two brightest planets had a close conjunction on August 12th. Three days before closest approach I took the following picture before dawn from my back yard patio at 5:44 am EDT on August 9th. Cloud free sky is rare here in southeastern Virginia, so I thought this might very well be the best conjunction image I would get. 

Venus (magnitude -4) is the brighter dot above dimmer Jupiter (magnitude -1.9). The planets were separated by 2.9 degrees. At this point in their orbits Venus was 10.14 light minutes from Earth, and more distant Jupiter was 49.68 light minutes from Earth.

Much to my surprise, the sky was clear again at 5:44 am on the next morning, August 10th. In the next image you can clearly see planet spacing had diminished. Venus was still above Jupiter, but the separation had diminished to 2.03 degrees. During the previous 24 hours Venus had receded from Earth to a distance of 10.19 light minutes while Jupiter had come closer to a distance of 46.61 light minutes.

What is happening here? We are looking from Earth toward Venus and Jupiter across the plane of the solar system. Near dawn the Sun is below the horizon, and the planets are west of the Sun above the horizon.

Earth, Venus, and Jupiter all orbit the Sun and we are viewing the conjunction from a moving Earth. When viewed from above the solar system (looking down on the Sun's north pole) all the planets are orbiting counterclockwise. They're all in separate nearly concentric curved lanes. Rapidly moving Venus (on an inside lane) is moving away from our slower moving Earth (on an outside lane). Venus is beginning to approach the Sun from our viewpoint, and we'll eventually see it pass behind the Sun. So Venus is receding from Earth, getting smaller, and nearing the dawn horizon as it approaches the (below horizon) Sun.

On the other hand, Earth (on an inside lane) is overtaking slower moving Jupiter (on an outside lane). Jupiter is getting closer to Earth as Earth catches up to Jupiter. From our point of view Jupiter had recently passed behind the Sun and is now swinging around its orbit increasing its angular separation from the Sun. So Jupiter is getting higher above the dawn horizon as it separates from the Sun. Venus and Jupiter are heading in opposite directions relative to the horizon. Venus starts out above Jupiter, but, eventually, Venus sinks and Jupiter rises, so they switch places. 

With naive optimism I hoped to show the daily decrease in separation over the next two days. Of course I should have expected disappointment. Annoying clouds ruined the view on August 11th! In the next image you can see a cloud gap. Unfortunately, Venus and Jupiter were located above the gap. 

Clouds again interfered on August 12th, the day of closest approach. This time, fortunately, the cloud deck was thin enough to allow bright planets to shine through. In the next picture you can see brighter Venus beginning to drop below Jupiter. The angular separation had now decreased to 52 arc minutes or 0.87 degrees!

The plane of Earth's orbit projected against the sky is called the ecliptic. On August 12th Jupiter was nearly in Earth's orbital plane - only 3.83 arc minutes or 0.06 degrees below (south) of the ecliptic. Venus was 55 arc minutes or 0.92 degrees below the ecliptic. This difference in ecliptic latitude accounts for nearly all the 52 arc minute separation. What about ecliptic longitude? Jupiter's longitude was 104.1 degrees and Venus'  nearly identical longitude was 104.28 degrees.

On August 12th Venus had receded further to 10.3 light minutes away and Jupiter had approached to within 49.46 light minutes of Earth. 

August 13th viewing conditions were hopeless. A low impenetrable cloud deck blocked everything. 

On August 14th conditions were similar to the previous picture, so it wasn't worth taking another picture of blank sky.

Before twilight on August 15th the dark sky was momentarily clear. I quickly took a photo and went inside to wait for twilight to grow. Only a few minutes afterward the sky became completely overcast! So the next image below was the best I could get on August 15th. You can see brighter Venus was now well below Jupiter. The angular separation had increased to 3.18 degrees. Venus had receded to 10.46 light minutes away and Jupiter's distance had decreased to 49.24 light minutes.

Clear twilight sky finally returned on August 16th. The planets had now separated further by almost a full degree to 4.13 degrees as shown in the next image. Venus receded to 10.51 light minutes from Earth and Jupiter, at 49.16 light minutes, continued to diminish its separation from Earth. 

While the sky was mostly dark before twilight on August 16th I used my camera's night mode to take the next picture.

The image scale above is wider than all previous pictures. You can see how the entire Venus/Jupiter planet dance took place within the constellation Gemini. Gemini's twin stars, Castor and Pollux, are left of the bright planets. (Pollux is below Castor.) Orion was rising above trees on the right. If you don't get up before dawn, you miss beautiful scenes like this one. I get up so you don't have to!

Before dawn on August 18th the Moon joined the planet dance. I used night mode again to capture the next image with the same image scale as the previous picture. A neighbor's unfortunate spotlight interfered some, but not enough to ruin everything.

It would have been nice to follow the Moon's approach toward the planets over the next three days, but completely cloudy skies made this impossible.

To see how the planets moved without cloudy interruptions I used Sky Safari 6 Plus to create an animation running from August 9th to August 20th. The animation steps forward one day at a time to show the predawn scene at 4:44 am EDT each morning. (To see the video properly click the full screen icon in the lower right on the video.) 

Notice how Jupiter lies almost exactly on the yellow line representing the ecliptic. The Moon makes an appearance in the last frame on August 20th making an attractive grouping with Venus and Jupiter. Also, notice how the stars get higher above the horizon each day as they rise approximately four minutes earlier each day due to Earth's orbital motion. 

It's fun to watch the solar system in motion when clouds don't interfere.

Sunspots Across the Sun

Brief Observing Window

I've waited two months for a suitable day for solar imaging. The dawn sky on August 9th was completely clear. Cloudless conditions promised to hold for a while, so I hurriedly set up equipment to take advantage of this rare opportunity. The temperature was in the low 70's when I began capturing images at 8:42 am EDT. There was no wind and seeing conditions were initially excellent.

My first task was to gather enough images to construct a mosaic showing features across the solar disc. On the following 19-panel mosaic seven significant sunspot umbras are visible along with a few white active areas and some filaments. (Click on the  image for an enlarged view.)

The major sunspot complex near the right limb contains sunspots 4165 and 4168. You can see complicated structure around this pair along with several white flare areas which were active during image capture. Examine other active areas in the enlarged image to see magnetic arches and a split umbra in sunspot 4169 left of center.

A beautiful prominence display added to the solar scene this day. The previous image was processed to make prominences more visible in the next image below. On the enlarged image you can see a small filaprom, the transition between prominence and filament, on the left limb above center. A double spike prominence on the lower left limb was changing while I gathered images. Several smaller spikes are on the right limb. 

After completing the disc mosaic above I made prominences brighter by increasing the camera's gamma value. The next four-panel limb mosaic shows prominences more clearly. In particular, notice the linear segment suspended high above the double spike prominence in the lower left.

The magnified image below shows the suspended prominence more clearly. When I first imaged this portion of the Sun only one spike was present. The next time I came to this spot there were two spikes. So these explosive emissions were happening on the scale of 10 minutes or so. Clouds prevented returning here to make a time lapse video of the eruption.

Another four-panel mosaic shows prominences on the Sun's right limb. 

While capturing the last image for the previous limb mosaic I noticed thin clouds encroaching from the west. Clouds and haze began to quickly build thereafter. The clear observing window had lasted only 41 minutes! Seeing also deteriorated drastically, so it was time to shut down. Such is life in southeastern Virginia.