Category: Astronomy

Four Planets in the Morning Sky

For several weeks the planets Mars, Jupiter, and Saturn have been visible in the same portion of the morning sky. These are all bright and easily visible even during twilight hours. Nestled in between these bright planets lies the minor planet Pluto.

Mars, Jupiter, Saturn, and Pluto.
Mars, Jupiter, Saturn, and Pluto.
Stellarium star chart showing positions of the planets in the morning sky.
Stellarium star chart showing positions of the planets in the morning sky.

So I thought it would be interesting to photograph Pluto. Pluto is much too faint (currently Mag. 14.3) for me to find with my camera/lens setup. However, Pluto and Mars passed very close to each other (~10 arc minutes, or less than the diameter of the Moon) on 23 March 2020 making it easier to find one based on the location of the other. Clouds forced me to shoot this image a day later on 24 March 2020, when they were farther apart.

Pluto and Mars.
Pluto and Mars.
Pluto.
Pluto.
Stellarium chart showing Pluto and neighboring stars.
Stellarium chart showing Pluto and neighboring stars.

I used Stellarium as a guide to hopping from one star to another—comparing the photographs with Stellarium star charts—until I finally located Pluto. As a magnitude 14.3 object, this was near the limit of what could be resolved with my Nikon 180mm AI-s f/2.8 lens shot wide open.

Images were shot at f/2.8, ISO 1600, and 30s. The best images were stacked to reduce noise. Post processing included large values of Unsharpen Mask to help sharpen the dimmest stars and Pluto—with the undesired side effect of creating halos around the brighter stars.

Check the video to see how much Mars moves in just 15 minutes.

I was able to capture four planets in the morning sky. In the previous post, I was able to capture four planets in the evening sky. It was a challenging project that I wanted to do and have now completed.

Maybe I should get a telescope.

Starlink cluster.
Starlink cluster.

Oh, one final point. Once again I was photo-bombed by a cluster of Starlink satellites. Sadly, the day is coming soon when night photography will be very difficult because of these satellites.

Objects in the Night and Twilight Sky—February 2020

The past few weeks have offered numerous opportunities for photographing objects in the twilight and night sky.

Venus and Mercury in the evening sky.
Venus and Mercury in the evening sky.

Above is a photograph showing the planets Venus (visible near the top of the image) and Mercury (located just below the center of the image). The glow of evening twilight on the horizon is reflected in the shallow waters of Mormon Lake.

Four planets and an asteroid.
Four planets and an asteroid.

Taken later on the same evening is a photograph showing four planets and an asteroid in a single frame. This was taken with a 24mm focal length lens to capture these solar system objects (SSO). I did this as a fun test to see if a wide-angle lens was able to capture these dim and distant SSOs. From top to bottom are the asteroid Vesta, Uranus, Venus, Neptune, and Mercury.

Zoomed-in crops (below) show the dimmer objects that are in the image above.

Zoomed in crops showing Vesta, Uranus, and Neptune.
Zoomed in crops showing Vesta, Uranus, and Neptune.

Before leaving that night I did a final wide-angle shot of the southeastern sky which included the constellation Orion as well as a portion of the winter Milky Way.

Wide-angle view of Orion and Milky Way.
Wide-angle view of Orion and Milky Way.
Pleiades star cluster.
Pleiades star cluster.

The following night I was out again to test my recently purchased Nikon 180mm ƒ/2.8 ED AIS manual focus lens. A few previous tests have shown that star images are pretty good at an aperture of ƒ/2.8 but much better at ƒ/4. At ƒ/2.8 there is just a hint of star spikes; at ƒ/4 they are quite prominent. This is a stacked sequence of images of the Pleiades star cluster. Image stacking was done with Starry Sky Stacker; histogram stretching was done with rnc-color-stretch.

Occultation of Mars.
Occultation of Mars.

On 18 February there was a Lunar occultation of the planet Mars. I had planned to get up early and drive to a dark location but an alarm failure meant I barely had time to get up and set up the gear on the rear deck of the house to start the sequence. Luckily, Flagstaff is a Dark Sky City and it was dark enough to get the shots. This is a sequence from just a few minutes before the Moon moved in front of Mars followed by a longer sequence after it reappeared.

Comet C/2019 Y4 (ATLAS)
Comet C/2019 Y4 (ATLAS)

Finally, Comet C/2019 Y4 (ATLAS) is in the northern sky making it an easy target—except that it is still very dim with a magnitude of about +12 at the time of this image. The still image is a stack of 49 images each 120 seconds duration at ISO 1600, 180mm, and ƒ/2.8. As noted above this lens is pretty good at ƒ/2.8 but better at ƒ/4. Because the comet is so dim I wanted the maximum light gathering ability so settled for an aperture of ƒ/2.8. Also in the image is M97 (“Owl Nebula”) and M108 (“Surfboard Galaxy”). The star Merak is part of the “Big Dipper.”

Also, there is an animation—made from the same images—showing the movement of the comet over a period of just under 2 hours.

Venus and Neptune in the Evening Sky

In late January, the easily visible planet Venus was located in the same part of the evening sky as the dimmer and distant planet Neptune. I’ve never tried to photograph Neptune but this pairing of the planets was a good reason to do so.

Venus and Neptune in the evening sky (2020-01-28).
Venus and Neptune in the evening sky (2020-01-28).

The first attempt was taken on the evening of 27 January (shown below) and I was limited to very short exposures as I was using a standard tripod. The second attempt was the following night from a better location and, more importantly, I was using my equatorial mount star tracker so that I could follow the stars (or planets) for longer exposures.

The image at the top is the second attempt. High, thin cirrus clouds were beginning to move in from the west and I was hoping that the clouds might make some of the stars more colorful. What I got was an amazing corona surrounding the very bright planet Venus while stars and the dimmer Neptune appeared relatively unchanged.

Venus and Neptune in the evening sky (2020-01-27).
Venus and Neptune in the evening sky (2020-01-27).

The image above is from the first night of shooting and shows diffraction spikes around Venus. Examing these two images you can easily see how far Venus has moved in one night by comparing the position of Phi Aquarii.

Photographing the North America Nebula

The North America Nebula has been on my To-Photograph list for a while. I had made one quick attempt previously to see whether I could actually resolve it with my Nikon 85mm f/1.8 lens. That was successful so I was ready to try again when the situation permitted.

I finally found the time, the right weather, and the right conditions. I shot a sequence of seven, 120-second exposures.

There are many star-stacking software packages available and I’ve often used DeepSkyStacker (DSS). More recently I’ve been testing StarrySkyStacker (a macOS-only app). The results have been pretty good.

The stacking complete, it was time to work on the histogram. Again, there are many histogram stretching packages. I’ve been evaluating rnc-color-stretch, available from Clarkvision.com. rnc-color-stretch is a set of scripts that calls the davinci application (not to be confused with the DaVinci Resolve video editing software).

North America Nebula (NGC 7000)
North America Nebula (NGC 7000)

The result is shown above. My next attempt at shooting this Deep-Sky Object (DSO) will be with my recently acquired Nikkor 180mm f/2.8 AIS manual focus lens.

A New-to-Me lens for Astrophotography

I recently acquired a used lens that I plan to use for astrophotography. The Nikkor 180mm f/2.8 ED AI-S is well-known as an excellent lens for this purpose—assuming, of course, you get a good copy of the lens.

Pleiades (M45).
Pleiades (M45).

Jerry Lodriguss, over at AstroPix, has this to say about the lens:

The Nikon 180mm f/2.8 ED lens is a legendary lens, and with good reason. It’s performance for normal daytime photography is simply outstanding. And it is pretty darn good for astrophotography also…

I have been looking at used copies of this lens on-and-off for several years but have never actually been excited enough to purchase one. That is, until I saw one listed in MINT condition for an extraordinary price. The lens was offered by Tempe Camera and the store was close enough that I could drive down there in a few hours. Off I went…

And the lens really was in Mint condition. After a bit of checking and a few test shots I bought it. Now it was time for testing. On my first night my results weren’t that great but I attribute that to the fact that it was COLD and my fingers weren’t very good at getting sharp focus and it was windy causing the camera to shake resulting in blurry images.

So, I headed back out again the next night. I sought a location without wind and at a lower elevation hoping for warmer temperatures. Well, it wasn’t warmer but there was no wind. And the results were pretty good. Comparing the results at various ƒ/stops (ƒ/2.8, ƒ/4.0, and ƒ/5.6) I could see how the image improved with smaller apertures. And a comparison with my very old Nikkor 80-200mm AI-S ƒ/4 showed that the 180mm was better than the zoom lens at equivalent apertures.

I’m pretty happy with the quality of the lens and the price I paid. Now all I need is some clear skies to get out and do some more shooting.