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Two snapshots of the ISS passing nearly in front of Mars

A week or so ago I saw that a series of visible International Space Station (ISS) passes were coming up for our area. While looking at the pass predictions I noticed that one of the ISS passes placed it almost in front of Mars at 9:00 pm local time on the 16th. A quick check with my astronomy program confirmed that the pass and Mars would be within the field-of-view (FOV) of the AT10RC telescope and ASI2600MC camera. Ok, I had to try to get a picture of that!

The AT10RC focal length (FL) is 2000mm and I normally add a 2x Powermate for planetary imaging. But I thought that 4000mm FL would reduce the FOV too much. But at 2000mm I didn't know how well the ISS would show up. So, not wanting to chance missing the ISS, I decided to use just the scope and camera for the set-up, no Powermate. I would use the planetary imaging capture program ASIcap to capture a video file during the time the ISS passes by Mars.

The predicted brightness of the ISS was somewhat higher than Mars. After centering the telescope's FOV on Mars, I adjusted the exposure time to 5ms to slightly underexpose Mars. With full frame (6248 x 4176) downloads the maximum frame rate for images this large was only about 2.5/second even with a USB3 connection to the camera. That meant that the system would be taking pictures at slightly less than a half-second apart. Hopefully that was going to be fast enough to catch the speeding ISS!

I started the video capture several seconds before the ISS reached Mars and continued a few seconds after it passed by. I thought I saw a blip on the screen and it turned out that two frames from the video had the ISS in them, one before passing Mars and one after passing. Somewhat surprisingly, the visibility of the main ISS features were not bad at all!

I combined the two video frames into this still image that shows Mars and the two ISS positions. This shows how much the ISS passed by Mars in less than a half second!  I was pleased to find out that a 2000mm FL scope and the 3.76um sized pixels of the ASI2600MC are good enough to capture a recognizable image of the ISS.

A favorite activity of visual astronomy is looking for distant galaxies. They are often hard to find and barely visible. "Faint fuzzies" is the term often used when looking at these.
Virgo-Coma Galaxy Cluster around M87
Galaxies tend to collect in clusters. A massive cluster is the Virgo-Coma cluster seen in this picture. While this is a relatively small area of the sky, not even a fist-full at arm's length, I lost count at over four dozen faint fuzzies in it. Anything in the picture that's not a point is a galaxy!
The distance to the galaxies in this cluster averages around 50 million light years. That means that the light captured in this picture has been traveling toward us for 50 million years! The galaxy in the center is M87, a monster with a super massive black hole in it's center. In fact, the first image of a black hole, published about a year ago, was the black hole in this faint fuzzy!

Do you remember the Great Conjunction of Jupiter and Saturn last December? That was a pretty cool event to watch. Well, a similar event is only a week away. This time it's a pairing of Jupiter and Mercury!
Jupiter Mercury Saturn
Mercury Moves Toward a Jupiter Conjunction
Since December, Jupiter has been slowly pulling away from Saturn. They've both rounded the Sun and are now in the morning sky. Mercury has been rising in our sky and is now in between Jupiter and Saturn. This photo was taken this morning about 30 minutes before sunrise and shows how all three planets are arranged.
During the next week Mercury will appear to speed toward Jupiter and on the mornings of Thursday the 4th and Friday the 5th the two planets will only be about a full-moon width apart!
If you're up during the morning twilight, look very low to the southeast horizon 45 to 30 minutes before sunrise. You'll actually be able to see Mercury getting closer to Jupiter every morning!

Winter Milky Way in H-Alpha Light

When you look up at the night sky, what do you see? Stars of different brightness and color, the Moon and some planets, constellations, and maybe the subtle glow of the Milky Way?

As amazing as our eyes are, they aren't all that sensitive to dim light. The night sky is actually loaded with objects we can't see. However, the invisible sky is easily seen with long camera exposures. A special type of light, Hydrogen-Alpha (Ha), is a deep red color and emitted by stars and nebula when their hydrogen gas is energized. This picture was taken with a Ha filter to more prominently show these nebulous regions.

Imaged almost from horizon to horizon, this mosaic of the Milky Way during our winter season is huge. But so are the nebula in it. For example, the bright round nebula just left of top center is the Rosette Nebula and it's more than twice the diameter of a full moon! Many are way larger than it. So the invisible sky isn't seen because it's small, it's because it's too dim for our eyes to see.

Several months ago I had made a mosaic of the Summer Milky Way taken in Hydrogen-Alpha light. Last night it was time to take the images to construct this picture, the Winter Milky Way, also in Ha light.

The mosaic is 11 frames taken with a 24mm lens on the SBig STF-8300M camera. Each frame covered 41 x 31 degrees and they are centered on 15 degree increments along Galactic Longitude 120 to 270. Every frame is actually a stack of (3) 180-second subs through the Ha filter. Stacking dramatically reduces noise in the image resulting in a smoother overall appearance.

I used AstroArt 7 to control the capture process. A script I wrote positioned my little iOptron ZEQ-25 mount toward the desired aim point in the sky, took the three images used for each frame, then moved to the next point. The whole capture process took about 2.5 hours.

A "big picture" like this helps to visualize how the various sky objects are positioned relative to each other. It also helps me to pick out future targets for close-up photos.

On Monday, December 21, 2020 the planets Jupiter and Saturn passed each other in the sky.  They appeared closer together during this conjunction than others in hundreds of years.

The planets do move about in the sky, but their motion is slow enough that it's difficult to visualize it.  So while leading up to the conjunction I started taking nightly pictures of the planets on December 6th.  The individual images were then combined to show their relative motion in about 24 hour intervals.  Unfortunately, two nights of bad weather prevented me from getting photos on those  nights.

The sequence images were taken with a TeleVue NP101is telescope with a Canon 60Da camera.  I also took a close-up photo of the planets using an AstroTech 10" RC telescope with ZWO ASI2600MC Pro camera.  The close-up was then superimposed onto the sequence photos for the final composite.

If you'd like to see my more traditional picture of the conjunction jump over to the Astrophotography Solar System page to see how it looked from the back yard at sunset. 

Comet Hale-Bopp was the last "great" comet prior to Comet NEOWISE that we saw back in July.  That was over 23 years ago! Of course, photography was still in the film age back then.  This picture was taken with my then-shiny Pentax ME Super 35mm SLR film camera and 200mm telephoto lens.

When I was looking through a box of old photos I came across an envelope with these in it.  I wondered if scanning the negatives would yield a superior image compared to the original prints?  On the night of April 4 1997, I had taken three photos at 60 second exposures.  I scanned in those negatives and using today's techniques of stacking and stretching, the result was the image above.  I'm happy to say that the newly processed image has much more detail in it than the original print.  I think that the result is reasonably comparable to astronomy photos taken today.  I'm glad I stuffed those photos in that box so many years ago!

In the mountains of New Mexico the temperatures vary quite a bit during the year.  Summer overnight lows are typically in the mid-60s, while winter lows are usually in the mid-teens.  Telescopes expand and shrink with these temperature changes.  It turns out that the telescope mount also changes a little.  The result is that the mount’s drive gear mesh needs to be adjusted to optimize performance for summer or winter operation.

In the case of my Titan mount, there’s a sweet spot in the gear mesh tension for best performance.  If the mesh is too loose then excessive backlash degrades guiding performance.  If the mesh is too tight then the motors have to work harder and may even stall or overheat.  Adjusting for the right mesh tension has been a try it and see how it does game.

Enter my latest project: the Telescope Mount Power Monitor.  This device displays the voltage and amount of current the mount is using.  Knowing how much current the mount’s motors are using can indicate how hard they are working.  So when adjusting the mount’s gear mesh watching for the point that the current starts to increase indicates “that’s tight enough”!

The monitor consists of three modules: a Feather M0 Express microcontroller, an OLED FeatherWing display and the INA260 Power Sensor.  All the modules come from Adafruit.  The software is written in “C” using the Arduino environment and is based on the example code that Adafruit provides.  The total cost of the project was about $60.00, plus my labor of course.

The Monitor is placed in series with the mount’s power source and gets its own power from any USB power supply.  The display provides real-time readouts of the current the mount is drawing and the supply voltage level.  Hopefully, this tool will ease the gear mesh adjustment process this coming winter.


When doing deep sky imaging of objects like nebula and galaxies the Moon's presence is generally considered to make it a "no-go".   Moonlight washes out all the object's faint details.  And, the brighter the Moon the worse its effect.  But avoiding moonlight severely restricts imaging time.

A relatively new type of filter, called a dual-band filter, can be used to regain some imaging time... even in moonlight!  Most narrowband filter pass light in a single region of the light spectrum.  The dual-band filter has two passbands, one centered on Hydrogen-Alpha (Ha) emissions and another centered on Oxygen III (OIII).  While allowing those bands to get into the camera, the filter blocks all the other interfering moonlight.  The dual-band approach is thought to work better for color cameras that the single band filters.

This time of year in New Mexico is monsoon season and cloudy nights are common.  So when last night promised to be clear I thought I'd give a dual-band filter a try, since a very bright 99% illuminated Moon was in the sky.  This image of the Eagle Nebula (M16) was taken using a TeleVue NP101is refractor and ZWO ASI2600MC Pro color camera.  I took similar images without using a filter and with using a ZWO Duo-Band filter.   

The comparison is pretty dramatic.  The Eagle Nebula is mostly a Ha emission object and a perfect candidate for the filter.  The reddish nebulosity is significantly more visible with the filter than without.  So when a clear night comes along, the Moon won't stop me anymore!

Ever wonder how astronomical objects got their name?  Dottie convinced our cat Mars to demonstrate how the Cat's Paw Nebula got its name.  Of course, now Mars wants me to rename the nebula the "Mars Paw Nebula"!

The Cat's Paw nebula (NGC 6334) is located in the lower part of Scorpio, near the "stinger", and is actually pretty big... larger than a full moon.  This area of gas and dust is an active star forming region.  The nebula is too dim to see with the eye but a long camera exposure easily reveals it.  


While Comet NEOWISE (C/2020 F3) continues to be a wonderful sight in the evening sky, I'm reminded of how weather dependent astronomy is.  Here in New Mexico we're in the monsoon season.  And true to its form, our night sky has been totally clouded out for the past several nights.  Finally, on Tuesday the forecast for that night had improved to "mostly cloudy".

It was five days ago that I took a picture of the comet so I planned to set up my photo rig in hopes of getting a new image tonight.  About sunset I started setting up the equipment:  finding a good spot in the yard to see low to the northwest horizon, setting up and leveling the iOptron ZEQ-25 telescope mount, attaching the camera and connecting it to the laptop computer.  By the time my neighbor Joe came over to watch the comet it was dark enough that I could polar align and synchronize the mount to the sky.

As it got darker, we waited... and waited.  Every now and then a portion of the comet would appear among the clouds.  Each time I'd start a sequence of  image exposures in hopes of getting  something useful.  A few times it cleared enough that we could see the comet and its dust tail with the naked eye.  Joe finally got to see why Neowise was special. 

Even though the sky wasn't cloud-free, this image of Neowise nicely shows the comet's yellowish dust tail and bluish ion tail.  And, in a way, the clouds add an interesting dimension to the picture.

Comet NEOWISE on 2020-07-21