Category: Astronomy

A 20 Year Project

by Yu Gu, posted in Astronomy, Photography, Projects

August 27, 2003: the day when Mars reached its closest point to Earth in 60,000 years.

There was a lot of hype (and hoaxes) around this Mars opposition. I was also preparing for it by making a 12.5” F6 Newtonian. Still a Ph.D. student at the time, I got help from several friends to make this happen.

The Mars season was a success! With a modified webcam (I sourced a monochrome CCD chip from Italy to replace the color sensor in the webcam!), I captured some really good Mars images.

The success fueled a dream, a larger scope for planetary imaging. I started to plan out a 16” F7.2 Newtonian on a tracking Dobsonian mount. As an engineer student, nothing seems to be impossible at the time.

The design used a mixture of steel, aluminum, and carbon fiber. While the mirror was on order, I built a 6” finder scope first as a testing piece. It was completed in 2004:

By summer 2007, the main scope was taking shape, again with the help of friends, and it was quite impressive 😊

The first light happened on Mar 2008, I believe (I have lost a few pictures of that…), and I remember the view of the moon was incredible.

If you look carefully, you may see motors on the dob mount in the picture above. Building the tracking system for the scope took a long time and was not successful. At the same time, I started on the market for a tenure-track position, and started realizing how inadequate my CV was. The work on the scope slowed, and then stopped.

Many things had happened between 2008 and 2020… The scope spent most of this period in the darkness of a garage, as evidence of “I once had a dream.” I still had the dream, just not the time and energy to pursue it. In the meantime, I found a 16” F5.85 mirror to replace the F7.2 mirror to make the scope more practical.

In 2020, I got a call from Mars again and resumed my astrophotography journey after a 16 year break. With improved cameras and image processing tools, I was able to take better Mars images with 11” SCT.

But what I really wanted was to complete the 16” scope. So, I started working on it again. I bought an equatorial platform to allow tracking but was disappointed to find out the poor quality of my new F5.85 mirror.

After an 18 month wait, now I have another mirror, a 16” F5.25 made by Zambuto. I also modified the scope to be mounted on an equatorial mount. It looks great, but a bit too tall on a pier… A shorter pier (see the photo at the beginning) solved the problem so I can take down the scope by myself at night.

My spaceship is finally ready to go, and I have been enjoying the ride since. Should I dare to dream bigger?

(Click on the photos to see larger size, and check out more photos in Gallery)

Reprocessing of Mars Images from 2003

by Yu Gu, posted in Astronomy

Mars opposition in 2003 was a big deal. The media hype was that the two planets (Mars and Earth) would be at their closest points in almost 60,000 years. A hoax claimed that Mars would look as large as the full Moon… That was a bit exaggerated, of course. Mars reached 25.1 arcsec on Aug 27, 2003, about 1/70 the apparent diameter of the moon.

I had to see all that myself; I made some plans.

First, I wanted needed to upgrade the scope. I was using a Celestron C9.25 and it gave good results on Jupiter and Saturn. But I felt I wanted something bigger. I was luckily approached by TEC’s Yuri Petrunin to loan me (for free!) a 10” Maksutov Cassegrain and a mount. That would have been a great setup; but at over $10k in cost, it was too much for a poor grad student without a car to handle (what if it was damaged or lost?). Plus, I had my own scope in the making…

It was a 12.6” F6 Newtonian on an equatorial mount. The primary mirror was made by Pegasus Optics. It was a very good mirror but was thick (2.1” Pyrex) and heavy. It would take a long time to cool down. With a lot of help from friends, a scope was finished on time.

Another challenge was that Mars would be low in the sky. In 2003, Mars would not rise more than 30 degrees above horizon from my location in Morgantown. It means the telescope had to see through a lot more atmosphere (as compared to higher angles), and the seeing would be poorer. There would also be more atmospheric dispersions. I had tried to make my own dispersion correctors using prisms, but with no luck. Another way of battling this was to image with a monochrome camera and color filters. However, specialized mono cameras were expensive at the time. The popular camera for planetary imagers was a webcam made by Phillips, called ToUcam, which had a color sensor. I was able to find (from someone in Italy) a mono replacement of the ToUcam CCD. After a small surgery, I had a working mono camera. I also made filter sliders that can be controlled by a RC transmitter to change filters remotely (not pretty looking but worked).  Finally, I was all set for imaging Mars.

I planned to observe Mars every clear night starting from April (I was young and ambitious at the time), but it rained the whole April.  The weather between August and October ended up being great, when Mars was at its best. I remember how proud I was with this set of photos (click to enlarge):

This animation shows the rotation of a cloudy planet. The images on the right were taken with a blue filter, which show orographic clouds over the volcanoes on the left and the morning fogs on the right side.

Fast forward 18 years. After completed a successful Mars imaging season in 2020, I became curious about older images. I thought the original raw data were lost but was fortunate to find some back in a hard drive. Here are reprocessed Aug 21 and Sep 17 images. What has changed since 2003 was mainly the ability to de-rotate the planet and stack images collected over a longer capture time (with WinJUPOS software). But it was really fun to play with older data and bring back those memories.

I also made a new animation of the blue channel images from the Aug 21 data. On that night, there was hardly any clouds on Mars, but the rotation of the south polar cap was fun to see.

Mars will not look any bigger than it was in 2003 for a very long time. But what’s more important is to not lose that passion.

A Good Jupiter Season

by Yu Gu, posted in Astronomy

Jupiter has always been my favorite planet to look at (beside Earth…). It’s big, it spins fast, and it’s always dynamic. Even during my long (~16-year) break from astrophotography, I have not stopped looking at Jupiter through eyepieces.

This year, Jupiter was not particular high (up to ~35 degrees elevation) from my location so I did not have high hopes. Surprisingly, advancements in modern astro imaging technology, e.g., higher sensitivity lower noise cameras, atmospheric dispersion corrector, and better post-pressing software have helped overcome a good portion of this challenge.

I started the season a bit late, but the first few nights turned out to be among the bests (click on the photos to enlarge).

I was also able to create a Jupiter map, a first for me!

There have been interesting moon events throughout the season, here are just a few examples

What’s most exciting, however, was the detection of a new eruption event near the Great Red Spot (GRS). It’s a very bright (like snow) region and I didn’t know what it was. Later I learned that it was a rising plume originated from the lower, warmer layer of Jupiter’s atmosphere. It carried ammonia and water vapor to the higher, colder layer and then froze, creating the high reflectivity. Here is an article that explains it.

It turned out that there were several of these outbreaks in 2021, two were captured earlier on Sep 15:

Finally, here is a Jupiter animation:

What looks interesting to me was what appeared to be very large-scale dark features in/near the north polar region. They look like darker shades that were rotating with Jupiter. Not sure what that could be…

Next year, Jupiter will rise a lot higher (for us northern observers)!

Photos from the Mars 2020 Opposition

by Yu Gu, posted in Astronomy, Photography

Here is a summary of my 2020 Mars imaging season.

After a 16-year break from astrophotography, I am back in the game gain. Compared to the 2003 opposition, Mars has changed quite noticeably. There have been two global dust storms (2007, 2018) and more smaller storms that altered the planet’s albedo features. I tried to label some of the potential changes here (please click on the photo to see a higher resolution one).

I also produced my first Mars map from my deck in Morgantown WV. The regions around the North Pole is still missing (just like Earth, the Mar’s rotation axis is tilted). I will have to wait for another opposition to complete the map.

The weather on Mars had been mostly clear, with hardly any clouds as compared to 2003. This was great for map making though. I did catch the beginning of a dust storm, which went on to spread to almost half of the globe in just a few days. Well, those were the few days that Mars turned its back on me, so I did not get to see it.

Sometimes, it’s hard to imagine the orange colored blob in the telescope is actually another planet; smaller but not that much smaller than our own planet Earth, and it’s changing over time. Maybe one day, we will get to visit Mars so we can point a scope at Earth and see it as a blue colored blob.

Last Quarter Moon

by Yu Gu, posted in Astronomy, Uncategorized

This is an 9-panel mosaic of the last quarter moon. The seeing was excellent at the beginning and it deteriorates a bit towards the end. My C11 also has some field curvature and collimation imperfection. But I think the end result looks quite good. I also added a Mars image from the same night (~8hours earlier) for comparison of their visual sizes.

See a much larger version of this photo on my Astrobin page.

Or click here for a full resolution (about 300 meters per pixel) version (make sure to zoom in!).

Starting a Deep Sky Gallery

by Yu Gu, posted in Astronomy, Uncategorized

After NEOWISE, I  am getting more interested in learning deep sky astrophotography.

With a recently acquired Astrophysics 92mm F6.65 Stowaway and a 0.8x field reducer/corrector, I really don’t have excuses.

Here are the first two images taken from my light-polluted backyard that I am quite happy about: M27, Dumbbell planetary nebula, and M13, the Hercules globular cluster.

The camera used was an unmodified Sony A7RII, no filter, 100 x 30s exposures at ISO 800 (to avoid the star-eating problem…).

Comet NEOWISE

by Yu Gu, posted in Astronomy, Uncategorized

In almost 45 orbits around the sun, I have only gotten to see a handful of comets.

Halley’s Comet’s return in 1986 was the single event that ignited my interest in astronomy. I was 11 back then. All of a sudden, everyone in school was talking about Halley. All the kids wanted to see it, and I wanted to see it too! The “instrument” I had at the time was a pair of toy 2X binoculars. I begged my parents to buy me a real telescope, but they could not afford one. One day, my dad borrowed a telescope just to check it out, but it was too expensive. It was about 50 Yuan (or 10 USD), roughly my parents’ salaries for a month.  I used my 2X binoculars to scan the sky every evening and I did not find anything. Nobody I knew seemed to have seen Halley, except for some rumors floating around. But we were just kids. We knew that if we take care of ourselves, we may get to see it in year 2061!

The interest in astronomy and telescopes stuck with me ever since. Years later, I have gotten to know several people sharing the same story: Halley helped them to discover the passion that they didn’t know existed, despite that they never got to see it.

Fast forward four years (1990), I was in high school. My dad’s best friend gave him a pair of 10×50 binoculars, after he visited America. I started to scan the night sky from my balcony anytime I can. One night, I came across a fuzzy cotton ball near zenith, which seemed strange. The next night, it was still there, but moved a little. Maybe I found a comet? I wrote a letter to Beijing planetarium about this finding. To my surprise, I received a reply a few weeks later. What I saw was a comet discovered by Levy (a famous comet hunter) a couple months earlier. That was enough excitement to keep me up at night! I became more diligent at scanning for comets; but with no success.

Five years later (1995), I was a college student in Shanghai. School load and light pollution had made astronomy a distant memory. That was until Hale–Bopp showed up, one of the great comets of the 20th century. It was supposed to be not only visible, but also spectacular to the naked eyes! But not for people in Shanghai. If you have sharp eyesight and patience, you maybe able to find 5-10 stars in the Shanghai night sky in those days. I had a homemade 3cm scope with me and I found Hale–Bopp from the top of a tall school building: a faint glow in the orange sky!

Another four years had passed before I arrived in the US (1999). One day, about one year later, I realized that I could actually afford a decent telescope, with my humble graduate research assistantship. I went all crazy on telescopes and planetary imaging. I have seen a couple comets over the years but nothing too exciting. Oh, I also saw the 2009 Wesley Jupiter impact event. Not sure if it was caused by a comet, but close enough to the famous comet Shoemaker–Levy 9 impacts that I missed.

Now, year 2020, comet NEOWISE is here to visit the sun. My son is now at the age when I was helplessly hunting for Halley in the sky and my daughter is only 2-years behind.  The whole family got up early one day to see NEOWISE rising before the sun. Now the comet is in the night sky, we can observe it from the comfort of our front porch. I have never taken a photo of a comet before NEOWISE so it’s an excellent opportunity to practice!

So, What Do We Do with It?

by Yu Gu, posted in Astronomy, Photography, Research, Robotics, Uncategorized

I am more of a telescope collector than a sky watcher. I have about a dozen telescopes of different designs: achromatic, apochromatic, doublet refractors, triplets, Newtonians, Maksutov-Cassegrain, Maksutov Newtonian, H-alpha solar scope, Dobsonian mounts, German equatorial mounts, roof prism binoculars, porro prism binoculars… you name it. I know way more about telescope designs than constellations of the sky or features on Mars. Most of my telescopes spend years collecting photons in a very dark place: my closet.

I am more of a camera lover than a photophile. I have several cameras from the film era to the mirrorless age. I have a couple dozen lenses with focal lengths ranging from 14mm-500mm, not counting telescopes.

I have learned to accept this. There is nothing wrong with being obsessed with equipment, I told myself, the hobby is supposed to be fun!

I also like robots. My lab, IRL, has about two dozen robots, plus a 50-robot swarm. The UAV lab I worked in before had about a dozen UAVs. Most (but not all) of these robots and UAVs were custom developed. I, as someone who always like toys, had a hand in the design of most of these systems.

So now, what happens when we have all the hardware we ever wanted? Of course, we can only get close, but not there. There is a pretty big difference between “wants” and “needs”, and we often rationalize “wants” as “needs”. As engineers and perfectionists, seeing small issues with the current setup makes us feel itching. We are constantly dreaming up next design iterations. We are telling ourselves better robots will make our research better.

Is that true? Do we really need more/better robots to do better research? Maybe to some degree. If we don’t have the appropriate tools, we can’t do certain experiments. If we don’t have high quality equipment, some work may be very hard to do (e.g., mapping without 3D Lidar or robotic pollination without a precision manipulator). I think another important reason for having the best robots, like having the best telescopes/cameras, is that we have no one else but ourselves to blame for the underperformance…

So, let me ask again, what happens when we have all the hardware we ever wanted? What do we do with it? The answer is simple: let’s focus on research. Instead of rushing to start on the next generation design and letting the existing robots collect dusts, let’s make them do things nobody else can dream of or believe!