Verna and Bob's Weblog

Nerdliness

Watching the ISS Fly Over

One of our activities is, and has been for quite a while (since living in California) watching the International Space Station fly over when visible. Last Sunday night’s pass was quite a treat in that it had nearly everything going for it: cloudless skies, convenient timing and an almost direct overhead pass.

In the image above, you can see the ground track of the ISS as it passed over the Southwestern US. The maximum predicted elevation for this particular pass was 88° which barely missed our exact location to the southeast, but watching the fly-over, one could not perceive any difference from a direct overhead pass. Image credit Heavens Above.

Another attribute that is not always the case during a pass is that the ISS remained sunlit during the entire pass. We live in a slight hollow below surrounding terrain and saw the ISS rise in the southwest above some local hills and it few over us and set in the northeast behind some other terrain. We always enjoy watching the ISS and other satellites flying over, but this one was unusually spectacular.

May 16, 2023 by Aerospace Arizona Nerdliness Something Shiny

A New Cholla Cactus in 3D

Sometime last year, we noticed a small protrusion of what appeared to be new cactus growth under the red rocks that cover the ground around our house. Eventually, this winter, the cactus had evolved into a two-prong sprout with each prong measuring six to eight inches in length. As of the emergence of spring, the growth has really taken off virtually tripling the size of the little cactus.

I took a side-by-side image of the cactus and made it into the anaglyph seen above. Click on the image to enlarge.

If you don’t happen to have your 3D glasses handy, you may view the 2D image here.

May 10, 2023 by Arizona Bob's 3D Stuff Home & Garden Nerdliness Photography

Solar Astrophotography

In anticipation of the Annular Solar Eclipse on October 14, 2023, I got out the Canon SL1 camera and associated accessories to photograph the solar disk. I used the Canon EF 100-400mm along with a Thousand Oaks Optical threaded SolarLite® filter to get the (clickable) image above. I had to experiment with the camera settings to get the image and further had to adjust it using a photo processing app.

The setup resolved the solar disk and a couple or three sunspots currently visible; the two larger sunspot visible are 3297 and below that 3294. Those numbers are according to SpaceWeather.com.

As I mentioned above, I had to experiment with the camera settings a bit. Using the camera’s Programmed (P) setting, the images were overexposed. I switched to the shutter speed priority setting and tried several exposure times from 1/1000 second, 1/2000 second, and 1/4000 second. The latter, which is the fastest shutter speed on the camera, captured enough of the details needed to produce the image seen above and will certainly be good enough for the annular eclipse. For the total eclipse in April of 2024, it will be necessary to remove the attenuating filter during totality in order to capture the details of the solar limb and the spectacular appearance of the solar corona.

May 6, 2023 by Astronomy Nerdliness Photography Something Shiny

Ephemeris Back On-Line

Old Sidebar Widget from February 11, 2021

Remember the Solar Ephemeris sidebar widget from our old blog theme? It gave daily information about the sun cycle — that is, sunrise, sunset and so forth. Well, I have it back on-line in the form of a sidebar link to a dedicated page that has the old widget code embedded in it.

I had some problems with making it work with the new versions of the server-side software that we use. There were some minor, but show-stopping changes to the platform that killed the Ephemeris code that ran on the old theme. I spent a couple of hours debugging the code today and now have the prototype running again in the “Bob’s Solar Ephemeris” page. Click on the link or select the page from the sidebar. Disclaimer: it’s still a work in progress and is subject to formatting changes.

One of these days, I might start on an interactive widget where users can put in their own geographical coordinates to see the sun’s daily times for their location.

January 5, 2023 by Blogosphere Nerdliness

Lunar Occultation of Mars

Verna and I witnessed the occultation of Planet Mars by Earth’s Moon this evening. At about 7:32 PM Arizona Time, Mars could be seen to disappear behind the Moon and would emerge again about an hour later on the opposite side of the Moon. In the image above (courtesy Griffith Observatory) you can see the tiny Martian dot just below and to the left of the Lunar limb. This is just about the same as we saw it around 7:30PM tonight. We came back outside at 8:30PM and witnessed the re-appearance of the Martian dot on the upper right Lunar limb – very impressive (and nerdy). We both enjoyed it and commented that it was a fun thing to do. We also had witnessed a visible flyover of the International Space Station about fifteen minutes prior to the beginning of the occultation.

From In The Sky — About this occultation:

The Moon will pass in front of Mars, creating a lunar occultation visible from parts of the Americas, Europe and Northern Africa.

Lunar occultations are only ever visible from a small fraction of the Earth’s surface. Since the Moon is much closer to the Earth than other celestial objects, its exact position in the sky differs depending on your exact location on Earth due to its large parallax. The position of the Moon as seen from two points on opposite sides of the Earth varies by up to two degrees, or four times the diameter of the full moon.

This means that if the Moon is aligned to pass in front of a particular object for an observer on one side of the Earth, it will appear up to two degrees away from that object on the other side of the Earth.

At the time of the occultation, the Moon will be 15 days past new moon and will be 100% illuminated.

December 7, 2022 by Astronomy Nerdliness Something Shiny

Avalon 1998

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