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User / hirocun / Asteroid 65803 Didymos October 1, 2022 Version 2
Hisayoshi Kato / 2,184 items
I've added multiple shorter exposure frames as usual.

The asteroid was drifting fast toward east northeast in Eridanus. It presented with showing an obvious linear dust distribution toward west northwest. Brighter round-shaped dust distribution was around the asteroid, stronger and wider toward northwest. North is up, and east is to the left on the frame.

Asteroid 65803 Didymos is a binary asteroid. The smaller asteroid or the minor-planet moon is Dimorphos.

The moon was the target of Double Asteroid Redirection Test, DART by NASA. DART prove reached and impacted the moon at 23:14 on September 26, 2022. The expected effect was said to be 73 seconds shortening of Dimorphos' orbital period. It must be possible to have changed the orbit of the binary asteroid.

The impact was observed by another prove, Light Italian CubeSat for Imaging of Asteroids, LICIA Cube as below.

James Webb Space Telescope and the Hubble Space Telescope also captured the DART impact.

equipment: AstroPhysics 130GTX "Granturismo," Field Flattener at f/6.7 focal length 873mm, 22.1mm Spacer, EOS Adapter, Kipon EOS-EOS R adapter, and Canon EOS R-SP4II, modified by Seo-san on Vixen AXD Equatorial Mount, auto guided at a star nearby with Fujinon 1:2.8/75mm C-Mount Lens, Pentax x2 Extender, ZWO ASI 120MM-mini, GPUSB, and PHD2 Guiding with comet tracking on

I have calculated tracking rate from the difference of ephemerises before imaging dependent on predicted ephemerises presented on StellaNavigator 11, a planetarium software by Astroarts. Calculated rate was +27.3 arcseconds par hour in right-ascension and 162" par hour in declination, though tracking was not accurate at the rate. Better tracking was possible at rate +26.2 arcseconds par hour in right-ascension and 162" par hour in declination. It took four times 10 minutes trial exposures for me to find the actual tracking rate then.

I have never experienced such difference on imaging of comet except for disintegrating one or remnant of comet like comet C/2010 X1 Elenin on November 1, 2011. .

C/2010 X1 Elenin near Simeis 147 on November 1, 2011 Enhanced

exposure: 8 times x 600 seconds, 3 x 240 sec, and 3 x 60 seconds at ISO 3.200 and f/6.7 focal length 873mm

The first exposure started at 16:49:02UTC October 1, 2022. I could not complete my initial imaging plan due to encroached clouds 40 minutes before the beginning of twilight.

site: 1,996m above sea level at lat. 35 21 53 North, long. 138 46 35 East in the public parking on the eastern slope of Mt. Fuji in Shizuoka 富士山須走五合目. SQM-L was 20.76 even after moonset, and ambient temperature was around 6 degrees Celsius or 43 degrees Fahrenheit. Wind was gentle.

Here is a frame of the site at the night.
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  • Taken: Oct 1, 2022
  • Uploaded: Oct 2, 2022
  • Updated: Oct 19, 2022