Neptune and satellites Triton and Nereid with C11 on 23/24th Sept 2025

[Dennis]

Here we have the Planet Neptune (Magnitude: 7.81, Size: 2.3") and satellites Triton and Nereid as imaged from Brisbane on the evenings of 23rd and 24th September 2025.

According to SkyTools 4 Imaging, Neptune has a Diameter of 49528.0 km.

Name      Mag  PA°    Sep"
Triton    13.4 344.6  11.2
Nereid    18.7  62.9  409.0

Triton has a magnitude of 13.4, with Nereid at 18.68.

ST4 also writes that on September 23, 2025, Neptune was at opposition at magnitude 7.8 and subtending 2.3 arc seconds, something I did not know at the time of taking this set of images.

Neptune lies at an Earth Distance:  28.9 AU and Sun Distance:  29.9 AU.

I must say, it is nice to find Nereid in ST4, I previously had to visit the JPL Horizons website,  generate then download an ephemeris for Nereid, then manually plot the position to GoTo the RA and DEC coordinates. I also no longer have to worry about J2000 and Apparent.

Celestron 11” EDGE HD at F10, ASI 2600 MM Pro.
30x60 sec exposures.

Dennis.

   

   

[theskyhound]

Wow, that so cool!

It looks like Nereid is off by just a little bit. I've been redoing moons with a new algorithm, and I'll check to see if this was one of them. I may be able to learn something from your image.

Thank you for sharing this!

[Dennis]

Wow, that so cool!

It looks like Nereid is off by just a little bit. I've been redoing moons with a new algorithm, and I'll check to see if this was one of them. I may be able to learn something from your image.

Thank you for sharing this!

Thanks Greg, the ST4 plotted position looked fine to me and I try to take the screen capture mid sequence of the imaging time rather than at the start or end.

I hope you do not have any plans to add Sycorax, the largest irregular satellite of Uranus (mag 20.7) to ST4, as that would force me to move up to an instrument in the 18-24 inch class!

I find it cool that Nereid was discovered quite recently, on May 1, 1949 by Gerard P. Kuiper with a ground-based telescope. It was the last satellite of Neptune to be discovered before Voyager 2's discoveries four decades later.

Dennis.