Comet C/2025 A6 Lemmon

Open sky but a lot of dew resulting in moderate images of Comet C/2025 A6 (Lemmon).

Using ASTAP, area magnitude is 5,4... cool!

ASTAP - Astrometric Stacking Program

I'm working my next challenge: making a light curve of a variable star. I was reading an article in magazine Heelal (November 2025 - Review Dwarf3 by Dmonique Dierckx) which explained the making of a curve using the Dwarf3 and ASTAP. So I went searching for more information on this software.

Downlaoding ASTAP was done via this link https://www.hnsky.org/astap.htm

I also downloading the following databases : D80 and V50

ASTAP, Astrometric Stacking Program, is able to stack images; so far I was only able to do this with Fits files. On top of this, it makes annotations, deepsky, asteroids, comets and variable stars.

There is a section Photometry, which calculates the magnitude and compares those with the database. Using color images, ASTAP can extract the green channel which makes values more accurate. 

When analysing the image with M51, two variable stars showed up. I let the software extract the green channel and measuring the magnitude. This data was copied into excel making the curve. 

Comet C/2025 A6 Lemmon on Halloween evening

Haloween evening, October 31, 2025 during a bright interval I was able to image Comet C/2025 A6 (Lemmon).
This time I used my Star Adventurer 2i together with Nikon D7500, a set up which made it possible to track the comet for 60s.

Setting: Nikon D7500

Mount: Skywatcher Star Adventurer 2i

Exposure : 4x60s ISO800; 2x10s ISO3200; 2x10s ISO6400

Software: APP, CS4 and DeNoise AI

Comet C/2025 A6 (Lemmon) October 27

On the evening of October 27 ... a cloud free sky. So time to observe Comet C/2025 A6 (Lemmon).
I took a wide field using more then 260 images, each 5s.

The other images were taken with a larger focal point but with a time difference of one hour. Due to this time difference, the comet was low above the horizon resulting in fainting out of the tail.

Sun October 26

A small opening in the clouds and windy, but still I took my chance resulting in only one capture of the Sun. Some nice prominences at the east side.

Setting: Sol'Ex by James R, 2nd Gen Slit, ASI678MM, TLAPO80/480

Herschel Wedge

Tilt: -0,7° Sx/Sy 1,12

Software: SharpCap, JSolex, Inti, CS4

Comet C/2025 A6 (Lemmon)

Finally an open sky for about half and hour, which was enough to capture comet C/2025 A6 (Lemmon).

Setting: Nikon D7500 with 112mm f/5.3, ISO6400 and exposure time of 5s

No Guiding

Software: APP 2.0.0. beta29, DeNoise AI, CS4

APP: Normal and MAD regression Avg (8;2)

Discussion:

Brigth core with both dust tail and ion tail. Structure in ion tail with knots aswell with small and wider regions. Tail extends minimum 5° .

Volcano Crater Hrossaborg (Iceland) - Apollo & Oblivion

During our trip through Iceland, we also visited the Hrossaborg Crater.

Hrossaborg Crater is a volcanic crater located in northeast Iceland, near Lake Mývatn. It’s actually an old tuff ring, formed by explosive volcanic activity, est 10.000 years ago, when magma came into contact with groundwater. The crater’s walls rise sharply and form a nearly perfect circle, giving it an otherworldly appearance—especially when seen from above or across the surrounding lava fields.

Because of its dramatic, barren landscape, Hrossaborg has been used as a filming location for several productions that wanted to capture a “moon-like” or alien environment.


Oblivion (2013) – The sci-fi film starring Tom Cruise used Hrossaborg as one of its key shooting locations. In the movie, it served as a backdrop for the scenes involving the base of operations on the desolate Earth. The stark volcanic terrain helped create the illusion of a post-apocalyptic world.

Apollo Connection – While not directly related to the Apollo missions, the resemblance of Iceland’s volcanic landscapes (including Hrossaborg and nearby regions like Askja and the Highlands) to the Moon’s surface led NASA to train Apollo astronauts in Iceland during the 1960s. They practiced geological fieldwork here to prepare for moon exploration.