Comet Lemmon: Early Morning Capture of a Fast-Moving Visitor

October 10, 2025 – I set my alarm at 5:00 AM – right when, according to the ephemerides, the comet C/2025 A6 (Lemmon) would finally clear the roof of my house.

The telescope was already polar aligned and ready to go. I loaded the comet’s orbital parameters into Stellarium a while ago, so I easily transferred them to NINA, and the imaging session began shortly after.

I captured a total of about 43 minutes of data: 50 exposures of 30 seconds and 18 exposures of 60 seconds, before the sky brightened with sunrise.

The comet was surprisingly easy to spot through the scope – even with just 10-second exposures! At this rate, I wouldn’t be surprised if it becomes visible to the naked eye once it reaches its minimum distance from Earth in a few days, when it will also shift to the evening sky.

Scope: Explore Scientific ED80CF
Camera: ZWO ASI533MC Pro (cooled to –10 °C)
Filter: Optolong L-Pro
Mount: Juwei17
Guiding: PHD2
Control: NINA on Mele Fanless MiniPC

Frames: 18min. total (18x60 secs. lights + calibration frames)
Processing: PixInsight (WBPP, CometAlignment, BackgroundNeutralization, NoiseXTerminator