3I/ATLAS, can't find/annotate

[Andrey D.]

Hello.

For some reason ASTAP can't find and mark that comet in .fit
Image seems to be Ok, comet must be right near to the center, but no go ((
I do understand that that's impossible to see the comet with this equipment. Considering this just like exersise to get familiar with ephemeris alignment.
AllCometsEls.txt is up to date. My planetarium sw with the same file shows the comet in it's place, no prob.
Tried to increase limiting magnitude in settings didn't help.

Previously I've already tried ephemeris alignment on C/2025 K1 (ATLAS) from the same seestar telescope and got nice result w/o any issues. So, I assume that .fit file and its headers, date/time format, etc are Ok.

ASTAP is the latest ASTAP version 2025.08.07, Intel 64 bit on Linux Ubuntu Noble

Thanks!

[han.k]

Hi Andrew,

Unfortunally the comet is outside the image. I have looked up the positions in JPL Horizons:

https://ssd.jpl.nasa.gov/horizons/app.html#/

See attached pdf. The comet has now it's definitive abbreviation C/2025 N1. But you can enter 3I/ATLAS as an input. So unfortunally you have to try/image again.

Success next time,
Han

[Andrey D.]

Hmmm... So you assume that MPC database is not correct, possible. I see 2hr diff in RA for JPL data vs MPC. Very strange isn't it?
But how is it possible? I use MPC data in ASTAP and in my favorite tool DSOPlanner.
The same AllCometsEls.txt in both programs.
DSOPlaner shows comet in ints place. ASTAP uses the same .txt, let it be wrong, but the same ephemeris file. No comet. How?

Thanks!

[han.k]

No idea why but I get the same position from the https://data.minorplanetcenter.net/explorer/

Enter
C/2025 N1

0003I KB2025 07 29.52787 16 58 18.94 -17 41 01.6 ZEP113D88

0003I KB2025 07 29.53344 16 58 17.98 -17 41 00.6 ZEP113D88

0003I KB2025 07 29.53899 16 58 17.06 -17 40 59.0 16.1 TZEP113D88

0003I KC2025 07 29.64466 16 57 59.669-17 40 30.18 16.3 VZEO159323

0003I KC2025 07 29.65106 16 57 58.584-17 40 28.81 16.0 VZEO159323

0003I KC2025 07 29.65640 16 57 57.698-17 40 27.37 16.1 VZEO159323

0003I KC2025 07 29.66414 16 57 56.743-17 40 29.39 17.3 GXEO159N42

0003I KC2025 07 29.66729 16 57 56.189-17 40 28.63 17.0 GXEO159N42

0003I KC2025 07 29.67003 16 57 55.750-17 40 27.70 17.3 GXEO159N42

[han.k]

I checked inside the ASTAP code which position was calculation for 3I/ATLAS using your image as input. So for 2025.07.29 14:42 UTC

RA 16.9680732
DEC: -17.67818

So the AllCometsEls.txt result matches with MPC explorer (observations) and JPL Horizons

[Andrey D.]

Ok, I see now.
So question to DSOPlanner authors.

Thank you for info and for great ASTAP! ))