SEESTAR PHOTOMETRY TOOL

Differential Photometry Utility optimized for Seestar S50 v1.0-beta

Back to S.C.O.P.E.

1. INSTALLATION & SETUP

This tool is available in two formats. Choose the package that fits your system.

OPTION A: WINDOWS STANDALONE (.exe)

No Python installation required.

  1. Extract the downloaded ZIP file.
  2. Double-click photometry_compare.exe.
* Note on Antivirus: This is a new scientific tool without a paid digital signature. Windows SmartScreen may flag it. Click "More info" -> "Run anyway".
Download for Windows

OPTION B: PYTHON SOURCE

For Mac / Linux / Advanced Users (Requires Python 3.8+).

  1. Extract ZIP and open terminal in folder.
  2. Run: pip install -r requirements.txt
  3. Run: python photometry_compare.py
* Linux Note: If tkinter is missing, install it via package manager (e.g., sudo apt-get install python3-tk).
Download Source Code

2. OPERATIONAL GUIDE

STEP 1: LOAD IMAGES

  • Click "📂 1. Load Img 1" for the Reference Epoch.
  • Click "📂 2. Load Img 2" for the Target Epoch.
*** CRITICAL NOTE ON LINEARITY ***

FITS files MUST be LINEAR (unstretched). Do not use visually processed images (Histogram Transformation, Auto-Stretch, etc.). Stretching destroys the mathematical relationship between ADU and photon flux.

STEP 2: SELECT STARS

Auto-Snap: Finds the star's core with sub-pixel precision. Turn off only in extremely crowded fields.

A. TARGET (Red Marker)

  1. Click TARGET star in Image 1.
  2. Click SAME star in Image 2.
  3. Aperture radius locks after first click.

B. REFERENCES (Green Marker)

  1. Click REFERENCE star in Image 1.
  2. Click SAME star in Image 2.
  3. Repeat for second reference (R2).
  4. MUST select AT LEAST TWO references!

3. PRO TIPS & UNDER THE HOOD

SEESTAR OPTIMIZATION

  • Spatial Sampling: Default 6.0 px radius tuned for Seestar scale (~2.4"/px).
  • Broadband Photometry: Sums R+G+B channels to exploit the IMX462's NIR sensitivity.
  • Performance: Crop huge FITS files in Siril before loading to increase UI speed.

ALGORITHMS

  • Centroiding: centroid_quadratic (Photutils).
  • Background: Sigma-Clipped Median on local annulus.
  • Significance: Evaluates Z-Score ($Z = |\Delta Mag| / Error$). > 3.0σ guarantees 99.7% confidence.
© 2026 Silvio Barbero | Released under MIT License