2025-03-14 Lunar Eclipse Processing Workflow
Synopsis
This lunar eclipse observation captured the dramatic “blood moon” phase when Earth’s umbral shadow covered the lunar surface. Totality lasted from 2:26am to 3:33am EDT. The night began with cloudy conditions that prevented photography during the initial phases of the eclipse. As the clouds cleared, imaging began during the deep umbral coverage, when the moon displayed its characteristic copper-red coloration caused by sunlight refracting through Earth’s atmosphere.
The three image sequences document different stages of the totality and emergence phases: Batch 1 shows the moon deeply immersed in Earth’s shadow with a brighter rim visible at the top edge; Batch 2 captures the moon during peak totality with the distinctive red glow across the entire lunar disk; and Batch 3 shows the beginning recession of Earth’s shadow as the moon started to emerge from the eclipse. Throughout these phases, the lunar features remained visible through the shadow with varying levels of contrast and color intensity.
Acquisition
Equipment:
- Telescope: Orion Newtonian 1000mm f/4.9
- Coma Corrector: TSWynne m68 0.95x
- Filter Wheel: QHYCFW-3L
- Filters: Chroma RGB filter set
- Camera: QHY268m (monochrome) with Photographic DSO 2CMS readout mode
- Mount: Equatorial mount with periodic error and slight polar alignment drift
- Software: NINA with Orbitals plugin for lunar tracking
Data Collection:
- Date: March 14, 2025
- Time: 02:55-03:35 AM EDT
- Location: Back yard in rural NC, Bortle 4 sky
- Exposure: 0.5s for all frames (fixed exposure)
- Gain: 56 (fixed for all exposures)
- Camera temperature: -7°C target (actual ranged from -6.7°C to -7.2°C)
- Filter sequence: R, G, B cycling pattern
- Filter offsets applied to ensure proper focus of each channel when looping between filters
- Auto-focus performed between batches using nearby starfield
Data Organization:
- Batch 1: 02:55:46 - 03:05:33 (90 exposures)
- Batch 2: 03:10:21 - 03:22:36 (75 exposures)
- Batch 3: 03:28:35 - 03:35:15 (60 exposures)
Preprocessing
Calibration:
- All frames calibrated with matching bias frames
- Filter-specific flat frames applied
Cosmetic Correction:
- Auto hot pixel sigma: 1.5
- Auto cold pixel sigma: 2.0
- Applied to all calibrated frames
Alignment
Registration Method:
- FFTRegistration script in PixInsight
- Reference image: First red frame of each batch
- All RGB frames registered to same reference frame
- Translation-only corrections applied (rotation disabled)
Integration
Stacking Approach:
- Files separated by filter after alignment
- Extreme Student Deviation (ESD) rejection algorithm used for Batches 1 and 2
- Additive with scaling normalization
- Batch 3 limited to first 10 frames with no rejection algorithm applied
Color Processing
Channel Combination:
- RGB channels combined with ChannelCombination process
- Background Neutralization with sampling from dark sky area
- Color Calibration using the brightest edge of the lunar limb for white reference
Stretching & Contrast Enhancement
Dynamic Range Adjustment:
- Generalized Hyperbolic Stretch applied to bring out detail in darker regions
- RGB color blend maintained for natural color appearance
Detail Enhancement
Wavelet Processing:
- AstroSurface’s Wavelet-Wiener Deconvolution
- Wiener Deconvolution strength: 2
- Wavelets HF: 3 with size 150
- Noise prefilter: 1
- X1 adaptive smoothing applied
- Exported result blended with pre-wavelet version in PixInsight using PixelMath
- Blend formula: 0.2*$T + 0.8*WaveletProcessed (preserving 20% of original detail)
Final Processing
Refinement:
- Images cropped and rotated to match visual orientation
- Exported as .jpg for sharing
Each batch was processed independently following this workflow, creating three final images showing different phases of the eclipse progression.