M31 - Andromeda Galaxy · RGB Session 4 · 2026-11-07

Observing conditions

Saved context for this physical observing session. Separate time spans remain visible below.

RGB · 2026-11-08 00:37:52 CET (UTC+0100) → 2026-11-08 03:01:15 CET (UTC+0100)

Moon · calculated

1.8%

Illuminated · Waning

Altitude -39.6° · below the geometric horizon

Reference: 2026-11-08T00:49:34.222 UTC

Observing site

—

Location not recorded, or withheld in this read-only share.

Weather · model context

ECMWF IFS archive · Open-Meteo

Cloud cover: 0.0–0.0 %
Dew point: -3.7–-2.9 °C
Relative humidity: 77.0–82.0 %
Air temperature: -0.8–0.3 °C
Wind at 10 m: 4.1–4.4 m/s

Ranges of hourly model samples. Air temperature is not sensor temperature.

Hourly values and coverage

UTC	Air temperature · °C	Relative humidity · %	Dew point · °C	Wind at 10 m · m/s
2026-11-07T23:00:00+00:00	0.3	77.0	-3.3	4.1
2026-11-08T00:00:00+00:00	-0.1	81.0	-2.9	4.3
2026-11-08T01:00:00+00:00	-0.4	82.0	-3.1	4.4
2026-11-08T02:00:00+00:00	-0.8	81.0	-3.7	4.3

Hourly gridded model context, not measurements at the telescope. Hourly samples bounding this exposure-group interval; no minute interpolation.

Cloud cover: 4/4 samples; Dew point: 4/4 samples; Relative humidity: 4/4 samples; Air temperature: 4/4 samples; Wind at 10 m: 4/4 samples

Retrieved 2026-11-09T03:28:57.435108+00:00

Provider and model documentation

Context provenance and limits

Recorded DATE-OBS time interpretation retained; if TIMESYS is absent it is provisionally UTC.

Saved calculation at this exposure group's midpoint. Geometric altitude assumes sea level, no terrain or refraction. Schematic orientation, not a sky photograph.

Weather does not establish seeing, transparency at the telescope, a Bortle class or a photometric correction. Missing values do not imply clear skies.

Saved context SHA-256: 66780c10e9b0bf707e78daa0b3acf4d322bbfaa7261530e589aa9d252f3f4c20

RGB · 180 s · 41 Lights

2 h 03 min · 42 exposures available.

Selected input exposures

Image quality at a glance

Selected inputs against your whole archive · RGB and DNB remain separate.

RGB · all contributing sessions

Star width / FWHM: 3.36 sensor pixels; Current archive average3.00 sensor pixels; Difference +0.36; 41/41 selected · archive 865/865 exposures · 11 sessions · 8 objects
Star shape / eccentricity: 0.42 dimensionless; Current archive average0.45 dimensionless; Difference -0.04; 41/41 selected · archive 865/865 exposures · 11 sessions · 8 objects
Background: 745.83 ADU; Current archive average749.61 ADU; Difference -3.78; 41/41 selected · archive 865/865 exposures · 11 sessions · 8 objects
Background scatter: 43.19 ADU; Current archive average34.26 ADU; Difference +8.93; 41/41 selected · archive 865/865 exposures · 11 sessions · 8 objects
Stellar model SNR: 205.25 dimensionless; Current archive average138.73 dimensionless; Difference +66.52; 41/41 selected · archive 865/865 exposures · 11 sessions · 8 objects; Stellar model estimate · different fields

Star width / FWHM — Selected exposure values · whole-archive RGB mean · physical sessions separated.

Star shape / eccentricity

Background

Background scatter

Stellar model SNR

How this archive average is calculated

Each unique original exposure contributes once per valid saved metric. Arithmetic mean across all objects; RGB and DNB separate. Missing or invalid values are excluded, never zero. This descriptive reference includes the selected exposures and later nights.

Exposure, camera settings, field brightness, sampling and stellar populations may differ. Background and stellar model SNR are not normalized measures of sky quality, master SNR or detection sensitivity. A difference is not a grade.

Stored per-frame medians of stellar fits are averaged; stars are not pooled. SNR requires a positive recorded effective gain and at least five stellar estimates. Units remain separate. Unknown method versions are recorded, not invented. Small, undersampled stars may bias shape measurements.

Archive version ab3717b4ec376ea87d5261c94fe6dbbd42a97237e09422490b5844921d286006

Matched acquisition settings · original session-weighted comparison

Selected input exposures

Image quality at a glance

Measurements of the selected input exposures, not the finished master.

RGB · 180.0 s · 41 Lights

Acquisition settings & contributing sessions

180.0 s · Gain 100.0 · Archive snapshot 2026-11-09T03:24:34.927460+00:00

Recorded focal length: 611.0 mm · separate header/settings cohorts, not additional observing sessions.

RGB Session 4 · 2026-11-07

Execution version was not saved: this comparison is limited to the same observing session.

Star width (FWHM): 3.36 sensor pixels; Current archive average3.40 sensor pixels; Difference -0.04 sensor pixels; 41/41 frames · archive: 1 Sessions
Star shape: 0.42 dimensionless; Current archive average0.42 dimensionless; Difference -0.01 dimensionless; 41/41 frames · archive: 1 Sessions; Eccentricity of stellar model fits
Background: 745.83 ADU; Current archive average745.69 ADU; Difference +0.14 ADU; 41/41 frames · archive: 1 Sessions
Background scatter: 43.19 ADU; Current archive average43.19 ADU; Difference +0.00 ADU; 41/41 frames · archive: 1 Sessions
Stellar SNR: 205.25 dimensionless; Current archive average205.95 dimensionless; Difference -0.70 dimensionless; 41/41 frames · archive: 1 Sessions; Model estimate · same target field

Star width (FWHM) over time — Star width (FWHM) · saved per-exposure values and current archive average. Sessions are separate; gaps are not joined.

Star shape · Trend

Star shape over time — Star shape · saved per-exposure values and current archive average. Sessions are separate; gaps are not joined.

Background · Trend

Background over time — Background · saved per-exposure values and current archive average. Sessions are separate; gaps are not joined.

Background scatter · Trend

Background scatter over time — Background scatter · saved per-exposure values and current archive average. Sessions are separate; gaps are not joined.

Stellar SNR · Trend

Stellar SNR over time — Stellar SNR · saved per-exposure values and current archive average. Sessions are separate; gaps are not joined.

Provisional star fits · stellar SNR is a model estimate, not master SNR.

Reading these values

Provisional stellar models: undersampled stars can bias the measurements. Differences are not quality grades. Stellar SNR is not nebular or master-image SNR.

Processing and calibration record

Processing for this session

Calibrationsuccess
Registrationsuccess
Stackingsuccess
ReportSaved results

42/42 Lights calibrated; {'bias': 100, 'dark': 58, 'flat': 40} calibration frames. Unknown compatibility fields: device_id, filter, optical_configuration, readout_mode.

Calibration and processing evidence

{
  "calibrated": 42,
  "calibration_state": "success",
  "crop": {
    "area_fraction": 0.9828110512605414
  },
  "integration_s": 7380.0,
  "planned": 42,
  "ready": 42,
  "registered": 42,
  "registration_state": "success",
  "selected_calibrations": {
    "bias": 100,
    "dark": 58,
    "flat": 40
  },
  "stacked": 41,
  "stacking_state": "success",
  "unknown_fields": [
    "device_id",
    "filter",
    "optical_configuration",
    "readout_mode"
  ],
  "warnings": [
    "Bias is used for flat correction only; exposure/linearity suitability remains unvalidated",
    "Flat exposure is not matched to light exposure; flat dark current, illumination and physical optical-state continuity remain unvalidated",
    "Raw ROTATOR/angle semantics are unverified; differences are not evidence of physical rotation.",
    "Short-Flat/Light temperature tolerance: +/-2 C; Dark and Bias tolerances unchanged. Flat diagnostics and optical-history approval remain required.",
    "device_id: compatibility unknown; permitted only by explicit warning policy",
    "filter: compatibility unknown; permitted only by explicit warning policy",
    "optical_configuration: compatibility unknown; permitted only by explicit warning policy",
    "readout_mode: compatibility unknown; permitted only by explicit warning policy"
  ]
}

Explore stars in the image

Image geometry is not sufficiently verified, or the exact catalogue is not yet saved.

Science & measurements

Experimental photometry · no confirmed transit. 0 unresolved technical review items.

Histograms, light curves & event evidence

Intensity histograms

RGB · 41/41 original exposures measured.

RGB · Raw pixel values

ADU · decoded digital value · Pixel count per bin; not a wavelength spectrum.

Channel Range Pixel count

All saved bins, including negative values.

Exact counts and measured values

Werte und Darstellungsbins · Complete unchanged bins (NPZ)

Histogram of this display product is unavailable.

Events · technical review

Not measured

0 unresolved technical review items · 0 Gaia IDs searched · 0 tested windows. Windows are not independent events.

No confirmed transit. Short artifact clusters and time-correlated errors can pass this screening. Real periodic search: insufficient coverage; no globally calibrated false-alarm probability is available.

Saved event evidence

Test windows, supporting exposures and limitations

Photometry precision and sampling · experimental

Photometry & transit readiness

Not measured for this scope. Use the manual Review → Measure action once native exposures, calibration and geometry are qualified.

Comparison-star evidence · experimental

Stack input review · 1 exclusions

Input image review

1 excluded from this imaging stack · 2 flagged for inspection · 42 original exposures retained.

Exclusions affect this image stack only. Raw measurements and calibrated scientific images remain available. A satellite-like line alone does not reject an entire exposure.

Typical reference exposure

Reference raw frame and representative star crops

Input abb84ccb8eac · Excluded from stack

Jointly broader and more elongated than this session; possible shake/tracking/focus effects, cause not established.

Star width (FWHM): 5.07 sensor px · session median 3.359. Broader than this session; inspect focus, tracking and sampling. The cause is not identified.
Star eccentricity: 0.74 dimensionless · session median 0.4151. More elongated than this session; inspect tracking and field position. This is not a guiding measurement.
Detected sources: 3072 sources · session median 4876. Fewer detected sources; clouds, focus, framing and detection thresholds are possible causes.

Actual raw exposure with marked representative stellar regions — Actual raw green samples; display stretch only. Marked stars are representative samples, not measured guiding vectors or a catalogue identification.

Input 1f30bedb925d · Retained · review suggested

Measurement differs from its session. Retained: this alone does not establish a defective exposure.

Star width (FWHM): 4.18 sensor px · session median 3.359. Broader than this session; inspect focus, tracking and sampling. The cause is not identified.
Detected sources: 3968 sources · session median 4876. Fewer detected sources; clouds, focus, framing and detection thresholds are possible causes.

Relative stack weights (R/G/B): 0.786 / 0.840 / 0.808

Method and all inputs

Median/MAD comparisons stay within the same session, exposure, recorded setup and orientation. At least 12 valid frames and 75% coverage are required. Only simultaneous strong width and elongation outliers with at least 20 fitted stars can be excluded automatically. These are engineering thresholds, not a validated defect classifier. Entire-night defects and satellite trails may escape these metrics; pixel rejection remains a separate stack operation.

Exposure	Imaging decision	Reason
Input ea7056643932	retain · weights R/G/B 1.399 / 1.350 / 1.389	no_supported_outlier
Input ea1fff6c17c6	retain · weights R/G/B 1.036 / 1.062 / 1.046	no_supported_outlier
Input 3f9df0672883	retain · weights R/G/B 0.991 / 1.013 / 1.004	no_supported_outlier
Input 2404b980e4ad	retain · weights R/G/B 0.998 / 0.958 / 0.970	no_supported_outlier
Input 60324d3e31ed	retain · weights R/G/B 1.028 / 1.061 / 1.041	no_supported_outlier
Input 2e68e6e9d483	retain · weights R/G/B 0.987 / 1.015 / 0.997	no_supported_outlier
Input 29ed5df2d0ee	retain · weights R/G/B 0.961 / 1.009 / 0.978	no_supported_outlier
Input f32f585830a8	retain · weights R/G/B 0.885 / 0.861 / 0.863	no_supported_outlier
Input b18f4e31b895	retain · weights R/G/B 0.801 / 0.784 / 0.809	no_supported_outlier
Input b0c5d5dcc5d9	retain · weights R/G/B 1.087 / 1.070 / 1.067	no_supported_outlier
Input feaff3858490	retain · weights R/G/B 0.836 / 0.857 / 0.835	no_supported_outlier
Input 1206c541bcc9	retain · weights R/G/B 0.615 / 0.667 / 0.646	no_supported_outlier
Input b91b6c56a76a	retain · weights R/G/B 0.699 / 0.668 / 0.712	no_supported_outlier
Input e6bffbda5acd	retain · weights R/G/B 1.326 / 1.284 / 1.309	no_supported_outlier
Input 11d6d0c80c07	retain · weights R/G/B 0.988 / 1.027 / 1.011	no_supported_outlier
Input 6c59503afb32	retain · weights R/G/B 1.040 / 1.022 / 1.025	no_supported_outlier
Input eefbc5cbe7ff	retain · weights R/G/B 1.036 / 1.029 / 1.023	no_supported_outlier
Input a4cbd7bf5a39	retain · weights R/G/B 1.007 / 0.971 / 0.983	no_supported_outlier
Input 6e974244f856	retain · weights R/G/B 0.560 / 0.619 / 0.595	no_supported_outlier
Input 326838cf6af3	retain · weights R/G/B 0.855 / 0.840 / 0.825	no_supported_outlier
Input da6253f0a1c8	retain · weights R/G/B 0.808 / 0.802 / 0.791	no_supported_outlier
Input 4a838e02adea	retain · weights R/G/B 0.979 / 0.931 / 0.985	no_supported_outlier
Input 476418215cba	retain · weights R/G/B 1.058 / 1.047 / 1.043	no_supported_outlier
Input 42a865063924	retain · weights R/G/B 1.309 / 1.265 / 1.305	no_supported_outlier
Input ac672d40fed1	retain · weights R/G/B 1.075 / 1.095 / 1.087	no_supported_outlier
Input 54187c612914	retain · weights R/G/B 1.014 / 1.001 / 0.997	no_supported_outlier
Input 02b44f61f914	retain · weights R/G/B 1.404 / 1.347 / 1.392	no_supported_outlier
Input abb84ccb8eac	exclude_from_imaging_stack	joint_width_elongation_outlier
Input b4ba3edbedfd	retain · weights R/G/B 1.391 / 1.334 / 1.377	no_supported_outlier
Input db5811fa5130	retain · weights R/G/B 0.983 / 1.022 / 0.997	no_supported_outlier
Input 000131e89001	retain · weights R/G/B 1.039 / 1.045 / 1.033	no_supported_outlier
Input 6830c2675af6	retain · weights R/G/B 1.031 / 1.018 / 1.012	no_supported_outlier
Input 1336398a9d16	retain · weights R/G/B 1.462 / 1.365 / 1.433	no_supported_outlier
Input 1f30bedb925d	retain · weights R/G/B 0.786 / 0.840 / 0.808	descriptive_outlier
Input 181bd36529fe	retain · weights R/G/B 0.971 / 0.972 / 0.994	no_supported_outlier
Input 1de0b26f1d63	retain · weights R/G/B 0.975 / 1.008 / 0.990	no_supported_outlier
Input bbbae9ca53e6	retain · weights R/G/B 0.986 / 1.039 / 1.005	no_supported_outlier
Input 0b1b4bf21424	retain · weights R/G/B 0.919 / 0.972 / 0.941	no_supported_outlier
Input 134abd20dc17	retain · weights R/G/B 0.858 / 0.853 / 0.842	no_supported_outlier
Input 21bcb90ffdc1	retain · weights R/G/B 0.977 / 1.029 / 1.000	no_supported_outlier
Input 608566edf7ee	retain · weights R/G/B 0.989 / 0.975 / 0.979	no_supported_outlier
Input ffdb124843de	retain · weights R/G/B 0.854 / 0.874 / 0.860	no_supported_outlier

Stack contribution weights

Native noise weighting used

Compared with an equal-weight control using the exact same exposures, crop, normalization and pixel rejection. Star width and shape are reviewed separately.

Matched stars: 64 · background-texture ratio R/G/B: 0.979 / 0.986 / 0.986. Ratios compare weighted / equal; they are not a calibrated SNR.

Per-exposure weights and method

Weights are proportional to inverse background variance after Siril additive-scale normalization, independently in R, G and B, normalized to mean one. Displayed native values are reconstructed from rounded saved statistics. A weight is not a universal quality grade.

Input ID	R / G / B contribution
3f9df0672883	0.9909 / 1.0134 / 1.0043
2e68e6e9d483	0.9865 / 1.0146 / 0.9970
1de0b26f1d63	0.9750 / 1.0079 / 0.9895
ac672d40fed1	1.0754 / 1.0950 / 1.0867
60324d3e31ed	1.0285 / 1.0612 / 1.0411
ea1fff6c17c6	1.0361 / 1.0619 / 1.0462
21bcb90ffdc1	0.9766 / 1.0286 / 0.9995
11d6d0c80c07	0.9876 / 1.0268 / 1.0114
0b1b4bf21424	0.9191 / 0.9719 / 0.9409
bbbae9ca53e6	0.9857 / 1.0387 / 1.0046
db5811fa5130	0.9826 / 1.0215 / 0.9970
29ed5df2d0ee	0.9612 / 1.0092 / 0.9778
000131e89001	1.0394 / 1.0454 / 1.0326
476418215cba	1.0583 / 1.0467 / 1.0432
b0c5d5dcc5d9	1.0865 / 1.0696 / 1.0673
6830c2675af6	1.0307 / 1.0181 / 1.0125
eefbc5cbe7ff	1.0358 / 1.0286 / 1.0231
6c59503afb32	1.0397 / 1.0216 / 1.0254
608566edf7ee	0.9890 / 0.9754 / 0.9792
54187c612914	1.0136 / 1.0006 / 0.9973
1f30bedb925d	0.7855 / 0.8402 / 0.8080
42a865063924	1.3093 / 1.2653 / 1.3045
02b44f61f914	1.4039 / 1.3472 / 1.3919
e6bffbda5acd	1.3264 / 1.2838 / 1.3090
b4ba3edbedfd	1.3906 / 1.3337 / 1.3773
ea7056643932	1.3987 / 1.3497 / 1.3889
1336398a9d16	1.4625 / 1.3654 / 1.4331
1206c541bcc9	0.6147 / 0.6672 / 0.6462
6e974244f856	0.5597 / 0.6194 / 0.5947
b91b6c56a76a	0.6989 / 0.6684 / 0.7120
181bd36529fe	0.9706 / 0.9715 / 0.9942
b18f4e31b895	0.8005 / 0.7841 / 0.8090
4a838e02adea	0.9786 / 0.9310 / 0.9851
da6253f0a1c8	0.8084 / 0.8021 / 0.7910
326838cf6af3	0.8549 / 0.8399 / 0.8250
134abd20dc17	0.8580 / 0.8532 / 0.8424
f32f585830a8	0.8855 / 0.8614 / 0.8625
feaff3858490	0.8357 / 0.8573 / 0.8354
ffdb124843de	0.8545 / 0.8737 / 0.8604
a4cbd7bf5a39	1.0069 / 0.9706 / 0.9830
2404b980e4ad	0.9978 / 0.9580 / 0.9698

Correlated noise, shared calibration errors and local pixel rejection are not represented by these frame-level weights. Individual-exposure photometry is unchanged.

Appendix · measurement methods & observing conditions

Observing nights and Moon

RGB

2026-11-08 00:37:52 CET (UTC+0100) → 2026-11-08 03:01:15 CET (UTC+0100)

1.8% Moon illumination · saved calculation

Altitude -39.6°Target separation —

Mitte des Aufnahmezeitraums

Original saved observation note

Time assumption: DATE-OBS interpreted as UTC because TIMESYS is missing. Astronomical context is provisional.

Original saved observation note

Moon altitude is approximate; local Earth-orientation data may be incomplete.

Original saved observation note

Geometric Moon altitude, without terrain or refraction; site elevation assumed to be 0 m.

Saved time assumptions are unchanged. Site and weather are shown on the session pages.

Explain this comparison

Comparison with your current archive: each physical observing session has equal weight. Valid per-exposure values are first averaged within each session, then the session means are averaged. Later sessions and the exposures shown here may be included. This is neither an independent test nor a formal quality grade.

Selected data use the exact input IDs of this product. RGB and DNB, methods, units, sampling and recorded acquisition settings remain separate. Unknown setup metadata do not establish physical compatibility. A few sessions form only a small descriptive reference. Missing values do not count as zero.

FWHM and star shape are saved medians of the stellar fits in each exposure; the display averages these per-exposure values. Stellar SNR is the saved median of model estimates from at least five stars per exposure. Model: source Poisson noise, background variance and uncertainty in the mean local sky. Circular aperture radius 3, sky annulus 5–7 sampling pixels, 3σ clipping. EGAIN in electrons/ADU is required. Different star selections remain a limitation even within the same field.

Background and scatter are raw green-grid ADU under compatible acquisition conditions. Field emission, gradients and stellar populations limit comparison. These are not measurements of pure seeing, nebular SNR or transit sensitivity. The previous grading rule requiring eight other nights has not changed.

RGB · Star width (FWHM): 41/41 valid selected exposures; archive 42/42 frames, 1 Sessions. Unknown properties: device_id, readout_mode, optical_configuration, filter, execution_method_version.

RGB · Star shape: 41/41 valid selected exposures; archive 42/42 frames, 1 Sessions. Unknown properties: device_id, readout_mode, optical_configuration, filter, execution_method_version.

RGB · Background: 41/41 valid selected exposures; archive 42/42 frames, 1 Sessions. Unknown properties: device_id, readout_mode, optical_configuration, filter, execution_method_version.

RGB · Background scatter: 41/41 valid selected exposures; archive 42/42 frames, 1 Sessions. Unknown properties: device_id, readout_mode, optical_configuration, filter, execution_method_version.

RGB · Stellar SNR: 41/41 valid selected exposures; archive 42/42 frames, 1 Sessions. Unknown properties: device_id, readout_mode, optical_configuration, filter, execution_method_version.

Archive version ab3717b4ec376ea87d5261c94fe6dbbd42a97237e09422490b5844921d286006. This export is a frozen snapshot; it does not update without a new export.

All measurements and frozen archive comparison

Individual-frame quality review · advisory

Image-quality assistant

1 selected frames worth reviewing · 41/41 inputs have enough same-session support. All frames remain selected exactly as before.

Separate raw measurements, compared with the median of the same session and recorded setup. No overall score, automatic rejection or diagnosis.

Review suggestions · 1 frames

Saved header time / input ID	Measurement	This frame	Session median	Why review?
2026-11-08T00:46:15.445964 1f30bedb925d	Star width (FWHM)	4.18 sensor pixels	3.359	Broader than this session; inspect focus, tracking and sampling. The cause is not identified.

Method, coverage and limitations

Review distance = (value − session median) / (1.4826 × MAD). The threshold 3.5 is an advisory rule, not statistical significance. At least 12 valid frames and 75% coverage are required; zero MAD is unavailable. SNR requires the existing gain and star-count checks. Background changes are flagged in either direction.

Shared tracking/focus problems can affect an entire night without producing an outlier. No independent validation labels exist yet. Raw-green sampling and changing star populations limit interpretation. RGB/DNB, exposure, method and recorded orientation remain separate; unknown metadata do not establish compatibility.

RGB · 180.0 s · session acq_8528bdce: Background level 42/42; Background scatter 42/42; Detected sources 0/42: too few valid session frames; Star eccentricity 42/42; Star width (FWHM) 42/42; Stellar SNR estimate 42/42. Unknown: device_id, filter, optical_configuration, readout_mode, recorded_orientation_deg.

Method session-quality-assistant-1. Saved measurements and existing archive comparisons are unchanged.