M 81 · RGB Session 1 · 2026-11-06

Observing conditions

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

RGB · 2026-11-06 21:22:17 CET (UTC+0100) → 2026-11-06 23:19:46 CET (UTC+0100)

Moon · calculated

5.9%

Illuminated · Waning

Altitude -51.9° · below the geometric horizon

Reference: 2026-11-06T21:21:02.052 UTC

Observing site

—

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

Weather · model context

ECMWF IFS archive · Open-Meteo

Cloud cover: 0.0–2.0 %
Dew point: 1.3–1.5 °C
Relative humidity: 81.0–87.0 %
Air temperature: 3.3–4.5 °C
Wind at 10 m: 5.7–5.8 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	Cloud cover · %	Wind at 10 m · m/s
2026-11-06T20:00:00+00:00	4.5	81.0	1.5	0.0	5.8
2026-11-06T21:00:00+00:00	3.9	83.0	1.3	0.0	5.7
2026-11-06T22:00:00+00:00	3.3	87.0	1.4	2.0	5.8

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

Cloud cover: 3/3 samples; Dew point: 3/3 samples; Relative humidity: 3/3 samples; Air temperature: 3/3 samples; Wind at 10 m: 3/3 samples

Retrieved 2026-11-07T15:18:46.200223+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: df3d1acb7cf4d9c0199629896d9e330a81aea24e5eeda341957ef3fb273ea002

RGB · 180 s · 32 Lights

1 h 36 min · 32 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: 4.05 sensor pixels; Current archive average3.00 sensor pixels; Difference +1.05; 32/32 selected · archive 865/865 exposures · 11 sessions · 8 objects
Star shape / eccentricity: 0.31 dimensionless; Current archive average0.45 dimensionless; Difference -0.14; 32/32 selected · archive 865/865 exposures · 11 sessions · 8 objects
Background: 929.97 ADU; Current archive average749.61 ADU; Difference +180.36; 32/32 selected · archive 865/865 exposures · 11 sessions · 8 objects
Background scatter: 41.87 ADU; Current archive average34.26 ADU; Difference +7.61; 32/32 selected · archive 865/865 exposures · 11 sessions · 8 objects
Stellar model SNR: 195.39 dimensionless; Current archive average138.73 dimensionless; Difference +56.66; 32/32 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 · 32 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.

Acquisition · 2026-11-06 · recorded DATE-OBS

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

Star width (FWHM): 4.05 sensor pixels; Current archive average4.05 sensor pixels; Difference 0.00 sensor pixels; 32/32 frames · archive: 1 Sessions
Star shape: 0.31 dimensionless; Current archive average0.31 dimensionless; Difference 0.00 dimensionless; 32/32 frames · archive: 1 Sessions; Eccentricity of stellar model fits
Background: 929.97 ADU; Current archive average929.97 ADU; Difference 0.00 ADU; 32/32 frames · archive: 1 Sessions
Background scatter: 41.87 ADU; Current archive average41.87 ADU; Difference 0.00 ADU; 32/32 frames · archive: 1 Sessions
Stellar SNR: 195.39 dimensionless; Current archive average195.39 dimensionless; Difference 0.00 dimensionless; 32/32 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

32/32 Lights calibrated; {'bias': 100, 'dark': 58, 'flat': 80} calibration frames. Unknown compatibility fields: device_id, filter, optical_configuration, readout_mode.

Calibration and processing evidence

{
  "calibrated": 32,
  "calibration_state": "success",
  "crop": {
    "area_fraction": 0.9763248377411806
  },
  "integration_s": 5760.0,
  "planned": 32,
  "ready": 32,
  "registered": 32,
  "registration_state": "success",
  "selected_calibrations": {
    "bias": 100,
    "dark": 58,
    "flat": 80
  },
  "stacked": 32,
  "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 · 32/32 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

Appendix · measurement methods & observing conditions

Observing nights and Moon

RGB

2026-11-06 21:22:17 CET (UTC+0100) → 2026-11-06 23:19:46 CET (UTC+0100)

5.9% Moon illumination · saved calculation

Altitude -51.9°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 shape: 32/32 valid selected exposures; archive 32/32 frames, 1 Sessions. Unknown properties: device_id, readout_mode, optical_configuration, filter, execution_method_version.

RGB · Stellar SNR: 32/32 valid selected exposures; archive 32/32 frames, 1 Sessions. Unknown properties: device_id, readout_mode, optical_configuration, filter, execution_method_version.

RGB · Star width (FWHM): 32/32 valid selected exposures; archive 32/32 frames, 1 Sessions. Unknown properties: device_id, readout_mode, optical_configuration, filter, execution_method_version.

RGB · Background: 32/32 valid selected exposures; archive 32/32 frames, 1 Sessions. Unknown properties: device_id, readout_mode, optical_configuration, filter, execution_method_version.

RGB · Background scatter: 32/32 valid selected exposures; archive 32/32 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

0 selected frames worth reviewing · 32/32 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.

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_188938f9: Background level 32/32; Background scatter 32/32; Detected sources 0/32: too few valid session frames; Star eccentricity 32/32; Star width (FWHM) 32/32; Stellar SNR estimate 32/32. Unknown: device_id, filter, optical_configuration, readout_mode, recorded_orientation_deg.

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