IC 1848 - Soul Nebula · DNB Session 1 · 2026-10-03

Observing conditions

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

DNB · 2026-10-03 22:10:36 CEST (UTC+0200) → 2026-10-04 05:41:48 CEST (UTC+0200)

Moon · calculated

45.1%

Illuminated · Waning

Altitude 24.6°

Reference: 2026-10-03T23:56:12.645 UTC

Observing site

—

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

Weather · model context

ERA5 reanalysis · Open-Meteo

Cloud cover
0.0–0.0 %
Dew point
3.0–3.5 °C
Relative humidity
47.0–67.0 %
Air temperature
8.9–14.6 °C
Wind at 10 m
1.9–3.4 m/s

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

Hourly values and coverage
UTCAir temperature · °CRelative humidity · %Dew point · °CCloud cover · %Wind at 10 m · m/s
2026-10-03T20:00:00+00:0014.647.03.30.03.4
2026-10-03T21:00:00+00:0013.651.03.50.02.9
2026-10-03T22:00:00+00:0013.052.03.20.02.8
2026-10-03T23:00:00+00:0012.055.03.10.02.4
2026-10-04T00:00:00+00:0010.958.03.00.02.6
2026-10-04T01:00:00+00:009.963.03.10.02.8
2026-10-04T02:00:00+00:008.967.03.20.02.4
2026-10-04T03:00:00+00:009.465.03.10.01.9

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

Cloud cover: 8/8 samples; Dew point: 8/8 samples; Relative humidity: 8/8 samples; Air temperature: 8/8 samples; Wind at 10 m: 8/8 samples

Retrieved 2026-10-20T16:42:33.930494+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: f4ba76bc1e2223714b8d2b62467bd1571ada7f9dbe291f290cb6df79e11ce4a9

DNB · 300 s · 77 Lights

6 h 25 min · 77 exposures available.

Session
Preview image · up to 2560 px

Selected input exposures

Image quality at a glance

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

DNB · all contributing sessions

Star width / FWHM
2.72 sensor pixels
Current archive average2.96 sensor pixels
Difference -0.24
77/77 selected · archive 342/342 exposures · 10 sessions · 6 objects
Star shape / eccentricity
0.49 dimensionless
Current archive average0.49 dimensionless
Difference +0.00
77/77 selected · archive 342/342 exposures · 10 sessions · 6 objects
Background
537.30 ADU
Current archive average574.41 ADU
Difference -37.11
77/77 selected · archive 342/342 exposures · 10 sessions · 6 objects
Background scatter
13.42 ADU
Current archive average17.93 ADU
Difference -4.51
77/77 selected · archive 342/342 exposures · 10 sessions · 6 objects
Stellar model SNR
20.15 dimensionless
Current archive average77.42 dimensionless
Difference -57.27
77/77 selected · archive 342/342 exposures · 10 sessions · 6 objects
Stellar model estimate · different fields
Star width / FWHM
Selected exposure values · whole-archive DNB mean · physical sessions separated.
Star shape / eccentricity
Star shape / eccentricity
Selected exposure values · whole-archive DNB mean · physical sessions separated.
Background
Background
Selected exposure values · whole-archive DNB mean · physical sessions separated.
Background scatter
Background scatter
Selected exposure values · whole-archive DNB mean · physical sessions separated.
Stellar model SNR
Stellar model SNR
Selected exposure values · whole-archive DNB mean · physical sessions separated.
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.

DNB · 300.0 s · 77 Lights

Acquisition settings & contributing sessions

300.0 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.

DNB Session 1 · 2026-10-03

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

Star width (FWHM)
2.72 sensor pixels
Current archive average2.72 sensor pixels
Difference 0.00 sensor pixels
77/77 frames · archive: 1 Sessions
Star shape
0.49 dimensionless
Current archive average0.49 dimensionless
Difference 0.00 dimensionless
77/77 frames · archive: 1 Sessions
Eccentricity of stellar model fits
Background
537.30 ADU
Current archive average537.30 ADU
Difference 0.00 ADU
77/77 frames · archive: 1 Sessions
Background scatter
13.42 ADU
Current archive average13.42 ADU
Difference 0.00 ADU
77/77 frames · archive: 1 Sessions
Stellar SNR
20.15 dimensionless
Current archive average20.15 dimensionless
Difference 0.00 dimensionless
77/77 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

  1. Calibrationsuccess
  2. Registrationsuccess
  3. Stackingsuccess
  4. ReportSaved results

77/77 Lights calibrated; {'bias': 57, 'dark': 40, 'flat': 33} calibration frames. Unknown compatibility fields: device_id, filter, optical_configuration, readout_mode.

Calibration and processing evidence
{
  "calibrated": 77,
  "calibration_state": "success",
  "crop": {
    "area_fraction": 0.8975868446485251
  },
  "integration_s": 23100.0,
  "planned": 77,
  "ready": 77,
  "registered": 77,
  "registration_state": "success",
  "selected_calibrations": {
    "bias": 57,
    "dark": 40,
    "flat": 33
  },
  "stacked": 77,
  "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.",
    "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

Verified image · DNB · 2026-10-03

572 verified identities; 12 spatially distributed highlights. Query: G < 16, at most 5000 sources; fainter neighbours may be absent.

Farb-Helligkeits-Diagramm · Gaia G / BP−RP

Scheinbare Kataloghelligkeit, kein HR-Diagramm; Staub und Distance wirken mit.

G (mag)BP−RP (mag)
Identity, data and limitations

Holdout residual: median 0.5138871867673964 px; 95 % 1.1267509647617382 px. G<16; fainter neighbours may be absent. Historical solver training set is unknown.

Temperature, mass and radius are catalogue model estimates, not stellar parameters measured from this photograph.

Exact catalogue values and geometry

Science & measurements

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

Histograms, light curves & event evidence

Intensity histograms

DNB · 77/77 original exposures measured.

DNB · Raw pixel values

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

-0.56.554e+044.793e+08BG1G2R

All saved bins, including negative values.

Exact counts and measured valuesWerte und Darstellungsbins · Complete unchanged bins (NPZ)

Current display image

8-bit display values · nonlinear · Pixel count per bin; not a wavelength spectrum.

-0.5255.51.933e+06BGR

All saved bins, including negative values.

Exact counts and measured valuesWerte und Darstellungsbins · Complete unchanged bins (NPZ)

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 evidenceTest 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
All saved stellar light curves
Appendix · measurement methods & observing conditions
Observing nights and Moon

DNB

2026-10-03 22:10:36 CEST (UTC+0200) → 2026-10-04 05:41:48 CEST (UTC+0200)

45.1% Moon illumination · saved calculation

Altitude 24.6°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.

DNB · Star shape: 77/77 valid selected exposures; archive 77/77 frames, 1 Sessions. Unknown properties: device_id, readout_mode, optical_configuration, filter, execution_method_version.

DNB · Star width (FWHM): 77/77 valid selected exposures; archive 77/77 frames, 1 Sessions. Unknown properties: device_id, readout_mode, optical_configuration, filter, execution_method_version.

DNB · Stellar SNR: 77/77 valid selected exposures; archive 77/77 frames, 1 Sessions. Unknown properties: device_id, readout_mode, optical_configuration, filter, execution_method_version.

DNB · Background scatter: 77/77 valid selected exposures; archive 77/77 frames, 1 Sessions. Unknown properties: device_id, readout_mode, optical_configuration, filter, execution_method_version.

DNB · Background: 77/77 valid selected exposures; archive 77/77 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 · 77/77 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 IDMeasurementThis frameSession medianWhy review?
2026-10-03T23:59:18.057621
29ab7d81f8d5		Star width (FWHM)3.394 sensor pixels2.708Broader 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.

DNB · 300.0 s · session acq_3ffd0489: Background level 77/77; Background scatter 77/77; Detected sources 0/77: too few valid session frames; Star eccentricity 77/77; Star width (FWHM) 77/77; Stellar SNR estimate 77/77. Unknown: device_id, filter, optical_configuration, readout_mode, recorded_orientation_deg.

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