Pleiades (M45) star cluster and reflection nebula, 10-minute stack, colour-calibrated, Seestar S30 Pro

Images and files

Record details

Object

Pleiades (M45, Seven Sisters)

Object type

Open star cluster with reflection nebula

Right ascension (RA)

56.7329°

Declination (Dec)

24.1335°

Reference frame (RADESYS)

ICRS (J2000), image centre from the Siril plate solve against Gaia DR3

Observation date (local)

2026-10-31

Start time

2026-10-31 15:23:17 (UTC)

End time

2026-10-31 15:48:17 (UTC)

Time scale (TIMESYS)

UTC

Time source

Camera clock

Telescope and instrument

ZWO Seestar S30 Pro (30 mm f/5.3 apochromat, built-in colour CMOS)

Filter

IR-cut (broadband visible)

Exposure time

60 s

Number of combined frames

10

Observing method

ZWO Seestar S30 Pro smart telescope (30 mm aperture, 160 mm focal length, f/5.3; 3840x2160 colour sensor, 2.9 μm pixels), built-in IR-cut (broadband) filter, gain 200, sensor about 25 °C. 11 frames of 60 s captured from 02:23 to 02:48 AEDT on 1 Nov 2026 (night of 31 Oct). In Siril 1.4: debayered and registered (two-pass), the frame below the best 90% by star sharpness (wFWHM) dropped, and the remaining 10 sigma-clipped (3/3) and stacked with wFWHM weighting (10 min total). The stack was then plate-solved against the Gaia DR3 astrometric catalogue (1693 image stars; 3.663 arcsec/pixel, effective focal length 163.3 mm) and colour-corrected with Siril photometric colour calibration (PCC) using Gaia DR3 star colours (691 stars), with RBF background gradient removal before and after. Then a linked auto-stretch and a mild saturation boost. No colour or detail painted in, no AI or star removal. No darks or flats applied. The main image is a crop around the cluster with Rob's semi-transparent 'rme' signature; the full frame is attached without it.

Bias frames

0

Dark frames

0

Flat frames

0

Astrometric solution (plate solve)

Solved by contributor

Calibration level

Partially calibrated

Processing level

Stacked

Processing software

Siril 1.4.0-rc2 (plate solve + PCC with Gaia DR3)

Description

The Pleiades (M45, the Seven Sisters) in Taurus: a young open cluster of hot blue stars about 440 light-years away, passing through a dust cloud that reflects their blue light. Ten 60-second frames restacked from the raw sub-frames and colour-calibrated against Gaia star colours. Taken low in the north-east from the Riverina, so the faint wisps of nebulosity are only just showing.

Uncertainty remarks

Only 10 minutes of data, so the faint outer nebulosity is weak and noisy. Colours are calibrated against Gaia DR3 star colours (PCC, broadband filter), close to true colour; spectrophotometric calibration (SPCC) was not used because it crashes in Siril 1.4.0-rc2. No dark or flat frames, so faint gradients and hot pixels may remain. The plate solve shows the north–south axis runs vertically to within about 1 degree; the image keeps the Seestar's display orientation. Distance is the literature value, not measured here. Site position deliberately generalised to the nearest whole degree (about 60 km) to protect a private home.

Data quality statement

10 of 11 frames stacked after star-sharpness filtering. Astrometry and colour from Gaia DR3 via local Siril catalogues (astrometric catalogue for the plate solve; PCC for colour). GPS and camera metadata removed from the published images; the raw FITS (which hold the site position) are kept privately.

Source

Seestar S30 Pro sub-frames Light_M 45_60.0s_IRCUT, 11 FITS from 2026-11-01 02:23 to 02:48 AEDT (Seestar stack Stacked_11_M 45_60.0s_IRCUT_20261101-025123); Siril log siril-20261103-siril.log; colour reference Gaia DR3 (ESA/Gaia/DPAC) via Siril local catalogue

Original FITS header retained

Yes

Place

Not shown on public record pages

From the Astronomy image profile, version 1.3.0, as signed for this record version. Not shown publicly: place, coordinate and site fields, fields the profile marks sensitive (such as observing times), and the names of observers, collectors and other credited people. In the title, captions and written descriptions, coordinates, street addresses, email addresses and phone numbers are replaced with a marker; other text, including any names or times written in it, is shown as the contributor wrote it.

Cite this record

Rob Evans (2026). Pleiades (M45) star cluster and reflection nebula, 10-minute stack, colour-calibrated, Seestar S30 Pro. Clio Online Museum. https://cliomuseum.org/records/record-816fdb96-7f7d-4991-85cd-c9037bfc9ff2

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https://cliomuseum.org/records/record-816fdb96-7f7d-4991-85cd-c9037bfc9ff2

Published recordVersion 1

Creators

• Rob Evans https://orcid.org/0009-0004-6391-4464 (opens in a new tab) (verified with ORCID)

Version and provenance

Version identifier

version-bc0a4221-aa0a-4dc6-bfbb-a52b1a77db40

Canonical commitment

sha3-384:3903bd924680853af52c31f436f7d6ae3e73632f497ed935acd3dcd905b05ba159d0ffc475a055b49e33e89a1557e778

Accepted

2026-11-03

Evidence profile and standards

• FITS
• World Coordinate System (WCS)
• IVOA Provenance Data Model