Delphinus

Job's Coffin

Delphinus diamond

skylore / traditional name · medium confidence

Delphinus's compact diamond and tail has long been nicknamed Job's Coffin. It is small, neat, and easy to hold in a single binocular field east of Altair.

Central RA: 20^h 40^m 06.2^s
Central Dec: +14° 36′ 07″
Brightest member: V 3.63
Best months from 50°N: June–September evenings
Suggested instrument: naked-eye
Approx. span: 5.8°

Finder context

This wider chart is deliberately schematic: it uses nearby bright-star context and boxes the asterism’s member-star footprint, but it does not draw official constellation boundaries or promise horizon/season precision.

Framing: Approximate member-star span: 5.8°; use at least 8.2° field for context.

Observing and imaging

Naked eye

Primary naked-eye pattern; suburban skies should show the main stars unless the description notes a low horizon or dark-sky need.

Binoculars

Binoculars are optional: use them to check colours, nearby doubles, or richer Milky Way background.

Small scope

A telescope is usually too narrow for the whole shape; use it after the pattern has guided you to a target.

Imaging

Frame as a wide-field scene in/near Delphinus; a field of view around 8° keeps context without claiming exact constellation boundaries.

Tonight from your latitude

Observability from your latitude: uses this asterism’s centroid RA/Dec with a schematic local clock from longitude, astronomical twilight (Sun below −18°), and the 2026 Moon heuristic. Month stays for the seasonal readout.

Latitude 50°NLongitude -114°Date Month Sky darkness Bortle 4 · limit V 6.1

Naked-eye visibility by sky class

Approximate limiting magnitudes: Bortle 3 ≈ V 6.6, Bortle 5 ≈ V 5.6, Bortle 7 ≈ V 4.6. The shape is counted recognisable when at least 70% of defining stars clear the limit.

Bortle 3: 5/5 stars — fully visibleBortle 5: 5/5 stars — fully visibleBortle 7: 5/5 stars — fully visible

Moon impact

Reference year 2026, Sep: 22/30 nights (73%) have a sampled ≥2 h window with Job's Coffin above 20° and the Moon below the horizon. At transit the Moon is up on about 57% of nights; the average moonlight penalty is roughly 0.52 mag of naked-eye limiting magnitude. Good nights below are the deterministic 2026 best-month mini-calendar for 50°N; green means a ≥2 h sampled dark window with the Moon down.

010203040506070809101112131415161718192021222324252627282930

Member stars

Name	Bayer / Flamsteed	HR	RA J2000	Dec J2000	V mag
Rotanev	6Bet Del	HR 7882	20^h 37^m 33.0^s	+14° 35′ 43″	3.63
Sualocin	9Alp Del	HR 7906	20^h 39^m 38.3^s	+15° 54′ 43″	3.77
Epsilon Delphini	2Eps Del	HR 7852	20^h 33^m 12.8^s	+11° 18′ 12″	4.03
Gamma² Delphini	12Gam2Del	HR 7948	20^h 46^m 39.5^s	+16° 07′ 27″	4.27
11Del Del	11Del Del	HR 7928	20^h 43^m 27.5^s	+15° 04′ 28″	4.43

Source and confidence

skylore / traditional name; medium confidence. Traditional or folk name carried through older public-domain star-name literature; the plotted stars are still BSC5 positions.

Citations

Bright Star Catalogue, 5th Revised Ed.: Hoffleit, D. & Warren, W.H. Jr. (1991). Positions, V magnitudes, Bayer/Flamsteed identifiers. source
Star Names and Their Meanings: Allen, R.H. (1899). Public-domain skylore and traditional names.
The Hipparcos and Tycho Catalogues: ESA SP-1200 (1997). Used as the modern astrometric reference named by the atlas; the MVP pages expose BSC5 J2000 fields for the plotted bright-star members.