M37
ILLUSTRATION FROM OPEN CLUSTER · MAJOR AXIS 11.4′
OVERVIEW
] STAR CLUSTERM37 is an open cluster in the constellation Auriga, 4571 from Earth, shining at apparent magnitude 5.60 (). Other catalogues list it as C 0549+325, MWSC 689 and NGC 2099. It was discovered in 1654.
- WHAT IT IS
- Open cluster
- HOW FAR
- 4571
- HOW BIG ON THE SKY
- 11.4
- HOW BRIGHT (V)
The light arriving now left it that long ago.
About 0.4 of the full Moon's width.
Bright enough for the naked eye, under a sky dark enough.
THE MODEL
] LIGHT ALONG THE RAYCALCULATED · NOT AN OBSERVATION · ANGULAR SIZE AT THE CATALOGUED DISTANCE · OPEN CLUSTER · MAJOR AXIS 11.4′ · NO SURFACE — DRAWN AS A VOLUME · MEMBERS DRAWN, NOT COUNTED
A cloud of gas glowing at the lines its class emits, brightest in the middle and fading through the colour of the outer gas. The shape of it is the catalogued class; the flattening is the catalogued axis ratio read as the object's own shape rather than as a tilt, because this is not a disc and its ellipticity is not an inclination. Nothing measured the depth, so what is drawn is the roundest object that matches the ellipse the catalogue holds. Every member is drawn at the one temperature its class implies; how many are drawn is a drawing choice and not a population. Drag it, or use the arrow keys, to look from another direction. The stars behind are the 498,631 this catalogue holds real distances for, drawn from where the camera actually is — but every one of them is within 170 parsecs of the Sun and this object is much further out, so from here that whole neighbourhood is a knot in one direction and the rest of the sky is empty. The view you land on looks the other way; turn back towards the Sun and the stars come with it. What the readout says is which of the two the frame is pointed at. The emptiness is not a missing backdrop — it is the edge of what this catalogue has measured.
OBSERVING
] FROM WHERE YOU AREWhat it takes to see M37 for yourself. Everything in this part of the page is worked out for a real horizon, a real night and the equipment you say you have.
Say where you are, and this line says when M37 is worth going out for.
THROUGH AN EYEPIECE
] 150 MM TELESCOPE · 25 MM EYEPIECEBright enough to see with your eyes alone, once you are away from town lights. M37 covers 11.4′ of sky against a of 1.08°, so at 48× it is comfortably framed.
- 48×
- 1.08
- 1.25
- 13.0
- SIZE ON THE SKY
- 11.4
- FILLS OF THE FIELD
- 18% of the width
- APPARENT MAGNITUDE ()
- 5.60 · within reach
M37 is not a point of light, so the limit above is the wrong one to hold it against: the same brightness spread over 11.4′ of sky is harder than a star of it, and goes first. Catalogued sizes are measured to a photographic contour, and the part an eye sees is usually smaller.
APPARENT PLACE
] EQUINOX J2026.8Where a telescope has to be pointed today, which is not quite where the catalogue records the object: the coordinate grid itself has turned since the year 2000 the catalogue is referred to.
- RIGHT ASCENSION
- DECLINATION
- GRID TURNED SINCE
- 22.3
- PROPER MOTION SINCE
- none published
Computed for 2026-10-11 00:00 UT. No proper motion is published for M37, so nothing here moves the object; what separates this from the catalogued position above is the coordinate grid turning under it — about fifty arcseconds a year of precession since 2000, and the small nodding of the Earth’s axis on top of that. The catalogue it came from publishes no error for that position, so nothing here says how far this arithmetic can be trusted — the digits above are as precise as the place they were computed from, and no more. Aberration, parallax and refraction are left out. Aberration swings every position by up to twenty arcseconds over a year; parallax stays under an arcsecond for all but the nearest stars; refraction is nothing overhead and about half a degree at the horizon, where it answers to the air, not the sky. The same figure for any date.
CATALOG DATA
] 10 FIELDSThe raw catalogue values, as the source published them, with the error bars where one was published — sorted by what each set of figures is about rather than by the order they happened to be stored in.
HOW BRIGHT IT IS
What the light adds up to, measured through one filter at a time. A magnitude is a brightness on a backwards scale — the smaller the number, the brighter the object.
- Apparent magnitude ()
- Apparent magnitude ()
WHERE IT IS AND HOW IT MOVES
Position, motion across the sky and the size it covers on it. These are measurements of the object as seen from here, so every one of them depends on where here is.
- 8
- Redshift (z)
- Major axis
- 11.4
WHEN IT WAS FOUND
Who first saw it, from where, and by what method.
- Discovered by
- Giovan Battista Hodierna
OTHER NAMES AND NUMBERS
The identifiers other catalogues file this object under, for anyone joining this data to theirs.
- OpenNGC type code
- OCl
- Wikidata item
- Q13878
- Wikipedia article
- Messier 37
WHERE THESE FIGURES CAME FROM
Which catalogue, paper or model each of the fields above was read from, where the source named one.
- Distance catalogue entry
- NGC 2099
ALSO KNOWN AS
] 4 DESIGNATIONS- IAU cluster C 0549+325
- Messier M 37
- MWSC MWSC 689
- NGC NGC 2099
LOOK IT UP ELSEWHERE
] 3 SERVICESEach link carries the identifier printed beside it. Nothing on this page is a measurement of our own, so a number that disagrees with one of these is worth reporting — and a service that has never catalogued this object under this name will say so plainly.
- SIMBADM37
Cross-identifications, measured values and the reference behind each of them.
- ADSobject:"M37"
Papers indexed against this object rather than against the string, newest first.
- VizieR342″ around 88.0765 +32.5530
Every published table with a row at this position, searched by coordinates rather than by name.
CITE THIS PAGE
] DR1This page is live and its numbers move when an upstream refreshes, so the citation names the release the rows belong to rather than the day you read them. The release itself is frozen, republished as a bundle, and is what a data-availability statement should point at.
SpaceCatalog. M37 [catalogue entry]. Data release DR1 (2026-08-21). https://spacecatalog.org/object/m37
@misc{spacecatalog_m37,
author = {{SpaceCatalog}},
title = {{M37}},
howpublished = {SpaceCatalog, data release DR1 (2026-08-21)},
year = {2026},
url = {https://spacecatalog.org/object/m37},
note = {Catalogue entry, data release DR1 (2026-08-21). Values from OpenNGC.}
}The values above were taken from OpenNGC — CC-BY-SA-4.0. Citing this page does not replace citing that catalogue, and its licence is share-alike: the terms reach whatever you build from these rows.
That catalogue asks for this acknowledgement: OpenNGC, Mattia Verga (github.com/mattiaverga/OpenNGC). Fields derived from it stay under CC BY-SA 4.0.
RECENT ACTIVITY
] 1 ITEMS- The Ghosts of Five Supernovas2026-09-24 · NASA APOD · IMAGE · Stephane Vetter, Yann Sainty Text: Cecilia Chirenti (NASA GSFC, UMCP, CRESST II)
NASA APOD · UPDATED DAILY