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Lacaille III.4 (6,208 of 18,816)

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Lacaille III.4

Lacaille III.4, IC 2488, Cl Collinder 208, Cl Melotte 97, Cl VDBH 69, C 0926-567, COCD 220

RA: 09h 27m 36s
Dec: −57° 00′ 0″

Con: Vela
Ch: MSA:994, U2:425, SA:25

Ref: SIMBAD, Collinder (1931), DAML02, Archinal&Hynes (2003)

(reference key)

Type: open cluster, 23r

Mag: B=?, V=7.4

Size: 18′
PA: ?

Image gallery

Sketches  (1)

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Historical observations

Lacaille (1755)

This cluster was discovered by Lacaille and included in his 1755 catalogue as Class III No. 4. In his half-an-inch 8x telescope he saw it as a "faint star in nebulosity."

Published comments

Bailey, S.I. (1908)

"cluster, coarse."

Bailey, S.I. (1908) A catalogue of bright stars and nebulae. Ann.Harv.Coll.Obs., 60(8), 199.

Melotte, P.J. (1915)

A catalogue of star clusters shown on Franklin-Adams chart plates. Mem.R.A.S., 60(5), 175-186.

Table, p.177: "Clusters" noted by Bailey but not included in the Catalogue:

"Does not appear as a cluster."

Mel 97: A loose clustering of fairly bright stars.

Raab, S. (1922) "A research on open clusters"

Mel 97: Discussed, Based on F-A plates.

Doig, P. (1926)

"A Catalogue of Estimated Parallaxes of 112 Nebulae, Open clusters and Star Groups", Vol 36 (4), p 107-115.

Mel 97: "loose cluster; fairly bright stars." He gives the approx. diameter as 40 arcmin.

Trumpler, R.J. (1928)

Trumpler (Lick Obs Bul, Vol 14, No. 420) gives the diameter as 18' and the class as 4 2 mU.

Hogg, A.R. (1965)

"Cat. of Open Cl. south of -45 Decl.", Mem. 17 Mnt Stromlo Obs.

Obvious groupnig of brighter stars near an 'edge'

James, Andrew (1998+)

From: "Neat Southern Planetaries - XII"

IC 2488/ Mel 97/ CR 208 (09275-5657) lies in Vela, a mere 5'min.arc. from the Carina border - literally on 'the ship's deck'. It can be quickly found some 52'min.arc. south of NGC 2899. (Figure 4) Easily visible in a 7.5cm., the cluster subtends 14'min.arc. The total integrated magnitude of the cluster is 7.4, and Lynga in his proper motion studies of IC 2488 determined that some seventy stars are associated. Cluster classification is given as '2 3 r -', saying that it is detached with a slight concentration, medium brightness and rich without nebulosity. Brightest star is the blue star B9 (SAO 237004; 09277-5700) at magnitude 8.9, followed by a yellow F5 star magnitude 9.3 (SAO 236995; 09272-5656) IC2488 contains many blue stars, and appears to me as various intersecting straight lines of stars moving north and south. Another solitary line is in an NW to SE direction. The two brightest components are contained within each line. It is likely that the yellow star is the centre of the gravitational potential, with the cluster's faintest stars ending at about magnitude 13.5. 6'min.arc.

To the northeast by 6'min.arc. is the faint magnitude 11.0 and 12.0 pair BRT 2548 (09281-5652). (Top left in Figure 4) Discovered by S.J.Barton in 1924, the solitary micrometric measure gives a separation of 3.6"sec.arc. at position angle 174O. Using medium magnification to the eastern field is an orange K5 III star. This is the third magnitude variable star N Velorum (SAO237067) (09312-5702). Sky Atlas 2000.0 suggests it N Vel is a possible slow irregular variable star, while some observers classify it is CST - constant. The true nature or existence of this variable is unknown. Visual magnitude changes are said to be between 3.12 and 3.15, and this is even uncertain. Observers should use this naked eye star to enable them to find the cluster and PN's. N Vel is a mere 24"sec.arc. from being in the constellation of Carina!

V Velorum (09223-5558) is a Cepheid type variable that varies between visual magnitude 7.19 and 7.95. The period is 4.370991 days as set from 30th May 1970 (JD2440736.25) at 18h UT. The rise in magnitude in the outward pulse takes about 1.3 days to reach maximum brightness. The spectra for the sub-giant star vary between F6 at maxima and F9 at minima.

Modern observations

ASV Journal (1971)

ASV Journal Vol 24 No 3 June 1971: "irregular shape in 3-inch 64x."

Brian Skiff

QBS: dk patches (15cm) not obvious, but there.

15cm - mod br mod rich cl 12' diam @ 80x. few outliers twd S, where there are two ~circ wk dk patches SW & SE of cl. brtst *s m10, most m12+. 140x shows 80*s. BS, 21Feb1990, LCO.

Contemporary observations

Auke Slotegraaf

1994 January 19

Since the brightest stars are of 10th magnitude, 7x50 binoculars under urban skies do not resolve the cluster, giving it a granular appearance. In 11x80 binoculars, the cluster appears moderately rich, estimated 30 members. It lies in a rich milky way field and appears fainter than most of the field stars. Overall it is an irregular grouping, but it seems to point towards its bright orange beacon star, N Velorum.

1994-01-19: 11x80's, The Boord, 02:00 SAST Appears as a puff of light west of the orange N Velorum. A star about 2x further west of the cluster appears reddish.

1994 February 05

1994-02-05, Die Boord, 11x80's tripod-mounted. The cluster appears as a distinct, nebulous object at first glance. The southeast portion contains what appears as a short. tight row or bar of stars, with a single prominent star further southeast. The rest of the cluster appears as a nebulous extension to the northwest.

1997 April 14

1997 April 14, 02:00 - 04:00 Jonkershoek. 11x80's tripod-mounted. Delightful grainy patch of fine stars.

1998 March 20

1998-03-20/21, 11x80 tripod-mounted binoculars, Stellenbosch Rifle Range site; seeing good. Large, 15' cluster, tear-drop shaped; three brighter stars arranged in a tiny narrow triangle, with tens of much fainter stars scattered towards the north-west. Bright orange-yellow star nearby (the cluster points roughly towards it.)

1980

A two-inch refractor at 30x shows it as a small and quite loose cluster, about 10 stars involved of which five are slightly more prominent.

1983

A 15.5-inch telescope reveals this object as a sparse, ill-defined open cluster, about 10' in size. It is very well spread out and has an irregular shape, suggestive of an elongated, rounded rectangle lying northwest-southeast. There are about half a dozen bright stars, and many much fainter ones. The cluster lies about half a degree west of the bright, reddish N Velorum.

1998 January 01

1998-01-26/27, 6-inch f/8.6 Newtonian, Stellenbosch Rifle Range site. Dew. Very large cluster with no noticeable border. Moderately detached from background. Great brightness range - a fine sprinkling of stars with a handful of brighter members thrown in. There are two areas of concentration - two parallel rows of stars running north-south; the western one is longer and more complex. Between these two chains in a noticeable dark gap. The rest of the cluster, which overall appears angular, seems scattered generally to the west of these two chains. No colours noticed.

Bright N Vel due east.

Sketch made, showing K25mm f.o.w.

2002 July 01

Stellenbosch (Paradyskloof Rifle Range)

11x80 tripod-mounted binoculars (12.5-mm aperture mask)

Conditions: Dark moon. Slight easterly breeze. NELM approx 5.5 at the pole. Dew.

Cluster due west of the beautiful bright (V=3.13) orange (BV = +1.55) N Velorum. A beautiful delicate cloud-like cluster, with a knot (perhaps two 9th mag stars) near the "centre", and around this are unseen other tiny stars. These very small stars seem scattered mainly in a spray off to the northwest from the "knot". Wonder why Herschel missed it?

2008 December 22

Mount Ceder

8-inch Dobsonian f/5 (EP: 25mm 48x)

Conditions: Clear, dark.

On the Carina-Vela border lies the moderately large & faint cluster IC 2488, its 20 or so stars making an obvious grouping at 48x (25mm). Its brighter members are clearly arranged in two parallel arcs, and there are more stars on offer. Third-magnitude N Carinae to the east acts like a beacon to draw attention to the cluster, which is a delight to sketch and study at higher powers.

Magda Streicher

2010 February 9

Location: Polokwane

16-inch f/10 SCT (127x 290x)

Full field of various magnitude stars, displays also a variety of colour yellow and white stars. This large, bright cluster is very much spacious with a small gathering towards the middle area. A few of the tighter middle stars displays a typical Chinese hat open towards the western side. With ease I could count up to 40 stars in the cluster in a low power eyepiece.

21 January 2009

OPEN CLUSTER

RA: 09h27m26s - DEC: -56o57'24" - Magnitude: 7.4 - Size: 18'

Tel: 12" S/C 218x - Date: 21 January 2009 5.7

The cluster is relative large and open in appearance with the bulk of stars towards SE. The part of the cluster also reminds me of a Milk Can shape pouring out faint stars in a NW direction. The extreme southern part of the cluster is cut of by star light immediately at the so called lit of the milk can, which is very much obvious.

2006 December 21

Pietersburg

16-inch f/10 SCT (102x)

Conditions: Good

I called this one the raindrop cluster. Various magnitude stars sprinkle like raindrops falling from the north in strings and faint droplets to the south of the field. Spacious and well outstanding against the back ground star field. The eastern part of the cluster is slightly more busy with faint stars.

Gary Lillis

2008 March 26

2008 March 26, 21:10

Walmer, Port Elizabeth

2.5-inch f/7.6 refractor (EP: 12.5mm 56x 30arcmin fov)

Conditions: Relatively stable, clear.

Easy to locate, highly visible because of mag 4.1 red/orange prominent star. Comprises of three prominent stars; southwest star red/orange M4.1, in the northwest M6.8, eastern star M6.8; north and south of the eastern star are two fainter stars M8.1 in the south, and 8.3 in the north. These five stars define the 15arcmin boundary, the inner body is completely stars. IC 2488 is surrounded by field stars of about M7 in all directions: 1.25 degrees south are three prominent stars M6.2, M6.3 and M6.9. There is an indication of very faint coarse stars, fainter than 9.5, around the red/orange prominent star, beyond the range of the telescope from this location.

Richard Ford

2012 March 25th, Sun

Location:Perdeberg.

Time:12:58am.

Sky Conditions:The fainter parts of the Milky Way are barely visible.Haziness only visible on the horizon.Atmosphere stable with little interference.

Instrument:12-inch Dobsonian.

This open clusters stars are not separated and most of the stars in this cluster are nearly the same brightness as each other.Around this open cluster some of the stars are slightly concentrated towards each other.This open cluster 11.2'*3.7'.The central stars in this open cluster is brighter compared to the stars on the far outskirts of this cluster.

Favourite lists

Lacaille's catalogue

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