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RA: 09h 21m 25.34s
Dec: −58° 18′ 40.7″
Ch: MSA:994, U2:425, SA:25
Type: planetary nebula
Mag: B=12, V=?
Select a sketch and click the button to view
Discovered by Sir John Herschel at the Cape of Good Hope with an 18-inch f/13 speculum telescope. As his observations set out below will show, Herschel might have suspected this nebula of being a real planet, and so he carefully measured the position of nearby stars to check on any possible motion. His first observation recorded on April 1 1834 reads: "The finest planetary nebula I ever remember to have seen for sharpness of termination; 3 arcsec diameter; exactly round; no more haziness about them than would be about a star of the same magnitude to-night (which is a favourable one) Light, a pale white = star of 9th mag. Position of companion star = ... 58.6 ; star = 15th mag. A very remarkable object. Showed to Stone, who distinctly perceived the total difference of appearance between it and a star 9th mag very near it. A second companion star suspected (at about half the distance of the 1st by diagram, and at an estimated position of 330 ) among multitude of large and small stars." The next night Herschel checked up on his potential 'planet': "Observed with Mr. Maclear, April 2, 1834, out of the meridian. Quite round, well defined, and about 3 arcsec or perhaps 4 arcsec diam. Much better seen (between clouds) than last night. The small star is still 1.5 diam. from edge. It has therefore not moved perceptibly, and is therefore not a planet." On 26 February 1835 he recorded it as "planetary nebula, perfectly sharp; exactly round; not the least hazy or mottled. At 1.5 diam distant from the edge (or taking 12 arcsec for the diameter of neb at 24" dist from the centre) there is a star at pos = 51.1 ; well examined with Mr Maclear. It bears 320 [power] well, and is quite sharp and uniform with that power." He next recorded it as "Planetary nebula. Pos of adjacent star = ... 58.0 ; Set micrometer to 51.1, the measure of last night, and carefully examined ... measured tonight with the utmost care; quite calm." His observation on 10 January 1836 recorded it as "planetary nebula, round, equal to 8th mag star; quite uniform in light; quite sharply terminated. Its diameter transits over a wire set to 60 in 4.03 seconds, by a mean of 5 transits. Has a star adjacent pos = 60.7 , dist = 1.5 diam from the edge. About 40 stars in the field, among which two are 9th mag." The observation on 10 March 1836 noted it as "Beautifully round and sharp; just like a small planet 3 arcsec or 4 arcsec in diameter at the utmost. Position of the attendant star = ... 58.5 ; distance 2.5 diameters from the centre. Shown to Captain Henning." His final observation on 9 January 1837 recorded it as "Diameter 8 arcsec; perfectly uniform in light; sharply terminated, just like a small planet; position of attendants star = 60.7 ; dist. 1.5 diam; 14th mag."
"Extract of a letter from Sir John Hershel to Francis Baily, Esq., dated Cape of Good Hope, October 22, 1834", Monthly Notes RAS, 3, 75-77.
"... A brief recapitulation of a few of the more interesting objects and remarks which have fallen under my notice may not be unpleasing to you. ... On the 1st of April, I discovered, in RA 9h 17m, NPD 147°35', a beautiful planetary nebula having a perfectly sharp well-defined disc 3" or 4" in diameter, and of a uniform light. Its appearance is precisely that of a small planet, with a satellite about 1.5 diameters from its edge. Mr Maclear has been obliging enough to determine its place with great exactness by the circle, by several observations, from which it appears to have no planetary motion."
Table IV: Plan neb., 0.3'.
Doig, P. (1925) Notes on the nebulae and clusters in Webb's 'Celestial Objects for Common Telescopes' (Sixth edition, Vol.ii). Part III. Southern Objects. M.N.R.A.S., 36(3), 91.
A photographic survey of bright southern planetary nebulae. M.N.R.A.S., 110(5), 429-439.
"The object is a bean-shaped ring nebula, the ring being broken up into spots of brightness, brightest in the Sp sector. The central star is faint. About 13''x 11'. (Fig4).
From: "Neat Southern Planetaries - XIII"
Continuing from Part XI, this month we move a further two degrees south of NGC 2899, in a selection on the eastern side of the 'False Cross'. First discussed is the easy to find NGC 2867, near the 2nd magnitude Iota Carinae. The two fainter planetaries follow this - He2-76 and He2-22, and further to the east is the faint planetary, IC 2501. For the surrounding fields, I have selected a few double stars, a pretty asterism and an eclipsing binary.
NGC 2867/ He2-27/ WRAY 16-43/ PK278-5.1 (09214-5819) has the advantage of being 1.2O NNE of the bright 2nd magnitude star Iota Carinae, or alternatively 1O SW of the 4.3 magnitude g Carinae. Contained in a densely packed starry field, and can be quickly found, by drawing an imaginary line between two field stars - a 9.5 and another 9.8 magnitude star. High magnification reveals a small aqua blue disk. I thought the colour was one of the most prominent and elegantly coloured of all the southern planetaries in this series. Considering that the measured B-V value is -0.5, this is understandable. (Note: As a comparison, Beta Centauri is -0.23) Few of the modern amateur references have little detail about this wonderful object. NGC 2867 has an interesting history as a deep-sky object - which is particularly unusual for a southern astronomical object.
John Herschel Discovery of the "Planetary Planetary".
John Herschel discovered NGC 2867 on April Fools Day, 1st April 1834 from Felhausen observatory at the Cape of Good Hope with a 45cm. (18-inch f13) speculum reflecting telescope. The appearance of its size and shape would have given John heart palpitations, as he first suspected he discovered a new planet - similar to his father's discovery of Uranus exactly 55 years and 2 weeks earlier. Like the comet observers and supernovae hunters of today, the wait of a possible discovery until the next night must have filled John with agonising anticipation. As a meticulous observer, on the night of the 1st, he began micrometric measurements of the positions of nearby stars to check the planetary nebula's suspected movement.
Why he thought he discovered a planet is a story in itself. Little did John Herschel know how much influence his father's discovery of Uranus would have had on his initial observations of NGC 2986, and his eventual astronomical experiences involving the planet Neptune. The possibility of a new outer planet for John Herschel was not a brand-new idea. In the 1820's and 1830's, discovery of this unknown planet was a real and exciting prospect. In the midst of this period, John Herschel left by sailing ship to South Africa in 1833, to conduct his labourious exploration of the southern skies and finish his father's work. Herschel had seriously considered travelling to Australia, but declined the offer made by Sir Thomas Brisbane, because he considered it too far and too long a journey - then several months by ship. His personal and verbal contacts in his younger days at the age of 22 with famous botanist and philanthropist Sir Joseph Banks (1744-1820) may have had some influence on this decision. Banks had become a friend of his father, whom initially contacted Sir William Herschel in November 1781, as President of London's Royal Society, in regards his discovery of Uranus and the presentation of the Society's the Copley Medal. It is likely, that a conversation had occurred between John Herschel and Joseph Banks, would have subconsciously persuaded that Australia was likely far too unsuitable for astronomical observation, and climate-wise, decidedly too unpleasant! Banks had extensive knowledge of coastlines of South America, Australia and South Africa, by his explorations in the 1760's and 1770's on the Endeavour with Captain James Cook.
Far more interesting is in the reasoning why they thought a new planet to exist, and why John Herschel was aware to be on the lookout.
The problem first began in 1782, when Lalande discovered that Uranus was not strictly following its celestial orbit, and was found to deviate significantly from its predicted position. Computations by the mathematicians left them perplexed, and for a time they thought it to be associated with poor observational positions. In the resulting decades, seventeen 'ancient' observations, back to 1670, were added to the data. The true orbit stayed in limbo until the 1820's when better ephemeris predictions were determined. Yet for all the data, Uranus refused to behave itself, and obvious speculations left few alternatives. A general feeling suggested that another trans-uranian planet was causing the perturbations. So from 1820, observers started a new search that was limited to 12th magnitude for the rouge planet. In the 1830's John Herschel had the opportunity to discover new bodies from his location in the southern hemisphere, being the man in the right place at the right time. After all he had a large aperture telescope, and fortuitously, an entire portion of the skies totally invisible from the larger and many moretelescopes throughout Europe and Britain.
History had shown in the decades since the discovery of Uranus, that misfortune had taken its hand on many occasions. In hindsight, both Uranus and Neptune could have been found much earlier.
For example, the brilliant French astronomer Joseph Jerome Le Francais de Lalande (1732-1807) observed and recorded Neptune in May 1795, seeing the planet twice over three nights. He attributing the slightly different positions to be observational error. It is amazing to think that Lalande has discovered Uranus a mere fourteen years before, especially being an active searcher for both the true orbital elements for Uranus and the hunt for new planets! Neptune's eventual discovery turned out to be not a matter of fortune, but a logical and analytical approach to a celestial mechanical problem - specifically the branch known as perturbation theory. On the 26th September 1846, the German astronomer Johann Gottfried Galle (1812-1910) found the new planet. Neptune had appeared near the centre of the field at the predicted position made independently by both the French astronomer Urbain Jean Joseph Leverrier (1811-1877) and English astronomer, John Couch Adams (1819-1892) - a triumph of their mathematical skills.
Sir John Herschel had also played a role in the discovery of Neptune. In June 1846, he was involved with the preparation of an observational search of the presumed trans-Uranian planet. After the planet's discovery, he along with four other prominent continental astronomers of the day; Encke, Gauss, Airy, F.GW.Struve, later proposed on 5th October 1846 the name 'Neptune' to this new planet, which still remains today. Over the next decade, Sir John Herschel remained a central figure in the nationalistic-based dispute between Leverrier and Adams for trophy of the true discoverer of Neptune. They concluded this a decade later, mainly through total boredom with the subject, that we eventually gave both the credit.
In the end, the observations of the planetary nature of NGC 2867 were a false alarm, as the position of the planetary remained fixed. Herschel did checked on it from time to time in the four years at Cape Town, before resuming his life in England, in a slow decline away from observational astronomy. It is appropriated that he discovered it April Fools Day, as the planetary was not truly 'planetary' at all!
John Herschel Observation Records of NGC 2867
1st April 1834;
"The finest planetary nebula I ever remember to have seen for sharpness of termination; 3"arcsec diameter; exactly round; no more haziness about them than would be about a star of the same magnitude tonight (which is a favourable one) Light, a pale white star of 9th mag. Position of companion star=...58.6; star=15th mag. A very remarkable object. Showed to Stone, who distinctly perceived the total difference of appearance between it and a star 9th mag very near it. A second companion star suspected (at about half the distance of the 1st by diagram, and at an estimated position of 330) among multitude of large and small stars."
2nd April 1834;
"Observed with Mr.Maclear, April 2,1834, out of the meridian. Quite round, well defined, and about 3"arcsec or perhaps 4" arcsec diam. Much better seen (between clouds) than last night. The small star is still 1.5 diam. from edge. It has therefore not moved perceptibly, and is therefore not a planet."
26th February 1835;
"Planetary nebula, perfectly sharp; exactly round; not the least hazy or mottled. At 1.5 diam distant from the edge (or taking 12"arcsec for the diameter of neb at 24"arcsec dist from the centre) there is a star at pos = 51.1 ; well examined with Mr Maclear. It bears 320 [power] well, and is quite sharp and uniform with that power."
10th January 1836;
"Planetary nebula, round, equal to 8th mag star; quite uniform in light; quite sharply terminated. Its diameter transits over a wire set to 60 in 4.03 seconds, by a mean of 5 transits. Has a star adjacent pos = 60.7 , dist = 1.5 diam from the edge. About 40 stars in the field, among which two are 9th mag."
10th March 1836;
"Beautifully round and sharp; just like a small planet 3"arcsec or 4"arcsec in diameter at the utmost. Position of the attendant star=...58.5; distance 2.5 diameters from the centre. Shown to Captain Henning."
9th January 1837;
"Diameter 8" arcsec; perfectly uniform in light; sharply terminated, just like a small planet; position of attendants star = 60.7; dist. 1.5 diam; 14th mag. [This is not the PNN.]"
Description of NGC 2867.
In the sixth edition of Rev. Thomas Webb classic 'Celestial Objects for Common Telescopes. Vol 2.'. Espin takes Herschel's original description of NGC 2867 as; "...perfectly sharp and round; 8"sec.arc." Steve Crouch (Southern Sky 1,4 pg.55) quotes; "This object is again fairly small at 12", but its bright bluish disk stands out prominently."
NGC 2867 can be found charted in both Sky Atlas 2000.0 and in Uranometria 2000.0 (Chart 425). It also appears in Norton's Star Atlas 2000.0 - that typically has very few planetaries marked in the charts for amateur observers.
Visual and photographic magnitude of NGC 2867 is 9.7. We can glimpse it in a 7.5cm., though we require an O-III to see it, though a 10cm. clearly sees the PN. The Journal of the Astronomical Society of Victoria 24, 3 (June 1971): "...at limit in 2-inch 200x." is claimed because it would push the optics too much, unless we make them in black skies and perfect seeing.
In size of the outer oval ring along PA 120O-300O covers some 14"sec.arc., though a 30cm. will only reveal the smaller 8"sec.arc. inner disk. We could glimpse the outer ring in a 40cm. using with an O-III, though I have not seen it. [N.B. The STScI image (Figure 1.) is overexposed, so we cannot see the 8"sec.arc. central core.] Classified as a Type 4 - ring structure, a smaller amateur 'scope will reveal a featureless circular disk. Greater than 25cm. may see towards the west and southwest, a mottled or darker region of material along PA 220O to 270O, and perhaps another dark spot at PA 30O. All these regions I thought I could see with averted vision.
Further out is a thin extended ring, some 30"-40"sec.arc. from the centre. This ring is unfortunately being invisible to all amateur telescopes except though CCD imaging.
They have undertaken some professional work with NGC 2867, mainly due to the rare occurrence of a Wolf-Rayet planetary nebula nucleus (PNN). This is one of a handful known with the far southern planetaries. (In all only 45 of all planetaries known have these rare very hot PNN stars.) According to calculations by Meatheringham, Wood and Faulkner (1988), the PN is a mere 2 750 years old. In human terms, this is as old as the first recorded Olympic Games held in Greece in 776B.C.!
Based on the measured 9"sec.arc. inner shell of this multiple shell planetary, and using a distance of 2.2kpc., the diameter of the nebulosity subtends about 0.2pc, or 0.6 ltys. If the distance is 1.7kpc., this size decreases to 0.15pc. or 0.45ltys. The mass of the nebulosity is about 0.33 (Solar Masses), though some later observations suggest a lower value of 0.2
NGC 2867 shows evidence of the P Cygni phenomena by observations of the Carbon IV (CIV) at 155.0nm., where removal of three electrons occur in a ratio of 1:7 in the ionisation of the gas. This ratio is the difference between detected electrons verses the total number of nuclei.
The Wolf Rayet Central Star in NGC 2967
Using the Tycho and Hipparchos data, the central PNN star (HD 81119; CSI -58-09200; GSC 8596-0189) is visual magnitude 14.9 (16.6p), having a spectral type of OVI (Smith and Aller (1969)), though Aller (1976) upgraded this into a Wolf-Rayet WC7-8. By 1990 astronomers suggested this to be perhaps closer to WC6, (Some references quote WC3; whose original source I could not find.) an they have often thought existence of a Wolf-Rayet's in planetary nebulae to be a strong indicator of youth. Where in evolution terms, age is based on the time when we reveal a planetary as an exposed white dwarf PNN.
Wolf-Rayets are fascinating stellar objects, and subdivide into two broad types - WN and WC. WN's contain prominent emission lines of Nitrogen, while their fellow WC's have those of Carbon. Unlike most stars, the numerals used in the normal spectral classification are based on temperature, where the lower number shows a slightly high the temperature. In Wolf-Rayets, the values refer to the intensities of the respective Nitrogen or Carbon lines, and to a lesser extent, the Helium (HeI) lines - where the larger the value, the more intense these emission lines appear. In all, the bright-line spectra will show these lines and no others. As Wolf Rayet's spectral profiles can also vary enormously, this confuses the classification system even further. For example, WC6 , WC7, and WC8 stars each display quite dissimilar spectra. Apparently the reason for this is the different ways that the star's energy ionises the surface and its nebulous atmosphere. At one temperature, for example, the C III line may become prominent. For example, at a slightly higher temperature most of the C III (C++) gas at 569.6nm. will ionised into a higher state of C IV (C+++) at 580.5nm. Spectrally, the subdivisions used in the examples follow;
WC6's display weak C III lines but stronger C IV lines, and the C III lines will be brighter than the O V (or O++++)
WC7's will typical show the characteristics; C III lines are weaker than the C IV lines, while any O V present
shows a weak spectral line.
WC8's, the C III and C IV lines are of similar intensities, while O V is either faint or not present.
The PNN in NGC 2967 suggests that the spectra may actually change over time, which depends solely on the mass loss from the stellar surface. The nucleus at magnitude 14.7, with the photographic magnitude c.16.6, and therefore, would only be visible using a professional telescope. PNN 1 100 times more luminous than the Sun, and the temperature is 79 000OK.
It seems that a strong superwind is driving the nebulosity, forcing the gas away from the PNN. Earlier estimates in NGC 2867 showed an escape velocity (EV) c.20kms-1, however, later values in 1988 tend to favour about twice this value. The shifting or broadening of the prominent spectral lines has measured EV's by Doppler shifting. For NGC 2867, the respective values are 37.1kms-1 [OIII], 47.1kms-1 [OII] and 33.3kms-1 [HeII]. Compared with most planetaries, the inner gas may be in a much high excitation state - so that many ionisation interactions can take place. We reflect this in the estimated moderately high electron density of between 2 200 and 5 000 e- cm-3. Observations by Gutiérrez-Morero and Moreno (1988) found and measured radicals ions within the nebulosity, that included S+, Ne++, Ar++, Ar+++, Cl+, C++, and C+++. (Sulphur, Neon, Argon, Chlorine and Carbon) From this they calculated the abundances of the elements including Hydrogen, Helium, Carbon, Oxygen, Nitrogen, Neon, Argo, and Sulphur.
NGC 2867 among all planetaries is also a moderate radio source at 1.3 MHz, which varies in a period of 13 minutes. It is also quite bright in the infrared.
The distance of NGC 2867 in the literature varies considerably. AOST1 suggests a distance of 0.8kpc, which is a gross underestimate. Direct measures of distance today tend to favour about 1.7± 0.5kpc., while the statistical distance is 1.82±0.7kpc.
NGC 2867 is a very interesting planetary, whose genre is similar to NGC3195 in Chameleon or NGC 3918 in Centaurus. Although smaller, it provides both an interesting challenge for any aperture. Observers may like to submit a few observations and say what they think! Overall, I think that NGC 2867 is so wonderful it should have a proper name. Perhaps the 'Royal Aqua Nebula' maybe an appropriate name, especially with it gem-like colouration.
Surrounding Field of NGC 2867.
Iota ( ) Carinae or Turais (SAO 236808/ HIP 45556/ HD 80404) (09171-5916) is a 2.3 magnitude bluish-white star (Oddly named Richard Allen's 'Star Names: Their Lore and Meaning', as pale yellow) marking the eastern side of the 'False Cross'. Today we know it under the common name of Turais, though others have known it as Scutulum meaning the Little Shield. The derivation of Turais, according to Allen;
"...probably referring to the ornamental aplustre at the stern of the ship in the sub-division of Carina..."
Others, like the Englishman Thomas Hyde, suggested the name as verbum ignotum - unknown meaning.
Drawings by the astrognosist Johann Ehlert Bode in the 15th Century, of the constellation of Argo Navis, is the likely derivation of Scutulum. Here he drew a few of the crews ancestral shields attached, for luck or pride, onto the side of the ship. (This was a common practice in early Anglo-Saxon's and the Vikings, though less common in the ancient world.)
Using the given parallax determined in 1963, the distance is 90pc. or 292ltys., though according to the Hipparcos observations it may be as far as 692±193ltys. As the Luminosity Class is Ib - Turais is certainly one of a few bright luminaries in the Milky Way. Spectra analysed between 1955 and 1962 showed it to be a F0Ib star, though after 1973 this was upgraded to an A8-9Ib star. If this is true, the temperature is about 7 000OK, with an absolute magnitude of c. -0.2. The proper motion is small, but the radial velocity has been determined as +13.4kms-1. Iota Carinae is also a suspected variable star known as NSV 4444. Variations are a mere V=0.04 magnitudes, however, a period is yet to be determined.
Turais can be found described in Burnham's Celestial Handbook Vol. 2 pg.472, but it seems to me both antiquated and dated.
Asterism (09180-5917) is a line of stars, east of Iota Carinae by 10'min.arc. The brightest star is magnitude 9.3, while the remainder is around 10th and 11th. Some eleven stars in total wind in a north-south direction. We easily see this asterism in a 10cm. telescope, using low magnification.
R107 (09165-5824) was discovered by H.C.Russell , sometime in 1881, as he unfortunately gives no specific date for this object's first observation. He estimated separation as 8"sec.arc., and said the magnitudes were 9th and 10th. Of the three observations between 1882 and 1917, separation has remained at 9.5"sec.arc. along the position angle of 285O. Observers can find it near a bluish 6.1 magnitude star in Carina (SAO 236772; Spectra B5), some 10'min.arc to the west, and 39'min.arc. almost due west of NGC 2867. Stated magnitudes are 9.5 and 11.2 make an attractive contrast, and the pair is in a rather pretty field of moderately bright stars. It is easily visible in a 7.5cm, though I could not distinguish any colour. This was the same in both a (C8) 20cm and a 10.5cm refractor.
R111 (09208-5716) is found in a starry field some 55'min.arc. SWW of IC2488 (See last month) or exactly 1.0O north of NGC 2867. Within a small horseshoe-shaped asterism, R111 lies next to another field 9.8 magnitude star to the east. Discovered by Russell at Sydney Observatory on the 5th March, 1873, with the first measure occurring on the 7th May 1880. His observations record the magnitudes as 11th and 12th, separated by 8.52"sec.arc. at position angle 209.1O. Later observations have determined the respective magnitudes as 10.0 and 11.0, with only three measures since this time, with the latest being in 1948. This last observation shows an increase separation to 9.2"sec.arc. at position angle 213O. My estimate in 1992 suggests the separation has increased to about 11"sec.arc. We know few details about this pair, and glancing at the proper motions of the components, it is likely that this is a chance alignment of an optical system.
The RNGC (Sulentic and Tifft 1973) notes that this is a 9.5 mag planetary nebula.
Hartung writes: "This bright pale blue planetary nebula lies in a field profusely spangled with stars; it is round, about 8 arcsec across, of very even light with no visible central star. Even a three-inch will pick it out easily from the field..."
ASV Journal Vol 24 No 3 June 1971: "at limit in 2-inch 200x."
QBS: U2000 * nr pn is pn itself. 24" diam, but OX. m15 * 30" NE. vf *
(dbl) 32" SE.
15cm - vbr (m9), non*ar @ 80x. 295x: annular w/sm fairly distinct hole; no cen
*. m14.5-15 * 20" ENE; neb diam about 2/3 this distance. threshold *
(m15.5?) about same distance SE. BS, 21Feb1990, LCO.
RA: 09h21m25s - DEC: -58o18'42" - Magnitude: 10 - Size: 0.13"
Tel: 16" S/C – 184x – 290x - Date: 25 November 2009 – Seeing 5. After midnight.
The very much frosted ice blue dot reminds me so strongly of the planet Uranus. Situated in a rather busy star field, and with averted vision the planetary just pops up very clearly. Detect a very faint star estimate around 13.5 magnitude on the north-east rim of the planetary (I could detect stars, with care, around 14+ magnitude).
RA: 09h21m24s - DEC: -58o19'00" - Magnitude: 9.7 - Size: 24"
Tel: 12" S/C – 218x - 346x - Date: 21 January 2009 – 5.7
Very much round with a slightly woollen appearance on the outer edge and even in surface brightness at 218x. Higher power 290x brings out the frosted blue colour, with a more define edge. The planetary stands out just beautiful against the background star field. The dark inside dot was seen with averted vision. To my surprise the extremely faint 14-magnitude star on the planetary eastern edge was quite well seen.
This planetary is bright and is easy to find, lying almost within the False Cross. It is flanked on its northeast and southwest by two 9th mag stars. In a 10-inch f/5 at about 120x is appears as a slightly bloated star, no colour apparent. It is not particularly large, but does not quite focus to a point as do other field stars.
1998-01-26/27, 6-inch f/8.6 Newtonian, Stellenbosch Rifle Range site. Even with the sweeping eyepiece, this 'star', which lies in a rich field, looks suspicious, appearing hazy. There are two companion stars on either side; both these focus to points. At higher power, the planetary is clearly seen as a bloated star.
The two stars, with the planetary inbetween, comfortably fit into the K7mm f.o.v.
The Messier objects
The Bennett objects
The Caldwell list
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