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ORION constellation description for the ground crew.......

594.12° square [1.4% of the sky]. Of the 88 constellations it is 26th in size. It is bordered by Gemini the twins, Taurus the bull and Lepus the hare, at his toes.

01 Orion is a bold hunter armed with a club and sword and faced by a charging bull, Taurus. This is a famous constellation with a glittering array of bright stars that are prominent for the best part of the night during autumn and winters frosty months [Northern hemishphere]. The most striking feature of the constellation is the alignment of three equally bright stars in the hunter’s belt. Its brilliance stems from the fact that most of its stars are quite young. This constellation dominates our winter-sky [northern hemisphere observers]. All human cultures in every time and place have given special note in story and myth to this wonderful array of stars. It is visible from every inhabited place on the surface of our planet. Orion moves stealthily across the southern night sky during the winter months, in his never-ending hunt for the Bull [Taurus] and the Hare [Lepus] on the banks of the river Eridanus.

For most observers Orion is the most impressive constellation of the sky, no doubt. With its large number of bright stars and the distinct group given by the three belt stars it is easy to find in the winter sky. In mid-January Orion culminates [its highest point in the sky], at about 22h local time, just after the late-evening news. Observers located at the terrestrial equator can see this constellation marching through the zenith [overhead]; the belt stars are at a declination of about 0°. Orion’s position is also close to the galactic equator. Orion offers a wealth of interesting and famous objects like the great Orion Nebula M042/M043 and the Horsehead Nebula [IC-434]. The brightest star is Rigel (Beta Orionis), visible in the lower right. Against the convention, that Greek letters are given to each star in a constellation in order of intensity - the second bright star Beteigeuze is named Alpha Orionis - an accident of history [Orions left ‘shoulder’].

One of the most famous and most easily identifiable constellations, Orion, comprises 73 naked-eye stars. It presents, basically, a quadrilateral, narrowed in the middle by a line of three stars [The Belt of Orion], known as Alnilan, Alnitak and Mintaka. Below the belt, in the center of the lower part of the quadrilateral, is Orion’s Sword - a small line of stars extending downwards, towards his foot, and shrouded in nebulosity. On locating this constellation, the naked-eye observer is struck by an abundance of bright stars. Three of these, Betelgeuse, Rigel and Bellatrix are in fact among the 25 brightest stars visible from Earth.

02 The principal stars of Orion are young, very hot and white or blue-white, with one great exception. Noticeable by its distinctly red colour, even to the naked eye, is Alpha Orionis, known as Betelgeuse, marking Orion’s right shoulder and its red hue striking with any optical aid. The correct pronunciation is Bet-el-jooz, the name coming from the Arabic Bayt-al-Jawza, ‘The Shoulder of the Giant’, but over the years that was corrupted through various forms down to a French version which we now use, Betelgeuse, which can also be spelled with a final -x or -ze. It fluctuates between +0.4 and +1.3 with an irregular period of several hundred days. Betelgeuse can be imaged directly due to it being large and close.

03 A-Rigel is at the lower-right of this figure and is fifty times larger than our sun. Rigel ‘The Giant’s Leg’ is a striking contrast in colour when compared to Betelgeuse. Whereas the latter is red, Rigel is a massive blue-white supergiant, the brightest star in the constellation at +0.12 with a faint +7.0 companion [difficult to spot due to the brighter primary]. It is of spectral type B8Ia. These stars typically have surface temperatures ranging from 10,000° K to 30,000° K. Rigel is about the same distance from Earth as Betelgeuse, and is a spectroscopic binary star with a +6.7 companion with a period of 9.86 days. Marking the Hunter’s left foot is another supergiant, the pure white Beta Orionis, or B-Rigel, its name also coming from Arabic, the word for ‘Foot’ being Riji, the brightest star of Orion is +0.1 and the 7th brightest star in our sky, so luminous that 60,000 Suns would be required to equal it! Its temperature is well over 11,000° C. It is a double star, though its +7 companion is hard to detect in small telescopes, overpowered as it is by Rigel’s intense white glare - and through a telescope the sheer brilliance of this glare is something you will notice. The colours of the two supergiants are all the more striking if you use binoculars and look first at one and then quickly at the other and back again, the glowing coal fire red of Betelgeuse contrasting vividly with Rigel’s almost magnesium flare-like white. The presence of either star would raise a constellation above the average. Orion has them both!

04 B-Rigel and not Betelgeuse should have the designation Alpha, being the brightest star, since the Bayer letter system - devised by German astronomer and celestial cartographer Johann Bayer in 1603 - catalogued the brightest star in each constellation with the first letter of the Greek alphabet, Alpha, the second brightest with the second letter, Beta, and so on in descending order of brightness. But it did not always seem to work out quite that way, so Rigel and Betelgeuse change places alphabetically.

05 Betelgeuse [armpit of the giant], the brilliant red star in the arm is at the top-right and is one of the largest stars known. It has a diameter greater than the earth’s orbit around our own star [93 million miles]. Betelgeuse from the Arabic ‘ibt al jauzah’ meaning ‘the armpit of the central one’ is a red supergiant of spectral type M21a. It has a diameter of about 595,000,000 km and a surface temperature estimated at 3000° K.

At approximately 1,400 ly distant, Betelgeuse is a variable star, with a period of 5.8 years and a normal magnitude range of +0.4 to +1.3. Betelgeuse is a red supergiant semi-regular variable, discovered by John Herschel in 1836, with a maximum range of +0.1 to +1.3, though its period - which is the interval between the points of maximum, brightness - is given as 2,110 days, it might be better classed as having no set period since its maxima are, even for a semi-regular, irregular to say the least. It is 520 ly away from us [a light year is the term for the distance light travels in one calendar year - that is almost six million, million miles. Light, the fastest thing in the known universe, has a speed of 186,200+ miles per second. This star is indeed a supergiant, slowly pulsating, expanding and contracting, its luminosity changing accordingly and giving it a variable diameter that exceeds 300 million miles, though, despite the fact that it’s volume is many, many millions of times greater than that of our own star, its mass is so low that the average density is less than that of the air we breathe. If mighty Betelgeuse were our Sun its vast globe would enclose the orbits of Mercury, Venus, Earth and Mars with quite a lot of room to spare! The core temperature of such a star is some 3,000° million C though the visible surface, or Photosphere, is much cooler than our Sun - ‘only’ 3,000° C which is why the cooler Betelgeuse is red and our Sun, at 6,000° C, is yellow - but at its maximum it has a luminosity equal to 15,000 suns and is among the ten brightest stars in ‘our part of our galaxy’, the Milky Way’.

06 The stars of the ‘belt-of-pearls’ have Arabic names. Just below the star Alnitak in Orion’s belt is the ‘Horsehead Nebula’ which takes its name from the shape which it forms [it is also known as the ‘Horse-Head’ nebula].

07 Under the belt of Orion is the ‘Great Orion Nebula’. M042 is seen as a patch of light covering a 1° square of sky on dark nights. The darker region that separates M042 and M043 is known as the ‘fish’s mouth’. Using averted vision you will see a fuzzy patch of light that hangs down like a sword from Orion’s belt. Inside the ‘Great Orion Nebula’ you will see a group of stars known as the ‘Trapezium’, four tiny hot young stars nestling within this celestial nursery in a trapezoid-shaped group. On nights of good seeing [transparency] this nebula takes on a mottled appearance.

08 Sirius - near the foot of Orion was known to the Greeks as Sothis - and has a much smaller white dwarf companion star:

O. ◄

Above: Sirius and its smaller companion as seen through my 16-inch telescope on a good-night!

09 ‘Sahu’ is the ancient Egyptian name for Orion. They believed that Sirius and Orion were the homes of departed souls and that their KIs became stars who navigate the ‘Duat’ [‘Starry afterworld’] with Osiris and other departed KIs [their royal ancestors]. They seem to have identified ‘Sirius-B’ with the ‘Morning Star’. Sirius-B is a white dwarf and super-dense. However, modern scientists do not believe that Sirius-B was visible to the naked eye during the pharaonic period. In Egypt Orion was depicted as a man standing, looking back over his shoulder and holding a scepter in one hand and an ankh sign in the other. On the ceiling of the tomb of Senmut there is a column devoted to Sah which includes three large stars arranged vertically and bearing a striking resemblance to the three stars we now call Orion’s Belt [Delta, Eta and Zeta]. The giant Sahu sky-image shows a striding man with one arm outstretched with his palm cupping a star. This star is Aldebaran in the Hyades, and marks the position of the mace of Orion the Hunter. The constellation pictures of the Egyptians were different to our modern ones which derive from Babylonian origins. The southern shaft of the KIs Chamber in the Egyptian Cheop pyramid pointed to Zeta in Orion’s Belt. The Pyramid Texts of the Egyptians state that the stars of Orion were the homes of departed souls. Osiris transfigured himself into a star being [Orion] and went on to rule the Heavenly Kingdom of the Dead - called the Duat.

10 The Apollo-16 lunar module was called Orion.

11 Greek: Orion as a son of Poseidon was able to walk on water and took the boy Cedalion to be his guide who sat on his shoulders and gave him directions towards the sunrise. This detail is the subject of a painting by Poussin. Placed among the stars he pursues the seven daughters of Atlas, the Pleiades. Bible: Job 38.

12 Dr Phillis Pitluga made an intensive computer-aided study of stellar alignments at Nazca [Peru] and concluded that the famous spider figure was devised as a terrestrial diagram of the giant constellation of Orion, and that the arrow-straight lines linked to the figure appear to have been set out to track through the ages the changing declinations of the three stars of Orion’s Belt. Recent theories have also linked the positioning of Egypt’s ancient pyramids with the celestial orientation of the three stars in Orion’s belt.

13 In Greek mythology, Orion was the son of Poseidon, the KI of the Sea, and a mortal mother. He was a man of mighty stature, a great hunter and the most handsome man who ever lived. Being extremely boastful, he never ceased to tell anyone who cared to listen, how good a hunter he was, that he was a great warrior, even claiming that he was, himself, a god. Was Poseidon not his father! Such boasting would surely bring about his downfall! In Greek mythology Orion was a great hunter being so busy bragging how he could kill the largest of animals that he overlooked one of the smallest and got himself stung to death by a scorpion. Placed in the sky by the Gods he now stands, shield held out in front of him and weapon raised above his head, facing Taurus the Bull, while the little perpetrator of the dastardly deed is represented by the constellations of Scorpius. Orion is remarkable in many ways. Its distinctive appearance makes it one of the most striking and easily recognizable constellations. It contains two supergiant stars of the first magnitude, a host of binary [double] and multiple stars, a dark nebula, one of the few known pre-main-sequence spectroscopic binaries and the most fantastic telescopic sights in the northern sky, even in a very small telescope. With some imagination it even looks slightly like what it is supposed to represent, unlike most constellations, which resemble nothing at all, the main shape given by a quadrilateral of bright stars called Rigel, Betelgeuse, Saiph and Bellatrix.

14A In one story Orion was blinded by the god, Dionysus, at the request of Oenopion, the father of Orion’s intended bride, after he insulted her following a drinking spree. Following the advice of an oracle, he journeyed east to let the rays of the rising sun fall on his eyes, and regained his eyesight.

14B Some say that Dawn, also known as Aurora, was in love with him, and Artemis, the goddess of Hunting, shot him in a fit of jealousy. Others say that he made Apollo angry, and that the god, by a trick, got his sister to kill him.

14C In another story, Orion was stung to death by a scorpion, in retribution for his boastfulness, and at the request of Artemis, was placed in the sky, where he faces his slayer, the scorpion, in the form of the constellation Scorpius.

15 Bellatrix at a distance of 685 ly is a luminous blue giant of spectral type B2III, +1.64.

16 Mintaka, the rightmost star in Orion’s Belt, is of rare spectral type - O9. It is therefore, a very massive blue star, +2.23 and it lies at a distance similar to that of Rigel.

17 Alnilan, in the middle of the Belt, belongs to the spectral group BO, +1.7.

18 Alnitak, the leftmost star in the Belt, has a magnitude of +1.77, and is also a type BO star.

19 Saiph, a supergiant of type BO, +2.06 completes the outline of the quadrilateral. Kappa Orionis, or Saiph, pronounced ‘Sah-if’ marks the Hunter’s right foot, 2,100 ly distant.

20 The only other worthy naked-eye object in Orion, apart from a short stretch of Milky Way, is of course, the Great Nebula in Orion - M042. This is one of the brightest emission nebulae in the entire sky, and lies about 1600 ly away. It is easily located by drawing an imaginary line from Bellatrix to Mintaka, and then continuing this line an equal distance onwards. You will see a small group of stars in this area - ‘The Sword of Orion’. M042 is visible [depending on weather conditions] as a luminous patch across this area, and is much more impressive in a pair of 7x50 Fujinon or 60mm Takahashi binoculars. The luminosity is caused by ionisation of gas atoms in the nebula. The Orion Nebula is a HII region ie, rich in ionised hydrogen, which is ionised by ultraviolet radiation from nearby hot, young O and B type stars. These stars are visible telescopically, and are, as a group, called the ‘Trapezium’ due to their configuration. The area is also very rich in X-rays. In a finder scope a faint star will be seen in the middle of M042 [center your crosshairs on this point]. In a telescope the nebula will appear as a bright, patch of light, with a few stars set like diamonds in the center of the patch. The darker/blacker the sky the more detail you will see in the cloud. Under very good seeing conditions you may detect a green tinge in the nebula. M042 and M043 are ‘Diffuse Nebula’.

21 Gamma Orionis, called Bellatrix, lying at 470 ly, +1.6 marks the left shoulder.

22 Orion is the home of the Orionid meteor shower. This shower, visible from October 2nd to November 7th, has an Observed Zenithal Hourly Rate (OZHR) of 30 meteors per hour, at maximum on October 21st. The Orionids are believed to be associated with Halley’s Comet, and the radiant, at maximum, is located in the far top left of the constellation, near the border with Gemini, and close to G-Geminorum. If you are lucky and the weather is good you may see some 25 meteors or so per hour.

23 Just above Rigel lies another double star, Tau Orionis, and if you take a line from Rigel through Tau Orionis, extend it about eight times that distance, you pass just to the east of Eta Orionis, a double of +4 and +5 components not easy to resolve properly in smaller telescopes. The most distinctive feature of Orion is the so-called Belt, made up of three stars in line that slant down across the middle of the quadrilateral, Delta Orionis, or by name, Mintaka, Alnilam and Alnitak, lying at 1,500 and 1,600 ly respectively, blue-white and very hot indeed, some 30,000 degrees C. Mintaka is an easy double to resolve in a 63mm telescope, with components of +2.5 and +6.8, the two making a nice contrast through the eyepiece, while Alnitak, whose name means ‘The Girdle’, is a close pair of +2.1 and +4.1 that requires high magnification to resolve. Poor Alnilam has no companion at all and must be content just to represent Orion’s belt buckle.

24A There are a number of double stars above and below the Belt, some very faint, and it is well worth taking time searching this area to see just how many you can find. One thing you must not miss, not that you could, is the beautiful multiple star system Sigma Orionis, lying south of Alnilam, which consists of four members, a blue-white star of +4, two +7, and a faint +10, the bright star surrounded by its fainter companions looking remarkably like a miniature version of Jupiter with three of its Galilean moons. It is a most attractive sight at any magnification. In a small telescope Sigma Orionis will appear like a triple star. A and B are about 100 AU apart. C and D are 3,000 AU and 4,500 AU. E is a third of a ly from A. Sigma Orionis, Struve-761 and the stars of the belt and the Orion nebula are part of the same aggregation of young stars.

24B If this remarkable object were not enough, in the same telescopic field is the triple star Struve-761, of +8 and +9 components, two very close together with the third very far away and forming a distinctive narrow triangle. Use low magnification and you will see a ‘double triangle’ effect that is rather nice, Sigma Orionis forming one point of a large triangle with two unrelated stars, and just below it the tiny triangle of 761 - and both pointing in the same direction!

25 Orion’s head is marked by Lambda Orionis, its close +3.7 and +5.6 components resolvable with small telescopes, and there is also a third member of +10. At the base of the right arm, just above Betelgeuse, is Mu Orionis, another double, and in the Hunter’s club is U-Orionis, a variable star of +5.5 to +12.6, with a 372 day period.

26 There is very extensive nebulosity across the Orion region, about 1,500 ly away, vast star-producing clouds of dust and gas, the main constituent being Hydrogen, which cannot be seen directly even in powerful telescopes, save for a few areas where it either contains very hot stars radiating ultraviolet energy which is absorbed by the gas, ionizing the hydrogen atoms, and is re-emitted as visible light [Emission Nebulae], or, if the cloud contains a lot of dust, shines by the reflected light of stars in or near it [Reflection Nebulae], or where clouds of dark dust, containing no stars to make them shine, simply overlap and blot out the light from brighter objects lying further away [Dark Nebulae]. Of course, Orion has them all!

27 Sigma Orionis is a multiple star with four members. Sigma is +3.7 with a companion of +6.5 [whitish]. Using a higher powered eyepiece reveals the 3rd member, a +7.2 star that is closer in. Larger telescopes reveal the 4th member at +10. If you extend a line from Sigma Orionis through Alnitak and continue it for about three times that distance you come to the reflection nebula M078, faintly visible as a diffuse cloud around two +10 stars, the light from which, reflected by dust particles in the nebula, provides the required illumination. To the east of Alnitak is NGC-2024, the Flame Nebula, also called the Christmas Tree Nebula, both for obvious reasons - in photographs at least - since lanes of dust through the glowing gas cloud give the effect of flames or branches. This is hard to see even if you keep Alnitak out of the field of view, and of course it is always important when looking for faint objects that lie close to a bright star to keep the star out of view, otherwise it will overpower the fainter object with its glare. There are a number of small patches of nebulosity around Alnitak, beautiful in photographs but hard to see directly, and the same comments apply to them also.

28 Extending southwards from Alnitak is the large but very tenuous nebulosity IC-434, a fine photographic subject but extremely difficult to see directly due to its low surface brightness. Protruding into it from the east is a cloud of dust, B-33, the famous dark nebula known as the Horse-Head, because it is shaped strikingly like a horse’s head! It is stunning on long exposure photographs taken with even quite small telescopes, but visually is elusive since it overlaps an object of such low brightness. It is on record however, as being observed with 150mm telescopes, though opinions differ greatly as to the degree of difficulty involved in seeing it. Some consider it all but invisible in even the largest amateur telescopes; Others say it is not easy to see with a small telescope. Use a nebula filter and a dark sky site!

29A Through a telescope M043 seems to be separated from M042, but in fact both are part of one vast cloud into which a dust lane called the ‘Fish Mouth’ protrudes, giving the separate effect. If you spent all night just looking at this one object it would be time well used, and you might still find subtle gradations of luminosity, dust lanes, faint wisps of gas trailing away beyond the limit of visibility, condensed brighter areas and the like, that you never noticed before - the Great Nebula is that fine a subject. It is bright enough to stand high magnification, bringing out yet more intricate detail, and also try averted vision - looking away from it but keeping your attention on it - and you maybe will be surprised how it will seem to stand out much more clearly. M042 was photographed in 1880 by Henry Draper for the first time.

29B Nebulae are stellar birthplaces, and some five thousand million years ago our own star was born in one just like M042/043, condensing out of the interstellar hydrogen and helium, shrinking by gravitational contraction and, during the pre-main-sequence stage, giving off heat and light by the conversion of gravitational energy. After ages and ages [ie, a very ling time - millions of years], as the core temperature rose to some 10° million C, nuclear reaction commenced, the hydrogen core ignited and our Sun began its life to shine as a main-sequence star, fusing hydrogen into helium, to produce its energy. This very star formation is still going on in the Orion Nebula, and there is enough gas there to make many thousands of new baby stars, the visible bright condensations known as Herbig-Haro Objects [named for the astronomers who discovered them], thought to be the embryo stars in this vast galactic maternity ward.

29C Within the Nebula lies Theta(1) Orionis, a multiple star known as the Trapezium. Why? Well, it looks like one, which seems a good enough reason! A trapezium being defined by eggheads as a quadrilateral figure with two sides only parallel. The four main components, of +5 to +8, are easy to see even with my 63mm telescope, and in larger instruments it is a fine sight - though I always think it is rather overwhelmed by the Great Nebula and loses something of its true effect. On its own it would be a splendid object, and if you use high magnification so as to see it without much of the distraction of the surrounding Nebula you will, I’m sure, agree. It is the hot stars of the Trapezium that ionize the hydrogen and make the Great Nebula shine so brightly and, since it lies on the Earth side of M042, we are able to see it. If it lay deep within the gas cloud its light would be clouded by dust and we would have no beautiful Orion Nebula to admire!

This is probably the best known multiple set of stars in our sky. It is also one of the most interesting for the small telescope [60mm to 90mm]. In many double star catalogs it has become customary to designate the fours stars A, B, C, and D in order of fight ascension rather than in the usual order of brightness. The star called ‘C’ is the true primary of the group with a visual magnitude of about +5.4. Star ‘D’ is the second in brightness at +6.3. ‘A’ is third at about +6.8. The faintest star, ‘B’, is an eclipsing binary with a period of 6.471 days. In 1975, Star ‘A’ was also identified as an eclipsing binary with a period of 65.432 days. [Burnham’s Celestrial Handbook, V2, p1327].

The +11 stars ‘E’ and ‘F’ are a well known observational challenge to amateur astronomers who often use them to judge the quality of the seeing as well as the quality of their telescopes. They have been observed with apertures of under 3 inches on nights of very good seeing. They become an easy target for telescopes of 10 inches of aperture or more.

Photographing ‘E’ and ‘F’ is an even more interesting challenge. Both of these dim stars are separated from their brighter companions by only 4s. The exposure duration required to record the +11 stars combined with the distortion created by atmospheric seeing generally cause the two fainter stars to become part of the blob of the brighter stars.

30 Something which is forever hidden from our view for that very reason is the ‘Becklin-Neugebauer Object’, named for its discoverers and known by the initials ‘BN’. This is thought to be a giant star with a luminosity possibly greater than a million Suns, its visible light absorbed by dust and only detectable by its very powerful Infra-Red emissions which, unlike visible light, can pass through the dust.

31 A remarkable object which ‘is’ visible is Parenago-1540, which is 10m west of Theta(1) Orionis, +11.3, first catalogued by Russian astronomer P.P. Parenago in 1954 but its true status only discovered in the 1980’s, and it was then only the third star of its kind to be discovered, the first was in 1982. It is a pre-main-sequence double-line spectroscopic binary, which is quite a mouthful - but remember it - say it quickly and impress your friends! A spectroscopic binary is double whose components are so close together they cannot be seen visually but must be separated by an astronomical spectroscope, the double set of spectral lines, one for each star, show not only that it is a binary but also enable astronomers to work out its orbital period, mass and age. Parenago-1540 consists of two cool orange stars, 1540-A and 1540-B, of 2.25 and 1.7 solar masses respectively. Millions of years from now both will light up their core hydrogen, the larger A first, followed a few million years later by B - and two new main-sequence stars will blaze in the heavens! All known visual pre-main-sequence binaries are so very far away that, even to be seen as doubles at all, they are so far apart that they orbit each other too slowly for astronomers to work out their vital statistics so to speak. Not so a spectroscopic binary, which may have an orbital period of only a few days, so this class of star is a vital link in the study of binary star formation, a process that is so far unknown. The parenago stars seem to have different ages, one million years for A, half that for B, which is odd if they are a binary system [twins] born together from the same mother [nebula]. These are the kind of technical problems that make astronomers go slowly bald! One theory put forward [by a balding astronomer], is this: a binary star has one component pulled away by gravitational interaction with a single star it just happened to run into, replacing the original partner with the new-found companion to form a binary of different ages, the divorced former partner now having to go it alone. Perhaps many binaries form in this rather shotgun wedding manner!

32 Just to the east of Theta(1) Orionis lies Theta(2) Orionis, a double of +5 and +6 stars resolvable with any optical aid. The point of the Sword is mainly composed of Iota(1) Orionis, called Hatysa, an easy to resolve double of +2.9 and +7.0, over 1,500 lys away and some 20,000 times as luminous as our Sun, and Struve-747, which is a double of the +5 and +6.

33 Now do not leave this wonderful constellation without sweeping at low magnification across the Milky Way itself, which comes down almost as far as Betelgeuse - the whole of the Hunter’s right arm and club lie in it - and those with large telescopes might keep in mind that there are some thirty galaxies in Orion, ranging from +13 down to +16 and including one - NGC-1709 that has an Irish connection, having been discovered in 1854 by that great Irish astronomer Lord Rosse with his famous 72-inch telescope, after both William and John Herschel had failed to see it. It is +15.2, RA 4h 58.7m, DEC 00 29m and is 0.9m x 0.7m in size. Most of the Orion galaxies can be located, under very good seeing conditions, in a properly collimated, dust-free, 10 to 12-inch telescope.

35 Horsehead Nebula, NGC-2024. A large telescope and nebula filter are needed to make a sighting of this object. It is seen as a 0.5° wide strip of nebulosity that hangs-down from zeta [the lower-left star of the belt]. The glare from zeta makes it difficult to detect the nebulosity and the small intrusion that is the horsehead itself.

36 VV Orionis. Eclipsing binary [easily seen in your binoculars]. +5.1 to +5.5 in 1.49 days.

37 CK Orionis, yellowish. Semi-regular variable. +5.9 to +7.3 in 120 days.

38 U Orionis. Mira type. +4.8 to +12.6 in 370 days.

39 NGC-1981. Cluster [just north of M042].