Remote Video Astronomy Group MECATX Sky Tour April 2016

Home , Messier 63, Messier 94, NGC 2787, NGC 4402, NGC 4476, NGC 4647

(1) Coma Berenices (COE-muh BER-uh-NICE-eez), the Bernice's Hair – April 2 (2) Canes Venatici (CAN-eez ve-NAT-iss-eye), the Hunting Dogs – April 7 (3) Circinus (SER-sin-us), the Compass – April 11 (4) Virgo (VER-go), the Maiden – April 30

April 2 Coma Berenices (COE-muh BER-uh-NICE-eez), the Bernice's Hair Com, Comae Berenices (COE-mee BER-uh-NICE-eez)

Coma Berenices

Meaning: The Hair of Berenice Pronunciation: koe' muh bear uh nye' seez Abbreviation: Corn Possessive form: Comae Berenices (koe' my ber uh nye' seez) Asterisms: none

Bordering constellations: Boötes, Canes Venatici, Leo, Ursa Major, Virgo Overall brightness: 5.951 (57) Central point: RA = 12h45m Dec. = +23.5° Directional extremes: N = +34° S = +13° E = 13h33m W = 11h57m Messier objects: M53, M64, M85, M88, M91, M98, M99, M100 Meteor showers: Coma Berenicids (10 Jan) Midnight culmination date: 2 Apr Bright stars: none Named stars: Diadem (a) Near stars: P Corn (124) Size: 386.47 square degrees (0.937% of the sky) Rank in size: 42 Solar conjunction date: 3 Oct Visibility: completely visible from latitudes: N of —56° completely invisible from latitudes: S of —77° Visible stars: (number of stars brighter than magnitude 5.5): 23 Interesting facts: (1) This constellation was created by Gerard Mercator on a globe designed by him in 1551. (2) The north galactic pole lies within the constellation of Coma Berenices. Its approximate 1950.0 coordinates are RA = 12h49m Dec. = +27.4°. (3) One of the most famous galaxies in the sky, and one whose photograph is often reproduced to show a classic 'edge-on' spiral galaxy is NGC 4565. This object lies slightly more than 30 to the southeast of y Corn. In a dark sky, even small instruments will show this 10th magnitude object to be a slender filament of light. Only the largest telescopes reveal its true character and beauty, however. NGC 4565 lies at a distance of approximately 20 million light years.

Blue Straggler Stars in Globular Cluster M53 Explanation: M53, also known as NGC 5024, is one of about 250 globular clusters that survive in our Galaxy. Most of the stars in M53 are older and redder than our Sun, but some enigmatic stars appear to be bluer and younger. Pictures of globular clusters like theabove image taken by the Hubble Space Telescope, astronomers use the abundance of stars like blue stragglers to help determine the age of the globular cluster and hence a limit on the age of the universe. M53, visible with a binoculars towards the constellation of Bernice's Hair(Coma Berenices), contains over 250,000 stars and is one of the furthest globulars from the center of our Galaxy.

M64: The Sleeping Beauty Galaxy

Explanation: The Sleeping Beauty galaxy may appear peaceful at first sight but it is actually tossing and turning. Collisions between gas in the inner and outer regions are creating many hot blue stars and pink emission nebula. The above image was taken by the Hubble Space Telescope in 2001 and released in 2004. The fascinating internal motions of M64, also cataloged as NGC 4826, are thought to be the result of a collision between a small galaxy and a large galaxy where the resultant mix has not yet settled down.

NGC 2787: A Barred Lenticular Galaxy: M85 Explanation: Lenticulars are relatively little studied, possibly because of their seemingly benign nature. Famous galaxies historically classified as lenticular include M84, M85, and M86. For example, the above image of NGC 2787 taken with the Hubble Space Telescope shows that the center of this lenticular galaxy has interesting structure. The image was taken to help determine how lenticular galaxies formed, and what happens in their centers. The span of NGC 2787 in the above image is about 4500 light years, while the galaxy lies about 25 million light years away toward the constellation of Ursa Major.

Virgo Cluster Galaxies: M85, M88, M91, M98, M99

Explanation: Well over a thousand galaxies are known members of the Virgo Cluster, the closest large cluster of galaxies to our own local group. This careful wide-field mosaic of telescopic images clearly records the central region of the Virgo Cluster through faint foreground dust clouds lingering above the plane of our own Milky Way galaxy. The cluster's dominant giant elliptical galaxy M87, is just below and to the left of the frame center. To the right of M87 is a string of galaxies known as Markarian's Chain. A closer examination of the image will reveal many Virgo cluster member galaxies as small fuzzy patches. Sliding your cursor over the image will label the larger galaxies using NGC catalog designations. Galaxies are also shown with Messier catalog numbers, including M84, M86, and prominent colorful spirals M88, M90, and M91. On average, Virgo Cluster galaxies are measured to be about 48 million light-years away. The Virgo Cluster distance has been used to give an important determination of the Hubble Constant and the scale of the Universe.

M100: A Grand Design Spiral Galaxy

Explanation: Majestic on a truly cosmic scale, M100 is appropriately known as a grand design spiral galaxy. It is a large galaxy of over 100 billion stars with well- defined spiral arms that is similar to our own Milky Way Galaxy. One of the brightest members of the Virgo Cluster of galaxies, M100 (alias NGC 4321) is 56 million light- years distant toward the constellation of Berenice's Hair (Coma Berenices). This HubbleSpace Telescope image of M100 was made in 2009 and reveals bright blue star clusters and intricate winding dust lanes which are hallmarks of this class of galaxies. Studies of variable stars in M100 have played an important role in determining the size and age of the Universe. If you know exactly where to look, you can find a small spot that is a light echo from a bright supernova that was recorded a few years beforethe image was taken.

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April 7 Canes Venatici (CAN-eez ve-NAT-iss-eye), the Hunting Dogs CVn, Canum Venaticorum (CAN-um) ve-nat-ih-COR-um

Canes Venatici

Meaning: The Hunting Dogs Pronunciation: kay' neez yen ah tee' see Abbreviation: CVn Possessive form: Canum Venaticorum (kay' num yen at ih kor' urn) Asterisms: The Diamond (of Virgo)

Bordering constellations: Boötes, Coma Berenices, Ursa Major Overall brightness: 3.224 (84) Central point: RA = 13h04m Dec. = +40.5° Directional extremes: N = +53° S = +28° E = 14h05m W = 12h04m Messier objects: M3, M51, M63, M94, M106 Meteor showers: none Midnight culmination date: 7 Apr

Bright stars: a2 (150) Named stars: Asterion (13), Chara (13), Cor Caroli (a), La Superba (Y) Near stars: 13 CVn (160), BD+36°2393 (181), BD+46°1 889 (196), BD+35°2436 A-B (199) Size: 465.19 square degrees (1.128% of the sky) Rank in size: 38

Solar conjunction date: 8 Oct

Visibility: completely visible from latitudes: N of -37° completely invisible from latitudes: S of -62°

Visible stars: (number of stars brighter than magnitude 5.5): 15

Interesting facts: (1) One of seven constellations still in use invented by Johannes Hevelius. In 1690, this group was included in a star atlas which accompanied his stellar catalog. (2) One-third of the way from 13 CVn to UMa (the bend of the handle of the Big Dipper) is the unusual star Y CVn, one of the reddest stars known. Because of its strange (and apparently wonderful) spectrum, Father Secchi dubbed it 'La Superba.' (3) One of the most beautiful spiral galaxies in the sky may be found within the confines of Canes Venatici. This is the 'Whirlpool Galaxy,' number 51 on Messier's list. In 1845, Lord Rosse saw the spiral structure in this object, making it the first galaxy to be observed with a definite spiral form.

Globular Star Cluster M3 Explanation: This immense ball of half a million stars older than the Sun lies over 30,000 light-years away. Cataloged as M3 (and NGC 5272), it is one of about 150 globular star clusters that roam the halo of our Milky Way Galaxy. Individual stars are difficult to distinguished in the densely packed core, but colors are apparent for the bright stars on the cluster's outskirts. M3's many cool "red" giant stars take on a yellowish cast, while hotter giants and pulsating variable stars look light blue. Itself about 200 light-years across, the giant star cluster is a relatively bright, easy target for binoculars in the northern constellation Canes Venatici, The Hunting Dogs, and not far from Arcturus.

Galaxies in the River: M51

Explanation: In fact, the practice is common in the universe and illustrated by this striking pair of interacting galaxies from the banks of the southern constellation Eridanus, The River. Located over 50 million light years away, the large, distorted spiral NGC 1532 is seen locked in a gravitational struggle with dwarf galaxy NGC 1531 (right of center). Seen edge-on, spiral NGC 1532 spans about 100,000 light-years. Nicely detailed in this sharp image, the NGC 1532/1531 pair is thought to be similar to the well-studied system of face-on spiral and small companion known as M51.

Messier 63: The Sunflower Galaxy

Explanation: A bright spiral galaxy of the northern sky, Messier 63 is about 25 million light-years distant in the loyal constellation Canes Venatici. Also cataloged as NGC 5055, the majestic island universe is nearly 100,000 light-years across. That's about the size of our own Milky Way Galaxy. Known by the popular moniker, The Sunflower Galaxy, M63 sports a bright yellowish core in this sharp, colorful galaxy portrait. Its sweeping blue spiral arms are streaked with cosmic dust lanes and dotted with pink star forming regions. A dominant member of a known galaxy group, M63 has faint, extended features that could be the result of gravitational interactions with nearby galaxies.

Starburst Galaxy Messier 94

Explanation: Beautiful island universe Messier 94 lies a mere 15 million light-years distant in the northern constellation of the hunting dogs,Canes Venatici. The face-on spiral galaxy is about 30,000 light- years across, with spiral arms sweeping through the outskirts of its broad disk. But this Hubble Space Telescope field of view spans about 7,000 light-years or so across M94's central region. The massive stars in the ring are all likely less than 10 million years old, indicating the galaxy experienced a well-defined era of rapid star formation. As a result, while the small, bright nucleus is typical of the Seyfert class of active galaxies, M94 is also known as a starburst galaxy.

M106 Across the Spectrum

Explanation: Also known as NGC 4258, M106 can be found toward the northern constellation Canes Venatici. The well-measured distance to M106 is 23.5 million light- years, making this cosmic scene about 60,000 light-years across. This composite highlights two anomalous arms in radio (purple) and X- ray (blue) that seem to arise in the central region of M106, evidence of energetic jets of material blasting into the galaxy's disk. The jets are likely powered by matter falling into a massive central black hole.

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April 11 Virgo (VER-go), the Maiden Vir, Virginis (VER-jin-iss)

Virgo

Meaning: The Virgin Pronunciation: ver' go Abbreviation: Vir Possessive form: Virginis (ver' jin iss) Asterisms: The Diamond, The Spring Triangle, The Y

Bordering constellations: Boötes, Coma Berenices, Corvus, Crater, Hydra, Leo, Libra, Serpens

Overall brightness: 4.481 (79) Central point: RA = 13h21m Dec. = —4 Directional extremes: N = +14° S = —22° E = 15h08m W = 11h35m

Messier objects: M49, M58, M59, M60, M61, M84, M86, M87, M89, M90, M104

Meteor showers: Virginids (26 Mar) a Virginids (9 Apr) i Virginids (25 Apr)

Midnight culmination date: 11 Apr Bright stars: a (16), y (117), (133)

Named stars: Alaraph (3), Arich (y), Auva (ö), Azimech (cc), Heze (c), Minelauva (s), Porrima (y), Spica (cx), Syrma (t), Vindemiatrix (s), Zania (i), Zavijava (3)

Near stars: Ross 128 (12), Wolf 424 A-B (27),Wolf 489 (94), Ross 490 (101), 61 Vir (127), Wolf 437 (149), Wolf 457 (162), 3 Vir (195), yVir A-B (198)

Size: 1294.43 square degrees (3.138% of the sky)

Rank in size: 2 Solar conjunction date: 12 Oct

Visibility: completely visible from latitudes: +68° to —76° portions visible worldwide

Visible stars: (number of stars brighter than magnitude 5.5): 58

Interesting facts: (1) The autumnal equinox, that point on the celestial sphere where the Sun crosses the celestial equator heading south, lies in Virgo. Its position is approximately 3°southeast of 3 Vir.

(2) The best known cluster of galaxies, called the 'Virgo Cluster,' lies in the region of sky just to the east of E Vir, near the border of Coma Berenices. This area has been labeled 'The Realm of the Nebulae,' a reference to times when the nature of the galaxies was not well understood. The Virgo Cluster lies at a distance of 50-60 million light years and contains about 2500 members, most of which are spiral galaxies. The most famous members of this cluster are M104, the so-called 'Sombrero Galaxy,' and M87, which seems to be ejecting a jet of material from its nucleus.

(3) One of the most famous double stars in the sky is y Vir, also known as Porrima. This system is so celebrated that no less an observer than Smyth wrote a poem containing 22 stanzas entitled, 'A Farewell to the Double Star y Virginis at the Epoch of 1858.' Since then many a college student, including this writer, has taken micrometric observations of this pair to calculate its orbital elements.

(4) Slightly less than 5° to the northwest of y Vir lies 3C273, the brightest quasar in the entire sky, shining with an apparent magnitude of 12.8. This is also the first quasar whose spectral lines were deciphered (by Maarten Schmidt) to show an incredible redshift. The approximate distance to 3C273 is 3000 million light years.

Messier 9 Close-up

Explanation: Renown 18th century astronomer Charles Messier described this 9th entry in his famous astronomical catalog as "Nebula, without star, in the right leg of Ophiuchus ...". But Messier 9 (M9) does have stars, known to modern astronomers as a globular cluster of over 300,000 stars within a diameter of about 90 light-years. This Hubble Space Telescope close-up resolves the dense swarm of stars across the cluster's central 25 light-years. At least twice the age of the Sun and deficient in heavy elements, the cluster stars have colors corresponding to their temperatures, redder stars are cooler, bluer stars are hotter. Many of the cluster's cool red giant stars show a yellowish tint in the sharp Hubble view.

Elliptical M60, Spiral NGC 4647: M60

Explanation: Giant elliptical galaxy M60 and spiral galaxy NGC 4647 do look like an odd couple in this sharp cosmic portrait from the Hubble Space Telescope. About 54 million light-years distant, bright M60's simpler egg- like shape is created by its randomly swarming older stars, while NGC 4647's young blue stars, gas and dust are organized into winding arms rotating in a flattened disk. Spiral NGC 4647 is estimated to be more distant than M60, some 63 million light-years away. Also known as Arp 116, the pair of galaxies may be on the verge of a significant gravitational encounter, though. M60 (aka NGC 4649) is about 120,000 light-years across.

In the Center of Spiral Galaxy M61

Explanation: M61 is a barred spiral galaxy located in the nearby Virgo Cluster of Galaxies. M61, also known as NGC 4303, in similar to our own Milky Way Galaxy. Light from M61 takes about 55 million years to reach us. The above image of the central regions of M61 was taken with the Hubble Space Telescope and adapted for release as part of the Hubble's Hidden Treasures image processing competition.

M86 in the Virgo Cluster

Explanation: Bright lenticular galaxy M86 is near center of this cosmic view, at the heart of the Virgo Galaxy Cluster. Other bright galaxies in the neighborhood include M84 at the upper right, edge-on spiral NGC4388 near the right edge, a striking pair of interacting galaxies,Markarian's Eyes, in the lower left corner, and edge-on spiral NGC 4402 at about 11 o'clock. With well over a thousand members, the Virgo Cluster is the closest large cluster of galaxies. On average the cluster galaxies are measured to be about 50 million light-years away. Theentire Virgo Cluster is difficult to appreciate because it covers such a large area, spanning over 10 degrees on the sky. This cluster close-upcovers a region just under 1 degree wide or about 1.5 times the size of the full moon.

M87: Elliptical Galaxy with Jet

Explanation: In spiral galaxies, majestic winding arms of young stars, gas, and dust rotate in a flat disk around a bulging galactic nucleus. But elliptical galaxies seem to be simpler. Lacking gas and dust to form new stars, their randomly swarming older stars, give them an ellipsoidal (egg-like) shape. Still, elliptical galaxies can be very large. Centered in this telescopic view and over 120,000 light-years in diameter, larger than our own Milky Way, elliptical galaxy M87 (NGC 4486) is the dominant galaxy of the Virgo Galaxy Cluster. Some 50 million light-years away, M87 is likely home to a supermassive black hole responsible for a high-energy jet of particles emerging from the giant galaxy's central region. In this well-processed image, M87's jet is near the one o'clock position. Other galaxies are also in the field of view, including large Virgo Cluster ellipticals NGC 4478 right of center and NGC 4476 near the right edge.

Spiral Galaxy M90

Explanation: Spiral galaxy M90 is near the center of the Virgo Cluster of Galaxies - the closest cluster of galaxies to the our own Milky Way Galaxy. Also dubbed NGC 4569, this galaxy has a very compact and bright nucleus. Most galaxies show a redshift which indicates that they move away from us.

The Sombrero Galaxy in Infrared

Explanation: The Sombrero Galaxy, one of the largest galaxies in the nearby Virgo Cluster of Galaxies. The dark band of dust that obscures the mid-section of the Sombrero Galaxy in optical light actually glows brightly in infrared light. The above image, digitally sharpened, shows the infrared glow, recently recorded by the orbiting Spitzer Space Telescope, superposed in false-color on an existing image taken by NASA's Hubble Space Telescope in optical light. The Sombrero Galaxy, also known as M104, spans about 50,000 light years across and lies 28 million light years away. M104 can be seen with a small telescope in the direction of the constellation Virgo.

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April 30 Circinus (SER-sin-us), the Compass Cir, Circini (SER-sin-eye)

Circinus

Meaning: The Compasses Pronunciation: sir sin' us Abbreviation: Cir Possessive form: Circini (sir sin' ee) Asterisms: none

Bordering constellations: Apus, Centaurus, Lupus, Musca, Norma, Triangulum Australe

Overall brightness: 10.712 (16) Central point: RA = 14h30m Dec. = —62° Directional extremes: N = —54° S = —70° E = 15h26m W = 13h35m Messier objects: none Meteor showers: none

Midnight culmination date: 30 Apr

Bright stars: none Named stars: none Near stars: none Size: 93.35 square degrees (0.226% of the sky) Rank in size: 85

Solar conjunction date: 29 Oct

Visibility: completely visible from latitudes: S of +30° completely invisible from latitudes: N of +36°

Visible stars: (number of stars brighter than magnitude 5.5): 10

Interesting facts: (1) This was one of the 14 constellations invented by Lacaille during his stay at the Cape of Good Hope in 1751-2.

No Messier In This Constellation

APRIL 2016 MOON PHASES CALENDAR

MONDAY TUESDAY WEDNESDAY THURSDAY FRIDAY SATURDAY SUNDAY

1 2 3

Waning Waning Waning Crescent, Crescent, Crescent, 39% 28% 19% 4 5 6 7 8 9 10

Waning Waning Waning New Waxing Waxing Waxing Crescent, Crescent, Crescent, Moon Crescent, Crescent, Crescent, 11% 4% 1% 3% 8% 15% 11 12 13 14 15 16 17

Waxing Waxing Waxing Waxing Waxing Waxing Waxing Crescent, Crescent, Crescent, Gibbous, Gibbous, Gibbous, Gibbous, 25% 35% 45% 56% 66% 75% 83% 18 19 20 21 22 23 24

Waxing Waxing Waxing Full Moon Full Waning Waning Gibbous, Gibbous, Gibbous, Moon Gibbous, Gibbous, 89% 95% 98% 98% 94% 25 26 27 28 29 30

Waning Waning Waning Waning Waning Waning Gibbous, Gibbous, Gibbous, Gibbous, Gibbous, Crescent, 89% 82% 74% 64% 54% 44%

April 2016 Killeen, Texas Sunday Monday Tuesday Wednesday Thursday Friday Saturday 1 2

Twi A: 5:58am Twi A: 5:56am Sunrise: 7:20am Sunrise: 7:18am Sunset: 7:50pm Sunset: 7:50pm Twi A: 9:12pm Twi A: 9:13pm Moonrise: 3:00am Moonrise: 3:48am Moonset: 1:57pm Moonset: 2:56pm

3 4 5 6 7 8 9

Twi A: 5:55am Twi A: 5:54am Twi A: 5:52am Twi A: 5:51am Twi A: 5:49am Twi A: 5:48am Twi A: 5:47am Sunrise: 7:17am Sunrise: 7:16am Sunrise: 7:15am Sunrise: 7:14am Sunrise: 7:12am Sunrise: 7:11am Sunrise: 7:10am Sunset: 7:51pm Sunset: 7:52pm Sunset: 7:52pm Sunset: 7:53pm Sunset: 7:54pm Sunset: 7:54pm Sunset: 7:55pm Twi A: 9:13pm Twi A: 9:14pm Twi A: 9:15pm Twi A: 9:16pm Twi A: 9:17pm Twi A: 9:17pm Twi A: 9:18pm Moonrise: 4:34am Moonrise: 5:18am Moonrise: 6:01am Moonrise: 6:44am Moonrise: 7:28am Moonrise: 8:13am Moonrise: 9:01am Moonset: 3:59pm Moonset: 5:04pm Moonset: 6:11pm Moonset: 7:19pm Moonset: 8:27pm Moonset: 9:36pm Moonset: 10:43pm New Moon: 6:25am 10 11 12 13 14 15 16

Twi A: 5:45am Twi A: 5:44am Twi A: 5:43am Twi A: 5:41am Twi A: 5:40am Twi A: 5:39am Twi A: 5:37am Sunrise: 7:09am Sunrise: 7:08am Sunrise: 7:06am Sunrise: 7:05am Sunrise: 7:04am Sunrise: 7:03am Sunrise: 7:02am Sunset: 7:56pm Sunset: 7:56pm Sunset: 7:57pm Sunset: 7:58pm Sunset: 7:58pm Sunset: 7:59pm Sunset: 8:00pm Twi A: 9:19pm Twi A: 9:20pm Twi A: 9:21pm Twi A: 9:22pm Twi A: 9:22pm Twi A: 9:23pm Twi A: 9:24pm Moonrise: 9:52am Moonrise: 10:46am Moonrise: 11:41am Moonrise: 12:38pm Moonrise: 1:35pm Moonrise: 2:31pm Moonrise: 3:25pm Moonset: 11:47pm Moonset: none Moonset: 12:47am Moonset: 1:42am Moonset: 2:32am Moonset: 3:16am Moonset: 3:56am First Qtr: 11:01pm

17 18 19 20 21 22 23

Twi A: 5:36am Twi A: 5:35am Twi A: 5:33am Twi A: 5:32am Twi A: 5:31am Twi A: 5:29am Twi A: 5:28am Sunrise: 7:01am Sunrise: 7:00am Sunrise: 6:58am Sunrise: 6:57am Sunrise: 6:56am Sunrise: 6:55am Sunrise: 6:54am Sunset: 8:00pm Sunset: 8:01pm Sunset: 8:02pm Sunset: 8:02pm Sunset: 8:03pm Sunset: 8:04pm Sunset: 8:04pm Twi A: 9:25pm Twi A: 9:26pm Twi A: 9:27pm Twi A: 9:28pm Twi A: 9:29pm Twi A: 9:30pm Twi A: 9:30pm Moonrise: 4:19pm Moonrise: 5:12pm Moonrise: 6:04pm Moonrise: 6:56pm Moonrise: 7:48pm Moonrise: 8:40pm Moonrise: 9:32pm Moonset: 4:33am Moonset: 5:07am Moonset: 5:41am Moonset: 6:14am Moonset: 6:47am Moonset: 7:22am Moonset: 7:58am Full Moon: 12:25am

24 25 26 27 28 29 30

Twi A: 5:27am Twi A: 5:25am Twi A: 5:24am Twi A: 5:23am Twi A: 5:22am Twi A: 5:20am Twi A: 5:19am Sunrise: 6:53am Sunrise: 6:52am Sunrise: 6:51am Sunrise: 6:50am Sunrise: 6:49am Sunrise: 6:48am Sunrise: 6:47am Sunset: 8:05pm Sunset: 8:06pm Sunset: 8:06pm Sunset: 8:07pm Sunset: 8:08pm Sunset: 8:08pm Sunset: 8:09pm Twi A: 9:31pm Twi A: 9:32pm Twi A: 9:33pm Twi A: 9:34pm Twi A: 9:35pm Twi A: 9:36pm Twi A: 9:37pm Moonrise: 10:24pm Moonrise: 11:16pm Moonrise: none Moonrise: 12:07am Moonrise: Moonrise: 1:43am Moonrise: 2:28am Moonset: 8:37am Moonset: 9:20am Moonset: 10:05am Moonset: 10:55am 12:56am Moonset: 12:45pm Moonset: 1:44pm Moonset: 11:48am Last Qtr: 10:30pm

CULMINATION of the CONSTELLATIONS

A culmination occurs when some star or constellation crosses the local meridian to reaching its highest (or lowest point) in the sky, and knowing when this occurs is very useful to both visual or telescopic observations of the night sky. By knowing when some celestial object crosses the local meridian, means that their general appearance will be at their very best, and without the hindrance of the atmospheric effects; such as seeing, refraction or air mass.

Culminations for non-circumpolar stars, that do rise and set below the horizon, will happen once per day. However, because of Earth’s orbital motion around the Sun, the time for each successive culmination falls earlier by about four minutes for every day that passes. Its exact instant of local time crossing the local meridian is formally called the Sidereal Time, which is exactly corresponds to the local meridian ’s Right Ascension. In other circumstances, if some constellation or celestial object appears circumpolar — never setting below the local horizon — two culminations can occur. These are an upper culmination(highest) and lower culmination (lowest).

Calculation of culmination times is not exactly simple, as the width of the constellation means that we need to determine the time of the mid -point. This can be approximated by the difference between the eastern and western constellations limits, but this should probably be better determined but knowing the right ascension of half area of the constellation — something far more difficult to calculate. A slightly more accurate way it the constellation centre of both right (cvp) ascension and declination, and this requires knowing the extreme of all the boundaries.

Furthermore, culmination times are also dependant on the precession of the equinoxes, so they should include the current epoch. Many tabulated culminations are still based on the B1950.0 epoch, meaning the culmination times are only off by a day or so. Most tables on culminations are only accurate to several days, but this is still quite adequate for most visual observation purposes.

The TABULATED DATA

The dates when this occurs are conveniently expressed for midnight (12pm) and in the early evening at 9pm, when most observers would be lookin g at the nighttime sky. Sometimes it can be given at 6pm, but then only useful in the winter months when it is dark at that time. Finding culmination times for other times of the year, subtract 15 days for ever hour that is earlier than this date. For time s that are later; add fifteen (15) days for every hour. If the date is different than specified, then add or subtract twenty- eight (28) minutes for each week that has elapsed or is to come.

Remote Video Astronomy Group MECATX Sky Tour April 2016

Revised by: Samantha Salvador 3.20.2016