The Monthly Sky for April 2016
Darkness fades with Mercury-shine
by Viktor Zsohar
April offers the last chance before fall, to observe the night sky in the Yukon. At the beginning of the month, we can still enjoy the astronomical night between 11:15 PM and 04:45 AM. Then, all observing astronomers of the beautiful Yukon inevitably find that living at a high geographical altitude : as darkness fades away day-by-day, they will be observing the midnight Sun. The “Return of the Night Stars” will commence in late August in the Yukon theatre of the Universe.
APRIL YUKON SKY EVENTS
April 1. Mercury at ascending node. Double shadow transit on Jupiter
April 3. Double shadow transit on Jupiter
April 5. Mercury at perihelion. Double shadow transit on Jupiter
April 6. Venus 0.7° South of Moon. Occultation will occur, not visible in the Yukon
April 7. New Moon
April 8. Double shadow transit on Jupiter
April 9. Vesta 0.02° South of Moon. Not visible in the Yukon
Uranus in conjunction with the Sun
April 10. Aldebaran 0.3° South of Moon. Occultation will occur, not visible in the Yukon
April 14. First Quarter
April 15. Mercury at greatest heliocentric latitude North
April 17. Mars is stationary
April 18. Jupiter 2° North of Moon
Main event: Mercury greatest elongation East (20°)
April 22. Full Moon
Lyrids meteors peak
April 25. Moon, Mars, Saturn, Antares in group. The bright quadrate is well visible low above Horizon, towards SE, between 02:00 – 04:00 am, before sunrise.
April 27. Juno at opposition
April 28. Mars in descending node
April 29. Mercury stationary
April 30. Last quarter
PLANETS IN APRIL
Mercury is well placed in Constellation Pisces, then in Aries in April, and the hideous planet can be observed in the Yukon in the evenings. In fact, this is the best apparition of the year for observers on mid-northern latitudes. The planet will reach its greatest elongation E (20 degree) on the 18th, with the altitude of 10 degree at around 10:00 PM. Use a pair of binoculars to spot the planet after sunset. Perihelion is on April 5th. Brightness between -1.5m and +0.5m
Venus is bright; it gets up together with the Sun in April. Practically, Venus is not in a favourable position for Yukoners. Venus shines with a magnitude of -3.8m
Mars is in Virgo. Visible every clear night in April. The Red Planet climbs up to 25 degree high above the Horizon in the middle of the night. Its size slightly increases as the planet gets closer to the Earth, from 11.8″ on April 1st, to 16.0″ on April 30th. Mars is getting brighter, from -0.5m to -1.2m
Jupiter in Leo, and visible all night during April. Transits the meridian around midnight, and its highest position in the sky is 37° high above the Horizon. Jupiter is getting away from us, the diameter of the planet starts to slowly decrease.
Saturn in Ophiucus. The Ring Planet rises earlier day-by-day, and visible during the second part of the night. However, it is a difficult target with an astronomical telescope, because it only climbs up to 8° above Horizon during April. Saturn’s magnitude is +0.3m in April.
Uranus is not in favourable position.
Neptune is not in favourable position.
USE ONLY safe and appropriate Solar Filters
that are designed for use with your telescope!
Be properly prepared to observe the Sun.
And if you have any doubts before pointing
your telescope towards our Central Star…
Any questions? Please ask us!
DEEP-SKY OBSERVATION GUIDE
Constellations of the Month: Coma Berenices (Com) and Camelopardalis (Cam)
Discerning the patterns of these two constellations, even if they are high above Horizon, are not necessarily easy. Navigating your telescope to deep-sky objects in these areas of the sky might be quite challenging, because it takes learning and patience to find these constellations and find adequate reference points for star-hopping. However, the results you may get are jaw-dropping views of galaxies and a great globular cluster.
Coma Berenices (Com)
Coma Berenices, in other words, the Hair of Queen Berenice can be found above the ecliptic plane, at the left side of Constellation Leo. Berenice II of Egypt, was the Queen of Ptolemy (246-221 BC). The Queen vowed to sacrifice her “amber tresses” in the temple of Aphrodite at Zephyrium, if the king returns safe from battle. After the offering mysteriously vanished, the court astronomer Conon convinced the royal couple that the lost tresses transformed to a constellation, and enshrined forever among the stars. Constellation Coma Berenices offers bright galaxies, beautiful star clusters and challenging double stars.
The constellation’s brightest star, Diadem (Alpha Com) is a double star with a maximum separation of 0.9″. The three brightest stars of the constellation forms a right-angle triangle, that gives observers a good reference for star-hopping.
Coma Berenices Star Cluster (Mel111). The other prominent feature visible to the naked eye in this Constellation is the best known galactic star cluster, the Coma Berenices Star Cluster. It is a conspicuous scattered group of naked-eye stars, centered about mid-way between stars Cor Caroli and Denebola. At a 250 light-years distance, the Coma Group is one of the nearest star cluster. It covers about 5° of the sky, including fifth magnitude stars, 12, 13, 14, 16 and 21 Comae. As a cluster, it can be best seen by wide -angle binoculars, but is completely lost in a narrow field of view of a telescope.
M53 can be found about 1° NE from the binary star Alpha Comae. It is a rich globular cluster which forms a pair of 1° separation with the more unusual cluster NGC5053. Bright and well condensed, this is an easy object for a small telescope, appearing a globulous spot in a 3″ refractor, but resolving to a wonderful swarm of tiny star images with bigger telescopes.
NGC5053 is an unusual object that can be classified either as a very loose globular cluster or a very dense galactic cluster. It may be detected with an 8″ telescope as a faint, hazy spot of 10.5 magnitude.
M64 the Black-Eye Galaxy is a large, oval spiral of the +9.0 magnitude and measuring about 7.5’x3.5′ in size, easily located about 1 degree East-North-East from the star 35 Comae. The spiral arms show a beautiful smooth and uniform texture. In the central nucleus, however, a huge dark dust cloud is present that shows great detail with large telescopes. The visibility of the dark mass is controversial among observers, but it is within the capabilities of a good 6 to 8″ telescope. This object requires very dark and clear skies with excellent dark-adaptation of the eyes.
M85 is one of the bright members of the Virgo Galaxy Cluster, the great aggregation of external systems which is centered some 5° to the South. Notable members of the Virgo Cluster that lying north in Coma Berenices, are: M85, M88, M98, M99, M100 and NGC 4565. M85 appears as a regular elliptical galaxy of about 10.5 magnitude, and 3’x2′ in size.
M88 is a bright, symmetrical galaxy of the multiple-arm type, oriented about 30° from edge-on position, and measuring about 5.5’x2.5′. This galaxy is considered one of the best of the Virgo galaxies for the small telescope, and is seems to be brighter than the reported magnitude of +11m. It is difficult to find, however, with no bright reference stars nearby. M88 will stand magnification well, and with averted vision, a considerable amount of details can be observed.
M98 is a large and much-elongated galaxy measuring about 8’x2′, and located 1/2 degree West of the 5th magnitude star, 5 Comae. According to Messier, it appears as a nebulae without star, of an extremely faint light, above the Northern wing of Virgo”, with a +11.m brightness. Herschel, who used a better and larger telescope, described it as a “large, extended, fine nebula”. A telescope of larger aperture definitely an asset to better see this classic galaxy.
M99 is a bright round spiral of type Sc, the “little sister” of M33, the “Pinwheel Nebula”. M99 located only 50′ South East of the star 6 Comae, and about 1.31° away from M98. It is a large, round, vividly sparkling light, its nucleus is more or less resolvable with large amateur telescopes. It is a +10.4m bright face-on spiral, with its apparent size of 4′ diameter. The spiral pattern is very well defined, although somewhat asymmetric, with an unusually far-extending arm towards the West. A large aperture astronomical telescope is an advantage for observing this beautiful galaxy.
M100 is the largest spiral galaxy in the Virgo-Coma Galaxy Cluster. it is located nearly in the center of the triangle formed by M85, M88 and M98. In the small telescope, M100 appears as a round glow of about 5′ in diameter with a total magnitude of about +10.0m.
NGC4565 is the largest, and the most famous of the edge-on spiral galaxies. It is located 1.71° East of star 17 Comae, and less than 31° away from the Northern Galactic Pole. NGC4565 is an interesting object with a small telescope. It appears as a bright, +10.5m, narrow streak in a good 6″ refractor or 8″ reflector. With a 10″ telescope, and dark skies, it is a perfect little needle of light which can be traced out right to the full photographic diameter of 15′.
Camelopardalis, our Canadian circumpolar Giraffe, may seem to be a very insignificant constellation near Polaris, at the first sight. Even those faint stars that make up the Giraffe-pattern, are difficult to find during a not-so-good night. However, Camelopardalis has some really interesting star patterns, variable stars and deep-sky objects that are well worth to note and observe. Moreover, it is also has Canadian acquaintances. But first let us see how to find Giraffe on the sky.
Finding Giraffe on the Sky
Find Capella, the brightest star in Auriga. Move NW from Capella, you enter Perseus. Half-way between Capella and Algenib (Alpha Persei) and five degrees North of this last star, are the feet of the Giraffe. Roughly half-way between Algenib and the North Pole is gamma Camelopardalis, the haunch of the Giraffe.
Return to Capella; move West three degrees and North seven degrees. This is 7 Cam, a binary (Struve 610) which serves as the Giraffe’s front foot.
Let’s move from 7 Cam to the first bright star, about seven degrees North. This is Beta Cam, also a binary.
Beta Cam is the brightest star in Camelopardalis, at 4.03 visual magnitude, a yellow supergiant that is a hundred times the size of the Sun, and about 1700 light years away.
Further North, another six degrees and you encounter Alpha Cam, which is nearly as bright at 4.3. This is a blue supergiant 4000 light years distant, with a diameter about half that of Beta Cam.
Northwest of Alpha Cam is Gamma, with a visual magnitude of only 4.63. This star is only twice the size of our Sun, and is about 180 light years away.
Variable stars in Camelopardalis
R Cam is a Mira-type variable with a period of 270.22 days, rising from 14.4 visual magnitude only to about 7, which makes it a telescopic variable all throughout its cycle.
VZ Cam is a semi-regular with an average period of 23.7 days, varying from 4.80 to 5. This is a popular semi-regular for binoculars.
Kemble’s Cascade is a string of mostly eighth-magnitude stars, that are nicely seen in binoculars. The Kemble’s Cascade seemingly flows into the star cluster NGC1502. This asterism is named for Father Lucian Kemble, a Franciscan and avid Canadian amateur astronomer who first drew attention to it in the late 1970s. This is the reason why Camelopardalis is well placed in the heart of many Canadian amateur astronomers. Our YAS logo design also contains the pattern of Constellation Camelopardalis.
NGC 1502 is a fine, irregular, 8′ diameter star cluster, a small group of perhaps fifteen stars with the binaries Struve 484 (+9.0m/+9.5m) and Struve 485 (+6.0m/+6.0m) at its centre. Struve 485 is an outstanding bright binary surrounded by a host of glittering 10- and 11-magnitude stars which make up the open cluster NGC 1502. This is a wide and easy binary, and a lovely sight.
NGC2403 is a large, loose-structured, Sc-type spiral galaxy that is located in a rather blank region of the northern heavens above Ursa Major’s nose, and now recognized as one of the closest spiral galaxy beyond the Local Group. It’s billions of stars shine at us about +8.8m brightness making it an excellent target not only for small astronomical telescopes, but for binoculars, as well. It may be seen easily as a large, hazy spot by a binocular on excellent nights. The apparent size is about 10’x16′. A definite degree of mottling becomes apparent in larger amateur telescopes, hinting at details which are fully revealed by imagers.
NGC1501 is a faint planetary nebula, lies 6.9 degrees West of magnitude 4.0 Beta Camelopardalis. Amateur astronomers call this object Oyster Nebula. A minimum 10″ telescope shows a circular disk, and larger telescopes reveal more details.
NGC2523 is an Sb-type barred spiral galaxy of unusual structure. The size is 1.8’x1.4′, and its brightness is +12.7m, thus a large aperture telescope is a must to detect this celestial object.
- Starry Night Pro7 software
- 2016 Observer’s Handbook, RASC
- Burnham’s Celestial Handbook
- Astronomy Magazine, Vol.44, Issue 3