Post by Dave Mitsky on May 1, 2015 18:41:10 GMT
May Celestial Calendar by Dave Mitsky
All times, unless otherwise noted, are UT (subtract four hours and, when appropriate, one calendar day for EDT)
5/1 May Day or Beltane, a cross-quarter day
5/4 Full Moon, known as the Milk or Planting Moon, occurs at 3:42
5/5 Saturn is 2 degrees south of the Moon at 16:00
5/6 The peak of the Eta Aquarid meteor shower (20 per hour for northern observers) occurs at 13:00
5/7 Mercury is at greatest eastern elongation (21 degrees) at 5:00
5/10 Venus is at its greatest heliocentric latitude north today
5/11 Last Quarter Moon occurs at 10:36
5/12 Neptune is 3 degrees south of the Moon at 21:00; the Curtiss Cross, an X-shaped illumination effect located between the craters Parry and Gambart, is predicted to begin at 7:08
5/15 The Moon is at perigee, subtending 32' 19'' from a distance of 366,024 kilometers (227,437 miles), at 0:00; Uranus is 0.2 degree north of the Moon, with an occultation occurring in western and central Africa and central South America, at 12:00
5/17 Asteroid 532 Herculina (magnitude 8.5) is at opposition at 22:00
5/18 New Moon (lunation 1143) occurs at 4:13
5/19 Mercury is 6 degrees north of the Moon at 7:00; Mercury is stationary at 11:00
5/21 A double Galilean satellite shadow transit begins at 0:06; a double Galilean satellite shadow transit begins at 13:29; Venus is 8 degrees north of the Moon at 19:00
5/23 Mercury is at the descending node today; Saturn (magnitude 0.0, apparent size 18.5'') is at opposition at 2:00
5/24 Jupiter is 5 degrees north of the Moon at 7:00
5/25 The Lunar X (also known as the Werner or Purbach Cross), an X-shaped illumination effect involving various rims and ridges between the craters La Caille, Blanchinus, and Purbach, is predicted to begin at 15:49; First Quarter Moon occurs at 17:19
5/26 The Moon is at apogee, subtending 29' 53'' from a distance of 404,244 kilometers (251,186 miles), at 22:00
5/28 A double Galilean satellite shadow transit begins at 2:01
5/30 Mercury is in inferior conjunction at 17:00; Venus is 4 degrees south of the first-magnitude star Pollux (Beta Geminorum) at 17:00
Nicolas Lacaille (1713-1762) and Joseph Lockyer (1836-1920) were born this month.
Nereid, Neptune’s third-largest satellite, was discovered on May 1, 1949 by Gerard Kuiper.
The May 6th peak of the Eta Aquarid meteor shower is compromised by moonlight from a waning gibbous Moon. Southern hemisphere observers are favored. Eta Aquarid meteors are debris from the famous periodic comet 1P/Halley.
Information on Iridium flares and passes of the ISS, the Tiangong-1, the USAF’s X-37B, the HST, and other satellites can be found at www.heavens-above.com/
The Moon is located in Virgo, is illuminated 90.8%, and is 12.2 days old on May 1st at 0:00 UT. The Moon occults Uranus from western and central Africa and central South America on May 15th. The Moon is at its greatest northern declination on May 20th (+18.4 degrees). The Moon is at its greatest its greatest southern declination on May 7th (-18.3 degrees). Longitudinal libration is at maximum (+5.6 degrees) on May 21st and at minimum (-5.6 degrees) on May 6th. Latitudinal libration is at maximum (+6.7 degrees) on May 21st and at minimum (-6.7 degrees) on May 8th. Visit saberdoesthestars.wordpress.com/2011/07/05/saber-does-the-stars/ for tips on spotting extreme crescent Moons. Times and dates for the lunar light rays predicted to occur this month are available at www.lunar-occultations.com/rlo/rays/rays.htm
The Sun is located in Aries on May 1st.
Brightness, apparent size, illumination, distance from the Earth in astronomical units, and location data for the planets and Pluto on May 1st: Mercury (magnitude -0.4, 6.8", 56% illuminated, 0.99 a.u., Taurus), Venus (magnitude -4.2, 16.7", 67% illuminated, 1.00 a.u., Taurus), Mars (magnitude +1.4, 3.8", 100% illuminated, 2.47 a.u., Aries), Jupiter (magnitude -2.1, 37.9", 99% illuminated, 5.21 a.u., Cancer), Saturn (magnitude +0.1, 18.4", 100% illuminated, 9.04 a.u., Scorpius), Uranus on May 16th (magnitude +5.9, 3.4", 100% illuminated, 20.80 a.u., Pisces), Neptune on May 16th (magnitude +7.9, 2.3", 100% illuminated, 30.21 a.u., Aquarius), and Pluto on May 16th (magnitude +14.1, 0.1", 100% illuminated, 32.22 a.u., Sagittarius).
In the evening, Mercury can be seen in the northwest, Venus in the west, Jupiter in the southwest, and Saturn in the southeast. Jupiter is located in the west and Saturn in the southeast at midnight. Saturn is in the southwest, Uranus in the east, and Neptune in the southeast at dawn.
At midmonth, Mercury is visible in evening twilight, Venus sets at midnight, Jupiter sets at 2:00 a.m. local daylight time, and Saturn is visible for the entire night for observers at latitude 40 degrees north.
Mercury, Venus, and Saturn are at their best this month.
Mercury is at its brightest during the first half of May. The speediest planet shines at magnitude 0.2 when it reaches greatest eastern elongation on May 7th. For mid-northern latitude observers, this is the best apparition of the planet in 2015. By May 11th, Mercury has faded to magnitude 1.0 as it passes 8 degrees north of the first-magnitude star Aldebaran (Alpha Tauri). Mercury is stationary on May 19th and in inferior conjunction on May 30th.
Brilliant Venus is situated between second-magnitude Elnath (Beta Tauri) and third-magnitude Zeta Tauri on May 1st. It exits Taurus and enters Gemini on May 8th. On May 9th, Venus passes 1.7 degrees north of the bright open cluster M35. Venus is 8 degrees north of a slender crescent Moon on May 20th and 4 degrees south of the first-magnitude star Pollux (Beta Geminorum) on May 30th. Venus brightens to magnitude -4.4 by month’s end.
Mars is a tiny, first-magnitude object that’s visible a few degrees above the northwestern horizon shortly after sunset early this month.
Jupiter sets around 1:00 a.m. local daylight time on May 1st and 11:00 p.m. local daylight time on May 31st. The waxing crescent Moon passes five degrees to the south of Jupiter on the morning of May 24th. Double Galilean satellite shadow transits occur on May 21st and May 28th. On the evening of May 30th, Callisto is the only one of the Galilean satellites visible from 10:57 p.m. to 12:55 a.m. EDT, since Europa is transiting Jupiter and Io and Ganymede are in occultation. Browse www.skyandtelescope.com/observing/interactive-sky-watching-tools/ in order to determine transit times of Jupiter’s central meridian by the Great Red Spot (GRS). GRS transit information also appears on page 52 of the May issue of Sky & Telescope. Data on the Galilean satellite events is available at www.skyandtelescope.com/observing/interactive-sky-watching-tools/ and www.shallowsky.com/jupiter/
Saturn is 1.2 degrees north of the second-magnitude multiple star Acrab (Beta Scorpius) on May 1st. It departs Scorpius and enters Libra on May 12th. The Ringed Planet reaches opposition on May 23rd and is visible all night. On that date, Saturn shines at magnitude 0.0 and has an apparent equatorial diameter of 18.5 arc seconds. Its rings are inclined by 24.4 degrees and subtend 42.1 arc seconds. At opposition, Saturn is located 8.97 astronomical units or 75 light-minutes from the Earth. Eighth-magnitude Titan is positioned north of the planet on May 3rd and May 19th and south of it on May 10th-May 11th and May 26th-May 27th. Saturn’s variably bright moon Iapetus shines at eleventh magnitude as it passes 2.5 arc minutes southwest of Saturn on May 1st. Iapetus is a magnitude brighter when it reaches greatest western elongation 9 arc minutes from the planet on May 19th. For further information on Saturn’s satellites, browse www.skyandtelescope.com/observing/interactive-sky-watching-tools/
Uranus rises during morning twilight for most of the month.
Neptune rises around 3:00 a.m. local daylight time by the middle of May. The gas giant is positioned approximately 2.2 degrees southwest of the fourth-magnitude star Lambda Aquarii. A finder chart is posted at freestarcharts.com/images/Articles/Month/May2015/Planets/Neptune/Neptune_May2015_Finder_Chart.pdf
Pluto lies in Sagittarius, approximately 5.5 degrees north of the handle of the Teapot asterism, and is high in the sky after midnight. Consult www.bluewaterastronomy.info/resources/MapsCharts/planets-2015/22pluto_2015_1.pdf for a finder chart.
For more on the planets and how to locate them, browse www.nakedeyeplanets.com/
Visit cometchasing.skyhound.com/ for information on comets visible this month.
Asteroid 532 Herculina travels southwestward through Serpens Caput this month. The minor planet passes within three arc minutes of a field star on the evenings of May 4th, May 10th, and May 21st and less than one degree south of the fifth-magnitude star Omega Serpentis on the evenings of May 22nd and May 23rd. The large, stony S-type main belt asteroid shines at magnitude 8.5 when it reaches opposition on May 17th. Asteroid 18 Melpomene (magnitude 10.3) reaches opposition on May 2nd. Consult www.minorplanetcenter.net/iau/Ephemerides/Bright/2015/index.html for ephemerides on these objects. Information on asteroid occultations taking place this month is available at www.asteroidoccultation.com/2015_05_si.htm
A wealth of current information on solar system celestial bodies is posted at www.curtrenz.com/astronomical.html
Browse astrocast.tv/ for an informative video on astronomical events taking place this month.
A free star map for May can be downloaded at www.skymaps.com/downloads.html and www.telescope.com/content.jsp?pageName=Monthly-Star-Chart
The famous eclipsing variable star Algol (Beta Persei) is at a minimum, decreasing in magnitude from 2.1 to 3.4, on May 2nd, 5th, 8th, 11th, 14th, 17th, 19th, 22nd, 25th, 28th, and 31st. For more on Algol, see stars.astro.illinois.edu/sow/Algol.html and www.solstation.com/stars2/algol3.htm
Eighty binary and multiple stars for May: 1 Bootis, Struve 1782, Tau Bootis, Struve 1785, Struve 1812 (Bootes); 2 Canum Venaticorum, Struve 1624, Struve 1632, Struve 1642, Struve 1645, 7 Canum Venaticorum, Alpha Canum Venaticorum (Cor Caroli), h2639, Struve 1723, 17 Canum Venaticorum, Otto Struve 261, Struve 1730, Struve 1555, h1234, 25 Canum Venaticorum, Struve 1769, Struve 1783, h1244 (Canes Venatici); 2 Comae Berenices, Struve 1615, Otto Struve 245, Struve 1633, 12 Comae Berenices, Struve 1639, 24 Comae Berenices, Otto Struve 253, Struve 1678, 30 Comae Berenices, Struve 1684, Struve 1685, 35 Comae Berenices, Burnham 112, h220, Struve 1722, Beta Comae Berenices, Burnham 800, Otto Struve 266, Struve 1748 (Coma Berenices); h4481, h4489, Struve 1604, Delta Corvi, Burnham 28, h1218, Struve 1669 (Corvus); H N 69, h4556 (Hydra); Otto Struve 244, Struve 1600, Struve 1695, Zeta Ursae Majoris (Mizar), Struve 1770, Struve 1795, Struve 1831 (Ursa Major); Struve 1616, Struve 1627, 17 Virginis, Struve 1648, Struve 1658, Struve 1677, Struve 1682, Struve 1689, Struve 1690, 44 Virginis, Struve 1719, Theta Virginis, 54 Virginis, Struve 1738, Struve 1740, Struve 1751, 81 Virginis, Struve 1764, Struve 1775, 84 Virginis, Struve 1788 (Virgo)
Notable carbon star for May: SS Virginis
One hundred and sixty-five deep-sky objects for May: NGC 5248 (Bootes); M3, M51, M63, M94, M106, NGC 4111, NGC 4138, NGC 4143, NGC 4151, NGC 4214, NGC 4217, NGC 4244, NGC 4346, NGC 4369, NGC 4449, NGC 4485, NGC 4490, NGC 4618, NGC 4631, NGC 4656, NGC 4868, NGC 5005, NGC 5033, NGC 5297, NGC 5353, NGC 5354, Up 1 (Canes Venatici); Mel 111, M53, M64, M85, M88, M91, M98, M99, M100, NGC 4064, NGC 4150, NGC 4203, NGC 4212, NGC 4251, NGC 4274, NGC 4278, NGC 4293, NGC 4298, NGC 4302, NGC 4314, NGC 4350, NGC 4414, NGC 4419, NGC 4448, NGC 4450, NGC 4459, NGC 4473, NGC 4474, NGC 4494, NGC 4559, NGC 4565, NGC 4651, NGC 4689, NGC 4710, NGC 4725, NGC 4874, NGC 5053 (Coma Berenices); NGC 4027, NGC 4038-9, NGC 4361 (Corvus); M68, M83, NGC 4105, NGC 4106, NGC 5061, NGC 5101, NGC 5135 (Hydra); M40, NGC 4036, NGC 4041, NGC 4051, NGC 4062, NGC 4085, NGC 4088, NGC 4096, NGC 4100, NGC 4144, NGC 4157, NGC 4605, NGC 5308, NGC 5322 (Ursa Major); M49, M58, M59, M60, M61, M84, M86, M87, M89, M90, M104, NGC 4030, NGC 4073, NGC 4168, NGC 4179, NGC 4206, NGC 4215, NGC 4216, NGC 4224, NGC 4235, NGC 4260, NGC 4261, NGC 4267, NGC 4281, NGC 4339, NGC 4343, NGC 4365, NGC 4371, NGC 4378, NGC 4380, NGC 4387, NGC 4388, NGC 4402, NGC 4429, NGC 4435, NGC 4438, NGC 4517, NGC 4526, NGC 4535, NGC 4536, NGC 4546, NGC 4550, NGC 4551, NGC 4567, NGC 4568, NGC 4570, NGC 4593, NGC 4596, NGC 4636, NGC 4638, NGC 4639, NGC 4643, NGC 4654, NGC 4666, NGC 4697, NGC 4698, NGC 4699, NGC 4753, NGC 4754, NGC 4760, NGC 4762, NGC 4866, NGC 4900, NGC 4958, NGC 5044, NGC 5054, NGC 5068, NGC 5077, NGC 5084, NGC 5087, NGC 5147, NGC 5170, NGC 5247, NGC 5363, NGC 5364 (Virgo)
Top ten deep-sky objects for May: M3, M51, M63, M64, M83, M87, M104, M106, NGC 4449, NGC 4565
Top ten deep-sky binocular objects for May: M3, M51, M63, M64, M84, M86, M87, M104, M106, Mel 111
Challenge deep-sky object for May: 3C 273 (Virgo)
The objects listed above are located between 12:00 and 14:00 hours of right ascension.
All times, unless otherwise noted, are UT (subtract four hours and, when appropriate, one calendar day for EDT)
5/1 May Day or Beltane, a cross-quarter day
5/4 Full Moon, known as the Milk or Planting Moon, occurs at 3:42
5/5 Saturn is 2 degrees south of the Moon at 16:00
5/6 The peak of the Eta Aquarid meteor shower (20 per hour for northern observers) occurs at 13:00
5/7 Mercury is at greatest eastern elongation (21 degrees) at 5:00
5/10 Venus is at its greatest heliocentric latitude north today
5/11 Last Quarter Moon occurs at 10:36
5/12 Neptune is 3 degrees south of the Moon at 21:00; the Curtiss Cross, an X-shaped illumination effect located between the craters Parry and Gambart, is predicted to begin at 7:08
5/15 The Moon is at perigee, subtending 32' 19'' from a distance of 366,024 kilometers (227,437 miles), at 0:00; Uranus is 0.2 degree north of the Moon, with an occultation occurring in western and central Africa and central South America, at 12:00
5/17 Asteroid 532 Herculina (magnitude 8.5) is at opposition at 22:00
5/18 New Moon (lunation 1143) occurs at 4:13
5/19 Mercury is 6 degrees north of the Moon at 7:00; Mercury is stationary at 11:00
5/21 A double Galilean satellite shadow transit begins at 0:06; a double Galilean satellite shadow transit begins at 13:29; Venus is 8 degrees north of the Moon at 19:00
5/23 Mercury is at the descending node today; Saturn (magnitude 0.0, apparent size 18.5'') is at opposition at 2:00
5/24 Jupiter is 5 degrees north of the Moon at 7:00
5/25 The Lunar X (also known as the Werner or Purbach Cross), an X-shaped illumination effect involving various rims and ridges between the craters La Caille, Blanchinus, and Purbach, is predicted to begin at 15:49; First Quarter Moon occurs at 17:19
5/26 The Moon is at apogee, subtending 29' 53'' from a distance of 404,244 kilometers (251,186 miles), at 22:00
5/28 A double Galilean satellite shadow transit begins at 2:01
5/30 Mercury is in inferior conjunction at 17:00; Venus is 4 degrees south of the first-magnitude star Pollux (Beta Geminorum) at 17:00
Nicolas Lacaille (1713-1762) and Joseph Lockyer (1836-1920) were born this month.
Nereid, Neptune’s third-largest satellite, was discovered on May 1, 1949 by Gerard Kuiper.
The May 6th peak of the Eta Aquarid meteor shower is compromised by moonlight from a waning gibbous Moon. Southern hemisphere observers are favored. Eta Aquarid meteors are debris from the famous periodic comet 1P/Halley.
Information on Iridium flares and passes of the ISS, the Tiangong-1, the USAF’s X-37B, the HST, and other satellites can be found at www.heavens-above.com/
The Moon is located in Virgo, is illuminated 90.8%, and is 12.2 days old on May 1st at 0:00 UT. The Moon occults Uranus from western and central Africa and central South America on May 15th. The Moon is at its greatest northern declination on May 20th (+18.4 degrees). The Moon is at its greatest its greatest southern declination on May 7th (-18.3 degrees). Longitudinal libration is at maximum (+5.6 degrees) on May 21st and at minimum (-5.6 degrees) on May 6th. Latitudinal libration is at maximum (+6.7 degrees) on May 21st and at minimum (-6.7 degrees) on May 8th. Visit saberdoesthestars.wordpress.com/2011/07/05/saber-does-the-stars/ for tips on spotting extreme crescent Moons. Times and dates for the lunar light rays predicted to occur this month are available at www.lunar-occultations.com/rlo/rays/rays.htm
The Sun is located in Aries on May 1st.
Brightness, apparent size, illumination, distance from the Earth in astronomical units, and location data for the planets and Pluto on May 1st: Mercury (magnitude -0.4, 6.8", 56% illuminated, 0.99 a.u., Taurus), Venus (magnitude -4.2, 16.7", 67% illuminated, 1.00 a.u., Taurus), Mars (magnitude +1.4, 3.8", 100% illuminated, 2.47 a.u., Aries), Jupiter (magnitude -2.1, 37.9", 99% illuminated, 5.21 a.u., Cancer), Saturn (magnitude +0.1, 18.4", 100% illuminated, 9.04 a.u., Scorpius), Uranus on May 16th (magnitude +5.9, 3.4", 100% illuminated, 20.80 a.u., Pisces), Neptune on May 16th (magnitude +7.9, 2.3", 100% illuminated, 30.21 a.u., Aquarius), and Pluto on May 16th (magnitude +14.1, 0.1", 100% illuminated, 32.22 a.u., Sagittarius).
In the evening, Mercury can be seen in the northwest, Venus in the west, Jupiter in the southwest, and Saturn in the southeast. Jupiter is located in the west and Saturn in the southeast at midnight. Saturn is in the southwest, Uranus in the east, and Neptune in the southeast at dawn.
At midmonth, Mercury is visible in evening twilight, Venus sets at midnight, Jupiter sets at 2:00 a.m. local daylight time, and Saturn is visible for the entire night for observers at latitude 40 degrees north.
Mercury, Venus, and Saturn are at their best this month.
Mercury is at its brightest during the first half of May. The speediest planet shines at magnitude 0.2 when it reaches greatest eastern elongation on May 7th. For mid-northern latitude observers, this is the best apparition of the planet in 2015. By May 11th, Mercury has faded to magnitude 1.0 as it passes 8 degrees north of the first-magnitude star Aldebaran (Alpha Tauri). Mercury is stationary on May 19th and in inferior conjunction on May 30th.
Brilliant Venus is situated between second-magnitude Elnath (Beta Tauri) and third-magnitude Zeta Tauri on May 1st. It exits Taurus and enters Gemini on May 8th. On May 9th, Venus passes 1.7 degrees north of the bright open cluster M35. Venus is 8 degrees north of a slender crescent Moon on May 20th and 4 degrees south of the first-magnitude star Pollux (Beta Geminorum) on May 30th. Venus brightens to magnitude -4.4 by month’s end.
Mars is a tiny, first-magnitude object that’s visible a few degrees above the northwestern horizon shortly after sunset early this month.
Jupiter sets around 1:00 a.m. local daylight time on May 1st and 11:00 p.m. local daylight time on May 31st. The waxing crescent Moon passes five degrees to the south of Jupiter on the morning of May 24th. Double Galilean satellite shadow transits occur on May 21st and May 28th. On the evening of May 30th, Callisto is the only one of the Galilean satellites visible from 10:57 p.m. to 12:55 a.m. EDT, since Europa is transiting Jupiter and Io and Ganymede are in occultation. Browse www.skyandtelescope.com/observing/interactive-sky-watching-tools/ in order to determine transit times of Jupiter’s central meridian by the Great Red Spot (GRS). GRS transit information also appears on page 52 of the May issue of Sky & Telescope. Data on the Galilean satellite events is available at www.skyandtelescope.com/observing/interactive-sky-watching-tools/ and www.shallowsky.com/jupiter/
Saturn is 1.2 degrees north of the second-magnitude multiple star Acrab (Beta Scorpius) on May 1st. It departs Scorpius and enters Libra on May 12th. The Ringed Planet reaches opposition on May 23rd and is visible all night. On that date, Saturn shines at magnitude 0.0 and has an apparent equatorial diameter of 18.5 arc seconds. Its rings are inclined by 24.4 degrees and subtend 42.1 arc seconds. At opposition, Saturn is located 8.97 astronomical units or 75 light-minutes from the Earth. Eighth-magnitude Titan is positioned north of the planet on May 3rd and May 19th and south of it on May 10th-May 11th and May 26th-May 27th. Saturn’s variably bright moon Iapetus shines at eleventh magnitude as it passes 2.5 arc minutes southwest of Saturn on May 1st. Iapetus is a magnitude brighter when it reaches greatest western elongation 9 arc minutes from the planet on May 19th. For further information on Saturn’s satellites, browse www.skyandtelescope.com/observing/interactive-sky-watching-tools/
Uranus rises during morning twilight for most of the month.
Neptune rises around 3:00 a.m. local daylight time by the middle of May. The gas giant is positioned approximately 2.2 degrees southwest of the fourth-magnitude star Lambda Aquarii. A finder chart is posted at freestarcharts.com/images/Articles/Month/May2015/Planets/Neptune/Neptune_May2015_Finder_Chart.pdf
Pluto lies in Sagittarius, approximately 5.5 degrees north of the handle of the Teapot asterism, and is high in the sky after midnight. Consult www.bluewaterastronomy.info/resources/MapsCharts/planets-2015/22pluto_2015_1.pdf for a finder chart.
For more on the planets and how to locate them, browse www.nakedeyeplanets.com/
Visit cometchasing.skyhound.com/ for information on comets visible this month.
Asteroid 532 Herculina travels southwestward through Serpens Caput this month. The minor planet passes within three arc minutes of a field star on the evenings of May 4th, May 10th, and May 21st and less than one degree south of the fifth-magnitude star Omega Serpentis on the evenings of May 22nd and May 23rd. The large, stony S-type main belt asteroid shines at magnitude 8.5 when it reaches opposition on May 17th. Asteroid 18 Melpomene (magnitude 10.3) reaches opposition on May 2nd. Consult www.minorplanetcenter.net/iau/Ephemerides/Bright/2015/index.html for ephemerides on these objects. Information on asteroid occultations taking place this month is available at www.asteroidoccultation.com/2015_05_si.htm
A wealth of current information on solar system celestial bodies is posted at www.curtrenz.com/astronomical.html
Browse astrocast.tv/ for an informative video on astronomical events taking place this month.
A free star map for May can be downloaded at www.skymaps.com/downloads.html and www.telescope.com/content.jsp?pageName=Monthly-Star-Chart
The famous eclipsing variable star Algol (Beta Persei) is at a minimum, decreasing in magnitude from 2.1 to 3.4, on May 2nd, 5th, 8th, 11th, 14th, 17th, 19th, 22nd, 25th, 28th, and 31st. For more on Algol, see stars.astro.illinois.edu/sow/Algol.html and www.solstation.com/stars2/algol3.htm
Eighty binary and multiple stars for May: 1 Bootis, Struve 1782, Tau Bootis, Struve 1785, Struve 1812 (Bootes); 2 Canum Venaticorum, Struve 1624, Struve 1632, Struve 1642, Struve 1645, 7 Canum Venaticorum, Alpha Canum Venaticorum (Cor Caroli), h2639, Struve 1723, 17 Canum Venaticorum, Otto Struve 261, Struve 1730, Struve 1555, h1234, 25 Canum Venaticorum, Struve 1769, Struve 1783, h1244 (Canes Venatici); 2 Comae Berenices, Struve 1615, Otto Struve 245, Struve 1633, 12 Comae Berenices, Struve 1639, 24 Comae Berenices, Otto Struve 253, Struve 1678, 30 Comae Berenices, Struve 1684, Struve 1685, 35 Comae Berenices, Burnham 112, h220, Struve 1722, Beta Comae Berenices, Burnham 800, Otto Struve 266, Struve 1748 (Coma Berenices); h4481, h4489, Struve 1604, Delta Corvi, Burnham 28, h1218, Struve 1669 (Corvus); H N 69, h4556 (Hydra); Otto Struve 244, Struve 1600, Struve 1695, Zeta Ursae Majoris (Mizar), Struve 1770, Struve 1795, Struve 1831 (Ursa Major); Struve 1616, Struve 1627, 17 Virginis, Struve 1648, Struve 1658, Struve 1677, Struve 1682, Struve 1689, Struve 1690, 44 Virginis, Struve 1719, Theta Virginis, 54 Virginis, Struve 1738, Struve 1740, Struve 1751, 81 Virginis, Struve 1764, Struve 1775, 84 Virginis, Struve 1788 (Virgo)
Notable carbon star for May: SS Virginis
One hundred and sixty-five deep-sky objects for May: NGC 5248 (Bootes); M3, M51, M63, M94, M106, NGC 4111, NGC 4138, NGC 4143, NGC 4151, NGC 4214, NGC 4217, NGC 4244, NGC 4346, NGC 4369, NGC 4449, NGC 4485, NGC 4490, NGC 4618, NGC 4631, NGC 4656, NGC 4868, NGC 5005, NGC 5033, NGC 5297, NGC 5353, NGC 5354, Up 1 (Canes Venatici); Mel 111, M53, M64, M85, M88, M91, M98, M99, M100, NGC 4064, NGC 4150, NGC 4203, NGC 4212, NGC 4251, NGC 4274, NGC 4278, NGC 4293, NGC 4298, NGC 4302, NGC 4314, NGC 4350, NGC 4414, NGC 4419, NGC 4448, NGC 4450, NGC 4459, NGC 4473, NGC 4474, NGC 4494, NGC 4559, NGC 4565, NGC 4651, NGC 4689, NGC 4710, NGC 4725, NGC 4874, NGC 5053 (Coma Berenices); NGC 4027, NGC 4038-9, NGC 4361 (Corvus); M68, M83, NGC 4105, NGC 4106, NGC 5061, NGC 5101, NGC 5135 (Hydra); M40, NGC 4036, NGC 4041, NGC 4051, NGC 4062, NGC 4085, NGC 4088, NGC 4096, NGC 4100, NGC 4144, NGC 4157, NGC 4605, NGC 5308, NGC 5322 (Ursa Major); M49, M58, M59, M60, M61, M84, M86, M87, M89, M90, M104, NGC 4030, NGC 4073, NGC 4168, NGC 4179, NGC 4206, NGC 4215, NGC 4216, NGC 4224, NGC 4235, NGC 4260, NGC 4261, NGC 4267, NGC 4281, NGC 4339, NGC 4343, NGC 4365, NGC 4371, NGC 4378, NGC 4380, NGC 4387, NGC 4388, NGC 4402, NGC 4429, NGC 4435, NGC 4438, NGC 4517, NGC 4526, NGC 4535, NGC 4536, NGC 4546, NGC 4550, NGC 4551, NGC 4567, NGC 4568, NGC 4570, NGC 4593, NGC 4596, NGC 4636, NGC 4638, NGC 4639, NGC 4643, NGC 4654, NGC 4666, NGC 4697, NGC 4698, NGC 4699, NGC 4753, NGC 4754, NGC 4760, NGC 4762, NGC 4866, NGC 4900, NGC 4958, NGC 5044, NGC 5054, NGC 5068, NGC 5077, NGC 5084, NGC 5087, NGC 5147, NGC 5170, NGC 5247, NGC 5363, NGC 5364 (Virgo)
Top ten deep-sky objects for May: M3, M51, M63, M64, M83, M87, M104, M106, NGC 4449, NGC 4565
Top ten deep-sky binocular objects for May: M3, M51, M63, M64, M84, M86, M87, M104, M106, Mel 111
Challenge deep-sky object for May: 3C 273 (Virgo)
The objects listed above are located between 12:00 and 14:00 hours of right ascension.