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Home , Mare Fecunditatis, Messier 49

APRIL from Hermanus 2021

1. SKY CHARTS

EVENING SKY 9 t h APRIL at 21h30 (NORTH DOWN)

EVENING SKY 9 t h APRIL at 21h30 (SOUTH DOWN)

1 PLEASE NOTE: All events predicted are as observed from Hermanus, Western Cape, South Africa. Times are South African Standard Time (UTC +2). Also please note : with the exception of Pluto (magnitude +14.4), all events predicted are visible with the naked eye.

2. THE SOLAR SYSTEM

HIGHLIGHTS FROM THE SKY GUIDE

Date Tim e It em 1 22H49 4.9º north of Antares 2 04h41 Moon at descending node 4 12h02 Last quarter Moon 04h08 Moon southernmost (-25.4º) 6 Moon near Saturn 7 Moon near Jupiter 11 Moon near Mercury 1 12 INTERNATIONAL DAY OF HUMAN SPACE FLIGHT (Y URI ’S NIGHT ) 04h31 New Moon Moon near Venus 14 19h48 Moon at apogee (406 119 Km) 16 Moon near Aldebaran 07h53 Moon at ascending node 18 18h02 Moon northernmost (+25.5º) 19 20h18 Moon south of Pollux (2.5º) 03H31 Mercury at superior conjunction 20 08h59 First quarter Moon 23h55 Moon south of the Beehive (M44) (3.2º) 22 Moon near Regulus 2 DAY 23 Venus near Uranus 25 Venus near Mercury 26 Moon near 27 05h31 Full Moon (357 620 Km, 33.4’) 17h25 Moo n at perigee (357 378 Km) 28 Pluto stationary 29 Moon near Antares 11h17 Moon at descending node 30 23h15 Uranus at conjunction

1 INTERNATIONAL DAY OF HUMAN SPACE FLIGHT (Y URI ’S NIGHT ) is the annual celebration, held on 12 th April, of the anniversary of the first human space flight by Yuri Gagarin. It was proclaimed at the 65th session of the United Nations General Assembly on 7th April, 2011, a few days before the 50th anniversary of the flight. https://www.skyatnightmagazine.com/space-missions/yuri- gagarin-first-human-in- space/?utm_source=adestra&utm_medium=email&utm_content=skan&utm_campaign=bbc%20sky%20 at%20night%20magazine%20april%202021%20newsletter_823153_sky%20at%20night_newsletters_17 987869&utm_source=adestra&utm_medium=email&utm_term=&utm_content=read%20the%20full%2 0story%20of%20gagarin%27s%20flight%20%3e&utm_campaign=bbc%20sky%20at%20night%20mag azine%20april%202021%20newsletter

2 EARTH DAY is an annual event celebrated around the world on April 22 to demonstrate support for environmental protection. First celebrated in 1970, it now includes events coordinated globally by the Earth Day Network in more than 193 countries.

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1st 1st APRIL 2021 Visibility April May Rises: 06h56 07h19 Pisces to Aries Never look at the sun Length of Transit: 12h47 12h40 without SUITABLE EYE PROTECTION! day 13:03 to 10:43 Sets: 18h38 18h01 Mercury Aquarius to Aries Rises: 05h34 08h29 Magnitude -0.5 to -1.1 Low in west after Phase 86% to 82% Transit: 11h49 13h34 sunset Diameter 5” to 6” Sets: 18h03 18h38 Venus Pisces to Aries Rises: 07h03 08h05 Too close to Sun Magnitude -3.9 to observe then Transit: 12h55 13h18 Phase 100% to 99% low in west after Diameter 10” Sets: 18h46 18h31 sunset Mars Taurus to Gemini Rises: 12h13 11h37 Magnitude +1.3 to +1.6 Phase 91% to 93% Transit: 17h04 16h26 Evening Diameter 5” Sets: 21h55 21h15 Jupiter Capricornus to Aquarius Rises: 03h04 013h31 Magnitude -2.1 to -2.2 Morning Diameter 32” to 37” Transit: 09h47 08h09 Sets: 16h29 14h46 Saturn Capricornus Rises: 02h07 00h17 Magnitude +0.8 to +0.7 Diameter 16” to 17” Transit: 09h00 07h09 Morning Sets: 15h53 14h00 Uranus Aries Rises: 09h07 07h18 In west after Magnitude +5.9 sunset then too Transit: 14h30 12h38 Diameter 3” close to Sun to Sets: 19h52 17h59 observe Neptune Aquarius Rises: 05h20 03h26 Magnitude +7.9 Low the east Transit: 11h33 09h39 Diameter 2” before sunrise Sets: 17h47 15h52 Pluto Sagittarius Rises: 00h53 22h52 Magnitude +14.4 to +14.3 Low in the east Transit: 08h00 06h02 before sunrise Sets: 15h06 13h09

Phase: In a telescope, the inner planets (Mercury, Venus and Mars) appear to us in phases, depending on the angle of the Sun’s illumination, as does the Moon. The is given in arc seconds (“). This is the apparent size of the object as we see it from Earth.

Magnitude : we are accustomed to hearing stars described in terms of ‘magnitude’. For example the planet Jupiter at magnitude -1.8 is considerably brighter than the star Antares (in Scorpius) at +1.05. The scale is ‘inverse’; the brighter the object, the lower the number . A ‘good’ human eye on a clear night can see down to a magnitude of about +6.

Transit: When an object crosses the local meridian it is said to ‘transit’ . The local meridian is an imaginary line from the horizon directly north passing overhead (through zenith, see charts on page 1) to the horizon directly south. .

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THE MOON

MARE FECUNDITATIS (The Sea of Fecundity)

Location : Close to the eastern limb bordering on . Description : The Fecunditatis basin formed in the Pre-Nectarian while the basin material surrounding the mare is of the subsequent Nectarian epoch. ( https://en.wikipedia.org/wiki/Lunar_geologic_timescale ) The mare material is of the Upper Imbrian epoch and is relatively thin compared to the neighbouring or Mare Tranquillitatis. This basin is overlapped with the Nectaris, Tranquillitatis, and Crisium basins. Fecunditatis basin meets Nectaris basin along Fecunditatis' western edge, with the area along this zone faulted by arcuated grabens. On the eastern edge of Fecunditatis is the crater . Near the centre lie the interesting craters and Messier A . It was here that the first automated sample return took place via the probe, in September 1970. Sinus Successus lies along the eastern edge of the mare. Mascons were identified in the centre of maria (such as

Serenitatis or Imbrium) from Doppler tracking of the five Lunar Orbiter spacecraft in 1968. Unlike other maria, there is no mass concentration (mascon), or gravitational high, in the centre of Mare Fecunditatis. The gravity field was mapped at higher resolution with later orbiters such as and GRAIL, which unveiled an irregular pattern. ( https://en.wikipedia.org/wiki/Mare_Fecunditatis )

Best Seen : 5 days after New Moon (17 April)

Lunar and Solar eclipses : none visible from southern Africa.

velo- hourly shower name date of maximum moon phase duration radiant city rate Km/s Waning 6th April 11 th March to Pavo , δ Pavonids cresc. moon 5 59 02h00 to 04h30 16 th April close to s. horizon 29% Waxing 10º south-west of 22nd April 16th to 25th April Lyrids * gibbous moon Vega (α Lyr) 15 49 02h00 to 05h00 April 70% close to n. horizon

Waxing 23rd April 15th to 28th 1.7º south of π Puppids gibbous moon <5 18 19h00 to 23h00 April σ Pup 80%

* poor prospects: the radiant position is very low on northern horizon (max altitude 4.5º). For more details regarding meteor watching, please see the 2021 Sky Guide Africa South, pages 86- 87.

4 1. LOOKING UP

SUGGESTED OBSERVATION SCHEDULE for APRIL (Lunar observations notwithstanding)

Date dusk end 3rd 19h58 moonrise 23h11 (61%) 15th 19h43 moonset 20h21 (8%)

CLUB STARGAZING – sorry, still no organised physical club gatherings. However, we do encourage our members to dust off telescopes, binos, cameras and eyes and observe from home or your favourite darkest, rural, cloudless spots.

Please consult our website for updates: http://www.hermanusastronomy.co.za

DEEP SKY HIGHLIGHTS

M49 NGC 4472

Description Elliptical Visibility on 9th April Constellation Rise Transit Set Distance 54 Mly, 17 Mpc 18h20 00h05 05h45 Magnitude +8.37 Absolute mag -22.73 Naked Eye No Apparent size 10.2 x 8.4 arcmin Binoculars Yes Actual size 161.2 Kly, 49.4 Kpc Telescope Yes Altitude/Azimuth +34º 40’ 12” / 47º 30’ 9” J2000 coordinates +8º 00’ 00” / 12h 29m 48s Discovery M49 was the first member of the to be discovered by who catalogued it in February 1771. It is also the second galaxy discovered beyond the local group after Lacaille’s discovery of M83. In 1779, Barnabas Oriani independently rediscovered M49. Admiral William Smyth, confusing this finding with Messier’s, erroneously stated, “This object was discovered by Oriani in 1771.” This error was repeated by John Herschel in his General Catalogue of 1864 and so found its way into J. L. E. Dreyer’s NGC. [so even the greats have their senior moments ! – ed]

5 ... M49 Description Along with M60 and M87, M49 is one of the giant elliptical in the Virgo B subcluster. It lies 4.5° away from the dynamic centre of the Virgo Cluster. Possessing a very clear circular 9’ x 7.5’ halo, it contains a bright 3.5’ nucleus. A 12 th magnitude star is superimposed upon the halo near the core’s eastern edge. At a distance of about 60 million light-years, M 49’s apparent size corresponds to a projected major axis of 160,000 light years.. M 49 is moving away from us at about 920 Kms/second and is of type E4 in Hubble's classification scheme. Early estimates suggested that M49 might be more massive than the nearby giant M87. It is now assumed that M87 has a higher star density and is in fact more massive than M49. Longer photographic exposures show a system of about 6 300 globular clusters around M49, much less crowded than that of M87. Though far more than the roughly 200 clusters orbiting the , it is dwarfed by the 13 450 orbiting the supergiant . As an elliptical galaxy, Messier 49 has the physical form of a but it only has the radio emission of a normal galaxy. Its nucleus is emitting X-rays, suggesting the likely presence of a with an estimated mass of 5.65 × 10 8 solar masses, or 565 million times the mass of the Sun. X-ray emissions show a structure to the north of Messier 49 that resembles a . To the southwest of the core, the luminous outline of the galaxy can be traced out to a distance of 260 Kpc. A 13th magnitude , SN 1969Q, was reported in M 49 in June, 1969. On average, the globular clusters of M49 are about ten billion years old. Between 2000 and 2009, strong evidence for a stellar mass black hole was discovered in one. A second candidate was announced in 2011.

Please keep in touch...

Have a look at our excellent website, edited by Derek Duckitt. http://www.hermanusastronomy.co.za/

Also...

6 ASSA website http://assa.saao.ac.za ASSA Deep-Sky Section Whatsappchat group: [ 074 100 7237 ] MNASSAhttp://assa.saao.ac.za/about/publications/mnassa/ Nightfall https://assa.saao.ac.za/?s=Nightfall Official Big 5 of the African Sky web page Official Big 5 Facebook group ASSA Deep-Sky Section mailing list

Contact ASSA Get in touch with officers of the Society - we're real people with a passion for astronomy, so contact us and let's talk ! You can find us on Facebook , Twitter , the ASSAInfo mailing list and the ASSADiscussion mailing list .

Grateful thanks to the following:

ASSA Sky Guide Africa South 2020 Sky Safari Stellarium Telescopius https://telescopius.com/

Edited by Peter Harvey e-mail: [email protected] Tel: 081 212 9481

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