October Observing Guide

Hi all,

Here is October's observing guide. Enjoy.

OBSERVING GUIDE
(Please note all times are DST unless otherwise stated and are based on an observing location of Belfast and covers the month of October)

The Sun

At the start of the month, the Sun rises at 07:30 and sets at 19:00. By the end of the month, it rises at 07:25 UT and sets at 16:50 UT.

The Planets

Mercury, Saturn and Venus perform a celestial dance in the morning sky in the first half of the month. On the morning of the 1st, the three planets line up with Regulus (Alpha Leonis mag+1.3). On the morning of the 8th, Mercury lies a third of a degree from Saturn with Venus to the West. On the morning of the 13th, Venus passes half a degree to the South of Saturn with Mercury to the East. On the morning of the 16th, the three planets are joined by a 5% illuminated waning crescent moon. On the morning of the 17th, the moon has waned further to a 1% illuminated crescent.

Mercury is a morning object during October and is best placed for observation at the start of the month when it is at greatest western elongation on the 6th. It is visible until around the 23rd of the month, after that it is too close to the sun to safely observe. At the start of the month, it rises at 05:50 and is mag +0.3; by the 6th it rises at a similar time but has brightened to mag -0.6. After the 6th, it then moves back towards the Sun, brightening as it does. By mid-month, it is mag -1.0.

Venus is a morning object during October. At the start of the month, it rises at 04:55, by month’s end it rises at 05:35 UT. It maintains its brightness at mag -3.9 during the month.

Mars is a late evening object during October. At the start of the month, it rises at 23:50, by the end of the month; it rises at 22:15 UT. It brightens during the month from mag +0.8 to mag +0.4. It moves from Gemini into Cancer during the month and lies near to M44 – The Beehive Cluster by month’s end.

Jupiter can be found in Capricornus during October. It is well placed for observation during this period, although by month’s end it sets before midnight. At the start of the month, it rises during daylight hours and sets at 02:30, by month’s end it sets at 23:30 UT. It fades during the month from mag -2.7 to mag -2.5. The four Galilean moons – Io, Europa, Ganymede and Callisto are visible with 10x50 binoculars or a small telescope and are worth a look. A list of eclipses, occultations and transits for the four moons can be found at the end of the guide.

Saturn is a morning object during October in Virgo and at the start of the month, rises over an hour before the sun at 06:15. By month’s end, it rises at 03:35 UT and brightens during the month from mag +1.1 to mag +1.0.

Uranus can be found in Pisces during October. It is well placed for observation during this period. At the start of the month, it rises during daylight hours and sets at 06:10. By the end of the month, it sets at 03:10 UT. It fades during the month from mag +5.7 to mag +5.8. It lies to the South of Lambda Piscium (mag +4.5) – one of the stars of the Circlet Asterism and to the West of 20 Piscium (mag +5.5).


Neptune can be found in Capricornus during October. It is well placed for observation during this period. At the start of the month, it rises during daylight hours and sets at 03:15 and by the end of the month, it sets at 00:15 UT. It maintains its brightness at mag +7.9 during the month. It lies to the North of Delta Capricorni (mag +2.9) and Gamma Capricorni (mag +3.7).

The Moon

In October, the full moon is on the 4th with the last quarter moon on the 11th and the new moon on the 18th. The first quarter moon is on the 26th. The full moon this month is the Harvest Moon as it is the closest full moon to the just past autumn equinox.

On the evening of the 2nd/morning of the 3rd, a 98% illuminated waxing gibbous moon lies to the North of Uranus.

On the evening of the 7th/morning of the 8th, a 85% illuminated waning gibbous moon lies close to M45 - The Pleiades.

On the evening of the 8th/morning of the 9th, a 76% illuminated waning gibbous moon lies close to NGC 1746.

On the 9th, the NASA LCROSS mission will slam two spacecraft into the moon’s South-pole. Unfortunately, it is timed to suit American astronomers and occurs at 12:30 +/- 30 minutes. The resulting plume is predicted to be mag +6 and makes for a hard observation from the UK. If you want to get further details on this, the link to the LCROSS site is below in the Links Section.

On the evening of the 9th/morning of the 10th, a 66% illuminated waning gibbous moon lies close to M35.

On the morning of the 12th, a 43% illuminated waning crescent moon lies close to Mars.

On the evening of the 27th, a 66% illuminated waxing gibbous moon lies close to Neptune to the North of the planet with Jupiter to the West.

Meteors

The ZHR or Zenithal Hourly Rate is the number of meteors an observer would see in one hour under a clear, dark sky with a limiting apparent magnitude of 6.5 and if the radiant of the shower were in the zenith. The rate that can effectively be seen is nearly always lower and decreases as the radiant is closer to the horizon. The Zenith is the overhead point in the sky for an observer. The radiant is the point in the sky, from which (to a planetary observer) meteors appear to originate, i.e. the Perseids, for example, are meteors which appear to come from a point within the constellation of Perseus. A fireball is defined by the International Astronomical Union as a meteor brighter than any of the planets, i.e. magnitude -4 or brighter. The International Meteor Organisation alternatively defines it as a meteor which would have a magnitude of -3 or brighter at the zenith.

There are six showers in October, five of which are minor in nature. The first one is the Delta Aurigids which have an ill-defined peak and may be visible for the first three or four days of the month. The ZHR is 3 with the radiant visible from about 23:00. There is lunar interference with a strong waxing gibbous moon in Pisces/Aquarius at the start of the month.

The second shower is the Draconids. They peak on the 8th with a variable ZHR and are typically very slow moving meteors. The radiant is circumpolar and visible all night, however the shower is badly hindered by a 77% illuminated waning gibbous moon rising in Taurus at 20:05 on the evening of the 8th.

The third shower is the Piscids which peak on the 13th with a ZHR of 10. The radiant is visible as soon as darkness falls. Lunar conditions are favourable with a 21% illuminated waning crescent moon rising at 02:50 on the morning of the 14th.

The fourth shower is the Epsilon Geminids. They peak on the 18th with a ZHR of 2. Lunar conditions are perfect with the shower falling on the new moon. The radiant is visible from about midnight.

The fifth shower of the month and the only major one is the Orionids. They peak on the 20th with a ZHR of 25. The shower is noted for fast meteors with persistent trains and the radiant is visible from about midnight. It is also noted for lesser peaks, so it is a good idea to observe the shower a day or so either side of the predicted peak. It has no problems with lunar interference as the moon is only a couple of days old.

The final shower of the month is the Leo Minorids. It peaks on the 23rd with a ZHR of 2. The radiant is visible from about 01:00 and there is no lunar interference with the moon already set.

Asteroids

Asteroid (18) Melpomene is at opposition on the 9th in Cetus with a magnitude of +7.9. At opposition it lies less than two degrees to the South of Theta Ceti (mag +3.6).

Comets

Comet 2006 W3 Christensen moves from Aquila into Scutum during October. The comet is heading South and this is the last full month it will be visible at our latitudes until next spring when it reappears low in the morning sky. It remains around mag +9 for the month and sets at about midnight at the start of the month and at about 21:00 UT by month’s end.

Comet 22P/Kopff is in Aquarius during October and is around mag +10 and fading slowly. It sets at about 03:00 at the start of the month and at about midnight by month’s end. Use Delta and Tau Aquarii (mag +3.3 and +4.0) as a guide to find the comet as it lies to the West of these two stars, forming a “triangle” with them.

Comet 217P/2009 F3 Linear moves from Orion into Monoceros in a Easterly direction. It is around mag +10 and fading slowly. It is visible from about 02:00 at the start of the month. By month’s end, it is visible from about midnight UT.

Deep Sky

On the deep sky front this month, galaxies M81 and M82 can be observed in Ursa Major. In Lyra – M57 – The Ring Nebula can be observed and in Vulpecula – M27 – The Dumbbell Nebula can be found. In Andromeda, M31 – The Andromeda galaxy can be observed along with its satellite galaxies M32 and M110. In Perseus, there is the open cluster M34 and the excellent Double Cluster – NGC 869 and 884. In Triangulum, there is the galaxy M33. Auriga reappears with its three open clusters M36, M37 and M38 as does Taurus with the excellent Pleiades – M45 and the Hyades. Orion returns to our skies with M42 – The Great Orion Nebula along with Gemini with the open cluster M35.

General Notes

Always keep an eye out for Aurorae. On the morning of the 25th at 1am, the clocks go back one hour and daylight saving time ends.

Other interesting naked eye phenomena to look out for include the Zodiacal Light and the Gegenschein. Both are caused by sunlight reflecting off dust particles which are present in the solar system. The Zodiacal Light can be seen in the West after evening twilight has disappeared or in the East before the morning twilight. The best time of year to see the phenomenon is late-Feb to early-April in the evening sky and September/October in the morning sky - it's then that the ecliptic, along which the cone of the zodiacal light lies, is steepest in our skies. The Gegenschein can be seen in the area of the sky opposite the sun. To view either, you must get yourself to a very dark site to cut out the light pollution. When trying to observe either of these phenomena, it is best to do so when the moon is below the horizon. If you are observing them when the moon has risen, restrict your efforts to the period 4 days either side of the new moon as otherwise the moonlight will be sufficient to drown them out.

Clear Skies

Neill McKeown

Information Sources Used and Links

www.skyviewcafe.com - Used for the Sun and Planets section. Also partly used for the Moon Section

Sky at Night Magazine Observing Guide and CD

www.aerith.net and cometchasing.skyhound.com – Used for the Comet Section for information and finder charts

www.ast.cam.ac.uk/%7Ejds/ - BAA and SPA Comet page

kometen.fg-vds.de/fgk_hpe.htm - German Comet page

www.rasnz.org.nz – Royal Astronomical Society of New Zealand

lcross.arc.nasa.gov/observation.htm - LCROSS Website

BAA Handbook

Stardust Magazine

Sky Guide 2009 – South Dublin Astronomical Society

www.heavens-above.com – For the latest ISS passes, Iridium Flares and Shuttle launches

www.irishastronomy.org – Irish Federation of Astronomy Societies Website

www.stronge.org.uk – Excellent weather site including Space Weather

irishastro.org.uk – Irish Astronomical Association website

www.eaas.co.uk – Northern Ireland Amateur Astronomy Society




Galilean Moons – Eclipses, Occultations and Transits – October 09

01-October-09 22:09 Ganymede's shadow exits off Jupiter's disc
01-October-09 22:49 Ganymede begins to cross Jupiter's disc
04-October-09 23:44 Io is eclipsed by Jupiter's shadow
05-October-09 21:01 Io's shadow begins to cross Jupiter's disc
05-October-09 22:07 Io begins to cross Jupiter's disc
05-October-09 23:18 Io's shadow exits off Jupiter's disc
06-October-09 20:55 Callisto reappears from behind Jupiter's disc
06-October-09 21:12 Europa is eclipsed by Jupiter's shadow
06-October-09 21:35 Io reappears from behind Jupiter's disc
07-October-09 18:53 Io exits off Jupiter's disc
08-October-09 20:44 Europa exits off Jupiter's disc
08-October-09 22:11 Ganymede's shadow begins to cross Jupiter's disc
12-October-09 20:21 Ganymede reappears from behind Jupiter's disc
12-October-09 22:51 Io's shadow begins to cross Jupiter's disc
13-October-09 20:01 Io is eclipsed by Jupiter's shadow
13-October-09 23:31 Io reappears from behind Jupiter's disc
14-October-09 18:32 Io begins to cross Jupiter's disc
14-October-09 19:37 Io's shadow exits off Jupiter's disc
14-October-09 20:49 Io exits off Jupiter's disc
15-October-09 18:05 Europa's shadow begins to cross Jupiter's disc
15-October-09 20:29 Europa begins to cross Jupiter's disc
15-October-09 20:55 Europa's shadow exits off Jupiter's disc
17-October-09 18:23 Europa reappears from behind Jupiter's disc
19-October-09 19:19 Ganymede's eclipse ends
19-October-09 20:46 Ganymede disappears behind Jupiter's disc
20-October-09 21:53 Io is eclipsed by Jupiter's shadow
21-October-09 19:12 Io's shadow begins to cross Jupiter's disc
21-October-09 20:28 Io begins to cross Jupiter's disc
21-October-09 21:29 Io's shadow exits off Jupiter's disc
21-October-09 22:45 Io exits off Jupiter's disc
22-October-09 19:55 Io reappears from behind Jupiter's disc
22-October-09 20:34 Europa's shadow begins to cross Jupiter's disc
22-October-09 22:24 Callisto is eclipsed by Jupiter's shadow
24-October-09 21:01 Europa reappears from behind Jupiter's disc
26-October-09 19:30 Ganymede is eclipsed by Jupiter's shadow
28-October-09 21:05 Io's shadow begins to cross Jupiter's disc
28-October-09 22:24 Io begins to cross Jupiter's disc
29-October-09 18:14 Io is eclipsed by Jupiter's shadow
29-October-09 21:50 Io reappears from behind Jupiter's disc
30-October-09 18:31 Ganymede exits off Jupiter's disc
30-October-09 19:09 Io exits off Jupiter's disc
31-October-09 18:03 Europa is eclipsed by Jupiter's shadow
31-October-09 18:40 Ganymede begins to cross Jupiter's disc

Thanks Niell!
October already....YAY!
:laugh: