Category Archives: Observing List

Posts describing the sky including lists of target objects.

Cygnus-Sadr Region – 2016-09-26

Friends of mine had a star registered with the name “MadVic” as a gift for their 60th wedding anniversary. So i decided to followup with an image of the region that showed the actual star.

Cygnus-Sadr Region - 2016-09-26

Cygnus-Sadr Region – 2016-09-26

The region around the centre of Cygnus is known as the “Gamma Cygni Nebula” (IC 1318); named after the bright star Gamma Cygni – Sadr. The nebula is a  large region filled with ionized hydrogen which shows up as the red background glow in the long exposure image above. The image is just a small section of the nebula. The bright stars also overwhelm the fainter background. The star Sadr in the lower right is particularly bright and it’s glow obscures the hydrogen cloud behind it.

Visually the region looks more like the image below. The star “MadVic” is marked with the green bars.

Cygnus-Sadr Region as it would look visual

Cygnus-Sadr Region as it would look visual

The star name was registered with the “International Star Registry” (ISR) as “MadVic”. While naming a star with the ISR isn’t quite the same thing as having the star name officially recognized by the “International Astronomical Union” (IAU), it is still fun.

ISR MadVic corresponds with official star catalog designations GSC 3160:00031 (Hubble Guide Star Catalog – GSC V1.2) and also USNO J2021000+412939 (the United States Naval Observatory – USNO-B1) . It is a magnitude 12.75 star in the constellation Cygnus at coordinates 20h 20m 59.95s D 41° 29′ 39.27″ (J2000). That’s about 1deg NW of the bright star Sadr at the centre of the cross in Cygnus.

The Constellation Cygnus

The Constellation Cygnus

While binoculars are great for finding constellations and large star clusters, MadVic is too faint to be seen even with binoculars. You can get a pretty good idea of where it is in the sky though.

MadVic Location in a 7x50 Binocular FoV

MadVic Location in a 7×50 Binocular FoV

A magnitude 12.75 star is just at the visual limit of a 4″ refractor even from a dark site.  The image below shows the view using a 4″ refractor with an 8mm eyepiece which translates to a magnification of 86x. The line of three stars just below “MadVic” will show up nicely and provide a guide to locating MadVic.

MadViv View using a 4" refractor and 8mm Eyepeice

MadViv View using a 4″ Refractor and 8mm Eyepeice

An 11′ scope would be better and then the star could be seen even from a moderately dark location. With a 8mm EP, the three “locator” stars are still in the field of view but much more obvious. MadVic is also easily identified as the corner star of a right angle triangle formed by three stars of similar magnitude.

MadVic using an 11" SCT and 8mm EyePiece

MadVic using an 11″ SCT and 8mm EyePiece

From a site with a limiting magnitude a little under 5, the 11″ SCT with 8mm eyepiece showed more or less the same stars indicated in the finder image above. The magnitude 12 stars were very faint though and at the limit of being visible. A darker site would make finding MadVic much easier.

MadVic sketch from the Eyepeice (redrawn to scale and flipped)

MadVic sketch from the Eyepiece (redrawn to scale and flipped)

The next two images show the precise location of MadVic. (Sorry, no fancy mouse overs.) Click on the next image to get the full sized version and then zoom in to see MadVic as photographed. The image at the bottom is a diagram highlighting the main objects in the camera field.

MadVic Locator in Image

MadVic Locator in Image

Cygnus-Sadr 2016-09-26 Annotations

Cygnus-Sadr 2016-09-26 Annotations

 

Vallis Alpes Comparison – 2013-04-21

I recently came across an image of Vallis Alpes on the moon (Alpine Valley) created by the Lunar Orbiter 4 space craft in 1967. It struck me as amusing that my own image taken in April of 2013 compares favourably with the Obiter’s image.

Moon - Vallis Alpes Comparison 2013-04-21

Moon – Vallis Alpes Comparison 2013-04-21

The Orbiter’s altitude varied from 2,100km to 6,000km so I nominally choose 5,000km as the distance of the Orbiter’s image. The mission cost in 1967 was $163m US. In today’s dollars (2015) that works out to about $1,2 billion.

My equipment is a little less expensive and i was about 371,000 km way when i took the image.

To be fair, there is a lot more detail in the orbiters image. For example, the rille (trench) running down the middle of the valley is between 700 and 1,200m across. This detail can just be seen on my image, while it’s quite clear on the Orbiter’s image and even shows the details of some small craters that impacted after the rill was formed.

My image of Vallis Alpes is a close crop to a much a larger image of the area including the crater Plato and the top mare Imbrium.

Moon Plato and Vallis Alpes 11.74days 2013-04-21 v1

Moon Plato and Vallis Alpes 11.74days 2013-04-21 v1

 

Finding the Andromeda Galaxy – 2015-11-05

M31_Andromeda_Galaxy_2010-11-08_v3_SJM
As night sky objects go, i think the Andromeda Galaxy has the most engaging story. And it’s a relatively modern story considering the ancient folklore associated with the constellations and the heavens in general.

In 1920 there was a raging disagreement among astronomers and scientist in general about the size of  universe. The generally accepted view at the time was that our Milky Way galaxy was somewhere between 7,000ly and 30,000 light years in diameter. And the Milky Way was the entire extent of the universe. The fuzzy dense objects visible in telescopes (that we now know are distant galaxies) were described as nebula – “a cloud of gas and dust in outer space, visible in the night sky either as an indistinct bright patch”. And these nebula were thought to be part of the Milky Way.

To jump forward a bit, the Milky Way is currently estimated to be between 100,000ly and 180,000ly in diameter and about 2,000ly thick. The “observable universe” is thought to be somewhere around 93 billion light years across.

The discussions about the size of the universe culminated in what has become to be known as “the great debate” between Harlow Shapley and Heber Curtis. Shapley argued that the Milky Way was the entire extent of the universe and that nebula such as Andromeda were contained within the Milky Way. Although he maintained that the main part of the Milky Way could not be more that 30,000ly across, he did propose that nebula such as Andromeda and globular clusters could form at the distant edges making the diameter 300,000ly. Therefore also fixing the upper size of the universe at 300,000ly. Curtis argued that the Andromeda nebula was in fact at a great distance and an “island universe” (a term coined by Immanual Kant). He accepted the thinking of the day that the Milky Way was no more than 30,000 ly in diameter but proposed that the Andromeda nebula was 500,000ly away and other such nebula as far as 100mly. (Current estimates put Andromeda at 2.5 million light years.)

Well before the debate reached this pinnacle, Henrietta Leavitt, a deaf astronomer working at the Harvard College Observatory, discovered a relationship between the absolute luminosity of a particular type of variable star and its period. In short, she found a way to measure, with certainty, stellar distances using the period of Cepheid Variables.

A variable star changes brightness over a predictable time frame – the period. In 1908, Leavitt noticed a relationship between Cepheid Variable periods and their absolute luminosity and published the results of her initial observations. Then in 1912 after analyzing more stars, she confirmed her observations. Essentially, she found that the actual or absolute brightness of a Cepheid Variable can be calculated from its period. And knowing the absolute brightness, its apparent brightness can be used as a measure of its distance – the further away it is, the dimmer it will appear.

As a side note, Shapley took over as director of the Harvard observatory in 1921 and promoted Leavitt to head of Stellar Photometry.

In 1919, the 100″ Hooker telescope – the largest telescope at the time – was installed on Mt Washington. At about the same time, Edwin Hubble started working at the observatory. Between 1922 and 1923, Hubble used the Hooker telescope to photograph the Andromeda “nebula” and was able to identify Cepheid variables. Aware of Leavitt’s observations, he was then able to calculate the distance to Andromeda. His initial estimate put it at 930,000ly – not quite the actual 2.5mly – but sufficient to declare that the Andromeda Nebula was indeed a separate galaxy. Shapley was still unconvinced as were many of the astronomers of the day. But by 1925 it was clear that the results were inescapable and the universe got a whole lot bigger.

Hubble went on to measure the distances to a number of other “nebula”; confirming that they too were separate galaxies. Then in 1929 Hubble published another ground breaking result – the universe was expanding! He discovered that the further a galaxy was away, the faster it was receding from us. (He used redshift to calculate relative velocity.) And if the universe was expanding, they it must have been smaller in the past. In 1931 Georges Lemaître, a Belgian cosmologist and Catholic priest proposed that the universe must have started out as a single point – later to be coined the Big Bang. As early as 1922, Alexander Friedmann had produced a solution to Einstein’s General Relativity field equations that showed space must be expanding.

So as late as 1920, the universe and the size of the Milky Way were thought to be in the range of 7,000 to 30,000 ly across. Then with a series of observations from 1908 (Leavitt) to 1924 (Hubble) the size of universe expanded to millions and billions of lights years.

The background is interesting, but what makes it even more engaging is that the Andromeda Galaxy can actually be seen unaided! At a distance of 2.5 millions light-years, it’s the furthest object that can be seen without a telescope or binoculars and only requires a moderately dark sky to see it.

By November it’s high in the sky facing south in the evening and appears as a faint, but distinct oval smudge. The darker the skies, the more obvious it is.

November_2013_AllSky_Chart

The chart below provides some tips on how to find it. Pegasus is due south in the November evening sky and is the large square (or diamond) shape as wide as your hand is stretched from thumb to baby finger. The Andromeda constellation is the “v” shaped arrangement of stars to the east and they share the star Alpheratz. Step 1: Start with Alpheratz in the upper left corner of Pegasus. Count three stars down to the left to Mirach (with Alpheratz being star No 1). Step 2: Then count three stars up (Mirach as No 1). The second set of 3 stars are faint so may not be obvious at first. Step 3: M31 will be 4° to the right of the 3rd star (about 2 finger widths) and elongated as shown.

finder_m31_star_hopping

Vega and the Constellation Lyra – 2015-10-30

The bright star Vega at magnitude 0.03 is the 5th brightest star in the sky and the third brightest star visible from the 45th parallel (Ottawa). Sirius at magnitude -1.46 is the brightest star in the sky and Arcturus magnitude -0.05 is the second brightest in the north. Although the yellow-orange star Arcturus is only marginally brighter than Vega, Vega has the advantage of being near the zenith on summer nights and the slight blue tint makes it seem even brighter.

Vega Closeup - 2015-10-30

Vega Closeup – 2015-10-30

Vega is in the constellation Lyra – the lyre or harp. Lyra is one of 48 constellations listed by Ptolemy in the second century and is on the International Astronomical Union’s (IAU) official list of 88 constellations. The long exposure image below shows the 4 bright stars of the harp as well as Epsilon Lyra (ε1, ε2 – the Double Double) left of Vega and Kappa Lyra (κ) to the right.

Vega in the Constellation Lyra - 2015-10-30

Vega in the Constellation Lyra – 2015-10-30

The chart overlay below  shows the location of the bright stars as well as the location of the M57 Ring Nebula. Vega is 25ly from earth while the other stars are at various distances. So the lyre shape is just a chance alignment when viewed from earth.

  • Vega: mag 0.03, dist 25ly
  • Epsilon 1: mag 4.65, dist 162 ly
  • Epsilon 2: mag 4.56, dist 161ly
  • Kappa: mag 4.31, dist 238ly
  • Zeta: mag 4.31, dist 154ly
  • Delta: mag 4.21, 906ly
  • Sheliak: mag 3.50, 882ly
  • Sulafat: mag 3.25, 640ly
Lyra Constellation Stick Figure

Lyra Constellation Stick Figure

The next image is modified to reduce the fainter stars and is more representative of what the sky might look like from a dark site. With this image, the bright stars of the constellation Lyra are more obvious.

Vega in the constellation Lyra - Less Stars -2015-10-30

Vega in the constellation Lyra – Less Stars -2015-10-30

While we think of constellations as the stick figure above or the elaborate drawings of mythical figures, the IAU defines a constellation as a non-overlapping region. So Lyra extends a little past the obvious 7 bright stars and defines a region in the sky between Cygnus to the east and Hercules to the west.

Lyra Constellation Boundaries

Lyra Constellation Boundaries

Lyra is home to a few interesting night sky objects:

Within the “stick figure” there are:

  • Epsilon – the double double
  • Messier 57 – The Ring Nebula
  • Zeta, Delta and Sulafat are doubles

Within the boundaries there are also:

  • M56 – an 8.3 magnitude globular cluster with an apparent size of 5arc-minutes
  • NGC 6791 – an 9th magnitude open cluster spanning 19′

The pair of stars Epsilon Lyra 1 and 2 (ε1, ε2)  are gravitationally bound to each other – meaning they are in the same region and rotate around each other (although in thousands of years). Each of ε1, ε2 is also a pair of stars that can be seen as doubles though a medium to large telescope. ε1, ε2 have a separation of 3.5′ which can be seen in binoculars. The doubles of ε1, ε2 each have separations of 1.3″ and 2.3″ making them challenging doubles to split in a 4″ scope. However, the two pairs are oriented 90° with respect to each other making it easy to compare the star shapes and aiding in detecting the separation. The periods of each pair are in the range of 600 to 1200 years. The finder chart below helps when trying to “split” the doubles.Finder_Chart_Epsilon-Lyra

The image below of the double-double doesn’t quite manage to show a gap between the close pairs. This is what might be typically seen in a smaller scope or a night of poor seeing. Still, by noticing that each pair is actually oval shape, the direction at least of the doubles gives a clue that they are doubles.

DoubleDouble_Epsilon_Lyra_2008-06-10_v1_SJM

Messier 57 (NGC6720) – the Ring Nebula is a large bright planetary nebula. Its visual magnitude is 9.5 and 3 arc-min across. On good nights and a large telescope, the remnants of the central star that exploded is visible. The ring is the expanding cloud of hot gas thrown off when the star shed its outer shell. The image below easily captures this detail as well as the colour which is not discernible through the eyepiece.

M57 - Ring_Nebula - 2011-07-30 - v2

M57 – Ring_Nebula – 2011-07-30 – v2

Vega rises during the late evening in April. It will be low in the north-east at about 9:30pm edt mid-April and makes its way across the sky during the night. By midnight it’s still in the north-east and only 25° above the horizon. It doesn’t transit (crosses due south) until 6am though!

Of course, if one is willing go out at much later times, Vega is also visible in the winter but after midnight. I tend think in terms of what objects are visible during normal evening hours.

Lyra Finder Chart - Sky facing East on 2015-04-15 at 21:30hrs EDT

Lyra Finder Chart – Sky facing East on 2015-04-15 at 21:30hrs EDT

Each month Vega rises two hours earlier. Which means it transits two hours earlier each month. By late summer at 9:30pm edt, Vega is due south and high in the sky near the zenith. The chart below shows Vega and Lyra high in the sky due south nestled between Pegasus and Hercules.

Lyra Finder Chart - Sky facing South on 2015-09-01 at 21-30hrs EDT

Lyra Finder Chart – Sky facing South on 2015-09-01 at 21-30hrs EDT

By December, Vega is low in the west in the evening and soon will disappear altogether from the evening sky.

Lyra Finder Chart - Sky facing East on 2015-04-15 at 21:30hrs EDT

Lyra Finder Chart – Sky facing East on 2015-04-15 at 21:30hrs EDTj

But … as said earlier, if one wanted to go out at other times, Vega can still be seen during winter. Starting in December, Vega is also visible in the early morning sky! The chart below shows Vega rising at 6:30 am (when it’s still dark in Ottawa) the day after it set in the west on the evening before.

Lyra Finder Chart - Sky facing East on 2015-12-16 at 06-30hrs EST

Lyra Finder Chart – Sky facing East on 2015-12-16 at 06-30hrs EST

Each month Vega will rise 2hrs earlier. So in January it rises at 4:30am and in February it rises at 2:30. By April it will be rising at 9:30 again.

So Vega is actual visible all year long, but to see it might mean going outside to look for it while sleeping is a better alternative.

 

 

 

 

 

The Sky for January 2014

For those attuned to western numerology, they are finally out the year xx13. In Asian cultures 4 is considered unlucky, so perhaps xxx4 will not be a good year for some people.

Winter is upon us in Northern America and aside for short walks for the dog, venturing outside in -25c temperatures in the dark is only done as a necessity and not for the pleasure of viewing the winter sky. However, the winter sky in North America does offer some spectacularly sites.

January Sky 2013

January Sky 2013

Winter Hexagon

Winter Hexagon

 

Orion, one of the most recognizable constellations, is front and centre in January. Surrounding Orion is the “Winter Six” – 6 of the brightest stars in the northern hemisphere arrange in a hexagon. At 9pm mid-month, Orion is about south-east. The winter six – Sirius (m -1.6), Procyon (m 0.4), Pollux (m 1.2), Capella (m 0.1), Aldebaran (m 0.8) and Rigel (m 0.2) surround Orion.

Orion The Hunter is home to a number of interesting and very accessible night sky objects. The Orion Nebula (M42) is a very bright and large HA emission nebula surrounding the middle star or Orion’s sword.
Unadied, the middle star of the sword appears a bit fuzzy. With binoculars, its apparent that the “star” is actually several stars surrounding by a grey cloud. With a 4″ refractor, the “cloud” starts to take shape as a distinct luminous region. Careful oberservers will also note that the “star” at the centre of the nebula is actually a multiple star. Visually it appears as a group of 4 stars known as the “trapezium”. Even Galileo observed this multiple star system and even noted the 5th and 6th memmbers of this complex multiple star system.

Comet ISON Officially Gone – 2013-12-03

Comet ISON (c2012 s1) encountered a solar flare while traveling around the sun and faded quickly. It was thought to have disintegrated, but a short time later it reappeared on one of NASA’s solar observatories. So for a little while there was a faint hope (pun intended) that it had survived. However, as of Dec 3rd, NASA has declared that the comet has broken apart. There is still a dense “debris pile” traveling along the comet’s path and this may still be visible in large telescopes. But this isn’t a comet anymore and won’t have a coma or a tail.

Comet ISON is known as a “sun grazer” – meaning it passes very close to the sun. On Nov 27/28th ISON passed through perihelion (point of closest approach of a body to the sun) with a orbital radius of 1,860,000 km. A million or so kilometers might seem like a lot, but when you consider the sun is 1,391,000 km in diameter (695,500km radius), 1.8m km starts to look really close. At closest approach then, ISON was only 1,165,000km from the surface of the sun.

For comparison, Mercury’s orbital radius of 58m KM and Venus’ orbit is 108m km. The Earth is on average 150m km from the sun.

Comet ISON Fading Fast – 2013-12-01

NASA’s solar observatories have been tracking comet c2012 S1 (ISON) as it rounded the sun. On Nov 27th it encountered a solar flare and then began to fade noticeably. They predict that “this development makes it unlikely that Comet ISON will put on a good show after it exits the glare of the sun in early December”.

For more info and a cool video of the comet actually rounding the sun see:
http://www.spaceweather.com/

Comet ISON Finder for December 2013

ISON disappeared from view in the last week of November as it races towards the sun. It will reappear again in the eastern pre-dawn sky in December. It might first be visible on Dec 4th with a better chance of seeing on Dec 6th. The best opportunity will probably be Dec 9th and 10th. It will be visible for a few weeks after that, but fades rapidly as it travels away from the sun.

The animation below shows the path that ISON will take as is makes a close approach to sun, swing behind the sun and then reappear on the other side. (The animation does not show the fly-by correctly. The comet really does go behind the sun. The Starry Night Pro animation misses the fast fly-by and just connects the before and after positions with a line crossing in front of the sun.) The animation covers the dates from Nov 15th to Dec 31st and shows the comet’s position at the same time each morning relative to the pre-dawn horizon (green line) for an observer at latitude 45°. The time selected is the start of astronomical twilight (end of official “night”)  so the sun is positioned 18° below the horizon.
Ison_Path_2013-11-15_to_2013-12-31_cover

ISON (c/2012 S1) is a “grazing comet” meaning it makes a very close approach to the sun. There are three possibilities for the return path. The least desirable scenario is that the comet breaks apart due to the intense heat from being so close to the sun. In which case there isn’t going to be a return path. The second scenario isn’t much better. The sun may burn off the majority of the volatile shell and that means that while the comet will survive, it will be hard to spot and won’t have much of a tail, if any. If the comet survives it’s close encounter, then it will brighten to an apparent magnitude of 4 as it first comes into view in early December.

From the observatory (which is at latitude 45°) the comet might first be visible on Dec 4th a little after it rises at 5:52am est. The estimated magnitude is 3.8, which is bright enough to see unaided although its low altitude might make that difficult. At 6:16am est – the start of nautical twilight – it will be just 3.5° above the horizon. The sun will be 12° below the horizon and the morning sky will be brightening. By 6:52 nautical twilight will be over and the sky will most likely be too bright to see the comet. It will be at altitude 7.5° at this time – still pretty low.

On Dec 6th, the comet will rise at 5:27am – before the end of official night (and the start of astronomical twilight). By 5:42 – start of astronomical twilight – the comet will still be only 2° above the horizon and the sky starting to brighten. The predicted apparent magnitude is 4.7, which might just be bright enough to find unaided. The thick hazy air near the horizon will make that a challenge. Through binoculars it should be findable and hopefully the tail should be obvious. Nautical twilight starts at 6:18 on Dec 6th and civil twilight starts at 6:53. So there is ample time to scan the sky with binoculars and hopefully get a good view.

Over the next few days ISON will continue to rise earlier which means it will be higher in the with more time to view it under darker skies. But as it gains distance from the sun, its magnitude will also decrease. So it’s a bit of a race between the darker skies, better elevation and the fading brightness. December 9th and 10th are probably the best days to see it.

The comet will be visible for a few weeks after it first reappears, but by late December, its magnitude will have faded to 9 and therefore only visible with a medium to large scope under dark skies.

The chart below shows the positions of ISON for the month of December. The time for each date shown is the start of astronomical twilight. The best viewing will be before the start of astronomical twilight when the sky is at its darkest. But the comet also needs to be at least 5° and more like 10° in altitude to be findable. December 9th or 10th might be the best opportunity, but try and see it as soon as possible.
ISON_Finder_Dec_2013

The details of date, time, magnitude and position are in the table below. For each date the table provides the estimated apparent magnitude. Then the time ISON rises with the azimuth position when it rises (0° is north increasing clockwise to the east). The start of astronomical twilight is given and then the azimuth and altitude of the comet at that time.

Date Mag Rise Az Twilight Az Alt
Dec 4 3.8 5:52 99° 5:40
Dec 6 4.7 5:27 94° 5:42 97°
Dec 8 6.6 5:03 89° 5:44 97°
Dec 10 6.7 4:38 83° 5:46 97° 11°
Dec 12 7.1 4:12 77° 5:47 96° 16°
Dec 14 7.3 3:44 70° 5:48 92° 21°
Dec 18 7.6 2:38 54° 5:51 86° 31°
Dec 22 7.9 12:59 32° 5:53 75° 41°
Dec 26 8.1 dnr 5:55 59° 49°
Dec 31 8.6 dnr 5:56 31° 52°

The Sky for December 2013

The chart below shows the southern sky mid December at 9pm EDT. The same view will be seen at 10pm on Dec 1st and 9pm on Dec 31st.
December_2013_AllSky_Chart
Comet ISON (c2012 s1) will be visible in the eastern predawn skies starting about Dec 4th at 6am. For a more detailed description including finder charts, see the Comet ISON Finder for December 2013 article.

Pegasus and Andromeda are now south-west of the meridian (the line defining south) in the evening sky. The constellations due south are more challenging than others to identify as the figures they define are not as obvious as others and the stars they encompass are on the dim side for urban or semi-rural viewing (mag 3-5) . Perseus is at the zenith (directly overhead) and is identified by the relatively bright mag 1.8 star Mirfak, but otherwise the constellation is hard to identify. Cetus is a rather ramshackle arrangement of stars near the celestial equator (red line) and marked by the mag 2.5 star Menkar at the top left and mag 2.0 Deneb Kaitos on the bottom right. Among this group though is the tiny constellation Triangulum – a distinctive group of 3 stars in an elongated triangle about 15° south of the zenith. It measures a little less than 7° on the long side and only 2° at the base. Still, its easy to spot.

M33_Pinwheel_2010-02-08_v3_SJMThe galaxy Triangulum (M33) lies about 4° west of the point star Rasalmothallah. M33 is difficult to see , even though some people have claimed to see it unaided from a dark site. A more realistic expectation is to be able to see it from a relatively dark semi-rural site sky using binoculars or a medium sized telescope (100mm +).

M33 is part of our “Local Group” and is therefore in our celestial backyard.

South east in the sky is the constellation Taurus (the Bull) marked by the bright orange mag 0.8 Star Aldebaran. And to the East is the spectacular constellation Orion. Rigel, mag 0.15, marks the bottom right corner of Orion and Betelgeuse, a mag 0.43 red giant, marks the upper left corner. Notice the three star star which mark Orion’s belt and the 3 stars hanging down below the belt which outline the sword. The middle star of the Sword is a complex structure of many stars and the Orion Nebula. More about that next month.

Rigel is a challenging double star observable in amateur telescope and actually has a third member which is beyond the reach for amateurs. Although the companion is 9arc-sec away (large for doubles), it is challenging to see because Rigel, being the 7th brightest star, overwhelms its mag 6.8 companion. However, even with a small telescope (70-100mm) it is possible to separate the double under stable seeing.

The brightest object in the night sky (other than the moon) is the star Sirius (the Dog Star) measuring a blinding (lol) mag -1.47. Mid-month at 9pm it will be low in the eastern sky (ESE). Sirius is the brightest star in the sky – north and south and in all seasons.

There is a smudge of a tight grouping of stars between Taurus and the meridian. If you look closely, even without a telescope, you might be able to make some sense of the grouping. With binoculars it appears as a mini dipper composed of 9 bright stars and several fainter stars. This grouping is the Pleiades (M45) – an open cluster – also named the Seven Sisters (plus two parents). An open cluster is a group of star that not only look closely connected visually, but are in the same region of space and gravitationally bound to each other. The Pleiades spans 1.8° and so is best viewed in binoculars or a low power, wide-field telescope.
M45_Pleiades_2010-02-10_v3_SJM
A long exposure photograph shows a reflection nebula – light from the bright blue stars reflecting off dust in the surrounding area. To the south of the cluster, an emission nebula composed of ionized hydrogen gas glows faintly red. These features aren’t visible in a telescope though.

Jupiter_Finder_December_2013Looking high to SW, the Gemini twins Castor and Pollux are a pair of bright stars marking the constellation Gemini (mag 1.56 and 1.15). The third bright object near the twins is the planet Jupiter. For reference, the separation between Castor and Pollux is 4°. Jupiter lies about 11° west of Pollux.

With 7×50 binoculars on a tripod or held firmly against a stabilizing structure (tree or post) the moons of Jupiter can be clearly seen. Even in binoculars Jupiter will appear as a discernible disk, although no surface structures will be visible. A 70mm scope will start to show some of the horizontal cloud patterns. When viewed through a 280mm scope (11″ SCT) some structure to the cloud patterns begins to emerge.

The Double Cluster (NGC 869 and 884) is still a feature of the the north sky and will continue to be visible for several more months. Double_Cluster_Finder_1_December_2013
I like objects that catch my attention with the unaided eye and then show up as as impressive object in binoculars or a small telescope. The Pleiades and the double cluster are great examples. While casually scanning the northern sky at this time of year, my attention is always drawn to the faint, just discernible fuzzy patch between the constellation Cassiopeia and Perseus (the bright star Mirfak).

Double_Cluster_Finder_2_December_2013
Looking north, Cassiopeia will be an upside-down /W/ with Mag 2.6 Ruchabah marking the right point of the upside down /W/. The bright star Mag 1.8 Mirfak will be close to the Zenith. The double cluster lies approximately mid-way between these two reference points and a little closer to Cassiopeia. Just point the binoculars at either of the two reference stars and scan towards the other.

Planets and the Moon

Uranus is a little east of due south by mid month and positioned at declination 2° so is well placed to view it. It’s magnitude 5.8 so requires a small telescope. It’s small so the disc is not discernible but it will appear blueish green in large telescope.

Neptune is further to the west and lower in that sky at declination -11°. At mag 7.9 it will be challenge to find in medium sized telescopes.

Jupiter mentioned above is in the eastern sky. Its declination is 22° and mag -2.6. By mid-month is transits at 2:45am. So its too early to good views. Wait a couple of months when it will be high in the south in the late evening sky.

At the start of the month Venus is low in the ssw sky at declination -24° (elevation 15° at 6pm). It’s about as bright as it gets at mag 4.65 and outshines everything except the moon. By late month Venus has moved closet to the sun and sets at 6:45pm in the sww sky.

By the end of December, Saturn will be seen in the pre-dawn sky. It will be few months yet before even an early morning view will high enough in the sky for good seeing.

The new moon is on Dec 3rd. Try looking for the slim crescent on Dec 5th. Dec 4th is a little too early with the moon only 1.3days old. The 1st quarter is on the 10th. This is best time to view the moon as it’s high in the sky in the evening and the terminator provides high contrast views of craters and other features. The full moon in on Dec 17th, but it will appear full on the 18th as well. The 3rd quarter is on Dec 25th.

Telescope Targets

Objects suitable for larger diameter scopes from a dark site.

Photography Targets

Objects suitable for astrophotography

Comet ISON Finder Chart 2013-11-20 6am EST

The sky is forecast to be clear tomorrow morning affording a last chance to see comet C/2012 S1 (ISON) before it disappears behind the sun. It will return a couple of weeks later, also in the pre-dawn sky.

On Nov 20th (2013) comet ISON will be low in the per-dawn sky and possibly visible about an hour or so before sunrise (7:09 EST). It’s reported to be magnitude 5, which is just bright enough to see unaided under dark skies. At 5:20 EST the sun will be 18° below the horizon which is the end of “night” and the start of astronomical twilight. At this time ISON will only be about 6° above the horizon bearing 114° (a little east of SE). So a magnitude 5 object won’t likely be visible through the thick dusty air near the horizon – even with a telescope.

Over the next 40 minutes, ISON will climb to an altitude of 12° (bearing 122°). 6:00am is the start of nautical twilight so the sky will be fairly light at that time. Only the brighter stars – those used for navigation – are usually visible to the naked eye during nautical twilight. But with binoculars or a small telescope, it might be possible to see the magnitude 5 comet.

After that, it will probably be too light out to see the comet. By sunrise at 7:09 the comet will be at altitude 21° and lost in the glare of the sun.
ison_finder_Nov_20_2013

Time Sun ISON Mag 5
EST Alt Alt Az
5:20 -18.8° 5.6° 114°
5:30 -17.1° 7.1° 116°
5:40 -15.4° 8.7° 118°
5:50 -13.7° 10.2° 120°
6:00 -12.0° 11.7° 122°