Monthly Archives: November 2013

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

Observing Report – 2013-11-20 Comet ISON

As planned, i observed comet c/2012 S1 (ISON) this morning between 5:45am and 6:15am est. It was actually higher above the trees than “Starry Night” predicted, so i could have started my observations earlier and therefore had darker skies. (Astronomical twilight ended at 5:20.) As it was, the sky was starting to brighten and i think this hid the tail.

Comet ISON was easy to find with the 10×50 binoculars – appearing as a fuzzy “non-stellar object”. With the 70mm f/6.8 scope and the 5mm Hyperion at 96x magnification it was clear that this was a comet. The core was obvious and brighter than the surrounding halo.  The tail could not really be seen but i had the impression that the halo was elongated in the correct direction.

I captured a few images with the Canon T4i (unmodified) with the 70-300mm zoom at 200mm and fully open at f/5.0. I was using the camera tripod so limited the exposure to 2seconds at ISO1600. Of the 17 images, only 4 were usable. The others exhibited serious camera shake even though i was using mirror lockup and a 2sec timer. I manually aligned and stacked (blended) the best 4 in Photoshop and then stretched them in PixInsight. I could not get the tail to show up very well, although with a little imagination the comet does appear teardrop shaped.

Comet c2012 s1 ISON 2013-11-20

Comet c2012 s1 ISON 2013-11-20

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°

M15 and M2 – 2013-10-08

Globular clusters more or less all look the same. And this is true of M15 and M2. M15 is billed as one of the densest globular clusters and it does photograph well. (I still think M13 in Hurcules is the best).

M15 and M2 are described as being 18′ and 16′ in diameter (angular size when viewed from earth). M15 is listed as mag 6.2 while M2 is mag 6.3 – hardly a discernible difference. However, photographically M15 came out much better. This is mostly due to M2 being quite low on the horizon from my lat 45° site.

I first to 2hrs of images of M15.

M15 - Pegasus Cluster - 2013-10-08 - v1

M15 – Pegasus Cluster – 2013-10-08 – v1


Then i turned the scope to M2 and took another 2hrs of data. M2 was only 9° above the horizon when i finished. I may have lost focus as well as the temp change was significant.
M2 - 2013-10-08 v1

M2 – 2013-10-08 – v1

Milky Way – 2013-09-25

I redid the Milky Way picture of Sagittarius, this time mounting the camera on the motorized tripod and guided the image. The image was still captured with the Simga 28mm lens. But this time i used the modified Canon T2i with captures more red in the spectrum beyond normal vision.

Milky Way - Sagittarius - 2013-09-25 - v2

Milky Way – Sagittarius – 2013-09-25 – v2


With the camera mounted on the tripod i could capture longer exposures and more of them. The picture obviously has more depth that the previous tripod mounted version. M20 and M8 are just visible in the centre towards the lower third.

With the camera setup, i decided to also take the same time of image of the Milky Way near Cygnus. Cygnus at that time was high over head so well placed for a wide field image.

Milky Way - Cygnus - 2013-09-25 - v1

Milky Way – Cygnus – 2013-09-25 – v1


The north america nebula (NGC 7000) is easily located. Its towards the centre on the right. That whole area is one large molecular cloud of ionized hydrogen.

The Sky for November 2013

The biggest advantage of winter for northern astronomers is it gets dark early. By mid November astronomical twilight is at 6:07pm EST and nautical twilight is 5:32pm. So observing the night sky is a lot easier than in late June when astronomical twilight is 11:24 EDT.

The moon plays a prominent role this month. Which is fine if you like looking at the moon, but not so good if you’re going to a dark site and want to hunt down some faint fuzzies. New moon is on Nov 3rd and will just be visible a couple days later in the western sky a few minutes after sunset. Try finding the young crescent moon on Nov 5th just after sunset which is at 4:45 est. The moon shows off the most detail when viewed along the terminator (line between light and dark). This is most true when viewing through a medium power telescope but also when using binoculars. So the moon is quite interesting to look at between new moon and 1st quarter – a waxing crescent –  also the waxing gibbous moon. (The waning moon also shows off a nice terminator but it transits much later at night.) The first quarter moon is Nov 9th when it rises 12:30pm est sets at 23:11. Full moon is on Nov 16 and rises 16:07 set the next morning at 6:55am and is a prominent object for the whole night. 3rd quarter is on Nov 25th when it rise 23:59. So its not until about Nov 23rd when the moon rises at 21:59 that it’s completely out of the way.

The chart below shows about 160° of the sky to the south on November 15th at 9pm. This corresponds to the same view at 10pm on Nov 1st and 8pm on Nov 30th.

November_2013_AllSky_Chart

Pegasus is now front and centre by mid-month, 2hrs earlier than in October. Cygnus is setting into the west and the winter constellations are starting to rise in the east with Taurus (the bull) first to appear. While not on the chart, the Big Dipper has sunk to its lowest point in the evening and is obscured from view unless you have an obstructed northern horizon.

M31_Andromeda_Galaxy_2010-11-08_v3_SJM
Last month’s feature object – the Andromeda galaxy (M31) – is now high in the southern sky at 9pm mid-month and so in a fine position to observe. (See the October Sky article for more info on the Andromeda Galaxy.)

The sky has rotated another 2hrs from the same time last month, so the reference stars to find M31 are in a slightly different orientation.

m31_finder_2013-11-15

Pisces_art
A challenging constellation to find is Pisces (the Fish). It is also due south at 9pm mid-month and just below the more prominent constellation Pegasus. It’s rather spread out with no obvious pattern to orient you. That and the stars are relatively faint and so hard to see, particularly from even a semi-rural sky. The main pattern is made up of stars that range in brightness from 3.6 to 5.2.

The best way find the whole constellation is to first locate the head of the bottom fish – the tight circle of 7 stars directly below Pegasus.
Pisces_chart
The square pattern in Pegasus is about 12° on a side – so a little larger than your hand (Hand Scale for Measuring Angles. The fish’s head is also about 12° below the bottom of Pegasus.

From there, try to trace the pattern of stars that form for the large v-shape.