What’s in the sky for September 2021 – Ian Bradley

For the August 2021 sky notes see last month’s sky notes.

Astronomy weather forecast sites

They are customizable to your location – the links below are set to Kendal.

This satellite view I find quite useful as it shows the cloud cover for the previous 212 hours or so. This lets you have an idea as to what cloud is coming … switch to infra-red to view the clouds at night.

Sky Notes for August – Ian Bradley

Nice resources

The nights are now noticeably drawing with the equinox on September 22nd when there is equal length of day and night. On 1st September, we have full darkness from just after 22:00 BST until 0400. By the end of the month, 21:00 to 05:00. So, there is plenty of time, much at reasonable hours, to get out and see things. Obviously, see below, the Moon will be in the way in the middle of the month.

The Moon

Phase   September October
New Moon 6th 6th
1st Quarter 13th 12th
Full Moon 20th 20th
3rd Quarter 28th 28th

ISS visible passes

A series of early morning ISS passes visible up to September 11th and then evening passes until the end of the month. Have a look at Heavens Above for a Kendal location for detailed timings.

The Planets

Mercury is very difficult to see as it will be very low in the evening sky setting a few minutes after the Sun this month.

Venus is prominent in the evening sky and setting about 1 hour after the Sun. At magnitude -4.1 and phase 68%, with an angular diameter of 17”, it should look fairly semi-circular in a telescope You will need a good clear unobstructed western horizon to be able to see it as it is rather low – only about 5° above the horizon at sunset on September 15th. On August 11th, Venus will be about 5° west of a lovely crescent Moon.

Mars is not visible.

Jupiter is still well placed and very obvious at magnitude -2.8. It isn’t that high in the sky, typically maximum 20° but is still a gorgeous sight in a telescope with its moons spread out in a line. Best time to look is when Jupiter is within an hour or so of due south as it will be at its highest altitude. If you are lucky, you may see a moon appear, disappear or even better, transit the disk. Using the Jupiter almanack you can identify and find the times of these events and also the visibility of the Great Red spot.

Jupiter on August 24th @ 01:47 BST. Taken using a webcam attached to the [shared EAS/CAS] Celestron CPC1100. Credit Ian Bradley. Click to enlarge.

Saturn is also visible early in the night but again low in the sky. It is much fainter than Jupiter at magnitude 0.4 but still an easy naked eye object showing a yellowish hue. A telescope is required to see its rings. Best viewing as it is near the meridian, about 1 hour before Jupiter. With a telescope, you might also spot some of its moons, Titan is the most obvious one. See Saturn’s moons in motion.

Saturn on August 24th @ 00:50 BST. Taken using a webcam attached to the [shared EAS/CAS] Celestron CPC1100. Same scale as Jupiter and Saturn is clearly smaller. Credit Ian Bradley. Click to enlarge.

Uranus is visible at magnitude 5.7 nearly all night in August, when it rises around 21:00 BST, and transits about 0400. Clearly best to look in the early hours of the morning.

Neptune is visible at magnitude 7.8 throughout the night when it rises around 21:30 BST, and transits about 01:00 BST mid-month.

Meteor showers

Not looking too good for the next few months.

Draconids meteor shower – October 8th/9th – radiates from the Head of Draco and worth looking for a day either side. Because Draco is almost overhead in the evening, this shower tends to be best in the evening rather than morning. But it is an oddball as generally it doesn’t produce that many meteors per hour but is prone to intense outbursts of 100’s per hour some years. The Moon isn’t an issue as moonset is around 7pm.

Orionids meteor shower – October 21st. The Moon is full so probably not worth looking out for. At best 10 to 20 per hour and usually better early morning. Tend to be fast-moving meteors which occasionally leave persistent trains and sometimes bright fireballs which might be visible over the bright moonlight.

Leonids meteor shower – November 17th/18th.  Another full moon. One of the better shows with the radiant inside the reverse question mark, The Sickle, of Leo. Typically, 10 to 15 meteors per hour but does have occasional very strong showings. Best after midnight.

Sky Charts – 15th September at 2300 BST

Looking up, south is at the bottom.

The asterism of the Summer Triangle consisting of Altair, Vega and Deneb is still very prominent, see Moira’s article, and probably the first stars you’ll see as the sky darkens. This is a great time of year to see objects of interest in the constellations at the zenith: Cygnus, Lyra and Cassiopeia.

The Milky Way goes right over your head so there are lots of star clusters to look out for. The most obvious one will be The Double Cluster (NGC 884/869) situated between Cassiopeia and Perseus. In addition, there is Caroline’s Rose, NGC7789, and M103 in Cassiopeia, M34 in Perseus, M29 and M39 in Cygnus for starters. The area is a joy to behold in binoculars on a dark night. There is the globular cluster M62, sometimes known as the Flickering Globular as it seems to change brightness – purely an optical illusion. In addition, there is the North America Nebula complex, NGC7000, in Cygnus and the California Nebula, NGC1499. With a tracked 70mm lens you could capture both NCC7000 and the Pleiades, M45, in one shot, although that combination might be better later in the evening when M45 is higher.

The Square off Pegasus is generally quite obvious. This acts as a good signpost to M31. My preferred solution to find M31 is to star hop from the corner nearest Perseus. This star is Alpheratz, magnitude 2. Following the line of the top of the square towards Perseus there is a fainter, magnitude 3 star, then and slightly higher is Mirach at magnitude 2. Turn a right angle ‘up’ towards the pole and at the second star (both around mag 4) you are almost there. With averted vision M31 should be visible to the eye if the sky is dark, and certainly in binoculars, as a faint smudge. Even in a reasonable telescope, it isn’t much better – always a slight disappointment until you think what it is! Photographically, it is magnificent. For wide field imaging photographic targets, what could be better than M31, The Great Andromeda Galaxy and nearby telescopic M33.

Lyra is an interesting constellation. The Ring Nebula, M57, is a splendid fuzzy ring in a small telescope. Just 2° from Vega is The Double-Double, ε−Lyrae, a binary star in binoculars, but with a telescope each of these two stars is seen to be a double star itself. Whilst on double stars, you must look at Albireo, β-Cygni and magnitude 3.3, at the end of the neck of Cygnus, The Swan. It is situated at the opposite ‘end’ of Cygnus to brighter Deneb (magnitude 1.25). This is a beautiful low power telescopic object the brighter star golden and the dimmer one blue.

Looking up. Click for a larger version.

Looking south

Three planets on show here. Jupiter and Saturn are low in the west with Jupiter setting round about midnight in the middle of the month. Neptune is visible all night but is only magnitude 7.8 and is quite tiny, 2” in diameter.

In the deep sky, the crowning object must be the Dumbbell Nebula, M27, planetary nebula in Vulpecula. Lovely in a telescope. Nearby there is the Coathanger asterism spanning about 1.5 degrees, a fine wide-field photographic target. The Wild Duck Cluster, M11, so named for the roughly V-shaped arrangement of its brightest stars, is the most distant open cluster in the Messier catalogue that can be seen with the naked eye. Low down, is the Helix Nebula, NGC 7293, another planetary nebula which will be a challenge to view or photograph as it is only as it is only 13.5 degrees above the horizon. There are two bright and large globular clusters M2 and M15 to enjoy, both about magnitude 6 and 12 arc minutes [‘] in diameter.

Have a look for the constellation Delphinus, the Dolphin, which roughly fills the field of view of a x10 pair of binoculars. I’ve somewhat of a soft spot for Delphinius as I remember seeing and sketching my first ever comet there back in April 1976 against the glow of the Teesside blast furnaces. Nearby between Delphinius and the globular cluster M15 lies the somewhat obscure constellation of Equuleus, the Little Horse or Foal. Even Patrick Moore had very little to say about it!

Looking south. Click for a larger version.

Looking east

The winter constellations will soon appear here. Already the Pleiades, M45, are visible at our map time. There are the interesting group of Messier objects, M36, M37 and M38, in Auriga to find which appear as faint misty clouds in binoculars. Most other objects have already been discussed.

Looking east. Click for a larger version.

Looking west

Many of the other major objects have already been discussed earlier: M27, M57, M11. In the constellation of Hercules, there are the magnificent (magnitude 6) globular clusters of M13 nearly 17’ in diameter and M92, a mere 11’ in diameter.

Looking west. Click for a larger version.

Looking north

Ursa Major and The Plough asterism are quite low mid-month during the map times of 2300 so the region is not at its best. In the handle of the Plough there is the nice double of Mizar and Alcor. This is an easy naked eye double as they are separated by 12‘. Mizar, itself, is a splendid telescopic double, with the fainter component separated from the brighter one by 15”. In fact, each component is a spectroscopic binary, so Mizar is at least 4 stars! The pair of galaxies M81 and M82 should be visible in binoculars. There are many other galaxies around the Ursa Major, but they will be better positioned later in the year. In particular M51, near the end star (Alkaid) of the handle of the saucepan asterism of Ursa Major in Canes Venatici is challenging in binoculars but nice in a small telescope. Probably much better to wait for this one until it is better placed.

Looking north. Click for a larger version.


Next Observing Evening

Given the current situation regarding coronavirus, observing evenings can not occur.