A spin around the Circlet, pop in on Neptume and try to split some doubles

with Steve Tonkin

1. The Pisces Circlet
You can see the seven-star circlet of Pisces in a dark sky with your unaided eye. There are no particularly bright stars in the constellation, but mag. +3.7 Kappa (κ) Piscium is one of the brighter ones, and others in the Circlet range in magnitude between that and mag. + 5.1 7 Piscium. Binoculars help to bring out the colours of the stars which, with one exception, are in adjacent pairs of similar colours.

2. TX Piscium
The exception to the adjacent pairs found in the Circlet is the easternmost star, the slightly variable (ranging from mag. +4.8 to mag. +5.2) TX Piscium, which is one of the reddest stars that is easily visible with 50mm binoculars. TX Piscium is a carbon star: it pulsates in size and throws off layers of soot as it contracts, causing it to dim slightly. It displays a phenomenon called the Purkinje effect, appearing to brighten as you look at it.

3. Neptune
A little more than 5Æ south of the Circlet you’ll find Neptune, just west of mag. +5.5 20 Piscium, shining at mag. +7.8 and being indistinguishable from a star in 10×50 binoculars. There are some stars of similar brightness in the immediate vicinity, but an easy way to ensure that you have identified this ice giant is to observe the region several times, a few days apart, and note which ‘star’ appears to have wandered slightly.

4. Rho and 94 Piscium
The final three objects of our tour are all double stars. The easiest of these is the pair mag. +5.4 Rho (ρ) Piscium and mag. +5.5 94 Piscium. They are separated by 7.5 acrminutes so, if the sky is dark enough for you to observe them, you should be able to see space between the two stars. Binoculars counteract the loss of stars due to skyglow, and also show you that 94 Piscium is the more orange of the two.

5. OΣΣ 19
Our next pair lies 2Æ north of mag. +4.8 Mu (μ) Piscium. The OΣΣ in its signifier tell us that it was catalogued by the 19th-century astronomer Otto Wilhelm von Struve. The stars of this pair have similar colours to those of our previous target, but there the similarity ends. They are separated by only 69 arcseconds and are very obviously of unequal brightness, being of mag. +6.2 and +8.0.

6. 77 Piscium
We complete the tour with a more challenging pair. A little more than 2Æ south of mag. +4.3 Epsilon (ε) Piscium lies a little triangle of stars of approximately 6th magnitude. The faintest and most southerly star of the triangle is mag. +6.477 Piscium, and your binoculars will show its mag. +7.2 companion a mere 33 arcseconds to the east. These two stars differ in brightness, but note how they have identical colours.