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Zeta Cnc - getting wider

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Observed Zeta Cancri twice this week and obtained a split on both occassions with a 150mm f/8 refractor. The split was also detectable when using a 111mm aperture mask. At 160x magnification, the two close components were elongated, at 320x, the split was clearly seen. The separation is now certainly getting wider making this triple star a lovely eyepiece view. Drawing below with North at the bottom.


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Excellent capture Towa. Over what sort of time period can you notice a change?

Thanks everyone for the comments.

Reading the double star book by Bob Argyle, the close components A-B have a period of 59.56 years. Widest separation will be around the years 2020 - 2022,

after that the two stars will start to close up again. So at least we will get plenty of time to observe the pair.

Edited by Towa
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Had several scopes out tonight to check out components A-B.

102mm f/8 Apo at various powers from 200 to 600x, two Airy disks seen, but very difficult to confirm a split.

During moments of best seeing there was some hint of black between the disks, but not enough to give a definite answer.

111mm f/10.8 Achro, split detectable at powers over 200x.

120mm f/8.3 Achro, good view of a split at 266x.

150mm f/8 Achro, no problem seeing the split over 200x.

Going by the view in the APO, I would guess that the separation is around 1.0 - 1.1 Arc second at the moment.

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That is a fantastic drawing from Towa and the colours really do seem so impressive in the telescopic field. I often wonder when observing double stars how they might have looked had we been fortunate enough to see them from closer distances.

For Zeta Cnc, here's an awesome painting that I found on google:




Edited by Starfleet
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