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 Post subject: Delta Cephei
PostPosted: Fri Feb 23, 2018 10:18 am 

Joined: Thu Jun 02, 2016 11:32 am
Posts: 478
Location: New Farnley, Leeds lat 53.8N long 1.6W
The old faithful of northern variable stars. The variability, in a period of a little over 5 days, was noted by John Goodricke in my neighbouring town of York during 1784-85. He also found eta Aquilae to be variable at about the same time. Impressive observations, since these cepheids have a visible range of less than a magnitude. Anyhow, I was estimating delta in our frosty back garden at about 22.00 UT with 8x32 binoculars last night; and I noted it as one step fainter than nu cephei (Nu is mag 4.3), making delta close to minimum at mag 4.4. The light curve of delta is like a shark's fin with a sharp rise to maximum (around mag 3.5) and a roughly 4 day fall to minimum. So, after waking up at 4am this morning for a purpose that we older gentlemen are only too familiar with, I noted the sky to the north was clear and that Cepheus was in the north-east. Binoculars are always left on the window sill, so I found delta and made an estimate; 4.15 by comparison with epsilon and nu. Delta is on the rise again. Have a go at following it, using the SPA vss chart that is available online.
Keep warm, Bob

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 Post subject: Re: Delta Cephei
PostPosted: Sun Feb 25, 2018 9:38 pm 

Joined: Fri Dec 03, 2004 12:51 pm
Posts: 2462
Location: Stoke-on-Trent
Hello Bob, I've never tried following the variability of Delta Cephei, but I'll have a go when I get chance.

It's reminded me that not far away from Delta is Mu Cephei, the red supergiant "Garnet Star", which I haven't observed in quite a while. This used to be one of my favourites to pick out because of its colour.

Best wishes, Jeff.

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