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Double Stars Eta Draconis and STF 2054

Posted: Sun Jul 04, 2021 1:38 pm
by John Fitzgerald
Last evening, July 3, 2021, while testing some eyepieces in my 10 inch f/5 Dob, I observed double Stars Eta Draconis and STF 2054.

Eta Draconis m 2.8, 8.2, sep 4.4 sec at PA 143 degrees. I observed this equally well with a 6mm TV Delos, 6mm Radian, and 6mm TMB Planetary for 208x. The tiny secondary was easily seen on the SE side of the primary as a tiny pinprick of bluish light next to a yellowish primary. The seeing was decent. This double is notoriously difficult in poorer seeing.
The distance to this pair is given as 92 light years.

In the same wide field of view lies the pair STF 2054, m 6.1, 7.1, sep 0.9 sec at PA 351 degrees. Both looked white, and were barely separated at the 208x magnification given by the 6mm eyepieces.

The distance to this pair is given as 507 ly, so there is no real association with Eta Draconis.

For these relativity high power views, the Dob was sitting on a Round Table tracking platform.

Re: Double Stars Eta Draconis and STF 2054

Posted: Sun Jul 04, 2021 5:00 pm
by John Fitzgerald
The high delta magnitude of 5.4 (145 to 1 ratio) makes it difficult. The actual distance between this pair is at least 125 AU, if we are looking face on at the orbit, which is unlikely. As far as I can tell, an orbit has not been established, but the period is likely thousands of years. The primary is a G8 spectrum giant with about 60x the sun's luminosity. The secondary's luminosity is about 2/5 that of the sun, with a K2 spectrum. The secondary will far outlast the primary.

Re: Double Stars Eta Draconis and STF 2054

Posted: Sun Jul 04, 2021 8:18 pm
by John Baars
Great job, well done!
Thanks for your report!

Re: Double Stars Eta Draconis and STF 2054

Posted: Sun Jul 04, 2021 11:33 pm
by Caddman
That's a very good report. Thanks.

Re: Double Stars Eta Draconis and STF 2054

Posted: Sun Jul 04, 2021 11:47 pm
by Bigzmey
Great splits John! This is when you need large aperture and good seeing.

Re: Double Stars Eta Draconis and STF 2054

Posted: Fri Jul 23, 2021 10:40 pm
by helicon
Congrats John on winning the VROD for today for your double star report!

Re: Double Stars Eta Draconis and STF 2054

Posted: Sat Jul 24, 2021 2:34 am
by Unitron48
Great splits, John! Congrats on the VROD award!!

Dave

Re: Double Stars Eta Draconis and STF 2054

Posted: Sat Jul 24, 2021 2:32 pm
by Makuser
Hello John. I really enjoyed your report on your double star splitting adventure and the information that you provided to us. Thanks for putting this observing report up on here for us to enjoy John, and congratulations on winning the TSS VROD Award.

Re: Double Stars Eta Draconis and STF 2054

Posted: Sat Jul 24, 2021 5:35 pm
by Gordon
Congratulations on the TSS VROD!!

Great report!