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80 Tau

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#1 rugby

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Posted 09 January 2020 - 04:59 PM

80 Tau also known as STF 554 lies in the familiar V shaped asteriism we know as the Hyades. From StellaDoppie the details are   5.7-8.1  1".5   14. Sissie Haas mentions it in terms from The Bedford Catlogue as "of no very easy measurement". I can add that it is also of no very easy resolution. Using a 120mm refractor with powers reaching 300 I could see no sign of a companion. My seeing was average at best. The first interference ring was not steady. I need to tackle this pair with a little more aperature.


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#2 fred1871

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Posted 10 January 2020 - 02:35 AM

Hyades look like an asterism but are a genuine open cluster. I looked up the Gaia DR2 parallax for the stars of 80 Tau (STF 554), and they match within the listed errors; and are a fit for this binary being part of the Hyades cluster.

 

I found a note from an observation I made of the pair some years ago,in which I recorded the companion visible close to the primary as  a separate point, with my 140mm refractor at 160x. I've now found another observation, seeing a bit less good; the 140mm still showed the companion at 160x, although 230x gave a clearer view. Seeing can make quite a difference with the closer significantly unequal pairs. In mediocre to poor seeing a double can remain single no matter the magnification; the same telescope on a better night will show a pair split neatly and well.

 

80 Tau has a calculated orbit of period 180 years, and the separation has not changed much in recent times, being in the widest part of the orbit. 


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#3 R Botero

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Posted 10 January 2020 - 02:46 AM

This is a tough one. I’ve split it with my 10” f/20 Mak but seeing is key. My notes from January last year were: “ Very difficult. PA15-20. White.” This at 300-325X.
Roberto

Edited by R Botero, 10 January 2020 - 02:46 AM.

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#4 gfeulner

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Posted 22 February 2020 - 10:31 PM

I tried 80 Tau tonight with my 140 mm refractor. There was no sign of the companion at 196x or 288x. The night was fairly steady and Propus was a beautiful sight.

Gerry


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#5 rugby

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Posted 23 February 2020 - 03:52 PM

I wil try this pair with a140 and a 152 tonight



#6 chrysalis

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Posted 23 February 2020 - 05:13 PM

From CdC:

 

Double Star
STF 554      
Magnitude:  5.70/ 8.12
1831:  1.7"/ 13°
2000:  1.7"/ 19°
Spectral Class: F0V+G0V  
Note: NO
DM:+15   636

J2000 RA:   4h30m08.50s   DE:+15°38'16.0"
Date  RA:   4h31m17.43s   DE:+15°40'49.4"



#7 gfeulner

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Posted 23 February 2020 - 09:59 PM

Tried again tonight but no go.
Gerry

#8 rugby

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Posted 23 February 2020 - 11:11 PM

Gerry can you detail the scope you are using and the kinds of eyepieces. Would also liketo know the amount of light pollution you face.

I tried 80 Tau tonight using a 140 TEC .I am pretty certain I could see the companion at 167x and 300x. Surprisingly (or maybe not) I was unnable to duplicate the success in the ES152 CF.

The last three nights in a row have given me a chance for first light using both of these wonderful refractors. I set both up side by side to compare the views. I will try to post my results in the next few days.



#9 gfeulner

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Posted Yesterday, 09:10 AM

Gerry can you detail the scope you are using and the kinds of eyepieces. Would also liketo know the amount of light pollution you face.
I tried 80 Tau tonight using a 140 TEC .I am pretty certain I could see the companion at 167x and 300x. Surprisingly (or maybe not) I was unnable to duplicate the success in the ES152 CF.
The last three nights in a row have given me a chance for first light using both of these wonderful refractors. I set both up side by side to compare the views. I will try to post my results in the next few days.

Hi Rugby
I also use a TEC 140 so I know I'm getting all the resolving power a 140 will give. My usual double star mags are 196x (5mm Delite) and 288x (3.4mm Vixen HR). I can of course go higher but only if the seeing is great which it hasn't been for a couple of weeks. The transparency is not good here in N.J. with shopping centers all around me. Maybe 3.5 mag on a "good" night. I go to a "dark" site when I can but lately it's been too cold to lug all my stuff up there. I have a Goto mount so I know it's on the right star. Just can't see the companion. Last night I was able to see the "E" star in the Trap and Eta Geminorum but not 80 Tau, I'll keep trying until it goes behind my neighbors trees.
Gerry


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