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(IAAC) Obj: Xi Sco (Struve 1998), Struve 1999 - Inst: 4.5" homemade Dobson reflector, f/8



  Observer: Ante Perkovic
Your skills: Intermediate (some years)
Date/time of observation: August 20th 2003, 21.13h
Location of site: above Sevid, near Trogir, Croatia (Lat 43.5 N, Elev 200m)
Site classification: Rural
Sky darkness: 6.0 <Limiting magnitude>
Seeing:
Moon presence: Minor - crescent or far from object
Instrument: 4.5" homemade Dobson reflector, f/8 ("babydob")
Magnification: 25x, 48x, 79x, 96x, 140x
Filter(s): None
Object(s): Xi Sco (Struve 1998), Struve 1999
Category: Multiple star
Class:
Constellation: Sco
Data: mag 4.9, 5.3, 7.3, 7.4, 8.0  size 8", 12"
Position:
Description:
Xi Sco is triple star with two brighter stars (mags 4.9, 5.3) separated 
by 1" and mag 7.3 star 7" to the west (?!).
Struve 1999 is fainter (mags 7.4, 8.0) double 5' south of Xi Sco, and is 
remote member of Xi Sco  system.
It took me 10 minutes just to find it! It's in the middle of nowhere!
- 25x: Xi Sco is just a point of light, but Struve 1999 is easily 
resolved as E-W oriented pair. The western star is a little brighter.
- 48x: Xi is not resolved yet. I can't find the faintest (mag 7.3) star 
to the W, but I see some faint point of light to the NE (that's not on 
my map!).
- 79x: I still can't resolve Xi. Faint star to the NE didn't go away.
- 140: Xi looks little elongated in E-W direction! Finally!
I decided to use homemade 19mm plossl (my favorite) with 2x barlow:
- 96x: Xi still looks elongated in E-W direction, but I still don't see 
it as 2 stars. Faint star to NE is definitely real!
The star was 27 deg above the horizon.