Old 05-09-2018, 09:43 PM
Tinderboxsky's Avatar
Tinderboxsky (Steve)
I can see clearly now ...

Tinderboxsky is offline
Join Date: Feb 2012
Location: Kingston TAS
Posts: 709
Lambda Ophiuchi - close uneven double star

Lambda Orphiuchi is a close, uneven double star and is one of the test pairs for Sissy Hass’ double star project. I had occasion to re-visit this pair back in July, when high in the sky, to test resolution of this pair at different apertures. You might be interested in the results.

Star magnitudes are 3.9 and 5.15 and the separation is 1.4”
Seeing was 5/5 and transparency 7/7. A good night. All of these observations are with my Vixen 140mm refractor stopped down with a set of aperture masks and an LVW 3.5mm eyepiece giving 228X

100mm aperture - clear, distinct separation.

90mm aperture- appearance of two stars “kissing”. It was apparent that there would be a gap between the two but it is was not showing. There were several fleeting moments where a gap appeared for an instant.

80mm aperture - two joined lobes, with one brighter than the other. No momentary gaps.

70mm aperture - distinctive oval shape with one end fainter than the other.

60mm aperture - slightly oval shaped star in comparison to pin point neighbouring stars. No distinguishing features. This slightly oval shape be missed in general observation if one did not know this was a close double star.
Reply With Quote


Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

All times are GMT +10. The time is now 04:26 AM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
Lunatico Astronomical
Astronomy and Electronics Centre