ARCHIVE · Login   · Main Index   · Search Observing >> Double Star Observing Previous   Index   Next   Threaded   Pages: 1 Mark K scholastic sledgehammer Reged: 12/16/04 Posts: 860 Loc: Bury, Lancashire, UK Zeta Cancri - a fine all-yellow triple       #311204 - 01/15/05 06:47 AM Edit   Reply   Quote Quick Reply   Manchester, UK, 12-01-2005 I came across Zeta Cancri whilst hunting for doubles and to my amazement I was able to see it as a TRIPLE in my ETX-125. The components were all yellow, and almost, but not quite, in a line with each other. The 'C' component was easy at 173x, but barlowing to 345x was able to split the 'A' and 'B' stars with a tentative black space between them. The epoch 2000.0 separation of the 'A' and 'B' stars was given as 0.8", but the orbital diagram in Richard Dibon-Smith's Starlist 2000.0 showed a widening to 1.0" by 2005, which is now within the Dawes limit of a 5-inch scope. Try viewing it on the next clear night ! -------------------- Mark K. Meade ETX-125 Post Extras:       EdZ Professor EdZ Reged: 02/15/02 Posts: 18806 Loc: Cumberland, R I , USA42N71.4W Re: Zeta Cancri - a fine all-yellow triple [Re: Mark K]       #311215 - 01/15/05 07:33 AM Edit   Reply   Quote Quick Reply   Hi Mark, Zeta Cnc is a real challenge for a 5". I have seen it in my 6", but I don't think I've seen it with my 5" SCT. However, I haven't tried it with the 5" in over two years and it has widened since then. This link to the WDS 6th Orbit Catalogue will give you the specifics on close binaries. It's the best source I've found. http://ad.usno.navy.mil/wds/orb6/orb6frames.html It shows Zeta is at 0.96" in 2005 and will reach 1.0" in 2007 You may have split this to thin black space, but Dawes limit is not an indication of a separation that will show two stars with a clean unbroken spilt. Dawes (116/D) gives you a dimension that will show two stars slightly overlapped, maybe 15-20% overlapped. Rayleigh limit (138/D) is a better indication of a separation you might be able to cleanly split. But some scopes are known to exceed the limit and Zeta would be just the type of star that would be a good candidate to break that limit. Since I've been using my 5" most often lately, I'll give it a shot next time I get a chance. edz -------------------- Teach a kid something today. The feeling you'll get is one of life's greatest rewards. member#21 Post Extras:       davidmcgo scholastic sledgehammer Reged: 10/09/04 Posts: 935 Loc: San Diego, CA Re: Zeta Cancri - a fine all-yellow triple [Re: EdZ]       #312494 - 01/16/05 02:03 PM Edit   Reply   Quote Quick Reply   You've found one of my favorite springtime multiple stars! I had a great view last night from Mount Laguna by San Diego with my "new" 1965 Celestron 10" f15, lots of black sky between the AB pair at 363x. Post Extras:       Pages: 1 Previous   Index   Next   Threaded   Extra information 0 registered and 6 anonymous users are browsing this forum. Moderator:  EdZ, RLTYS  Print Thread Forum Permissions       You cannot start new topics       You cannot reply to topics       HTML is disabled       UBBCode is enabled Thread views: 1384 Jump to *Announcements and News* -----   Cloudy Nights Announcements   Discussion of CN Articles, Reviews, and Reports   Beginners Forum   Celestial Events   Light Pollution*Equipment Discussions* -----   ATM, Optics and DIY Forum   Binoculars   Binoviewers   Cats & Casses   Classic Telescopes   Equipment   Eyepieces   Mounts   Observatories   Reflectors   Refractors    Celestron SkyScout and Meade mySky   Video and Electronically Assisted Astronomy*Telescope Specific Forums* -----   Celestron NexStar    NexStar GPS / CPC Telescopes   Questar Forum   Meade ACF/RCX / LX / GPS    Meade ETX*Other* -----   Science of Astronomy & Space Exploration   Pets   Cloudy Days & Microscopes   Gardening   Audiophiliacs   Cameras & Photography   AstroWebsites*Speciality Forums* -----   AstroArt   Astronomy Software & Computers   Stellar Media   Astro Outreach, Clubs and Star Parties CN Forums Home

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