Kurt, Siegfried and I split Porrima A-B easily with dark sky between them with a 7" refractor last Thursday night at 450X. I also split it last year when it was closer with an 8" SCT at 812x. I think the key is good seeing for such close double stars. My best clean split of a close double was of Gamma 2 Andromedae at .5 arc seconds around 1995 using a Ceravalo 216. Gamma 2 Andromedae is now about .25 arc seconds, too close to split except in very large scopes under excellent conditions. Gamma 2 is particularly difficult because of the brightness difference between the two components. I was able to split Eta Corona Borealis last year at about .5 arc seconds but the components are fairly equal. I haven't had a chance to try this year. See http://www.dibonsmith.com/orbits.htm. Clear Skies, Don Colton -----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Canopus56 Sent: Saturday, May 31, 2008 4:11 PM To: Utah Astronomy List Serv Subject: [Utah-astronomy] Porrima split - documentation pic 20080531 Ealing Posted a small documentary image showing the newly enlarging split of Porrima A-B (gam Vir) now at around 1". After being unseparable for a couple of years at perigee, Porrima B is now again becoming accessible by small telescopes. This binary split is discussed in Alan MacRobert's S&T note on page 68 of the June 2008 issue. http://gallery.utahastronomy.com/main.php?g2_itemId=11377 Porrima was only at 38 degs alt at my op and seeing was Pickering 1 or 2. Because of this, an asthetic image was not possible. 83 short 0.125" exposures where taken of the atmospheric speckle pattern. The two best images showing the split and the two components are included in the posted image. Visually, at 564x with a 16" apeture, Porrima AB, in moments of still air, appeared as figure-8 pattern or a just-touching kiss split, using Haas's 2006 split nomenclature. My computed split of 1.4" has a high degree of uncertainty and, due to observation error, is not in consistent with the S&T article predicted separations of 1.0" on April 20th, 2008, increasing to 1.1" on Sept. 15th. It is not consistent with the 6th Orbit Catalogue ephemeris split (rho) values of 0.91" for 2008 increasing to 1.168" in 2009. The WDS 6th Orbital Catalogue ephemeris plot of observations for Porrima can be viewed at: http://ad.usno.navy.mil/wds/orb6/PNG/wds12417-0127r.png The entry for Porrima in the WDS 6th Orbital Catalogue references neither the ids gam Vir or Porrima. Search the catalogue using the alternative id STF1670AB. Alternate designations for Porrima include: gam Vir 29 Vir WDS12417-0127 STF1670AB ADS8630 HD110379 Peace - Kurt WDS 6th Orbit Catalogue: http://ad.usno.navy.mil/wds/orb6/orb6frames.html _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com