Gamma Virgo – “Porimma” – Famous Double Star

By Debbie Ivester

This is one of my first telescopic observations of a double star. I was using a 102 mm Orion/Vixen refractor at a magnification of 196x.  Conditions were only fair, but I could make out two individual stars of the same magnitude on an intermittent basis.  Both stars appear white in color.  When observing double stars, it’s important to keep your eye very still, and look into the center of the eyepiece…referred to as, “on-axis.”    Debbie  Ivester


 Gamma Virgo has always been one of my favorite doubles.  It is a true binary with a 170-year period.  I began observing double and multiple stars many years ago.  The current separation of Gamma is 2″ and was very easy with the 102 mm refractor at a magnification of 169x. I made the following pencil sketch on May 13th from my backyard in the foothills of western North Carolina.  Conditions were fair, and only during moments of steady viewing could I see dark-sky between the pair, most of the time they were merging or “notched.”  The following sketch was made with a No.2 pencil and a blank 5 x 8 note card.  The colors were inverted using a scanner.  

Roger Ivester 

Gamma Virgo - Correct Position Angle

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