Comet C/2007 N3 (Lulin) presented observers with a stunning display early in 2009. The geometry of its orbit placed the slender dust and ion tails on separate sides of the coma prior to opposition. After finishing some photography and allowing my dark adaptation to build up, I moved to a visual observation and sketch with 15 x 70 binoculars and a mirror mount (for comfortable viewing).
The linear structure formed by the tails on both sides of the comet appeared very strong at first glance, like a softly glowing horizon with a subdued but lustrous, turquoise-colored sun rising in the middle. Trying to pin down position and size on the eastern dust tail was wonderfully straightforward. The ion tail however, was still more of a horizontal suggestion than a definite structure.
Because I used the mirror mount, I mirrored the sketch back to a right-reading presentation. For the field sketch, I used 2H and HB graphite applied with a blending stump on acid-free sketch paper. After scanning and mirroring, I inverted the sketch to be viewed as a positive image, and used a paint brush set to 'color' mode to gradually apply the subtle turquoise hue to the coma.
Subject: C/2007 N3 (Lulin)
Position:
03:00 UT Virgo: [RA 12 27 22.8 / Dec -2 34 58]
04:30 UT Virgo: [RA 12 26 18.8 / Dec -2 28 23]
Size:
Coma: 50 arc minutes in diameter
Degree of Condensation: 7
Ion Tail: 100 arc minutes at 290-320 degrees
Dust Tail: 80 arc minutes at 110 degrees
Brightness: est. 4.8 vMag
Date/Time: FEB 20, 2009, 3:00 - 4:30 AM MST (FEB 20, 2009, 10:00 - 11:30 UT)
Observing Loc.: Cinder Hills Overlook, Sunset Crater National Monument, AZ
Instrument: 15 x 70 Oberwerk Binoculars
Conditions: Clear, calm, cold (11° F)
Seeing: 6/10 Pickering
Transparency: Mag 7+ NELM