Comet Pan-STARRS 13/03/2013

Contains: Comet

Technical card

Imaging camera: Canon 40D

Resolution: 3652x2426

Dates: March 13, 2013

Frames: 25x1" ISO400

Integration: 0.0 hours

Avg. Moon age: 1.18 days

Avg. Moon phase: 1.56%


Comet C/2011 L4 (Pan-STARRS) in Pisces at 19:15 UT, 13 March 2013.

I ran 3 trips from Leeds to Tow Scar (above Ingleton on the Kingsdale to Dent road) on 10th, 12th and 13th March. All were forcast to have clear skies from a high vantage point overlooking Morecombe Bay and the Irish Sea. On the 10th low cloud was on the horizon and the comet was also very low at sunset having just passed perihelion on that day. Consequently it was not found. The 12th ended up with a thickening cloud build up contary to the forecast - no clear sky at all. Out of desparation I repeated the trip on the 13th and this time 90% cloud cover at 17:00 diminished to less than 5% in one hour leaving a near perfect horizon with few clouds and a perfect view of the comet. A total of 300 miles driven to capture this image!

The two stars visible are HIP 2358 (rightmost and brightest) and HIP 2510 in southern Pisces

The sequence was shot with 24 x 1.3 second images with a Canon 40D and a Sigma 170-500mm telephoto set at 500mm and F5.0 (-2/3) . The camera was mounted on an Astrotrac/Manfrotto tripod combination and polar aligned using compass (for north) and protractor (for latitude). The time interval of the sequence was 19:14:50 to 19:16:20 UT.

Proccessed in Photoshop CS2. Pairs of images were co-added and the results were stacked manually in photoshop using a reciprocal opacity sequence (100%, 50%, 33%, 25%, 20% etc) in two equal groups before combining these to create the master. The comet tail edge contrast was slightly enhanced using a radial blur filter to create an offset-difference image from the original. The offset was set at 128 for mid tone gray. The offset-difference image was recombined with the original image using the soft light blending mode. This technique is the same one used to enhance solar coronea images



Tony Cook


Comet Pan-STARRS 13/03/2013, Tony Cook

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