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Hartley 2 in 1997

Nov 18 image of Hartley 2 from the 1997 apparitionClick for full size image.
Dec 30 image of Hartley 2 from the 1997 apparitionClick for full size image.

Caption: Images of comet Hartley 2 from November 18 (top) and December 30 (bottom), 1997 (34 days before, and 8 days after perihelion, respectively). EPOXI will encounter the comet 17 days before perihelion, when the comet is at the point in its orbit roughly halfway between where these two images were obtained. The comet was 0.97 AU from the Earth when the November image was obtained, and 0.83 AU for the December image. For comparison, Hartley 2 will be only 0.14 AU from Earth at the time of the EPOXI encounter, providing a much better view for Earth-based telescopes. The streaks are background stars that appear to move as the telescope guides on the comet.

Technical Details:

Both of the above images were taken at Lowell Observatory with the Hall 1.07-m telescope. Both were 300 sec exposures through the R filter. Below are the observing circumstances from 1997 along with the values for 2010 for comparison.

November 18, 1997
t - T = -34 days
r = 1.136 AU
Δ = 0.970 AU
Φ = 55.3°
December 30, 1997
t - T = +8 days
r = 1.038 AU
Δ = 0.828 AU
Φ = 62.4°
October 11, 2010
t - T = -17 days
r = 1.085 AU
Δ = 0.138 AU
t - T is time from perihelion (- is before and + is after)
r is the distance from the sun
Δ is the distance from Earth
Φ is the phase angle


Credit: Tony Farnham/Lowell Observatory

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