Pear Tree Observatory

Comet Heinze continues to climb above the plane of the solar system and the Earth is now pulling away from the comet. It is still outside Earth’s orbit as it heads toward perihelion on the 21st of February. It now appears in Cassiopeia on its tour of our constellations.
 

 

These images were taken last night (the 6th). The comet’s tail is becoming more apparent. There were some high thin clouds that were passing and are evident in the animation. I added a second pass thorough the images at a slower rate to make it easier to pick out the two satellites that photobombed the comet. One is in one frame and passes from bottom left to right center (or vice versa). The second is a much slower satellite. It takes two frames (10 min) to pass from bottom center to top right.

The PTO’s tree obstructed view of the sky. Chart generated by TheSkyX.

Comet Heinze continues to approach the Sun. As of the 3rd of January it was still in the constellation Lynx and still outside Earth’s orbit. The comet will not cross Earth’s orbit until the 16th of January but by then the Earth will be well ahead of and well below the comet.
 

 

All objects that orbit the Sun obey Kepler’s laws of motion. This comet is no exception. The 2nd law states “a line segment joining an orbiting object and the Sun sweeps out equal areas during equal intervals of time”. Simply stated, the closer the object is to the Sun, the faster it moves. You can see this in action by comparing the previous animations. Each of the individual exposures are 300 seconds long. By comparing the length of the streaks made by the stars you can easily see the comet moving farther in 300 seconds the closer it gets to the Sun.

The PTO’s tree obstructed view of the sky. Chart generated by TheSkyX.

 
Also visible in the first exposure is the bright streak of a satellite. There are so many satellites in orbit around the Earth it is not unusual for a series of exposures to capture one. For long exposure images I have to leave those sub-exposures out of the processing. The bright streak will skew the final image.

This comet was discovered by Ari Heinze of the University of Hawai’i using their ATLAS system. He came across the 18th magnitude object on the 2nd of October.
 

 
The 12 frames that make up the animation were taken the evening of the 25th of December. Each frame is a 300 second exposure for a total of 1 hour of movement. Just visible is a hint of a curve in the tail. As is usual for my images, north is to the right and east is towards the top.
 

C/2017 T1 (Heinze) is quickly traversing the constellation Cancer. It is currently between the orbits of the Earth and Mars and is passing up through the plane of the solar system. It will pass closest to the Sun (perihelion) on Feb. 21st but come closest to the Earth on the 4th of January.

The PTO’s tree obstructed view of the sky. Chart generated by TheSkyX.

 
Calculations for the comet’s brightness predict it will be brightest viewed from the Earth on the 6th of January. If it gets as bright as predicted (Mag. 8.8) it will be visible in moderately sized binoculars or small telescopes. However, a comet’s response to the Sun’s energy is very unpredictable and thus brightness predictions are very unreliable.