C/2017 T1 (Heinze) – Getting closer

 Comet, Solar System  No Responses »
Dec 302017
 

The PTO continues to follow comet C/2017 T1 (Heinze) as it gets closer to the Sun and, for now, the Earth. Closest approach to the Earth is still forecast for the 4th of January, so it has a few more days to go yet. This animation is only eight 300 second exposures. Earlier maintenance work I was doing in the observatory left the telescope out of focus and I did not notice until the third exposure of the 11 I had scheduled.
 

 

The comet has now crossed into the northern constellation Lynx. It is still between the orbits of Earth and Mars and is now slightly above the plane of the Solar System.

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

 

 Posted by at 12:33

C/2017 T1 (Heinze) – A Christmas comet

 Comet, Solar System  No Responses »
Dec 262017
 

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.

 Posted by at 15:23

C/2015 VL62 (Lemmon-Yeung-PanSTARRS)

 Comet, Solar System  No Responses »
Aug 202017
 

Last night I took images of a comet. My standard exposure length of 300 seconds was too long and during that period the comet moved enough to smear into a streak rendering the images useless for analysis. The video is an animation of 11 300 second exposures and shows the amount of movement over 55 minutes. In this case, North is to the top.

Currently, the comet is between Mars and Jupiter and above the plane of the ecliptic but headed south to where most of its orbit lies.

I will try a different tracking technique and exposure duration later tonight to see if I can get accurate astrometric data to report to the MPC and to get a prettier picture of the tail.

 Posted by at 13:34

45P/Honda-Mrkos-Pajdusakova (Take 2)

 Comet, Solar System  No Responses »
Feb 112017
 

Comet 45P’s motion over one day brought it above my treeline about an hour earlier than Thursday night. Unfortunately, the Moon’s daily motion brought it higher in the sky and closer to the comet. These combined to lessen the amount of time I could image the comet.

Honda-Mrkos-Pajdusakova (45P) [C:3x300s]


Thursday night the mount was tracking at the sidereal rate. This is the rate the Earth rotates using the stars as the reference. This is why the stars are round after a timed exposure.

An object’s orbit in the solar system can be accurately modeled by 6 numerical values known as orbital elements. Once enough observations of a solar system object are taken, those 6 values can be derived. The Minor Planet Center (MPC) publishes the orbital elements once they are calculated. In this case we are discussing comet 45P and depending on where the comet is in its orbit, the gravitational effects of other objects (say Jupiter or the Earth) can change its orbit and, as a result, the calculated orbital elements. These values can change fairly quickly. My first pointing attempt Friday night left me with an empty image of stars. With the comet nearing the Earth, the orbital elements from Thursday night were no longer accurate and I had to download Friday’s values.

By using the orbital elements published Friday I was able to change the rate and direction the mount moved to match the orbit of the comet. But since the mount is now matching the comet’s movement and not the Earth’s rotation, the stars get streaked. This is why the comet looks natural even though the exposures were 300 seconds long. The image is a stack of three 300 second images.

 Posted by at 17:29

45P/Honda-Mrkos-Pajdusakova

 Comet, Solar System  No Responses »
Feb 102017
 

I stayed up a little later (earlier?) than usual to see if the skies would still be dark enough to get some images of comet Honda-Mrkos-Pajdusakova (45P). Yesterday the comet rose above the eastern horizon just after 1 AM. Unfortunately, my eastern tree line has an elevation of 53° and the comet didn’t clear the trees until 5 AM, leaving just 35 minutes of dark sky. So, after taking pointing and test exposures, I was able to get twenty 60 second exposures before the PTO sky meter measured the sky starting to brighten.

Honda-Mrkos-Pajdusakova (45P) [C:20x60s] Exposures correlated to the stars.

Chart generated with Cartes du Ciel


Predictions made last December forecast the comet to be naked eye visible after perihelion on the 31st. But once it passed the Sun and started its outbound trip the comet did not meet the forecasts; not even close. The most obvious difference is the complete lack of a tail. Pre-perihelion photos show a small tight coma with a long thin tail. One current theory is the comet came close enough to the Sun to sublimate most of the surface volatile material leaving just enough to form the now large diffuse coma.
 

Honda-Mrkos-Pajdusakova (45P) [C:20x60s] Exposures correlated to the comet.


It is obvious from the above image how fast the comet is moving. The image shows only 60 seconds of motion yet the comet is badly streaked. The comet is currently traveling about 51,000 mph, but the apparent motion is primarily due to how close it is to the Earth, and right now the comet is quickly getting closer. The comet will pass perigee tomorrow morning (the 11th) at 2 AM (CST) at only 7.7 million miles.

The fact that the comet is so diffuse is what is preventing naked eye visibility and makes it a difficult binocular target as well. The approaching Moon is not going to make seeing the comet any easier for the next several days.

 Posted by at 15:16
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