Sep 082021
 

67P/Churyumov–Gerasimenko is a short period comet completing its orbit around the Sun every 6.45 years. Right now it is heading back into the inner solar system towards a perihelion on the 2nd of November. It is still below the ecliptic and has just crossed the orbit of Mars. Currently, it is visible in the constellation of Taurus.

This animation is a 31 image set of 60 second exposures.

67P’s orbit viewed from above the solar system.
Graphic courtesy of the JPL Small-Body Database Browser.

67P is one of the most intensely studied comets of all time. Sitting on the surface of 67P is the now inert Rosetta spacecraft along with its Philae lander. Rosetta rendezvoused with the comet in 2014 and orbited the comet throughout its 2015 perihelion. At the end of its mission the spacecraft was soft dropped onto the comet. The Rosetta mission ended on 29 September 2016 when the spacecraft impacted the comet at an estimated speed of 2 mph.

 Posted by at 11:07
Apr 282021
 

UPDATE: I was able to image the comet on the morning of the 29th and shot enough imagery to assemble a short animation showing its motion. The animation is sixty 60 second images.

 

Comet C/2020 R4 (ATLAS) spends only a brief time above the ecliptic during its 956 year orbit of the Sun and for now it is. This image captures it on the 21st of April after it passed perihelion and is heading back out into the far solar system. The comet was located in the constellation Hercules when the image was taken, but is moving quite rapidly and as of today (the 28th) is in Boötes. If you look closely, you can see the comet’s shape is elongated due to its motion even though it is only one 60 second exposure. The comet is crossing the FOV from upper left to lower right.

The comet was discovered by the Mauna Loa telescope of ATLAS on the 12th of September last year.

ATLAS stands for Asteroid Terrestrial-impact Last Alert System. The system consists of two 0.5m telescopes; one at the Haleakala Observatory on the island of Maui in Hawai’i and the other at the Mauna Loa Observatory on the big island of Hawai’i.

Comet C/2020 R4 (ATLAS)[CV:1x60s]

The diagrams below show its orbit in full and much closer to the Sun to illustrate its location in relation to the Earth at the time of the photo.

C/2020 R4’s orbit in an high overhead view of the solar system.
Graphic courtesy of the JPL Small-Body Database Browser.

C/2020 R4’s orbit in an oblique view of the solar system.
Graphic courtesy of the JPL Small-Body Database Browser.

 Posted by at 14:08
Jan 182021
 

The list of observable comets issued by the MPC yesterday has 953 entries. One of them is 156P/Russell-LINEAR. The comet was initially discovered by K.S. Russell in September 1986 at Siding Spring Observatory, Australia.

The following animation is made of 99 sixty second exposures. You may see a satellite pass through the field of view and there is also some low altitude haze that passed overhead.

The ‘P’ indicates the comet is in a periodic orbit. 156P takes 6.7 years to orbit the Sun and its orbit comes just inside Mars’ orbit at perihelion and just outside Jupiter’s at aphelion. Right now, the comet is above the ecliptic and heading back out into the solar system after close approach on the 17th of November last year. Right now it is visible in the constellation Triangulum.

I measured the magnitude of the nucleus at 15.0 so it will take a fairly large telescope to view visually but would be visible photographically in a small scope.

156P’s orbit viewed from above the solar system.
Graphic courtesy of the JPL Small-Body Database Browser.

156P’s orbit in an oblique view of the solar system.
Graphic courtesy of the JPL Small-Body Database Browser.

 Posted by at 15:28
Aug 012020
 

The skies finally cleared enough to try to see the comet. We headed north to an area just south of I-10 off of Hwy 285. It is a large field cleared of trees and has an excellent western horizon. Unfortunately, it also has a surprising amount of nighttime traffic.

We set up just before sunset and waited. The setting Sun was pretty enough to take a shot. The camera I was using does not have a live view capability so I just pointed it using a compass and a guess as to altitude and hoped the comet was in the FOV. One of the first shots during dusk was lucky. If you click on the image on the right it will display full size. The comet is just visible to the lower right of the two stars. Although the picture shows blue skies it was taken after the sunset picture but at a 6 second exposure.

For the rest of the evening I took images using the guess method, but after processing, 10 of the 22 images contained the comet in some way.

During the evening Donna and I were joined by a NWFAA club member Walter Dunn. None of us saw the comet naked eye but each of us was able to find and view it in binoculars. Ultimately, clouds and haze moved in and hindered viewing the comet. We left just before the comet set.

 Posted by at 13:32
Apr 172020
 

This image shows comet C/2019 Y4 (ATLAS) as it continues to break up the closer it gets to the Sun. This is a single 600 second exposure with the mount’s movement matching the comet’s motion. Two primary fragments are obvious but I have convinced myself I can see at least one more bright spot trailing the other two in the comet’s tail.

C/2019 Y4 (ATLAS) [CV:1x600s]

I took advantage of a software capability I hadn’t used before to take this image. APCC (Astro-Physics Command Center) is software that sits in between the user and the AP mount, in this case an AP1600. It has the capability of using data generated by the JPL HORIZONS web based tool. That tool takes the orbital elements of an object and generates an ephemeris of the desired solar system object based on user specific parameters.

I use the tool due to its extreme accuracy. It is also convenient since JPL lists the PTO in its list of observatories. I had always used the output ephemeris manually before, printing out the table of data, reading the objects location at the current time and manually sending the mount to that location. This is the first time I had the software read the data directly and adjust the mounts tracking rates to match the comet. I am pretty sure this will not be the last time I use HORIZONS.

 Posted by at 16:34