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The Jupiter observing season for 2021 began for me in the pre-dawn early morning of June 19th.
When I finally landed Jupiter on the camera’s imaging chip and brought the view into focus, I was pleasantly surprised to see that the Great Red Spot was visible and, as an added bonus, a shadow transit by Jupiter’s moon Ganymede was in progress.
The first image (top left) shows the black dot of Ganymede’s shadow already having transited across two-thirds of Jupiter’s disc when I started imaging. Ganymede itself is just outside the field of view to the left.
In the second image (middle left), taken a little over thirty minutes later, Ganymede’s shadow has moved close to Jupiter’s limb, and Ganymede is just entering the field of view along the upper left edge of the image. At this point, with the transit nearing its end, Ganymede’s shadow is no longer a round dot, but appears as an elongated egg shape. This is because the shadow is no longer being cast on Jupiter’s relatively flat disc, but instead is being cast on the curved edge of Jupiter’s limb.
In the final image (bottom left), captured an hour after the first, Ganymede has moved further into the image but its shadow has now slipped off Jupiter’s face, being cast into empty space. The transit is now over.
The seeing conditions during this session were mostly poor, but occasionally rose to fair/average. Luckily, I captured some video sequences during these brief periods of improved seeing and was able to cull enough good frames from each video to create these images.
Notes:
Date: June 19, 2021
Telescope: Celestron C8 (203mm F10) and Orion Shorty 2x Barlow
Camera: ZWO ASI224MC
Captured in FireCapture. Aligned and stacked in AutoStakkert. Wavelets and color balance in Registax. Color levels, unsharp mask, crop, in GIMP.
[1] 09:31:47 UT 1800/5317 frames, 48fps, 13.91 ms.
[2] 10:08:07 UT 2000/5407 frames, 56 fps, 11.45 ms.
[3] 10:30:19 UT 2000/5595 frames, 97 fps, 10.22 ms.
Comet C/2020 T2 (Palomar) was in the southwestern sky in June. I was able to image it late in the evening of June 15th and into the early morning of June 16th.
This animated image shows C/2020 T2 Palomar as it crawled through a rather barren area in the constellation Bootes southwest of the bright star Arcturus.
If you notice a slight brightening of the background in the lower right quarter of the animation (southwest quadrant), you are seeing noise creep into the telescope’s field of view from a nearby crescent moon. When these images were taken, the Moon was only five fist widths (50 degrees) southwest of the comet.
During this pass through the inner solar system, C/2020 T2 (Palomar) isn’t showing a tail. All we can see of the comet is its coma, the diffuse cloud of gas and dust that enshrouds its tiny nucleus and keeps it hidden from view.
At the time of this image, the night of June 15-16, the comet’s brightness was being reported by various observers around the world as magnitude 10.5. This is approximately sixty times fainter than a bare eyeball can see from an extremely dark observing location.
Comet C/2020 T2 (Palomar) made its closest approach to Earth on May 12th, and will reach perihelion, closest approach to the Sun, on July 11th. After passing perihelion, the comet will recede from the Sun out into more distant areas of the solar system, well past the orbit of Pluto.
Note:
This animated sequence was captured with a Celestron C8 telescope (203mm f/10) and F0.63 focal reducer, using a ZWO ASI224MC camera. Each of the eight images in the sequence is made up of a stack 10-23 sub-images, each exposed for 20-30 seconds. The sequence was captured, live-stacked, and live-processed using SharpCap. The animation was created using GIMP.
