Recently Browsing 0 members
No registered users viewing this page.
By Victor Boesen
Perhaps the title is lying a tiny bit... After sleeping for one hour I woke up not able to fall asleep again after numerous attempts. I took the obligatory gaze outside at the bright summer sky with some faint noctilucent clouds towards the north. Jupiter and Saturn looked beautiful in the south and that was when I felt a sudden itch to get out my small grab and go setup. I quickly grabbed my tripod, mount-head and telescope to head downstairs to the parking lot where I quickly set up the scope. Cool-down was almost not a problem because of the hot 20 degree air which was very comfortable observing temperatures.
Starting with Jupiter, after I had achieved focus on Altair, the two main cloud bands very obvious together with three of its moons hovering like pin-points around the perfect round sphere. I've previously been a little disappointed with the view of Jupiter with this small Skywatcher Evostar 72ED DS-Pro but I blamed it on my own patience and this morning I proved myself right. After studying the planet for a couple of minutes I noticed the Ganymede shadow transit located just above (almost on the edge of) the northern equatorial belt and letting the planet drift through the FOV at 90X magnification with the 4.7mm explore scientific eyepiece the shadow together with the bands popped at me at times of great seeing. The moments where you're almost "falling into" a better and better planetary image is truly amazing and the small 72mm scope did a very good job also resolving the shadow transit as a "globe" rather than a dot. Only rarely could I tell the slight variations in the two main cloud bands of Jupiter but this was very difficult with only 72mm.
Saturn proved to be equally fascinating just like every other time I point the telescope towards the ringed planet. Immediately slight banding was visible on the planet and the rings were very defined with the Cassini-division visible in moments of good seeing but really standing out in brief moments of very good seeing. The small evostar 72 has no problem on Saturn whereas more patience is required with Jupiter because of its low contrast features. Saturn never disappoints.
Moving on to Mars I noticed how it had increased slightly in size since I observed it last time about a month ago. The southern polar cap was still very obvious but for some reason I recalled it being even more noticeable last time I observed Mars but I could be wrong. Right above the polar cap was a dark spot which extended to the planet's equator but not covering the entirety of the disk's width. I didn't notice any features on the northern half of the disk. The evostar does a surprisingly good job on Mars, which often causes problems for other doublet refractors with trouble correcting the red part of the visible spectrum. The evostar doesn't have much unfocused red light around the planet and the view isn't "mushy" like it would be in cases of a badly corrected refractor.
I love my grab and go setup but I also feel like I need a higher magnification eyepiece since my current weapon of choice is my 4.7mm explore scientific 82 degree eyepiece which delivers about 90X magnification. I've almost always felt I could easily push magnifications to the plus side of 100X and the Nagler zoom 3-6mm is ranked very high on my wish list:) August this year marks the first year of owning the Skywatcher Evostar 72ED DS-Pro and I haven't had a moment where I didn't love it. The size of it is perfect and the supplied flight case for the scope is airline portable together with some room for accessories. The optics are very good even for decent planetary observing like it was the case this morning, and I feel like I haven't utilized the scope's abilities entirely just because I think it could take even higher magnifications. I have also used it for astrophotography on my star adventurer which yields very good results with the OVL field flattener and my old Nikon D3300.
This post ended up being quite long but I hope it was worth the read anyways. If you're considering the Evostar-72 I once again highly recommend it if you couldn't already tell from this post;)
Clear skies, Victor
By Cosmic Geoff
Following my effort of 22 June, being unable to lift anything heavy, I set up my lighter weight telescope in a different position from the previous night to get some images of Mars. This was the first serious use of my EQ-5 with Synscan upgrade. I set up the gear and left it tracking the assumed GoTo position of Jupiter for a couple of hours. At 2am, Jupiter was not within the 25mm eyepiece field. Not so impressive.
I repeated the imaging of Jupiter and Saturn, and also took images with the ZWO infrared filter. While slewing back to Jupiter, now apparently past the meridian, the mount did a meridian flip and ended up pointing at a street lamp. I was not impressed. ☹️
Eventually Mars emerged from behind an adjacent building, and I took images in IR, visual, and visual with a x2 Barlow lens.
Equipment: 127mm Maksutov 1500mm fl, ASI224MC camera, ADC, x2 Skywatcher Barlow, best 20% of 5000 frames (visual), processed in Registax6. EQ-5 Pro Synscan mount.
Key: Monochrome images were taken in infrared. Larger Mars image with Barlow. Mars was jigging about in the poor seeing by nearly its diameter (11"). Note: the hottest moon (Io, to left of planet) seems slightly brighter in the IR images. I think the 127mm Mak punches through poor seeing better than larger apertures.
By Cosmic Geoff
I recently had a minor chest operation which has temporarily left me unable to lift anything heavy, which has curtailed my astronomical activities. Last night, being clear in the late evening and early hours, seemed too good to miss, so I set up my 127mm Maksutov in place of the CPC800.
I had intended to image Mars as well, but discovered in the early hours that having set up in a different position to my 30 May effort, Mars was blocked by an adjacent building till dawn.
Equipment: 127mm Maksutov, SLT mount, wood tripod, ASI224MC camera, ADC, each best 20% of 5000 frames, processed in Registax6. The Great Red Spot should just be visible disappearing around the side of Jupiter. Part of the Cassini division is visible in the Saturn image. Overall these have not turned out too badly, considering the low altitude and poor seeing.
Few days ago I decided to observe the spectra around Na lines for Jupiter and Saturn. I had a little time and some problems with Bluetooth communication. It took me about 30 min.
About 3 am the sky was getting brighter. I set 20 μm slit of my Low Spec spectrograph along the equator:
These images were taken few years ago.
1, 2, 3 - positions of spectral profiles
The goal was to record the impact of planetary rotation on the shape of spectral lines. Interestingly, the spectra contain not only the inclined lines created due to the Doppler effect.
There are also visible vertical absorption lines of the Earth's atmosphere, there are quite a few of them.
Below two stacks of Na doublet area, resize 200%:
Spectral profiles for Jupiter:
Spectraf profiles for Saturn Rings:
The result of calculations of the rotational velocity at the equator and comparison with data in the public literature:
Result of calcutations Jupiter Saturn Rotational velocity 13.2 ± 1.3 km/s 10.5 ± 1.3 km/s Equatorial diameter 149890 km 128744 km Public literature Jupiter Saturn Rotational velocity 12.6 km/s 9.87 km/s Equatorial diameter 142984 km 120536 km The velocity of Saturn's rings is variable, the rings closest to the planet have the highest velocity, the furthest rings are the slowest.
The calculated average velocity based on the recorded spectrum is 15.8 km/s.
As an example, the velocity of the crumbs moving on the outside of the Cassini Break (ring A) is 17.5 km/s. Pretty close.
I took half a pixel as a measurement error.
Can't see that this has been flagged-up anywhere, but on on Dec 21 this year, Jupiter and Saturn will pass within 6 arcminutes of each other. Closest approach will be at 1300(UT), but UK sunset will be about 4pm and they will still be 8 degrees above the horizon an hour later.
Got to be worth a try!