Pleiades (M45) and Mars...

Conjunction of M45 and Mars

Object: M45 (the Pleiades or Seven Sisters), Mars

Type: Open cluster and planetary conjunction 
Constellation: Taurus

Date: March 5th., 2021
Equipment: ATIK 460EX with EFW2, Samyang 135mm lens @f2.8, Vixen GPDX mount, guiding with Lodestar X2/PHD

Subframes: 20 x 10s each for luminance, red, green and blue, flats, no darks (hot pixel removal in Astroart).

This image was an unplanned shot; I was attempting to gather 600 second subs for my Sh2-273 project, but clouds began to intermittently drift over, making long subs impossible. Rather than waste a rare clear, dark and moon/free evening, I swung the rig around to M45 and its conjunction with Mars. The planet is long past opposition but it was still as bright as nearby Aldebaran, and was only about 2 degrees from the cluster.  As it won't be this close to the Pleiades until March 2036,  I thought it was worth capturing.

The short and numerous exposures allowed me to reject the cloud-fogged ones. I was pleasantly surprised by the amount of cluster nebulosity captured given the very short exposure length.

Each of the R, G and B channels were stacked in Astroart, and a nasty gradient removed with the AA plug-in.  An RGB image was prepared in PaintShop Pro. No stretch was applied, but a mild Gaussian blur was used to smooth out the rather blocky stars (the 4.54u pixels are rather under-sampling at 135mm).

The luminance stack was similarly gradient-scrubbed then blurred, and star reduction applied in PSP (background selected with "magic wand", inverted to select stars, selection expanded and feathered by a few pixels, then "eroded").  A mild edge-preserving smooth was applied to reduce noise, and a selective mild stretch applied to bring up the Pleiades luminosity was applied.  This was then pasted over the RGB one in luminance mode to given the final image. 

Mars...

 

Mars, showing rotation over 90 minutes

Object: Mars
Type: Planet 
Constellation: Pisces
Distance: 45 million miles

Date: November 7th. 2020
Equipment: Phillips TouCam Pro, x2 barlow, Celestron C9.25, Vixen GPDX mount

Subframes: 15 images, each compiled from 1000 frames shot at 30 fps and aligned/stacked/wavelet processed in Registax v2.

The above gif is made from a series of images of Mars, and shows the rising of the feature of Martian geography known as Sirtis Major over the eastern limb of the planet over a period of about 90 minutes.

The evening of November 7^th was a foggy, soggy one, but Mars was very visible above the vapours and the evening represented one of the few opportunities I had to try and photograph the planet during its current opposition. 

Mars made its most recent close approach to Earth on October 6^th, when it was 38.5m miles away and appeared around 23 arc-seconds across in the sky. It won’t get that close again until September 2035, an event I am unlikely to witness. 

The closest Mars ever gets to Earth is about 34.5 millions miles and thus never appears to be more than around 25 arc-seconds across, effectively still looking like a bright star. Bear in mind that the full Moon is around 30 arc-MINUTES across and you can see how stupid social media stories of “Mars as large as the full moon” really are. 

Although a month past opposition, Mars was still a respectable 18.8 arc-seconds across and at magnitude -1.9, was brighter than any star and nearly as bright as Jupiter, which was setting in the west. 

To photograph Mars, I set up my old Celestron C9.25 SCT, and used an ancient (c. year 2000) Phillips TouCam Pro webcam as the image capture device. 

Planetary details are extremely small and views are constantly distorted by atmospheric fluctuations. Using a video camera to record 20 or 30 frames a second for a minute or so gives a bank of thousand or so pictures that can be processed by software (I use Registax) that selects the sharpest few frames and stacks them together to give a detailed result – in theory. In addition, Mars has a day that is about the same length as Earth’s and it therefore rotates quite quickly: a video longer than about a minute will suffer from blurring caused by the movement of planetary features as the planet spins on its axis. 

In practice, achieving a sharp focus on an image that is bouncing around your laptop screen like a demented ping-pong ball is a pretty tall order, and conditions have to be exceptional to get images that show much detail. This wasn’t one of those evenings, and indeed, I gave up at around 8.30 because the dew was dripping off of everything and was worried it would get into the electrics! 

Nevertheless, the individual processed image stacks showed up recognisable features when compared with the BAA’s Mars mapper…    

 

Mars at 19.30 compared to BAA map (click on image to enlarge)

My image shows a hint of the Martian phase at the time (97%) which is not shown on the Mars map above.

Mars and Saturn...

Mars has just passed opposition but is low down in the constellation Capricorn, rising to no more than about 12 degrees above my southern horizon. As a result of this, the combination of unsteady, hot summer air and atmospheric refraction makes conditions rather difficult for planetary imaging. Added to that, surface features on Mars have recently been obscured by a planet-wide dust storm, which is only just subsiding.

Nevertheless, I thought it might be worth trying to record a closer view of the baleful, dull red coal that is currently rising in my south-eastern sky at around 21.00.  Other than the moon, Mars is, at the moment, the brightest object in the night sky, with an unmistakable fiery hue that fully justifies its name of "the Red Planet".  Its magnitude is -2.7, but this will fade over the next few months as the planetary orbits open up the distance between us.

Mars, August 2nd. @ 23.15

This was taken using an old Phillips TouCam and a x2 barlow lens fitted to a Celestron C9.25.  The planet is too low down to be seen from my observatory so I set the scope up on my balcony, which offers unrestricted views to the east and south.  A one minute AVI file was taken at 25 fps and the output processed in Registax.

The southern polar ice-cap is just discernible as a lighter smudge at the bottom of the disc but other than that, surface details are just blurry blobs.

Similarly, I thought I'd have a go at Saturn, which passed opposition in June and is also low down in southern sky in the constellation of Sagittarius,  Although at a slightly greater elevation than Mars, (16 degrees at best at the moment), seeing conditions are just as poor.

Saturn, August 2nd. 22.45.

Set-up and exposures were as for the Mars shot above. Some planetary banding and the Cassini division in the rings are clearly visible, although again the image is blurred.