Astrophotography – equipment

Warm Astronomy – first attempt.

So, the clocks have gone back, the dark evenings are here and (when the clouds and rain leave us alone) there’s some great stargazing to be done. Within reason I’m quite happy to get my thermals on and put up with a bit of cold to enjoy the show, but I also like to share (inflict?) my hobby with my nearest and dearest and my chances of getting them outside in this weather for any length of time are pretty slim. Over the summer I’ve been good friends with eBay and have picked up some bits and pieces to enable me to bring the hobby indoors.

The kit I’m using is: HEQ5 Mount, Skywatcher 130P-DS, ZWO ASI224 Camera (with an LP filter) and a laptop running Cartes du Ciel (I know lots of club members like Stellarium, but my geriatric laptop doesn’t!) to control the mount, SharpCap to run the camera and TeamViewer to control the laptop remotely (I tried using Remote Desktop, but Windows wasn’t having any of it).

First chance to use it came up on Sunday night- full moon or not! Altogether it took about half an hour to set up (hopefully this will drop with practice). Pictures below show the setup (complete with frost) and then images of what we could see in the session. Whilst we were running I saved the captures and later stacked them along with a dark stack (not sure I’ve got this bit right) and did a histogram stretch- these are shown alongside.
Altogether, it worked well- both being able to easily show images and the novelty of pointing at something on screen and then images of it appearing a minute or two later. Some friends popped over and they were quite taken with being able to all see it at the same time and discuss rather than taking turns at the eyepiece and being unsure of what they were seeing.

The brighter objects were certainly better- the targets we looked at were:
Albireo – right image is 15 x 10s exposure.
M57 Ring Nebula – right image is 15 x 30s exposure.
M27 Dumbbell – right image is 30 x 30s exposure.
M15 – Globular – right image is 35 x 30s exposure.

Gain was set to 300 throughout. I also tried the Double-double, which became the Single-single and M81 which just came out as a blob- I think this and the Dumbbell might work out better with a bit less moonlight. Overall it was a really successful evening- the setup time is a bit of a pain compared with the 5 mins it takes to set the Dob up (and that includes making a cup of tea!), and it lacks the magic of finding it yourself and seeing with your own eyes. But for sharing with others it’s brilliant, and later on I even managed to get my month-end books done with the scope still on which made that task less of a drag than usual!

Oh- and thanks for the earlier post in the blog about using old storage boxes to protect your laptop/shield the light from its screen- worked a treat!

 

Observing Log Friday 27/10/2017 7-9:30 pm

The forecast was correct, clear skies, a chance to used the skywatcher ST102 bought earlier in year and only used for solar work so far. ( see pic.1)

I started under the carport ,as moon was not visible from back garden, not quite first quarter, used it to complete lining up red dot finder, took some getting use to smaller image after the 8″ Newtonian or the 9.25″ SCT. When at IAS I bought a smartphone adapter to take afocal images using the wifes’ new smartphone, now was on opportunity to try it out, pic.2 shows adapter and phone, pic.3  image of moon, notice the chromatic aberration, however visually it was not noticeable. The image was taken with a 30mm plossl eyepiece with this 500mm focal length refractor this gives a mag of x17. The crater marked with a red dot in the centre is Ptolemaeus, at slightly higher magnifications the centre of crater appeared to have horizontal bands across it, is this an artefact, blemish on objective/ diagonal?? at a mag of x83 (6mm plossl) all was revealed there were shadow bands from the peaks on the Eastern crater wall, the wall reaches heights of 3000m (9000+ ft) and with the sun relatively low on the moons horizon the peaks cast some long shadows, it was fascinating watching the shadows shorten even over a relatively short period of time , Liz had taken her phone back, so I have attempted a sketch of the shadows cast over the crater floor ( see pic.4),  the floor is relatively smooth, having been flooded with lava, some very minor impact craters formed since, the darker shading on the west is due to floor slumping towards crater wall. This was the first time I have seen such marked shadows on a crater floor formed by the crater walls, shadows from central  peaks are usually observed and just blanket shadow from the wall, the continual changing of relative positions of sun and moon makes the terminator a dynamic visual environment, there is always something new to see, even in one evening.

I then relocated to the back garden, starting in the SW with Albireo in Cygnus, the 10mm plossl  ( x50) clearly showed B1 cyg ( Alberio) as a orange red K class star and B2 cyg B class blue star. Taking a line down to zeta Aq from Albireo, bisecting the line from Vega to Altair, just slightly left the Coat hanger asterism fell neatly into the field of view using a 40mm plossl ( x12.5) , normally I would use binoculars for this target, but the wider field of view afforded by this small refractor enables it to be seen in its entirety. Up into Lyra,aiming between Sulafat and Shellak to locate the Ring Nebula ( M57), fuzzy ring but no hint of central white dwarf in this planetary nebula. Continuing west into Hercules M13 and then up to M92, even with 6mm plossl ( x 83) not a lot of detail. Better with the double cluster in Perseus and as I headed to M31, Andromeda galaxy the cloud had rolled in bring the session to a close at around 9:30.

It was nice to get out with some clear skies and I found the AZ3 mount that came with the ST102 easy to use and manoeuvre and although the refractor shows some chromatic abberation as shown by the photograph of moon , visually it was not noticeable enough to be a problem.

here’s to more clear skies!!!

Pete H


Scale for focussing tube

Hi, it’s useful to know the focussing position especially when imaging and using different combinations of filters/ lenses with the camera, although my sky watcher 120 Evostar has a graduated Crayford focuser, the newly acquired ST102 doesn’t, so rather than replace the rack & pinion focuser with a calibrated Crayford I managed to source some transparent adhesive scale tape, which I have attached to barrel, after cleaning the area with some isopropyl alcohol, its still on but have yet to put it to use. The tape was relatively cheap, and I do have an excess of repeating 40cm lengths, so if any one fancies adding a scale to their focussing tube get in contact.

 

Pete Hill

Solar – Mikrokular with or without barlow?

One of the reasons I like the Mikrokular is that it is full HD. It should therefore stand more magnification before being limited by pixels (the PD and Toucam are 640X480). So as an experiment, I took the last solar image I posted, cropped out the “no barlow” part including the prominences, desaturated it, re-sized it by 200%, “unsharp masked” it slightly, and set it alongside the X2 barlow version for comparison.

Although I think the barlow version is better, there is not much in it! (Just look at the prominences detail, not the disc)

Sun in a new Light – Cak

Using recently acquired skywatcher ST102 refractor, see above with collapsible dark box and shroud.  Along with a Baader CaK double stacked filter 390 – 398 nm covering both CaK 393.7 nm and CaH 396.85 nm I managed to image the sun in Ca k.

The filter was attached to a DMK41 mono CCD camera with a x0.5 focal reducer to enable whole disc imaging.

 

The CaK filter needs an energy rejection system to be used on scope, it comes packaged with 3.8 OD Baader film, but a Herschel wedge can also be used.

Other CaK systems like those available from Lunt contain both Cak filter and energy rejection system, hence the cost.

I missed the early morning activity recorded by Nick and Roger and by this afternoon there was little prominence activity according to Gong, so I just concentrated on Sunspot AR2670, imaging using CaK filter and the Baader 590nm Contiuum filter.

Whole disk in White light, continuum filter.

Whole disk in CaK, showing Plages

Colourised CaK whole disk.

 

Left white light image without x0.5 focal reducer.

Centre CaK without focal reducer.

 

 

Below colorised Cak

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

With x2 Barlow (below), smaller image white light. Trying to dodge between clouds meant that the sun was getting lower during the session and subsequently I was imaging over my neighbours roof and the garage roof, started to get lots of atmospheric wobble. However I was reasonably pleased that different detail could be imaged with the CaK filter, couldn’t take H alpha (656.78nm) at same time as I’d used the vixen rail I normally attach it to, to mount the ST102 on the HEQ5. Compare the rese CaK images with Rogers H alpha.

The white light image shows what is happening on surface of suns photosphere, the observeable surface at 5500k, H alpha shows what  is happening in the chromosphere, the layer above the photosphere where the temperature rises to 50000K at its upper level. CaK images show what is occurring between the upper photosphere and lower chromosphere.

At 393.37 nm CaK is not visible to eye , in fact there is a lot of UV being passed, not good for the eyes, so this filter is for imaging purposes only.

Future activity will compare Herschel wedge / Baader film combinations with CaK filter and comparison with H alpha images from Coronado PST.

Pete H


Nice All Sky Camera timelapse

Hi Folks,

Here’s a nice little timelapse from a few days ago, edited using a free bit of software for windows called Shotcut (https://www.shotcut.org/). It’s a bit like Windows Media player and VLC player but it allows you to export a speeded up video, which is very handy

This one is effectively running at 60fps and was a timelapse recorded on my All Sky Camera with iSpy recording at 1 frame per minute over about 6 hours, although, I’ve cropped this much shorter as it was getting light

It’s quite nice as you can see the Plough moving down the screen, and the after about 20 seconds you’ll see Cassiopeia coming in at the top right near the tree . You can also faintly see the Milky Way moving down the screen after that.

I think for a cheap DIY camera it’s not bad

Ed Mann

07802 350187

ed.mann@btinternet.com

A Challenge to the Quarkers out there – – –

To quote Holmes: “When you have eliminated the impossible, whatever remains, however improbable, must be the truth”

I have been musing over my recent post concerning the apparent lack of fine detail on my solar images (https://roslistonastronomy.uk/h-alpha-question-puzzle). While they are comparable with other LS35 images I have seen, and with GONG images, they do lack the fine detail you sometimes see in other published images. I am not 100% convinced it isn’t a stacking artifact, but setting this aside what else could it be?

Daytime observing suffers from atmospheric turbulence big-time, and you need a fast shutter speed to reduce this. I wonder if I simply have not got the sensitivity to employ an appropriately fast speed.

Simple optics would inform me that a Quark with an 80mm scope has the potential of being at least 2 stops faster than my LS35, everything else being equal.

So, the challenge to the Quarkers – I know that there are at least 3 of you out there, and one of them at least (mentioning no names, Andy), has a Mikrokular, the same as I use:

Can you get finer detail than I get using a fast shutter speed? Simple stacking is likely not to help, as the images you stack will be slightly displaced due to the turbulence, thus blurring the final stack.

 

 

NASA salute A.S.B.O successful installation with flypast!

NEWS FLASH – Wednesday 24th May 2017

NASA scientists can be seen here celebrating the success of their latest endeavour…

It was all systems ‘GO’ at A.S.B.O Headquarters last night as final checks took place for this historic event:

The site was deemed clear for operations around 9pm

Due to cables on-site, all Perimeters were secured from any invading – ‘Andrews!’ > CHECK!

Comms > CHECK!

Visuals > CHECK!

Data storage > CHECK!

At 00.58am BST, A.S.B.O picked up the link and the NASA ‘flypast’ commenced……. the ISS (plus some stray plane getting in on the action – possibly the RAG Chair flying back from ESA) !

Pass took over two minutes, the movie is speeded up x4

The ISS passed through Bootes (Arcturus to the left) and headed through Hercules and just north of Vega in Lyra before comms cut-off.

With thanks to Heavens-Above, below !

Damian ( a pyjama clad ‘Operations Director’ at A.S.B.O)