Author Archives: Andrew Thornett

Cross-polarised views of mosquito larva from pot pond

For the last few weeks, I have created myself a garden pond in a large plastic pot about 80cm across and similar height. Today, I noticed a large population of mosquito and other larvae.

I sacrificed one of these larvae today to view its structure under crossed polarisation on my LOMO Polam P-113 polarising microscope.

I had read online that muscle shows up on crossed polarisation. Certainly, the photos below show birefringence which might be muscle.

I am particularly pleased with the photo at the bottom. I managed to work out how to use layers in GIMP2 and change relative transparency between the layers and consequently combine the bright field and crossed polarisation images so that you can see where the colourful polarised tissue is located.

Andy

Bright field view of larva, x3.5 objective:

Crossed polarisation views x3.5 objective mosquito larva:

Combined bright field and crossed polar image:

The strips of birefringence follows down the side of the larval body. The photo above this one shows this follows the organism around. From http://www.sciencephoto.com/media/74993/view/mosquito-larva-light-micrograph, it would appear that this represents muscle bundles down the side of the insect.

Crossed polarisation of salt crystals

The following salt crystal is seen using x20 objective on LOMO Polam P-113 Polarising Microscope.

The crossed polarisation images required a lot longer exposure on my Bresser Mikrocam 5.0 MP microscope camera and this has shown up a lot of hot pixels.

So, for the first time ever, I took a dark frame and subtracted it from each image using PIPP software (Planetary Imaging Pre-Processor, https://sites.google.com/site/astropipp/)

You can see the effect below – it is quite dramatic!

The following is from

https://www.hamptonresearch.com/documents/product/hr007641_cg101_salt_or_protein_crystals.pdf :

“A protein crystal, unless it is cubic, will typically be weakly birefringent under cross polarizers. Salt crystals are typically strongly birefringent under cross polarizers. Some plastic plates and materials are also birefringent so this test is more easily performed and interpreted in an all-glass environment or in a plate made from a low birefringent plastic.”

The initial photos show birefringence but I would not describe them as highly birefringent…..that is until you get to the 11x objective photos at the bottom of the post – now that is a highly birefringent salt crystal!

Andy

Crossed-polarisation image x3.5 objective (dark frame subtracted in PIPP, cropped and changed to greyscale in GIMP2). The salt crystal shows birefringence:

Bright field image, x20 objective:

Crossed-polarisation images before dark frame subtraction in PIPP, x20 objective:

Same fields of view as above but this time after dark-field subtraction using PIPP, x20 objective:

x11 objective, post subtraction dark frame with PIPP – for some reason the salt crystal on top right is particularly highly birefringent (below):

Site of the Peter Bolas Observatory 27/5/2018

Heather told us all on Friday night that building of the new Peter Bolas Observatory at Rosliston Forestry Centre will start soon. It has taken such a long time to get to this point. The family and I (Hannah, Ean Ean, and Rhys) felt this was a good time to record what the site looks like prior to the start of building for prosperity!

The observatory is going to be build on the corner of the archery field near the bird of prey centre and next to the tree trail and large sundial, and not far from the café and seminar room.

Andy

Observing Log 26/5/2018, LRO, Lichfield, UK

Observing Log 26/5/2018, LRO, Lichfield, UK, Andy and Damian.

Damian came around to my house and he demonstrated that the iPad Air 2 that he owns works with my older SkyFi wireless box on my Synscan EQ 6 mount – important as I need to upgrade my very old iPad and have been considering what is the best option to replace it. Earlier today, I had great difficulty getting my Windows 10 laptop to link to it, ruling out the option of a windows-based tablet.

The sky is quite bright tonight with a virtually full moon. For a bank holiday Saturday, the main A38 is quite noise at this time of night – unexpected. Also, it is very windy. Thunder predicted later in the night. On the positive side, Damian is having a whale of a time playing around with his laptop controlling the mount whilst I write this!

ISS (ZARYA), Satellite in Ophiuchus,26 May 2018, 23:22:36, Just watched the ISS rise over my house and brighten greatly as it rises higher until it was a spectacular sight near culmination and then slowly fade as it moved to the east.

Bode’s Nebulae – Messier 81, Spiral Galaxy in Ursa Major,26 May 2018, 23:43:23, Took two attempts at alignment to get scope working well tonight. This is often the case. I have read online that it may be due to backlash when the user must fiddle back and for with the controls to centralise alignment stars, causing errors to creep in. Second time lucky today! M81 proved that alignment had been successful by appearing in the centre of the field of view. It only appeared as faint smudge with brighter nucleus – and looked smaller compared to our usual view, again demonstrating the poor sky. Currently, we are using my Explore Scientific 14mm 100-degree field of view eyepiece.

Hercules Cluster – Messier 13, Globular Cluster in Hercules,26 May 2018, 23:49:41, Top left of view of field so not quite spot on re GOTO but is putting objects in field of view of 14mm eyepiece tonight.

Whirlpool Galaxy – Messier 51, Spiral Galaxy in Canes Venatici,26 May 2018, 23:50: 39, which means that the fact that we could not see this pair galaxies demonstrates again the poor sky quality as we would expect to see it with this scope from this location.

Messier 92, Globular Cluster in Hercules,26 May 2018, 23:51:35, Seen but difficult to resolve stars similar to limitations in our view of M13 – I think sky is not transparent even though can’t see the cloud easily.

Ring Nebula – Messier 57, Planetary Nebula in Lyra,26 May 2018, 23:52:44, Better view but higher in sky. clear Outside app suggested 68-90% cloud by midnight – not that from here but still there is something obscuring view, suggesting the app has identified correctly deteriorating sky conditions.

Double Double – Epsilon1 Lyrae, Double Star in Lyra,26 May 2018, 23:54:44, With 14mm eyepiece we can just about split each of pairs.

NGC 6229, Globular Cluster in Hercules,26 May 2018, 23:57:31, Visible without too much difficult. Mag 9+ so surprising we can see it but prob as high up. This is a globular that we rarely look at – in fact, I can’t remember seeing it before. Not a bad one – recommend folks add it to their observing lists!

Kuma – Nu1 Draconis, Star in Draco,26 May 2018, 23:59:52, Lovely bright easily split double – to me looked like white and yellow/white stars, about same brightness.

Cat’s Eye Nebula – NGC 6543, Planetary Nebula in Draco,27 May 2018, 00:01:04, In Draco too, easily seen as out of focus star.

17 Draconis, Double Star in Draco,27 May 2018, 00:02:55, To me this double star looks like blue white and yellow white pair.

100 Herculis, Double Star in Hercules,27 May 2018, 00:04:03, A little known and little seen double star pairing, Sky Safari says – but we saw it tonight!

Omicron Herculis, Variable Double Star in Hercules,27 May 2018, 00:05:39, I could not split this even with 6mm Ethos, but it did not appear round but oval suggesting the double. These are 0.1 arc seconds apart, so we were asking too much of the scope in this sky to see this.

Nu Herculis, Variable Double Star in Hercules,27 May 2018, 00:10:55, Could not split this either – 0.5 secs.

(With all these double stars, we feel like we are following IN Nick’s footsteps!)

b Herculis, Double Star in Hercules,27 May 2018, 00:12:50, Can’t split this either tonight – 1.4 arc seconds.

Mu Herculis, Double Star in Hercules,27 May 2018, 00:15:31, these stars are 35 arc seconds apart according to Sky Safari app in the iPad. To me, the second one is much fainter than the primary component – easily seen pairing.

Sarin – Delta Herculis, Double Star in Hercules,27 May 2018, 00:20:26, Strange that we could not see this double star at all, even after checking the alignment of the mount to ensure that we were pointing at the correct location in the sky. Possibly the reason we can’t see it is that the sky is deteriorating. It is starting to feel like rain soon and the sky has a varying tint across it which suggests high moisture content and formation cloud. We will try to view M13 again. That will be a good test of sky conditions….

Out last object we viewed tonight: Hercules Cluster – Messier 13, Globular Cluster in Hercules,27 May 2018, 00:23:20, We could just about resolve some stars but not a great view. Time to pack up.

Andy

Bright field vs. Crossed Polarisation filters of slide cultured in pot pond at LRO 27/5/2018

LOMO Polam P-113 microscope.

Microscopy forum posts discuss using polarisation to view microscopic slides of pond life – apparently it can be quite spectacular! Well, my observations today were not spectacular but I had some success – see below…

Andy

x11 objective, bright field – a piece of pond weed (below):

This is the most successful observation today. The above field of view after introducing crossed polar filters (below, showing bi-refringence in the plant material) (x11 objective):

The following is a little weird – bi-refringence at the edge of the cover slip! (Below, again x11 objective):

However other parts of the slide do not show bi-refringence, such as this collection of material (below, x11) – bright field followed by crossed polars (there is a tiny amount of bi-refringence only at the lower right):

I had hoped to get more luck at higher magnifications – here is a slide at x20 – crossed polars followed by bright field (below):

LOMO Polam Fossiliferous Steinheim Impact Crater Lake Bed Miocene crossed-polarisation using LOMO Polam microscope

LOMO Polam Fossiliferous Steinheim Impact Crater Lake Bed Miocene crossed-polarisation using LOMO Polam P-113 microscope.

Andy

x11 objective:

x20 objective (panorama of 15 frames) – two fossils present with birefringence in crystals in the matrix in which they are embedded: