31.03.20 New AR

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Blogger is broken.

12.15 Now back to normal.

Tuesday 31st: Captured the new AR in White Light.
Then moved onto H-alpha.

SharpCap 1.66ms, Gain 161, 320fps, 800x600, 30% of 3000 frames in AS!2. ImPPG, PhotoFiltre7.



These images show variations of processing of H-alpha images.

These lower images have exceeded all common sense and have pushed the processing into art. There is detail hidden behind the captured mush but it doesn't look like a sharp image should.


The seeing is high frequency simmering bubbles overlaid on slow boiling movements.

I keep hoping for a late afternoon improvement in seeing conditions.


The snapshot image shows how fuzzy the original frames are that "lucky imaging" processing software had to work with.

The seeing is slowly improving.  Tried 20% of 5k frames.

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30.03.2020 Lunar:

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Monday 30th. The sky remained clear with a crescent moon high overhead. 

I left the D-ERF and internal protective filters in place for some lunar imagery.

8:00 Set up on the moon. Thank goodness the wind has dropped!

1.4ms, 320fps, Gain 395. 800 x 600. Mono8.
1024 x768 250fps. Gain 400. Mono8
640x480 400fps. Gain 400. Mono8.

8.35 34F in the dome. Captured lots of videos. Both SSDs full! Laptop full. Pack up for dinner.

Will post images tomorrow. The seeing looked good on the monitor. Even with the 2x WO Barlow and 640x480 frame. I was deliberately keeping the brightness low to avoid overexposing the brighter details.

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30.03.2020 PST Etalon tuning. New AR on NE limb!

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Monday 30th, 47/44F, The wind has dropped but there is rather a lot of cloud coming from the north east. The forecast is full sun later.

11:10 Already set up with the open etalon available for the full tuning range. Not enough sunny periods to do more than center and focus the 120MC camera so far.  

11:20 A bit more sun. Changed to the ASI174 Mono camera. Discovered there is no extreme range of etalon tuning. The tuning adjustment disk hits the top plate [with its negative lens] on the rise. Which limits the adjustment in that direction. Going downwards there is an obvious limit to compression when the torque required to tune increases rapidly.

There is a severe asymmetry to the brightness of the sun's disk. This changes with tuning but cannot be eliminated. It is also very dependent on frame size.

The next question is whether the etalon is optically symmetrical. Is there a best orientation? The sponge ring has left a slight surface mark on the etalon. So I, quite naturally, returned it to that position. Assuming that the factory deliberately chose that orientation after testing. Should I try the etalon in reverse? It takes only a few moments to reverse it. I might as well do it now. While I am waiting for all this cloud to clear the sun.

12:00 Marginally better surface definition? The images are with the reversed etalon 640x480 with 2x WO Barlow. SharpCap, AS!2, ImPPG & PhotoFiltre7. Cropped.

1215 Better images with cropping and enlargement for local detail.

12.35 Still lots of cloud with very brief sunshine. Another capture and deliberately sharpened.

14.00 48/43F Back from lunch. Cloud continues to tease but coming from the north east and east now. The forecast is for clear skies after 15.00.

15.00-16.00Continued to capture and process but the seeing wasn't very good. The wind has really picked up too.

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29.03.2020 PST etalon components.

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Sunday 29th March: Today I read the familiar description of how the PST etalon works:

The tuning disk [or visible arc] is rotated via the hidden drive screw. Causing the etalon to tilt. The tilt is what causes the change in tuning band around the nominal H-alpha frequency. 

There was the additional information about a block being added to the soft, orange, foam ring on which the etalon unit rests. So that pressure from above automatically cause the additional block to tilt the etalon against the soft base. 

My problem as that my orange ring has no additional tilting block. So how did turning the tuning ring cause the etalon to tilt? It was very obvious, in use, that rotation of the disk did change the tune of the etalon. But how was it doing so in my case? 

 I proceeded to completely dismantle my PST etalon unit. I was thinking that the etalon tilt must be applied somewhere else.

So, out came one of my well used Mitutoyo, vernier calipers and I proceeded to measure the depth of every recess in the housing looking for variations which might tilt the etalon.

I even removed the white Teflon O-ring in the compression/tuning plate and measured the thickness of that. It was perfectly symmetrical in thickness [minor diameter] all the way around.

So then I measured the depth of the recess on top of the re-inserted Teflon ring. No variation there.

The etalon glass sandwich certainly doesn't rotate. Though there is a coarse thread on the compression plate which presses onto it.

I measured the sponge ring thickness and it was identical all the way around. There is no obvious variation in density.

Could the sponge ring be sitting on a sloping bed? That would have a similar effect to a tilting block. It would not be impossible to machine a tilted bed using an advanced CNC machine but it wouldn't be easy.

How much etalon tilt is actually required? Could the angle be so small as to defeat my clumsy measurements? The wind has dropped overnight so I hope to do some real life trials on the sun. With the etalon open and available for continuous tuning in either direction using a suitable rod in the tuning disk holes. I suspect the tuning is a result of linear compression of the etalon gap. But this is pure guesswork.

 Extract_Lunt_Patent.pdf

 https://patents.google.com/patent/US7149377

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29.03.2020 Northerly gales!

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Sunday 29th March. Light overnight snow with fierce gales. Still blowing 35mph from the north in bright sunshine. It shouldn't blow into the dome itself but whether imaging is possible I shan't discover until I try. I will need my warmest clothing because I made the building as draughty as possible. Anything to try to reduce thermal effects from the sun. So, naturally, the wind whistles across under the observatory floor. Also up the open stairwell and around the gap in the cladding under the open, timber and plywood pier. 

The problem with my huge, pyramidal, pier design is when any ground floor storage bridges the gap between the pier timbers and the building itself. Gardening tools, offcuts of timber from the observatory build and other debris has tended to accumulate unnoticed. If the building shakes then the detritus can conduct those vibrations directly to the independent pier and thence to the telescope. Which is working on a very long focal length with considerable optical amplification of any movement.

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28.03.2020 Same prom. Another day.

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Saturday 28th. 28-43F. Hard white overnight frost. 

10:30 Early mist has finally cleared to sunshine.

10.47 48/45F Thermal shaking and displacement of image. First processed capture of 10 o'clock prominence. 640x480 plus 2x WO Barlow for increased image scale. [Right]

278fps, 40% of 3k frames. 3.6ms with max Gain at 400. For over-exposure to show the prom clearly against the background.

11.44 51/47F The seeing is getting steadily worse! The prom has flattened on top and extends a more obvious chain of clouds towards the north.

12.35 50F. Lunch.

After lunch I was commandeered as the token domestic lumberjack to tidy up an overgrown hedge. It was well after 3pm before I could return to my solar imaging duties. Seeing conditions now absolutely awful with lots of cloud crossing as well.

I had left the drives running over lunch because it ALWAYS, ALWAYS stops when it passes the meridian. At least it does during a slew of any kind. Not today! I returned to find the telescope on the north side of the pier facing south west. No damage done but I shan't ever trust it again.

At least the date and time are keeping track now that I have replaced the button battery in the AWR IH2 paddle. One remaining oddity is CduC/Sky Chart's habit of turning east into west for the observatory site. It lost longitude altogether today. As soon as I reset the correct easterly figure it promptly changed it to west! Grr?

Pointed the telescope at the lovely, crescent moon. It promptly clouded over from the north and was never seen again! 

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27.3.20 A tiny prom.

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Thursday 27th 50/46 [In/Out] sunny from a clear sky after an overnight frost.

10:00 Prom at 10 o'clock. Indistinct smudges north and south. First capture near southern limb. 800x600. 35% of 3k frames.

10:20 The "seeing" is steady but not very detailed.

10:40 More thermal, bodily movement of the image on the monitor now.

Very difficult to capture the small prom at 10 o'clock. Poor contrast again.


11:29  640x480 x2 WO Barlow and cropping in PhotoFiltre7  to produce a barely visible image of the prom.


12:20 56/51F, Have spent some time processing to try to improve on my original still image.



14:15 60/51F. Back after lunch. The prom continues to change. Resembling the smoke from a bonfire.

14:28 60/51F. Still capturing the prom with a 2x WO Barlow.


15:28 The prom changed again.




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26.3.20 PST etalon, tilt and tuning errors.

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While I was replacing the camera I noted a huge difference in the evenness of the lighting if I tilted the camera as it was inserted into the fitting. I was almost able to have even surface texture over the entire 1936x1216 maximum frame size. The images show the extent of etalon tuning error on image variation of brightness.

My tilting plate won't allow so much tilt with the standard thumbscrews. The whole thing soon locks up. It would require one set of  holes be opened out to allow tilting clearance and then longer tension screws fitted.

When square-on, half, of the image is too bright. The other half is fine. The real question is why the field of view is so asymmetrically badly lit and heavily biased to one side? It must be the etalon which is causing this. This can be checked by removing the rubber band and outer shell. Then rocking the etalon with a close fitting rod in a suitable hole in the inner, tuning arc.

I rotated the tuning band to find the most even surface texture. Then flexed the entire filter stack. To find that an even, full screen was almost attainable.

The PST etalon sweet spot is a well known characteristic. I can produce a dark ring or various other shapes of shade in the field of view simply by turning the etalon tuning band. By reversing the tuning band back and forth only slightly the dark ring shifts bodily right across the image. So there must be unwanted slop in the etalon adjustment. Or in the etalon's support system.

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26.3.2020 Temperatures at focus of 6" f/10 H-alpha telescope.

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12:45 53/50F. I removed the complete PST etalon and filter stack to check the temperature at focus. I was using the outdoor capsule of my Indoor/Outdoor digital thermometers.

With only the Baader D-ERF in front of the 6" objective the temperature went right off the scale! Over 65C or 150F. I drew smoke from the white, plastic coated, external sensor! So much for a cool optical train after a Baader D-ERF! I'll try the thermal "gun" with a thin, metal target immediately after lunch.

14:00 I found a 130C spirit thermometer in my collection. With the bulb close against some Scotchbrite, maroon, abrasive fiber, I reached 122C before my arms became tired. I was unable to register a high temperature with the thermal pistol on a small piece of black painted metal.

So I used the fiber as a target and held the pistol "muzzle" close against the surface with the fiber at a slight angle to allow the gun a clear shot without casting a shadow. It registered over 130C! 

After adding the two protective filters in series with the D-ERF I registered 47C maximum at focus. [2" Baader 35nm H-alpha and a Beloptik KG3 about 230mm inside focus.]

I allowed the filters to "soak" in the telescope while it tracked the sun for a few minutes and then measured 18C on the back of the KG3.

Using the Scotchbrite as a target while facing the sun, inside the dome, I measured 35C. Which suggests the fiber is quite a reasonable thermal target. Having low thermal capacity but useful thermal absorption. Ambient temperature in the shade inside the dome was 57F with 51F in the shade out in the open behind the building.

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26.3.20 AWR IH2 battery. Sun and light wind.

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Thursday 26th Only a light easterly wind today. Very little cloud.

I replaced the 3V button cell battery in the AWR IH2 paddle yesterday. I was sick of having to enter the date, time and Home [Set park] Sync every single day. It even forgot the date and time after a lunchtime switch off! So I did a battery swap for a new one. 

This involved removing  the screws from the back of the IH2. Then gently separating the two halves of the yellow body moulding. There was a multi-pin plug and socket on one edge inside. Which needed to be separated perpendicularly. 

Then the internal screen needed to be removed to get at the battery underneath. Two more screws and another multi-pin and socket underneath. I didn't take any photos but it was all very neat in there. The date and time had zeroed, without battery power, so needed to be re-entered via the keypad. Job done.

10:00 50/45F. [In/out] Set up for imaging. The AWR date and time had held overnight after the new battery was fitted. Zooming the 800x600 view in

SharpCap showed large scale, thermal "shaking" of the sun's image. This is reflected in the quality of the resulting image from the first video capture.

There are a couple of subtle darker patches on the southern surface texture and I shall attempt to capture those. I am still getting what I assume to be magnetic "threads" on the sun's surface in these images. Though the seeing isn't remotely as good as it was later yesterday afternoon. 40% of 3k frames in AS!2, ImPPG and PhotoFiltre7.

I have opened the door on the ground floor door to improve air circulation. The image quality did not improve as it had later in the afternoon yesterday.

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