20070331 Solar Observation

It's very cloudy, but there were a lot of small cloud gaps so that I could capture some shots, but since cloud was moving in and out, and thus, they couldn't be processed properly, so I instead, I posted the video:-

1343-1345 (GMT+8), 3 short AVIs combined together:-



Tried to stacked the one at 1343, uneven illumination is due to moving cloud:-



Finally, a prominence shot, this can be done since we can simply overexpose it and then we will have prominence frame, unlike surface detail which must be correctly exposed, 1346:-

20070329 Borg 45ED II Saturn

Saturn is hanging outside my window, but in a very poor angle, I added a long platform plate, mounted a 410 head on the far side and then put my Borg 45ED II there so as to catch it.

The setup:-


My DMK is operating at 1/4s at medium to high gain, barely enough signal, at 3.5 fps.

Seeing was okay, at around 6-7/10, transparency was pretty low at 3/10.

~1000 frames captured.

67 frames selected and stacked:-



Realigned and re-stacked, ~600 frames:-



I call it key chain Saturn, for it's small enough as a key chain.

PST blocking filter and BF10

This morning, I did a very simple comparison of my BF10 (comes with Solarmax filter) and the blocking filter from the PST.

Some people said PST blocking filter is basically a BF5, yes, in terms of aperture, it really is, but the normal BF5/BF10 has two parts mounted in the nosepiece of the diagonal and the visual back side. My friend told me that the PST blocking filter has the same thread as the visual back part of a BF10, and I believe the similarity ends here. I mean the PST blocking filter has only part of a regular BF10/BF5.

I hold them side by side to my eyes on terrestial objects. I found a BF10 is basically opaque, I mean it cuts a lot of light so that regular terrestial objects are not bright enough to be shown after it. However, the PST blocking filter has quite high transmission, one can see a lot of things with it in front of your eyes. I feel it's more like a deep sky type narrow band H-alpha filter! It can filter out the harmonics left by the etalon, but it does not block a lot of light.

Then, I hold the PST etalon and PST blocking filter in front of my eye, to look at terrestial targets again, and I can still see basically everything clearly. That means this combination does not indeed cut a lot of light!

This simple experiment strengthens my idea that this combination is going to work behind a Herschel Wedge, what I mean is, Herschel Wedge should be able to act as a very scalable ERF for the PST etalon and blocking filter combination.

If that ever works, the problem will then be focus travel issue. My Borg 45ED II is going to work without problem, but my Ranger, or Sky90 is not going to work, since with the Herschel Wedge alone, all the back focus were used up with only 1 few millimeters left so that there would be no room for a PST etalon and blocking filter.

PST etalon adapters

Photograph of a PST etalon module, rubber band removed:-




The two sides have the same thread size which is M50*1, one side male and one side female. Therefore, the PST golden tube can be screwed into the PST black focuser body directly without the PST etalon module, that indicates the thread size is identical.

In order to use the PST etalon module as an internal module, the following adapters have to be made:-



One of the adapters is to allow it to attach to a 1.25" focuser, that side is originally attached ot the PST golden tube, facing the objective.

The other adapter is to make the other end (originally attached to the PST black focuser body) to accept 1.25" eyepiece or any camera with 1.25" nosepiece.

There two adapters should be able to screwed to each others without the PST etalon module, by then it will become a 1.25" extension tube, with a fat body. Since the male thread side of the PST etalon body has a protruding part, if PST etalon modules are to be double stacked in the future, empty tube with M50*1 thread should be made to connect them together despite they have identical thread.

The whole chain of adapters with the PST etalon will eat up 7.2cm+ of back focus.

[Additional Remarks on 30th of March: adapters are being made... I guess they will be available after my trip]

Last night, we also found that older version (orange objective) and newer version (blue clear objective) PST etalon modules are not very identical, they looked so at the first glance, but if you hold it towards a bright light source, the old version will show very clear newton rings but the new version will not, we don't know why, however.

PST disassembly (DONE)

Finally success! I went to a friend's home and he did it with me, basically, it's not the problem about insufficient force, but it's because we didn't have tool to fix the black part in place, tonight we use our foot and our body weight to fix it, and a "slight" turn make it.

Here're the results:-

A PST without all the important components, i.e. the etalon and the blocking filter:-


The etalon module:-




I was told the thread size is "M50 x 1mm ISTR", sounds good.

Making parallel ray for Solarmax 40

If a 70mm f=500mm objective is used, we can place a 40mm aperture f=-286mm lens at around 214mm behind the objective to get parallel ray.

The outcoming parallel ray will be around 40mm in width.

If my simple calculation works, that would be a good afocal lens system for the Solarmax 40.

--

Reverse engineering:-

PST lens to etalon = ~210mm
Aperture of the PST lens = 40mm
Aperture of the afocal lens = 20mm

40 / 20 = (210 + x) / x

~ x = 210mm

Therefore, focal length of the afocal lens = -210mm

And from the black box, I believe the focal length of the rear lens should be around 150mm, with the etalon to lens distance = 100mm + 50mm from the prism to the visual back, it should be slightly more due to the longer optical path of the prism, but the difference is not very much due to the small focusing prism.

[Additional Remarks on 29 March: I guess that I've enough reason to say that the design assumption for the above calculations were probably wrong]

PST etalon module idea

1) should make a 1.25" interface for it, so that I can use it with my Herschel Wedge

2) measure the focal length and optical characteristics of the afocal lens system, see if one can be made for SM40

3) a 2nd hand Borg 125ED would be the ultimate tool if the Herschel Wedge idea works, by then even the C5 can be sold for the 125ED is both light enough and large enough, should be better than using the Cheapy-ERF both in terms of safety and elegance... I found an old 2nd hand one cost 10K HKD, which is very nice indeed... but that depends on luck!

4) shall also made a 1.25" interface for the BF5 of the PST, to fully utilize them

5) so three parts to make: [1] 1.25" interface for PST etalon [2] 1.25" visual back for PST etalon [3] 1.25" interface for PST BF5... also to consider how to make a cell for Cheapy-ERF

20070325 Short Observation

Just back from a nearby playground with my daughters.

Got several minutes of cloud gap, took some H-alpha shots, Borg 45ED II, SM40/BF10 at prime focus, part of the aperture was blocked already:-

1713 (GMT+8), exposure optimized for surface detail:-



1714 (GMT+8), exposure optimized for prominences:-



1718 (GMT+8), cloud rolled in, got only a few frames to stack:-

2007030324 Borg 45ED II Herschel Wedge

And 20mm Widescan Type III, the sky is very cloudy, until 17:21 (HKT), I got a peek in cloud gap (thin cloud indeed).

No time to setup anything, just hand held.

Zero sunspot detected, cloud in front of the solar disc is 3D!

20041123 A moon shot without record

Didn't know which scope, where, no idea. Just an image in my hard drive, together with an AVI:-



The date is just a record from the file system. Anyway, just a record, better than simply throw it away.

20070320 Misty Sky

The sky remains bad. We can see trace of sunlight through pretty thick cloud. Got a chance to take some images today since I got an annual leave today.

CaK revealed a boring sun, contrast further washed out by the thick cloud and moving thin cloud:-



H-Alpha does not give anything, too. Pushing up the exposure does not bring up any prominences:-





Zero detail on the surface too, due to poor contrast as a result of the cloud.



Just a record.

20070319 Partial Solar Eclipse

It was raining this morning, the floor is still wet, but we got some thin cloud gaps, I managed to get some shots, already very much satisfied.

My setup:-



It consists a Borg 45ED II equiped with JMI NGF-S on a Gitzo G106, with 410 head... it's the minimal setup since I hate to take everything out to end up in a big failure. For solar filtering, I got my APM Herschel Wedge with me, also those ND3 and Polariser (didn't used), a Baader CaK, and finally, a piece of cloud for filtering with my Konica Minolta Z5 (danger!). For simplicity, I also bought my ToUCam Pro (color) for my notebook does not have 6-pin 1394 port which is needed to power my DMK.



The location is a small playground near my home (3 minutes walk), I also took my little daughter Almy to go as well, but later went with my housemaid to another place since that park is all wet and she couldn't play.

So, let's go to the pictures, belows are all taken by my KM Z5, with no filter except cloud, I took these shots when it's too dim to be taken with my ToUCam Pro with Herschel Wedge, time is in HKT (GMT+8):-

While Waiting:-



0944 first shot of the day:-



1000:-



1014 wider field to get a little bit more context:-



1017 wider field, and you can click for full size for this one:



1026 end time:-



Finally, to end the DC shots and go to the ToUCam Pro shots through Borg 45ED II, we have a shot taken by the DC target on the LCD screen, taken at 1021:-



ToUCam Pro shots through Borg 45ED II, Herschel Wedge for white light and for the blue shots, with Baader CaK added:-

Really really bad news.... I was spoiled by the IC Capture of DMK, forget to rename the filter everytime for a new clip, so the result is, I only got one clip, and it's after the partial solar eclipse.



Luckily, I still got the above, otherwise, none.

Bad weather persists

Bad mood, indeed.

Coming Solar Eclipse

There will be a partial solar eclipse in the coming Monday morning here, but the weather forecast is very bad. Let's see.

The last observable (meaning not cloudy) solar eclipse was more than 10 years ago.

DIY USB Battery Box

Preface: USB is now very popular, not only as a data transmission and peripheral control standard, but even as a power supply, things like fan, cup heater, light, vacuum cleaners, etc are available. I found that it's nice to have USB power (i.e. 5V DC) anywhere so that we can charge up our devices, and to power them, in case a notebook is not always very convenient.

Some mounts like my TG-SP II is driven by 6V DC and thus USB can even serve it, and when a notebook is not available, such a USB power box would be useful. It can even re-charge a mobile phone or other devices with rechargeable batteries.

These kind of battery box is available at $59 HKD (7.7-7.8) or as high as $15 USD in ebay. It's pretty expensive for a simple battery box with USB socket, and so I come up with an idea to DIY, here's the information that we need for DIY, however, do it at your own risk:-



In order to provide power via USB socket, we need to give ~+5V (1) and ground (4) according to the pin-layout as above. So, the next question is, where can we find a USB socket. USB extension cable immediately comes to my mind, but that could be a real waste. I searched around my drawers and I found some PS/2->USB mouse adapters lying around, useless, then I know they're what I wanted, and then we will want to know its pin-layout as well:-



Very simple, right? So basically we're just connecting the +5V of the PS/2 plug (4) to positive terminal of a 4AA battery box and the ground (3) to the negative terminal. In order to play safe, we need a multimeter to check if the connection is correct, and to check the polarity of the USB port of your PC:-



Then, it's time to do the hacking and soldering job. I found removing the outer sleeve of the PS/2 plug would make the job far easier. Unused pins can be bended, or removed to avoid unwanted contact. If power is provided to the unused pin, most probably data pins, undesirable results could occur, or even damage the device, so be careful.



And here's a final product, not very beautiful but quite elegant. Testing could be done with a cheap USB hub first, instead of using your expensive device.



Finally, I tested it with my phone and it proves the DIY work is correct. Since USB port has 5V, and so it's better to use AA rechargeable so that the total voltage will be 4.8V, instead of 6V is your use alkaline batteries.

After all these work, suddenly I realized that maybe we can simply made a simple power plug for the AA battery box to provide power to a USB hub? Will the USB hub then provide power to the USB ports cleanly? I think yes, but I didn't try. That would be a cleaner solution to the problem. Anyway.

Takahashi TG-SP II

This is a very interesting mount indeed.

As you can see from the above picture, it's about as small as a German Equatorial Mount (GEM) can be. Actually, you will need to provide a wedge in order to make it work. Typical GEM has built-in lattitude and azimuth adjustment for polar alignment, but the TG-SP II has none and it relies on your camera tripod or a wedge to archieve polar alignment.

From the above picture, you can also see that the plate for the attachment of the counter weight shaft is optional, that means if you only want to use it with a small camera with a small lens, you can actually use it wihout a counter weight. In this configuration, it's about perfect for overseas star field shots.

It's motorized only in RA axis for tracking, DEC adjustment can be made manually with a very smooth slow motion knob of typical Takahashi quality. Since this mount is mainly for long power purpose, DEC adjustment might not need required at all, I mean you're going to limit yourself on wide field unguided shots of under 200mm, or better yet, around 100mm.

More accurate polar alignment is hard to do, but a Manfrotto/Bogen 410 Junior Geared Head is going to help. TG-SP II has an optional polar alignment scope, but I found it hard to use and not accurate indeed, so I didn't buy it.

The main purpose of my TG-SP II is to allow me to take wide field shots, and at the same time, allow me to do solar/lunar/planet imaging with my Philips ToUCam Pro as well as my DMK 31AF03 firewire camera.

It has enough capacity to take a Celestron C5 for planet/lunar imaging, and I suspect even a slightly larger model, like a C6 will do. For solar imaging, I mainly use a PST or my Borg 45ED II with Coronado SM40/BF10 which are both very light weight.

With my current lifestyle and my collections of scopes, this mount is the best I can get.

Disassembling PST (cont')

I've bought a large clamp to help the disassembling, the belt clamp couldn't provide enough grip, but I found that I was wrong, even this clamp did not quite work out.

The problem is on my arm, leg. I step on the black PST body to fix it in place, and rotate the PST etalon with the clamp, but I found foot/leg is not strong enough to fix that. Then I put the black body in a gap between my furniture and begin to turn it, however, it still didn't rotate. Even both arms are used.

I've even tried to place that black part under heavy furnitures, and turn with the clamp, but it still didn't move a bit.

Let me see if I have any further way.

See some photographs below, it's quite heavily scratched, I avoid using excessive force, for I think this might hurt the etalon:-



Close up:-

Disassembling a PST, first night

I had school yesterday night, but I still got a short moment to try out my belt wrench.

The wrench is not as powerful as I imagine, or better said, the PST required far stronger torque than I imagine to unscrew!

On unscrewing, the black body of the PST serves a very good function: you can lay it flat on a chair or table or whatever, and then step on it, and use the other hand to unscrew with the belt wrench! After one or two minutes struggling, the golden tube is loosen and then I can use bare hands to unscrew the rest. Some red "screw" glue can be found on the thread and that explains why it's so hard to turn.



I even tried to unscrew the etalon module from the black body, but I ran out of time and also force, my arm was feeling weak and so I called it a pause.

Now, the blocking filter/visual back is removed, the extension tube before the visual back is removed. And the objective along with the tube is removed from the black body. The last thing to do is to remove the etalon from the black body.

The optical window on the etalon module is pretty large to my eyes, it measures ~2cm with a ruler. From my understandings, this optical window is part of an afocal lens system to make sun light parallel again before passing through the etalon. Therefore, it does not mean to be the size of the etalon.

The black body should contain the focusing prism, which is spring loaded to the focuser knob. And it also contains the sun finder, which I think, is pretty good to use. Maybe I will find a way to re-use it somehow.

Once the etalon is detached, I shall find a local friend to cut down the original tube to be inserted into 2" focuser, and to machine a 1.25" visual back to allow the BF10 to be attached on.

On the other hand, here's a drawing of a cell mounting to my mounted Cheapy-ERF, which is indeed a filter for an aerial camera:-



Here's the Cheapy-ERF:-



I have also inspected the rusted objective, I found it's really pretty opaque. I've looked through an objective of a new clear blue PST objective before, and this one is really way different.

--

The second night is hard night, keep unscrewing with the belt wrench, but in vain after ~30 minutes, very tired.

Removed some allen screws from the black body, but two remained in place, the hexagonal pattern is somehow distorted, might not be able to remove them easily.

PST modification stage 2

Previously I imagined that I will leave my rusted PST intact for a couple of weeks before diassembly, but after the testing on last Saturday, the rust seems affecting the performance much by dimming the image by several factors (20x difference in terms of required exposure time), so I'd rather do the modifications first, to fully exploit its potential.

I just bought a belt wrench during my lunch break today, it's slightly more costly than I heard from local friends, but I assume this one should be of better quality. I'll try it out tonight to see if unscrewing the parts could be an easy job with it or not.

First step is to unscrew the tube, second step is to unscrew the etalon from that black body. I shall see if a 1.25" tube would be enough to cover the etalon, and then how the 1.25" visual back should be made. Finally, time to make a better illustration about the solar filter cell as well. It's simply a piece of relatively thin metal sheet rolled around the existing cell, and to add thumb screws to fix it on any telescope objective.

Really no need to wait for April as originally planned.

For indoor remote usage, I think a deep red 52mm objective filter will make my Borg 45ED II as the replacement OTA, let's see.

False color for H-alpha shots

People asked about how to make color from monochromatic image of the sun. Here're the steps which I usually do:-

1. Adust the level of the whole picture as you would do in any picture, astronomical or not, solar or not, to maximize the usage of the whole dynamic range

2. Adjust the level, this time only blue channel. Push it all the way to the right, around 90% to 95% depending on your preference

3. Adjust the level, this time only the green channel, observe the histogram, push it to the point where it peaks

4. Adjust the level, finally, only the red channel, only minor tweak is required to get good color, again up to your own preference.

That's about it. You might also want to adjust the curve a little bit to bring out some more subtle detail, especially when you're shooting with a non-double stacked system.

20070304 Solar

Could see the total lunar eclipse due to thick fog and cloud.

First shot of the sun is by Borg 45ED II at prime focus, 52mm IR pass filter on objective, APM Herschel Wedge and ND3, DMK 31AF03:-



Second shot is taken with 2x barlows added:-



IR pass filter removed, exposure reduced from 1/30s medium gain to 1/1241s and zero gain:-



ND3 removed to replace with Baader CaK, exposure is now 1/736s:-

- for some reason this clip is corrupted and lost.

2x barlows replaced by 5x powermate, exposure is now 1/77s:-



The result is pretty encouraging even at ~f/41.

Finally, c5 + baader visual film, prime focus, CaK, exposure 1/8s, medium gain... cloud rolled in, in the middle of the capture, only ~500 frames available and thus noisy:-



Baader visual film is too strong for CaK usage, even at f/10, it's far dimmer than my Borg 45ED II at f/41 with Herschel Wedge.

20070303 PST First Light; Comparison of PST, PSM, and SM40

AR944 is the only more apparent tiny active region.

First two by PST alone, 1/30s low gain:-

1237 (GMT+8), monochromatic:-


1239 (GMT+8), false color:-


Third by PST + SM40, very dim image, 1/15s with medium gain.



Some more surface detail can be revealed, no doubt it's an improvement but the rust is preventing it to go to full potential.

Forth is by Borg 45ED II + SM40/BF10, 1/736s with zero gain, so it:-



It shows that the PST rust is very opaque when we compare the exposure time, you may refer to earlier entry of this blog for a shot of the objective. Bandwidth is well maintained for the amount of detail surprised me actually, so the etalon is in perfect condition, indeed.

On the other hand, some white patch and some small filaments can be found in the PSM shots but not apparent and absent in the PST only shot, double stacking really helps.

Fifth is by APM Herschel Wedge + Polarizer + Baader CaK, Borg 45ED II:-



Sixth is like the above with Borg 45 ED II replaced by Ranger, this time I used a purple color scheme and push the contrast slightly higher than before:-



Next is like the above with 2x barlows, contrast really pushed during processing to bring out more detail:-



Since the Herschel Wedge is already in place, I shall really at least taken one shot. Finally is like the above but in White Light (ND3), notice that white light is far more affected by poor seeing condition than H-alpha and CaK:-



White light, again, is the hardest thing to take, most affected by seeing condition, you see how ugly the contrast and detail here.