Thursday, August 30, 2007

20070830 Vesta and Jupiter Conjunction

Magnitude of Vesta ~= 7.2

Angular Seperation ~= 0.373 degrees (at 17.2 GMT, Jupiter already set, so expect wider seperation)

Simulation by KStars at 2030 (GMT+8)

Borg 45ED II with reducer should be able to keep both in the same field of view with my DBK, however, the compsition might not be optimal, the Cosmicar 150mm f/3.2 might be better, and I think I will need some trial and errors.

Let's see.


I could see Jupiter while going home, but after I setup my gears, I couldn't see Jupiter except on the monitor if I pushed the exposure very highly, no Vesta could be detected. So, I waited.

Cloud cleared up at around 2130 (GMT+8), observation is done with a Cosmicar 150mm f/3.2 C mount lens, gain is 463, exposure is 5.761s, 18 frames, 2134 (GMT+8):-

Then added a 1.4x teleconvertor, zero gain, exposure is 4s to minimize overexposure of the Jupiter, 18 frames, 2138 (GMT+8):-

13.749s exposure, 0 gain, only got 8 frames before cloud rolled in.

2140 (GMT+8):-

Fun, I would say. Finally, a simulation from KStars at 2136 (GMT+8), the ugly yellow mark is roughly the same as the size of the overexposed Jupiter disc:-

The Cosmicar lens and the DBK camera:-

Tuesday, August 28, 2007

Total lunar eclipse

The weather seems bad at least up to this moment. Funny is that, Hong Kong Observatory (weather centric) has already moved tonight's total lunar eclipse to the page of "lunar eclipse of the past", somehow showing that it's already a past thing, not to be observable tonight at all. :-)

With me, I just got my 12x zoom DC. I didn't bring any scope or mount for the chance to see it would be very small, added to the fact that I'll be having class tonight, I only got a very short time window to observe it before going to the class, and I will be engaged in the class for most of the time, maybe I can take a shot if the weather permits during the break?

Anyway, no high hope indeed.


Additional remarks on 29th morning:-

I didn't see the moon at all last night. Before the class, we have some cloud gaps around but not to the direction of the moon. During the break, it's fully covered and then it even started to rain after the class.

Some local folks managed to capture a few shots during the partial phrase with very narrow cloud gap, so Hong Kong is not really blessed in terms of astronomical observation.

Sunday, August 26, 2007

20070826 Sun

Cloudy day, the sky is all white, cloud are running along, no hope to take any image originally, but later I found stacking can somehow average out the cloud!

This is the raw video, we have not only cloud but also bird....

This is the stacked image from the above video:-

Taken at 1532 (GMT+8), Borg 45ED II, SM40/BF10, DMK 31AF03. We got AR969.


DMK and DBK compared, I mean physically. They're identical essentially.

The looked very much the same from outside, the DBK has a 1.25" nosepiece attached. When I bought mine, they didn't come with 1.25" nosepiece, but AFAIK, it comes as a standard item now.

My DMK is way lighter than my DBK for unknown reason.

Can you tell which is which? The one with bigger imaging area is the DMK, and the one which generates colorful reflection due to the Bayer matrix is the color chip DBK.

From the side, very similar in appearance. Notice that the ring on the imaging port is a CS to C mount adapter, C mount and CS mount are identical except the difference in back focus which can be made up with a simple ring as shown here. They come standard with a DBK/DMK.

Newer model has longer mounting plate, DMK on the left and DBK on the right.

At the back, they're the same, nothing but a 6-pin 1394 port.

Friday, August 24, 2007

On DSLR again

It's always tempting to buy a DSLR for astronomy and some low light snapshots. Starting from the launch of 300D, I was thinking. The file is nearly closed with the discovery that 400D is a bit too noisy for astronomy purpose. With the re-launch of 350D, the file is open again but then it's only available as kit, that makes the decision more complex. And now with the announcement of 40D, the problem is even more...

First of all, 40D is not going to be very good in terms of noise, I expect it's slightly better than 400D at most, but it comes with live preview. Live preview should be pretty nice for astronomy purpose, and the new one from Nikon also supports live preview and I believe that it will become a standard feature after one or two years.

In terms of noise, it's closely related to the pixel density, but it seems like it's growing without stopping, that's the real trouble. I mean if you want to wait one or two years for live preview, you're going to get a sensor with heavier noise due to the pixel war.

The current best choice should be:

kit lens for daily snapshots (forced)
EF-S 10-22mm for milkyway and natural scene
EF 200mm f/2.8 for star field

really need to plan for the solar eclipse next year, should make the purchase within 2007 to make myself experienced before going.

Sunday, August 19, 2007

20070818 Half hour of lightning

Half hour of lightning is "compressed" into ~20s, each subframe is 8-12s long and played back at 30fps. My Cosmicar 8.5mm is out of focus, need to adjust it. Not exact astronomical, so it's more like a equipment testing.

Taken by my DBK 21AF04.AS mostly with Cosmicar 8.5mm, part of the video is taken with Fujinon 25mm, both at around f/12.

20070819 Sun

Nothing special about the sun, the big prom were gone. Seeing quite good at 5-6/10, transparency is very low at 1-2/10. Foggy white sky. All taken with SM40/BF10, Borg 45ED II, DMK 31AF03 at prime focus.

1510 (GMT+8), colorized:-

1511 (GMT+8), prominence only:-

1512 (GMT+8), original black white:-

As an record.

Saturday, August 18, 2007

20070818 Monster size prominences!

And a lot of bird too, the typhoon from Taiwan is bringing a foggy day for Hong Kong, transparency is like 1/10, the sky is all white but you can still see some deep yellow sun light when the cloud is thinner. Seeing 2-3/10, typical. Don't now why there're so many birds flying around today, maybe due to the far away typhoon?

Let's see the birds first:

first one:-

second one, keep looking at the 4-5 O'Clock location:-

Now, back to the sun, SM40/BF10, Borg 45ED II, DMK 31AF03 at prime focus:-

1446 (GMT+8):-

1457 (GMT+8):-

1458 (GMT+8), colorized:-

Now, the monster prominence, taken with the same setup as above, but with 3x barlows:-

1501 (GMT+8), 1/15s at 15 fps, highest gain without overexposure:-

1504 (GMT+8), slightly lower gain when compared as above:-

1507 (GMT+8), 1/8s exposure, 7.5 fps to allow lower gain at the expense of fewer frames to choose/stack:-

1512 (GMT+8), 1/8s exposure like above:-

1513 (GMT+8):-

Tuesday, August 07, 2007

20070807 Jupiter

Transparency was like 6-7/10, seeing was 6/10, C5 with DBK 21AF04.AS, 3x Tele Vue Barlows for f/30 and 5x Tele Vue Powermate for f/50.

2155, 2157, 2159 (GMT+8), f/30:

2209 (GMT+8), f/50:-

Maximum gain was used at 1/15s (to maintain 15 fps), still underexposed. It's more like a practise of f/50 for the coming Mars opposition.

Hirsch f/6.3 SCT reducer arrived

It's on my desk this morning when I back to work, I was off duty yesterday.

It comes with a thick black paper box (typical), and a piece of lens cleaning cloth, no end caps. The lens sit inside a very well machined cell, pretty much the same as my old Celestron model, it also comes with a rubber grip, very nice.

The 41mm lens comes with deep greenish coating, very uniform and without any defect, high quality and nicely applied. On the cell, it marks "HIRSCH f/6.3 SCT Reducer/Corrector", no "made in XYZ" or any other indication.

If you asked me, I would say it's from the same factory of those well known brands. But since there is no "made in Japan" there, I'd guess it's more like a clone, a very well made clone.

I got it from ebay, the price including shipping is less than a 2nd hand one from astromart or any other place. It's more than 40% off from the new one from Celestron/Meade.

Visual testing and photographic testing pending.

1. C5 with f/6.3

I was so lazy not to test this combination. The NGF-S was attached to the C5 and thus I was lazy not to remove it and reattach it just for testing. Jupiter was there on the sky so I prefer to take images rather than testing equipments.

Do it later.

-- Finally "later" comes --

3 sets of blade measures 13.91 with reducer in PS, and 16.54 without, so the reduction factor is 13.91/16.54 = 0.84x

It's done with the reducer sandwiched between the C5 rear port and 1.25" visual back.

2. Borg 45ED II with f/6.3

Since the NGF-S was with the C5, this scope has no focuser now and it's too short to reach focus. Therefore, I've attached the reducer to the 2" visual back via a 2"->SCT adapter, and then I use a 2" SCT visual back after the reducer and to connect to the eyepiece. It could reach focus without problem, the field of view seems sharp, but the magnification is too low to tell the quality, also, terrestial targets are not suitable to really test the optical quality.

Since I was to shoot Jupiter, I didn't even measure the effective reduction factor, too. Preliminarily, I would say, with a 1/4" to 1/3" CCD, there should be no problem. However, the real question is a DSLR - for if I were to stay with small CCD, I'd rather go for a f/3 reducer instead of this one.

-- Some more test --

When the NGF-S is attached, the whole system will only reach focus when the reducer is sandwiched between the focuser and the 1.25" visual back, even the 2" visual back won't work. There's insufficient in-travel by a hair. Field of view is noticeably wider.

Monday, August 06, 2007

Equipments lineup for the coming camp

It's a 2-day camp for the youngsters in the church, we will be around in southern Lantau Island which is pretty dark in Hong Kong. The moon shows partial phase and will set soon after sunset. Jupiter will be sinking rather early.

Since visual observation will dominate, I suppose I shall use my C5 for the deepest possible sight. It's also not bad for wide field scanning with a 40mm Pentax XL, even there's a bit vignetting, but the field size is still like 2 degree.

For the mount, if I take my TG-SP II, it would provide chance for me to take images if I also take my DBK/DMK + Sony Vaio but there will be no GOTO. If I take my DSX mount, there will be GOTO but there will be no imaging. I believe early night would be spent with them for visual observation, so GOTO would be nice.

I suppose that I shall not leave the kids alone to take images myself, so I'd rather take the DSX, time to test if the DSX can support the C5 for higher power. And how long the battery would last.

Saturday, August 04, 2007

Field of view test of C mount lenses

First of all, it's not a quality check for the lenses since I shot with long uncleaned plate glass window :-)

Cosmicar 8mm:-

Fujinon 25mm:

Fujinon 75mm:

Cosmicar 150mm:

It's also a day time test of the "Casio UV/IR blocking filter", auto white balance is used.

20070804 Solar

Seeing 2-3/10, transparency 7-8/10, Borg 45ED II, SM40/BF10, DMK 31AF03:-

1450 (GMT+8), at prime focus:-

1452 (GMT+8), at prime focus again, different T-max setting:-

A 3*2 mosaic, taken from 1456 to 1500 (GMT+8), Borg 45ED II with 2x barlows:-

Variation of seeing conditions render the non-uniformity of sharpness across different pieces, poor day time seeing is making is really hard to do. Anyway, just keep trying!

Friday, August 03, 2007

20070803 Jupiter by Tele Vue Ranger

My Ranger has a special relationship with me, it's my second scope but it's actually my real first scope, I mean it's the scope which I really use, and really got me involed in this hobby.

Tonight my daughter has been slow in playing piano so that I couldn't start imaging before the Jupiter sinked too low. But I told myself, why not try my Ranger with my new DBK? So, here is this session.

Tele Vue Ranger with extension tube instead of the diagional which otherwise required for reaching focus, Tele Vue 5x Powermate, first shot without UV/IR block, second shot with, manual white balance... auto white balance couldn't be used for the chromatic abberation really confused its algorithm!

2244 (GMT+8), without UV/IR block:-

2249 (GMT+8), with UV/IR block:-

The result is quite similar, originally, I think the UV/IR block can help to reduce the purple halo probably also due to UV/IR other than only chromatic abberation, but I found it's not very much so.

Finally, I took away the camera and have a look through the eyepiece. The 20mm Japanese Widescan Type III render nice image with the 5x Powermate, my eye is more forgiving for the CA than the camera. I then switched to use a 7mm Japanese Ortho without the Powermate, the image is nice, too. However, for unkown reason, I preferred the 20mm + 5x view a bit more.

A big heat sink

Found a really big heat sink with fan, that one is for CPU... the heat sink looked very effective both for its material, design and size. However, it's just very heavy.

To keep a camera on with just a small set screw in a 1.25" focuser with a small nosepiece, if that big heat sink is added, I'm sure it will drop suddenly without warning.

So, it's not really feasible.

However, I think if the whole thing is used with c mount lens, i.e. the camera is fixed by itself to the mount directly, I guess it's okay... If I were to keep myself under 150mm which is my longest c mount lens, it will work.

The bigger heat sink idea comes with the fact that my existing smaller heat sink/fan is not enough to keep the Peltier module cool at 12V, keeping a seperate 6V power supply is troublesome, and the cooling effect is not very good at only 10 degree below ambient. Let's see.

Thursday, August 02, 2007

20070802 Jupiter

Transparency was quite good at 8/10, seeing at 1-2/10 at first and improved to 3-4/10 sometimes, not bad for planet imaging. C5 at f/30 at first, add a short extension tube for the last few shots , DBK 21AF04.

2138 and 2140 (GMT+8) respectively, f/30:-

2146, 2148, 2151, 2154 (GMT+8), 3x barlows with a short extension tube:-

Planning for the upcoming Total Lunar Eclipse

Local moonrise time will be 1842 (GMT+8), so no shot is possible before that.

I'll need to attend a class on 1930 (GMT+8), so no shot can be taken afterward, except maybe during the break, but no extensive setup could be done, hand held snapshot is all that will be possible, and I don't think the break will be given before 2023 (GMT+8), so no need to take this route.

So, my observation/imaging window will be from 1842 to 1930 (GMT+8), adding the time for me to tear down the setup and going back to school, I can only do it until around 1910 (GMT+9) at most! A complete red moon can be acquired before 1922 (GMT+8), so within the time window, I can actually only shoot the red moon.

However, since the moon will only appear from the horizon at 1842 (GMT+8), so it will be still in pretty low in the sky even at 1910 (GMT+8)! I think I will need a find a pretty high location or any place which can clear the east. The moon will be pretty dark, I wonder whether rough polar alignment is enough to take it....

Altitude: 8.4 degrees at 1922 (GMT+8), rise to 21.5 degrees at 2023 (GMT+8), so basically no chance.

Not very optimistic. Therefore, I guess I will only take my Konica Minolta Z5, even don't bright a tripod.