LtE in CMO #273

From Eric NG

. . . . . .Subject: Re: RE:Reprocessed 20030522 Mars


Dear Minami,


Thank you for your kind email and thank you for your kind comment. In fact the images previously I sent were taken without IR blocking filters and each RGB channels were seriously "polluted" by the IR. The effect was even worse due to atmospheric dispersion that leading to the "ghost" IR on G and B frame. Attached image was taken this morning, seeing and transparency were poor. However, this one was taken with IR blocker and the RGB frames already improved a lot.


Actually, I have been discussing with Tan Wei Leong of Singapore and Damian of UK for the leakage of G to B for the Sony sensor used by ToUcam Pro. We are thinking of using interference filters for the ToUcam Pro. We will keep reporting our result to you, hope it works. :-) As the seeing is quite fluctuated in Hong Kong, it is quite hard to capture good and static images with low frame rate cooled CCD camera. We hope we can get the best way to obtain sharpest, beautiful and useful images!


Yes. The rush version of my 20030522 Mars seems over-processed and also the IR ghost may generate the "fake" details.


Kind Regards,

(27 May 2003 17:06:24 +0800)


. . . . . .Subject: 20030529 Mars observation


Dear friends,


The sky finally clear but very hazy. I have to gain 60% for 1/25 sec at F34. I split the Mars into RGB components so that you can review some features in different colour channels. The Solis Lacus is visible and the region of Mare Erythraeum and Aurorae Sinus can be seen near the CM. Nilokeras is bright. Some dark region on the south polar cap. No hints of dust activity on the image.


Please kindly comment.


(30 May 2003 email)


. . . . . .Subject: Re: RE:20030529 Mars observation


Dear Masatsugu,


Thank you so much for your kind and prompt reply. I always can learn the invaluable knowledge from your expert comment.


Yes. The blue channel is tailed in green so the B frames contains some signal of green though it is weak. But I would say the B frame after the IR blocked already quite close to the one taken through interference filter with cooled CCD. As you may know that the transparency was very poor when I was imaging in this morning, the hazy sky absorbed the blue quite much that leading poor SN of Blue. Also the thermal noise seems has effect on it (today 31 degree C). I will use the modified cooled ToUcam Pro shortly.


We will try our best to tackle the B frame problem. We are testing some different method with Wei Leong. Will show you the result. heheh. As I am not that experience in describing Mars, all my comment is in newbie tone. ^_^ I compare my image with the Mars Map and I just found the region between the Nilokeras and Niliacus Lacus is light. I am not sure whether I am correct or not.


I just got my 12.5" F6 mirror. The setup will be completed in mid June. I will move to my rural observing site for 3 months Mars observation where the seeing is much better than my home roof in the center of city. Now I only have 45 mins for imaging Mars as it is being blocked by the high rise building which is as high as 45 degree from horizon.


(30 May 2003 10:11:02 +0800)


. . . . . .Subject: 20030530 Mars in this morning


Dear friends,


Attached was the Mars image taken on 20030530 this morning. Both seeing and transparency were poorer than yesterday. I had to gain 80% at 1/25 sec with ToUcam Pro. I needed to stack 1000 frames out of 1700 to achieve acceptable SN. I tried the B-(GX0.3) method introduced by KUMAMORI and found that it did help very much in aligning the RGB components and no visible dispersion effect after realignment. As the B frame contains the some G signal, so the blue colour fringes usually appear out of the north edge ... After applied KUMAMORI's method, the misaligned blue fringes will align back with R and G which is actually the detail of haze hood above North polar region. Thanks the information by Damian.


Minami, my image is not high resolution enough. Seems the dust storm you have mentioned is not visible well in my image. Please kindly comment,


Clear Skies,

(31 May 2003 08:04:43 +0800)

. . . . . .Subject: Another 20030530 Mars


Dear friends,


Here is the image taken at 20:39UT. The seeing was slightly better. Meridiani Sinus is visible near p. limb. SN ration of blue frame is especially poor due to low transparency


Minami, the dust streak you mentioned seems better shown in this picture.


Kind Regards,

(31 May 2003 14:43:48 +0800)

. . . . . .Subject: Re: RE:20030530 Mars in this morning


Dear Minami,


Hehe. Thank you. The sky will be clear in coming few days but just will be very very hazy. I will try my best to obtain good result.


Kumamori's method is the way I can do better before I get the interference filter for getting better Blue. We will keep posting the results to you. I would say if I used cooled CCD for today situation, I believe the Mars would be blur and no details visible on the Globe.


If the transparency is good, I believe the B frame would have better SN. Let's keep see the result. Moreover, Wei Leong and I are waiting for the interference filter.


(31 May 2003 16:12:05 +0800)


. . . . . .Subject: 20030531 Mars in this morning


Dear friends,


The sky continues clear, but it also continues bad seeing and poor transparency due to the strong easterly air stream is affecting south China coast. The worst thing is quite strong wind occurred while imaging.


Attached is the best one I could captured from a dozen of avi recorded. The CM is similar to the one I posted yesterday. The image was stacked with 500 raw, so it appears a bit noisy.


The dust streak is barely visible and seems moving towards Solis Lacus region. May someone kindly comment on it. Polar hood is visible and the limb brightening is not as obvious as previous two days.


Clear, steady and high transparent skies.

(1June 2003 email))


. . . . . .Subject: 20030601 Mars in this morning


Dear friends,


The sky condition is similar as last night. I tried using F42 by increasing the back focus of CCD sensor to the barlow lens. I found there is a yellowish streak near the region of Aurorae Sinus ... I am not sure whether it is the same dust streak as the one taken by Maurice and me respectively on 29 June. It is visible on both the red and green. The limb haze and NPC hood is beautifully shown on B frame. I have compared the recent images and it do shows the changes of the limb brightening and the polar hood.


Hope the seeing and transparency can be improved as I hate such noisy image. :-(


(2 June 2003 email)


. . . . . .Subject: Satisfactory 20030602 Mars in this morning


Dear friends,


This morning the seeing and transparency were better. I took some Mars shots and attached is the one I am quite satisfied with it. The image was taken at F34 and I resized to 160% after processed. The transparency is still not very pleasing and through the eyepiece, mars appear quite orange tone. Some cloud features can be found on "B" frame.


The most interesting is the dark region of SPC. You can see some detail on it and it seems the surface of Mars inside ice cap is visible. May some other kindly comment on the image.



(2 June 2003 email)


. . . . . .Subject: Reprocessed 20030602 Mars


Dear friends,


I have reprocessed the 20030602 Mars that I posted earlier. This time I separately process the RGB components. For the B frame, seems the wavelet filter reduced the brightness very much for previously version. So this time I use weaker processing for it.


May I seek your comment on this version as I would like to refine my processing.


Kind Regards,

(3 June 2003 email)


. . . . . .Subject: 20030604 Mars


Dear friends,


Seeing and transparency are similar as 2nd June in this morning. I was able to capture some shots. This one was captured at 21:24UT. This time I increased the Focal Ratio to F42 (approx). As the transparency is not pleasing, the image appear a bit noisy (80% gain) after processed. Seems high focal ratio is better be used under high transparency.


The AM limb brightening is well shown on the image and the NPC hood is smaller. The SPC is very bright and some region is saturated. No visible dust activities detected


It will cloudy and raining in coming days until early next week in Hong Kong according to the weather forecast, I can take a rest already. :-) Hope I can get well prepared to meet the Syrtis Major region.



(5 June 2003 email)


. . . . . .Subject: Another 20030604 Mars


Dear friends,


Here is another 20030604 Mars. Seeing was not as good as the one sent earlierThe Syrtis major with haze can be seen at the p. limb. The GAMMA setting for this image is too high so limb darkening looks too contrasty. Moreover, transparency during this shot is not good so I used F34.


Kind Regards,

(6 June 2003 email)

. . . . . .Subject: 200300617 mars (good seeing)


Dear friends,

Finally the sky was clear last night until this morning. Not only the seeing was good, the transparency improved a lot too!!! (compare with the one taken on 4 June). This time I used the Baader UV/IR Blocker instead of TrueTechnology one. The transmission of the visible wavelength is 98%.


As I was quite rush to back to office this morning. After selected and stacked the avi, I was lucky to see Damian is online in my ICQ list. He is so kind to process the composite raw I sent to him. Such joint effort is really great, both of us appreciate it very much.

As Wei Leong pointed out toucam + IR blocker, the results is no obvious difference with the restricted bandpass 400-500nm and 600-700nm by using magenta filter. Therefore, I preliminary stacked the one without magenta filter in this morning. I shall process another one with magenta filter with RR(G)B or R(G)B and see the results.

It seems there are some yellowish (dust?) clouds above the Hellas at the AM limb.

Please kindly comment on it.


Clear Skies,

(18 June 2003 email)


. . . . . .Date: Thu, 19 June 2003 15:34:47 +0800

From: Eric Ng <>

To: "M. Minami" <>

Cc: Damian Peach <>,

Tan Wei Leong <>

Subject: Test result of Magenta filter for Mars imaging


Dear Minami,


During the imaging section on 17 June, I have taken some shots with Magenta filtered for cutting out 500-600nm bandpass according to the method suggested by Weileong and Damian. The image contains no 500-600nm signal. I have processed one of the shot taken with it. I am attaching it for your reference. This one the (G) is the average R and B. From the raw image, you can notice the serious atmospheric dispersion of R and B. Here is the link contains the idea and concept of Magenta filtering for Mars imaging with ToUcam by Weileong and Damian peach.

As the ToUcam Pro CCD sensor too mix in RGB channels which is your major concerns for Mars. The attached image is for your comment and advice. I am not sure whether the result is satisfied or convincing. Your invaluable experience surely vital to our trial in this experiment.

I will keep reporting the test results in coming imaging section. Many Thanks. BTW, many Hong Kong observers appreciate you and your colleagues' effort in maintaining CMO. Really great effort!!!

Cheers and Kind Regards,


. . . . . .Subject: 20030618 Mars


Dear Friends,


Attached image was captured at 20:51UT. The sky was no cloud but lower transparency compared to 17 June. Seeing was fair. UV/IR cut added, RRGB combined.



(20 June 2003 email)


. . . . . .Subject: 20030619 Mars


Dear friends,

Last night sometimes cloudy and clear near sunrise. The transparency was bad (Yellow moon with the halo). Luckily still be able to capture the relative steady moment. The captured time of this shot is same as the 20030618 I posted. I am waiting the region where has the orographic cloud a few days later.



(20 June 2003 email)


. . . . . .Subject: 20030617 Mars (joint effort)


Dear friends,

Attached is the 20030617 Mars image stacked with Szeto's and mine. What a coincidence that we captured Mars at same time in Hong Kong at different sites respectively. It allows us to joint effort for further improve the image quality by combining our image together. This is the practical method to stack more images within the time window limit of the optical instrument for improve S/N ratio.


Quite interesting. Please feel free to comment.


Clear Skies,

(20 June 2003 email)

. . . . . .Subject: 20030622 Mars in this morning


Dear all,


Attached please find the Mars images taken in this morning. Seeing was very fluctuate and clouds were keep rolling across the sky. The orographic clouds near the AM limb.



(23 June 2003 email)

. . . . . .Subject: 20030623 Mars


Dear friends,

Attached was the Mars taken on 20030623 at 21:00UT. Some problem for the mounting so that only captured a very few shots. :-( ...Olympus nix can be seen near the PM limb).



(24 June 2003 email)

Eric NG (Hong Kong)

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