LtE in CMO #289

FromChristophe PELLIER

 


. . . . . . . . .Date: Sun, 29 Feb 2004 15:58:02 +0100

Subject: Jupiter, february 28th -29th 2004

 

Hi all

These images are the "return" of the 7" newtonian - I was tired of the low-contrast images given by the C14. Seeing was quite good. The NEB is becoming more disturbed at those longitudes maybe...

With a shorter focal length, an UV image can be recorded with this little instrument (4 mn - 180 x 0,5 sec.)

Best wishes

 

. . . . . . . . .Date: Mon, 1 Mar 2004 21:19:56 +0100

Subject: Jupiter, march 1st 2004

 

Here are some images from last night - fair conditions only. Note that the big bluish region in SEBn/EZs is coming into view on the following limb (IR images).

 

Best wishes

 

PS I'm still getting some images on my last e-mail - please be certain that you use my new email address

 

. . . . . . . . .Date: Tue, 2 Mar 2004 23:04:24 +0100

Subject: Jupiter, march 2nd 2004

Hi everyone : last night seeing was good. I have split the data into three sets because there were many images.

Best wishes

 

. . . . . . . . .Date: Sun, 7 Mar 2004 17:27:14 +0100

Subject: Jupiter, march 6th-7th 2004

 

Hi all

Last night, good seeing degrading with the time. As a curiosity, I have made an image at 1 micron wavelength - I have recently purchased an IR 1000 filter to image Venus, but I tried it also on Jupiter. There is a methan band at 1000 nm and the image does seems to behave more or less as a methan one : EZ and GRS are a bit bright, while the SEB and NEB remain dark... Used on every day objects the amount of light given by this filter seems to be equivalent to that of the UV filter, but surely due to this absorption band it was much more difficult to use on Jupiter.

Best wishes

 

. . . . . . . . .Date: Tue, 9 Mar 2004 20:46:20 +0100

Subject: Venus march 1st and 8th

Hello :

Two more set of Venus images - poor seeing on march 1st but good on the 8th. In the UV images of march 8th, note the famous "psi" feature near the venusian limb. I have tested the IR 1000 filter on Venus for first time (exposure 1/33th (UV 1/50th)), but the result look disappointing. The three IR images do seem to show the same details (of incredibly weak contrast), like for example a dark patch to the left of the center with a white spot over it, but the IR 1000 apparently brought no improvement in terms of contrast.

Best wishes

 

. . . . . . . . .Date: Wed, 10 Mar 2004 18:47:39 +0100

Subject: Re: Venus march 1st and 8th

 

Frank, yes it's clear that IR is less interesting for Venus - however Galileo imaged some details in near IR when it passed Venus - I'm not talking about its thermal IR images. However the precise wavelength is not indicated on the images, and I don't know if it's before 1 micron or

after...

For the CH4 filter, it should behave for Venus exactly as any near IR filter!!

 

. . . . . . . . . Date: Wed, 10 Mar 2004 19:07:45 +0100

From: "Christophe Pellier"

To: "JULIUS BENTON"

Subject: UV imaging for SCTs

 

Hello Julius and all,

After the very first UV images I have made with the C14 of my club, several osbervers did not believe it was UV because of the correcting plate. They were thinking about an IR leakage instead. However I think that near UV images is definitely possible with an SCT, I have tested this on Venus, Jupiter, Saturn and Mars and it was relatively easy. Also see Antonio's past UV images of Jupiter with his former 10" and Damian recent UV images with his C9.25. Surely some light is absorbed, but not enough to make this kind of observation uninteresting with an instrument with a correcting plate...

Possibly, the UV absorption by glass is strong only before 350 nm, but anyway due to the very low CCD response before this wavelength the majority of the recorded UV belongs to the band 350-400 nm and there is no problem.

Regards

 

----- Original Message -----

From: "JULIUS BENTON" <jlbaina@msn.com>

Sent: Wednesday, March 10, 2004 12:40 PM

Subject: RE: Venus, March 8, 2004

 

> Thanks, Tom, for your images.

> 

> I am doing some studies now to determine just how much UV transmission

> occurs through corrector plates of SCTs, etc. Several observers have

asked

> about this, and it would be interesting to know more.

> 

> Regards,

> 

> Julius L. Benton, Jr., Ph.D.

> Coordinator

> Saturn, Venus, & Lunar (SAP) Sections

> ASSOCIATION OF LUNAR AND PLANETARY OBSERVERS

 

. . . . . . . . .Date: Wed, 10 Mar 2004 18:38:41 +0100

Subject: Re: Venus march 1st and 8th

 

Paolo, here is the "Psi" : Hope you can read it in the message. Together with Y-shaped feature, this shape is one of the first recognized in UV images of Venus.

Frank, no image today nor tomorrow nor...

 

. . . . . . . . .Date: Wed, 10 Mar 2004 19:20:31 +0100

Subject: Jupiter, march 9th 2004

 

Hi all

Seeing mostly fair, variable.

Best wishes

 

. . . . . . . . .Date: Wed, 17 Mar 2004 21:32:41 +0100

Subject: Jupiter, march 13th, and 16-17th 2004

 

Hi everyone

The first image has been taken with the CN212 of a friend (the same that already allowed me to use this instrument on Mars in 2003 august), during a regional star party. The seeing was poor but the arrival of a big cloud improved the seeing at the very last minute (300 frames exactly !).

On the 16th-17th, there have been a good moment in an otherwise fair night.

Regards

 

. . . . . . . . .Date: Fri, 19 Mar 2004 10:50:06 +0100

Subject: Venus march 16th and an animation

 

Hi all

I managed to have time to observe Venus in a full aftern oon on march 16th. I took one UV image every hour since 14 H 40 TU to 18 H 40 TU and got five images in four hour to make this short animation showing the rotation of UV features during that time ! Note a kind of dark "equatorial belt" in IR, oddly found also in integrated light ? As a visual report, I want to point out that with the W47 the polar cusps looked definitely brighter than the rest of the disk. This is the first time that I see a detail on Venus.

Best wishes

 

. . . . . . . . .Date: Sat, 20 Mar 2004 00:01:08 +0100

Subject: Re: Venus march 16th and an animation

 

Thanks Frank

It would be nice to do the same job with a different pattern of details...

That one on march 16th was not the most spectacular I have seen !

Regards

 


Christophe PELLIER (Bruz, Ille-et-Vilaine, France)

Coordinateur Section Mars et plantes telluriques de la SAF

http://astrosurf.com/pellier


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