Mars morning of Nov 6th

[Quark (Trevor)]

Originally Posted by Lester

Fantastic detail Trevor. Are you using a DMK camera, just interested in what FPS you can use with the IR filter? Thanks.

Thanks Lester, yes I am using my DMK.
Lester, I have never imaged Mars prior to this apparition with the DMK, in all truth I have never really put much time into imaging Mars with anything. So for for this apparition I have imaged it on 5 different mornings and obviously this has involved a lot of experimentation.
The IR filter that I am using cuts back a lot on the light that passes it and I have tried various combinations of frame rate, exposure and gain. Based on the results with this image I think I am approaching the optimum setting for this target for my setup. For this image I used 30 fps and 1/30 sec exposure. The size of my aperture allowed this, a 16" primary collects a lot of photons.

Originally Posted by multiweb

Hi Trevor, excuse my ignorance but planetary imaging is like black magic to me. Is this a 2" IR filter we're talking about? And you're unaffected by the seeing?

Hi Marc, I use an Orion manual filter wheel that can take 5, 1 1/4" filters. I have it loaded with LRGB and IR filters all are Astronomik. There are many different IR filters. Visible light is 400 to 700 nm and there are various IR filters as we move past 700 nm into the infrared. The particular filter I use passes the electromagnetic spectrum from 807 nm onward. Of course the seeing is still relevant but not to the same extent.

I don't know if you are aware of the work of Andrea Ghez. Using the Keck's with adaptive optics and in the IR she was able to see through all of the considerable amount of gas and dust right to our galactic centre and image directly the high velocity stars in very close orbit around the super massive black hole candidate Sag A* that resides there. Just as professionals use IR to peer into dense regions so amateurs can utilize IR, especially when imaging objects close to the horizon to help alleviate the effects of the considerably larger airmass at low altitudes. IR is also beneficial for many other reasons for planetary imaging but I think I have probably rambled on to far already.

The image of Mars that is the subject of this post had other things going for it beside the IR filter. My Peltier cooler had been running from 2am through to 3am and by the time I started imaging at 3:30 the air currents generated by the cooling system had subsided and my mirror was at its optimum temperature. The collimation of my scope was as close to perfect as was humanly possible, adjusted with the scope in the same orientation that the images were captured. I cannot overstate the need for attention to detail when imaging at very high power.

[dpastern (Dave Pastern)]

Stupid question, but how did you get such magnification? I presume a combination of barlow + high power eyepiece + projection?

Excellent shot, tonnes of detail there.

Dave

[kinetic (Steve)]

Originally Posted by Quark

... and I have tried various combinations of frame rate, exposure and gain. Based on the results with this image I think I am approaching the optimum setting for this target for my setup. For this image I used 30 fps and 1/30 sec exposure. The size of my aperture allowed this, a 16" primary collects a lot of photons.lter I use passes the electromagnetic spectrum from 807 nm onward. Of course the seeing is still relevant but not to the same extent.

Trev, you are probably going to find ,(as I did),that just as soon as you
find that combination of exposure etc that works, it changes in a few
weeks as Mars gets bigger! It's frustrating game!

You might have already found this, although maybe not as pronounced,
on Saturn and Joop as it neared opposition?

Steve

[Rob_K]

Great job Trevor, can't wait to see what you get when Mars is 14 arcseconds in the New Year!

Cheers

[StephenM (Stephen)]

Great image Trevor! Amazing detail given the size.

I still remember seeing Syrtis Major and other features for the first time back in 2003 (using a wobbly old 4 inch Newt) - being able to make out ground features like that really impressed me!

Looking forward to seeing what you can come up with at opposition next year.

Cheers,
Stephen

[Quark (Trevor)]

Originally Posted by dpastern

Stupid question, but how did you get such magnification? I presume a combination of barlow + high power eyepiece + projection?

Excellent shot, tonnes of detail there.

Dave

My unit instructors at Swinburne impressed on me that there is no such thing as a stupid question, which was good as I am sure I asked many.

David, from the texts I have read I gather that a 640 x 480 CCD at prime focus is approximately equivalent to a 6 mm eyepiece. The FL of my 16" F4.5 scope is 1827 mm. A 6mm eyepiece would deliver 304 x.

I use a Televue 3 x Barlow with an extension that delivers 5 1/2 x so my imaging is at high power indeed.

Originally Posted by kinetic

Trev, you are probably going to find ,(as I did),that just as soon as you
find that combination of exposure etc that works, it changes in a few
weeks as Mars gets bigger! It's frustrating game!

You might have already found this, although maybe not as pronounced,
on Saturn and Joop as it neared opposition?

Steve

Steve, I really have very little experience with imaging Mars, the vast difference in brightness of the various regions has thrown up some interesting problems. The orbit of Mars is quite elliptical so its angular size varies considerably, as you have mentioned.

As it gets larger it will be brighter. With all of my planetary imaging I am guided by my histogram, for Saturn and Jupiter it really does need to be nearly full but Mars is a different situation entirely.
Let me add that. especially with Saturn as the rings closed, I had to alter the gain to maintain my histogram at about 250. This is also the case with Jupiter, when it is lower the gain needs to be slightly higher and when Jupiter is very high the gain can be dropped off a little to maintain the same histogram setting.

The much slower rate of rotation of Mars allows the collection of much more data and the variation in albedo is such that, I think, the histogram needs to be set lower so that the bright regions don't become saturated.

All good fun Steve and the experimentation is a great way to learn.

Originally Posted by Rob_K

Great job Trevor, can't wait to see what you get when Mars is 14 arcseconds in the New Year!

Cheers

Thanks Rob, this has really exceed my expectations for so early in this apparition.

Originally Posted by StephenM

Great image Trevor! Amazing detail given the size.

I still remember seeing Syrtis Major and other features for the first time back in 2003 (using a wobbly old 4 inch Newt) - being able to make out ground features like that really impressed me!

Looking forward to seeing what you can come up with at opposition next year.

Cheers,
Stephen

Thanks Stephen, yes I look forward to opposition with great expectations.

[RobF (Rob)]

This thread has been a fascinating read! Inspiring image too of course - congrats Trevor.

[dpastern (Dave Pastern)]

Thanks for answering my question Trevor, much appreciated.

Dave

[Troy]

good picture Trevor did you do a RGB run?

[Paul Haese]

Nice going Trev. Never imaged Mars in IR. Maybe this year.

[Quark (Trevor)]

Originally Posted by dpastern

Thanks for answering my question Trevor, much appreciated.

Dave

No probs Dave.

Originally Posted by Troy

good picture Trevor did you do a RGB run?

No Troy, I didn't try any RGB's, I have a bit of a time constraint with the capture of my Mars data, the project I am involved with requires the Mars data interspersed with a stellar comparison target and each time I go from Mars to the star I have to take the DMK out and use an eyepiece to locate and centre either Mars or the star, so from 3:30am I really only have enough time for maybe 3 sets of captures in IR for Mars and the star.

Originally Posted by Paul Haese

Nice going Trev. Never imaged Mars in IR. Maybe this year.

Thanks Paul, don't know how you are set regarding IR but I would highly recommend this Astronomik 807+nm filter, I reckon it would sizzle on your C14.