The Moon in 3nm Ha

[Bassnut]

This was fun. 20 off 0.5 sec exposures in 3nm Ha on a ST8MXE, G11, LX200R (no guiding, darks or flats). Processed in CCD soft (NOT designed for planetary).

The moon is a broadband reflective light scorce, not suited to NB filters, but Ha does limit urban pollution. Not supposed to be imaged this way, but the result was interesting anyway.

http://fredsastro.googlepages.com/home

[tornado33]

Interesting idia
You could go further and image it in O3 and S2 and make up a narrowband colour pic of it :)
Scott

[Bassnut]

Scott

The moon in full NB?, I like it, youre brain is so left field, its impossible of course, but ll do it anyway. Thank you.

[iceman]

Nice Fred, I like the rays coming out from Tycho.

[Garyh]

Not bad Fred!
Nice detail!
cheers

[Inmykombi]

Stunning images.
I found myself "lost" in them for quite a while.

Keep up the good work.

[RB]

Nice one Fred.

:thumbsup: :thumbsup:

[Bassnut]

Thanks Guys. Going by the quality and sharpness some of you guys get on the moon, I think now it couldve been better, but I was just supprised what Ha could do. It probably acted as a light reducing filter, otherwise the exposures wouldve been too short for a CCD. Ill give SII and OIII when I get them.

[seeker372011]

you are one seriously narrow band addicted fella

(says someone who has had a single shot colour camera for 8 weeks and has yet to take a colour image with it )

[Ric]

A nice image Fred, very sharp.

I didn't think you could do that with narrowband but there is the proof. I might have to try that myself.

Cheers

[ving]

i am not too sure what you have achieved here... yes yuo used a HA filter but what exactly has it done that no filter of some pp couldnt do?

strange fellow :P

[Bassnut]

Ke ? :shrug:

umm, CCDs generally dont have exposure times short enough to handle the moon, and I dont have a neutral density filter (who has ?), so the Ha filter served that purpose I guess. The point was, the NB filter worked on a broadband refective scource, and probably sharpened detail a bit on the way, which was a slightly interesting left field result on a CCD others might find interesting, ive never bothered before cause I thought it wouldnt work.

In what way could I have done this with a DS rig to make it less strange?, And, others have done a better job with fast webby type cams with no filters, so?.

[Ian Robinson]

One word .... WOW !!!!

Not much interested in the moon .... the other photos I am wowwed by.

How's the camera cooling arrangement coming along. I would have thought that thermoelectric cooling would be more efficient and easier to impliment. I know TE is used in industrial thermography cameras and it is very efficient , I've used them in very hot environments ring next to steel furnaces and steel rolling mills (ambient temps over 50oC where we were where making observations and producing thermographic images).

TE cold sides maximum current ranges from 0.3 to 10 Amp, single stage DT - 74oC to 150oC in multi-stage configurations. See http://www.rmtltd.ru/tec_modules.htm?gclid=CJbB0ZuzrZMCF RpciAodBi_W4g
In summer that would give you a chip temp about -40oC and a dark current <0.05 electrons / pixcel / sec !!!.
(http://www.sbig.com/sbwgifs/4020_dark_temp_graph.gifhttp://www.sbig.com/sbwgifs/4020_dark_temp_graph.gif )

[ving]

OIC!

so you were just cutting back light so you could capture the moon... god i am slow.:rolleyes:

[rat156]

Hi Fred,

The other narrowband filters will do the same as the Ha filter, i.e. just cut the light down.

The sun emits a pretty much continuous spectrum of light over this range and the moon simply acts as a mirror (though some bits will be absorbed, our instruments aren't sensitive enough to detect this) so you'll just get darker frames.

If you recombine in the time honoured Hubble pallete, you'll get an idea of the spectral output of the sun, though the light and dark regions should be slightly different colours as the scattering off the moons surface will effect some wavelengths more than others depending on the surface. This is the only reason we see different shades of grey in the first place.

Cheers
Stuart

[Bassnut]

Yep, thats it.;)



Ive since seen some full NB moon images, not that attractive, what you say makes sense, thanks.



Thanks Ian. The project came to a screaming stop for a variety of reasons, but it was fun trying, and I learnt a lot. They can be efficient, but designing all the mechanics to make the overall result efficient (cold chip) was hard. Stacking was tricky, a triple stack was very unstable and ranaway thermally in seconds, even double stck in the end wasnt worth it and I ended up with 1 on each side of the cooling finger. The stacking is more complicated than simply stacking, the heat generated from a lower unit was way more than the cooling effect of the one above it, so there must be carefull power managment involved in commercial designs to keep it stable (I didnt want to spend that much).

The finger was inefficient, thermal fllow was restricted by a narrow neck. Other designs such as the cam Houhgy has, come out the side of the camera without this restriction.

I used cooled water instead of air cooling, which worked very well, but it got difficult to manage tubes and wiring on the scope, more work would have fixed that. I was determined to get a very large delta or not bother at all, so another problem was constant addition of ice.

Frosting killed it in the end, a sealed bag and lots of dessicant just didnt work.

I could have done lots more work to fix all of this, but then the 40D came along, so that was it, why bother :). I find the noise of the 40D, at ambient winter night temps anyway, and lots of stacking, is fine. And going lower than -10 deg, as the graph you posted shows, is fairly marginal unless your really fussy.