Log in

View Full Version here: : Mars 18th from tassie - not all is lost


davidpretorius
19-12-2005, 08:57 AM
Hi,

had the fan on and the scope outside from at 8pm. It had been a nice hot day. As i am preparing to go outside at 10pm (nice and close to mar's transit), my wife comes in and says, gee it is getting cold out there. Now remember, with my fan that blows or sucks air thru the side of the tube and over the face / away from the face. i get a cooling rate of over 2 degrees per hour. So i check the temps and there was a 5 degree temp difference. 9 degrees for ambient, 14 degrees for mirror.

I had given up in disgust with raw mode for saturn and had decided to take it off the toucam and do a night of std mode on mars / saturn / jupiter.

The first video is a compressed 10 odd seconds of toucam in std mode.

I switched back over to raw mode and converted it to colour and it is the second video.

The third attachment is the jetstream as it was at 6am sunday morning

I have never imaged in conditions as bad as this. I looked through the 5mm vixen LV and the whole planet shimmer with heat haze. No chance in hell of surface detail. Looking at the stars re sparkle, they were sparkling but not too bad. So seeing due to jetstream = 4 or 5/10. throw in the temp diff between mirror and ambient and seeing is now at 1/10 or zero!!

The fourth attachment is when i had better seeing conditions and temps were within 1 degree at around 4am sunday morning.

By the way, this colour i am getting saturn is giving me the #!$%s

So not a loss, something else learnt and that is, i am going to build a Bird inspired peltier cooler. I had read his cooling pages on his website over the weekend and last night nailed it for me.

I also slept through getting up for saturn and jupiter!

iceman
19-12-2005, 09:09 AM
lol those are horrible! I got up this morning to do Sat/Jup as well but my seeing was like yours. I couldn't make out the Cassini Division or any belts on the globe through a 7.5mm eyepiece, so I packed up and went back to bed.

Darn jetstream!

bird
19-12-2005, 09:38 AM
I've had nights/mornings like that - seeing so poor that you could barely make out that saturn was a planet with rings :-(

Bird

iceman
19-12-2005, 09:46 AM
yeh this morning it looked like a cup with 2 handles.. horrible.

ving
19-12-2005, 09:52 AM
they are pretty davo! dont listen to them :P

whatcha gunna do with the avis? burn them? ;)

davidpretorius
19-12-2005, 09:55 AM
ving, give em to a lsd freak to watch whilst high!!!

acropolite
19-12-2005, 11:46 AM
Dave, you might want to peltier cool the Toucam as well. Philip Davis (no not me) has an excellent site detailing both the long exposure ToUcam mod and a peltier conversion of the ToUcam as well. He hasn't yet posted any meaningful test results from the conversion so I'm unsure of how effective the mod is. http://www.philip.davis.dsl.pipex.com/peltier_mod.htm

bird
19-12-2005, 12:30 PM
For planetary work (i.e. short exposures) I'm not sure cooling the camera will help much. No doubt it will make a small improvement, but probably not enough to be worth the effort until you've taken care of everything else...

regards, Bird

davidpretorius
19-12-2005, 12:48 PM
true, mirror first and then down the track the camera. i still have to get the filter wheel, install the b/w chip etc

now mr bird sir, i have read your excellent cooling pages on your website and now know what the peltier is, what direction would you point me in to start peltier cooling of my mirror. Do i buy some of your old stuff (seeings you are up to series III) or start from scratch ie and get a peltier, some aluminium plates, an exchanger and a fan?

asimov
19-12-2005, 02:40 PM
"Holy steaming cow pats batman!....Their lovely!!" "Robin! I didn't know you were into LSD man!?"

A+ for getting out there & giving it a shot anyway Dave.

davidpretorius
19-12-2005, 02:43 PM
born in 1970, but my parents might have been hippies???