Wednesday, April 23, 2008

"2nd" light with the 18" Obsession

Yesterday evening I had my "2nd light" with the Obsession. Again a nice success, as the tracking and the goto were performing well this time. The issue was just the ArgoNavis cable, it was not fully plugged in the ServoCat. So problem solved - all works well.

The speed of the Goto is amazing. Much faster than with my 20cm Newton. Also, with a Dob you don't have the issue of crossing the meredian, something I continuously faced with my Newton on a German mount.

The accuracy of the goto is not bad, all object were in a FOV of 30'. But it can still improve with some of the AN functionality. Something I will have to find out by reading the manual.

I'm still not very confident in moving the scope fully assembled (with UTA). I use the red spring clamps to hold everything tight, but I'm not yet sure if this is totally OK. For now I prefer to observe close to my home. But there I have quite some issues with a street light. Once I'm more confident I'll move at the back of my garden, it's much darker there.

Today I had also dew on the secondary. I did not fix the dew heater yet (not sure which type of glue I need) but I feel the pressure now to do it quickly. Unfortunalty, the whole weekend I'm out, so it will be something for in 10 days.

So far the technical stuff. In terms of observation I limited myself to the classical objects (using goto) such as M3, M51 (spiral arms visible), M81/82, the Whale, M65/M66, M65, Markarian Chain and BlackEye. Naked Eye Limit Magn was 4,5, maybe 5.0 at the end of the session.
After something more than an hour observing clouds were appearing (at the same time as the dew ...).

As a conclusion: everything works well (it's a relief), and now I need to increase the observing comfort and start to migrate at the back of my garden.

Ckear skies to all of you



Freddy Meiresonne said...


If you are still unsure to move your Obsession you can move without the UTA. It's much more stable and i guess you can move it much better to the end of your garden where there is less lightpollution

Myself i did not glue the dewheater to the secondary. The whooly stuff should be able to press it against it in the holder. This is also explained on the Obsession website. Glueing optional. IF you still want to glue it use some silicone or TEC7.

DeepSky said...

Hi Freddy,

With the Az axis engaged it seems save to move the scope with the UTA. So I have done this a few times now to go at the back of my garden. Works well.

Thanks for the tip on the dewheater.

Did you observe last night (April 30). At 11pm it was completly clear here in Boutersem. Observed until 2 am.

Freddy Meiresonne said...

I had to wait until midnight.
Then i was clear. I observed untill 02:00 PM.
M3,M53 with resolved stars, can't see or find NGC 5053
M81,M82,NGC 3077, NGC 2976, NGC 2595, M57 and surrounding stars, faintest i could detect was m15.3 but M57 was not yet high up enough.
M108 and M97 , only one eye seen , difficult but the nebulae is very bright especially with OIII