LX Trials & Tribulations

Posted by XTSee on 5th March , 2010

Its the end of another long cold session with my Celestron C6-SGT and everything is packed away. Ice is melting off the screen of my laptop as I type and drink a nice mug of hot chocolate. Its been a very nice clear night and finally, at last, I have been able to try out the Long Exposure mod on my webcam. Hooray!

After another short session grabbing a couple more sequences of Mars, trying to improve and refine on my previous session shooting Mars (but poor seeing again - I think it must be heat rising from the neighbouring houses, particularly with their boiler fumes puffing out).

I felt the best and least taxing astro object to have a go at for “first light” with the LX mod would be the Pleiades. Orion and M42 would have been nice to try, but they’ve set below the neighbours house already.

The webcam has quite a narrow field of view, and even with a focal reducer I can’t get much coverage of M45. The next obstacle I’ve discovered when moving into the not-so-bright territory of stars, clusters and DSO’s is that finding them and focusing them is a lot harder than something bright and big like the Moon or Mars. First off, centering the view with an eyepiece, then replacing it with the webcam, and refocusing the scope while watching the image in K3CCDTools on the laptop takes time.

I’m having to learn to count 4 half-turns anti-clockwise of the focuser when changing from eyepiece to webcam, and something like 16 half-turns anti-clockwise when the focal reducer is also added to the webcam.

Anyway, I’ve managed to get a few nice bright stars of M45, and it seems plenty of colour. I will probably have to experiment more with settings of the webcam and exposure times, which I’ve been trying out 10, 15, 20 and 30 second durations. Above 15 seconds some motion of the stars is noticeable because even though I took my time to polar align the EQ5 mount as best as possible, I have not yet attempted “drift alignment” (all in good time, and one thing at a time).

The next target I tried was M81 (Bodes Galaxy?) and after quite a bit of time and effort finding it, swapping eyepiece for webcam, refocusing and recentering, while using a fairly short exposure of 2 or 5 seconds to make the process easier, I turned up the exposure, and could definitely see the core of the galaxy glowing quite nice and brightly.

There was also some haze around the core, and I’m wondering how much the processing of the images will improve the view, and whether I can expect to see the arms of the galaxy? I’ve also taken a dark map image so that hopefully this will improve things too.

Next I attempted finding M51 and M101, but they didn’t look very bright in the eyepiece, and it was hopeless trying to find them with the webcam. After a while, I thought I would check the glass on the front of the scope, and to my dismay found it completely covered with dew!

Damn, maybe I need to turn up my dew controller heater? So I flicked the switch to constantly On, and played tug-o-war with my dog while I waited a few minutes. When I came back, it seemed like nothing had happened, and I was beginning to curse my homemade dew controller thinking it was useless, or too cold, when I suddenly noticed, duh, even though the dew controller LED was flashing on and off, I hadn’t plugged the bloody heater cable into the controller box. What a freakin idiot!

So about 5 minutes later it was obviously working as the condensation was starting to disappear off the glass, and after about 15 mins was almost all gone, nice one it does work.

I also noticed on the preview screen for the image that the scope was catching some light at an angle from a cursed streetlamp at the end of my garden, so decided to try a different region of sky, and aimed at the Triplet of galaxies in Leo. Again it took a fair bit of work getting M66 centred and focused, but managed to take 5×15 second frames and 1 dark map frame.

I felt this was a good first attempt with Long Exposure images, and I should do the processing in K3CCDTools to see how things have turned out, before getting too ambitious with drift aligning or attempting even longer exposures.

I’m also starting to appreciate how much work goes into getting even basic astrophotography results. Very satisfying and exciting nonetheless.

Ok, its 1.20am and work tomorrow, so the processing will have to wait! Goodnight.

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One Response to “LX Trials & Tribulations”

  1. SPC900NC webcam: Pleiades, M81 and M66

    [...] my experimental “first light” imaging session with my newly modified Phillips SPC900NC webcam for Long Exposures (Steve Chambers mod), I have now [...]


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