Astrophotography Report : The Moon, Collimation woes, Neptune, Uranus and Jupiter

ThatDrGuy

I had a pretty interesting nights astronomy Friday night so I thought I would document it. The great sages at MET Eireann had decided it was going to be a cold clear night perfect for observing. Around 7pm I got home from work and set my scope out cooling. The scope is an 11 inch OTA mounted on a rugged steel tripod so moving it takes herculian effort. Once I got it outside I took off the back plate to let it cool and put my DSLR camera battery charging. Next stop theskyX software to chose a target. Sadly my wish list was either behind my house, behind a tree or beside the near full moon. No DSO imaging for me tonight

Once the scope was cooled I turned it on and started the alignment process. It has a built in GPS so it finds its position first then points itself at where it thinks Polaris is. Unfortunately it thinks Polaris is somewhere in New Zealand so I had to correct this. The huge wedge for the scope is beyond my capabalities to man handle so I had to settle for Alt Azi tracking. I aligned it with Polaris and Capella as the other targets were behind my house. Next step was the addition of my trusty light pollution filter. In response to my request to put light pollution shields on the council sodium light overlooking my garden my local council installed 4 more unshielded lights instead which bathe my garden and the sky in a beautiful orange glow. The LPR filter is a 2 inch filter which cannot screw-in anywhere in my setup. An adaptor costs around 130 euro. I get around this by sticking it to the aperture in my back plate with blue-tack. Next I screwed in the focal reducer and went to get my camera. My mission for the night was to try and collimate my scope. In the 5 years my telescope has been around I know no-one has ever even attempted to collimate it. Given the amount of abuse it gets being hauled around I figured it was long overdue.
For some reason everytime I check the collimation it seems perfect (with defocusing technique) I intended to try a new method using CCD Inspector which uses the camera to get a supposedly perfect collimation. Unfortunately the battery wasn't charged so I got out my Neximage camera and had a shot at lunar imaging. I left the focal reducer in place (my hands
were too cold to remove it) and took a few lunar shots without a barlow :


Beautiful Craters Gassendi and Mersenius


The craters Sharp and Bianchini

The bottom of the images is messed up due to some dust I didn't realise
was covering the CCD chip.


Camera battery finally charged I tried the new collimation proccedure. Tracked to Polaris, defocus and image. Then
you get readout of collimation error and then simple correct by turning the 3 screws. Easy in principle but it took
30 minutes of freezing and swearing at the blasted thing to get the first measurement. The result - 79 Hah! I knew it
was poorly collimated. 10 minutes of very gingerly turning screws later I got it down to a much more acceptable 6. Eager
to give my new super sharp scope a trial I swung it towards the great Orion nebula. Hmm now the stars on defocus DEFINATELY
look out of collimation. Maybe its just a visual artefact... Orion looked great otherwise, the violet nebula glowing brightly
certainly overshadowed the not so collimated trapezium. I was in a planetary mood and I had never taken an image of Neptune
before so next stop was the region it hides in. The scope eagerly tracked there, slowed down into fine slew mode and ...
kept slewing in one giant 360 circle ! Bugger. Ok turn off, re-align. Slew to Andromeda to check its tracking - again kept
slewing in a crazy micro orbit. Arghh. Power out, system reset. Re-align again - sooo cold. Now its working. Slew to Neptune
region. No sign of Neptune' disc so I have to guess. It took a lot of rotating
and squinting at astronomy software until I finally found it ( I think ! )






Next stop Uranus. I want to try and capture its large moon Titania. Its right beside the near full moon so chances are very slim.
I used 45 second subs which is near the limit of Alt Azi imaging. Only took 30 each - I wasnt in a DSO mood.



As you can see the lunar brightness has totally obliterated the faint light of Uranus's moons



After some heavy image processing I found a hint of Titania:






Very subtle. Will have to try again when the moon isnt out,



After this Jupiter peeked over the house so I snapped a few quick background photos for later. That seemed to exhaut
the DSLR potential for the night so I turned my hand to making flats. These are callibration images that allow you to subtract the dust dirt etc that builds up in your imaging train. Id never successfully managed to make good ones before. My method this time was to use my white shirt and tie from work. Put the shirt one layer thick over the OTA. Then
tie the tie around it and stretch it until it is a taught white surface. Put a torch ( balanced in one of your room mates shoes) pointing at the covered OTA. Then set the camera to AV mode and voila ! Finally usable flats:



Those circles represent gunk on my OTA and I can now subtract them from my images to clear them up.


A bit too bright yet but I can move the shoe torch a bit back next time. One of my neighbors peeked out and saw me dressing up my telescope in a shirt and tie. This was worth an eyes-to-heaven-head-shake followed by a firm curtain closure. I took 10 45 second darks after this. Camera battery promtly died. I took off the camera, LPR filter and focal reducer and slewed over to Jupiter. Arghhhh it looked terrible! The collimation was a mile out. 20 minutes of visually recollimating it, I had it back within about 10% of where I started. The tracking was dead on. I took 10 or so 5 minute sequences of Jupiter at different resolutions and 2x and 4x barlow:





The collimation in these is quite bad , Ive missed a lot of subtlety in the bands. Also a bit more processing and cleaning up wouldn't go amiss.

My last goal for the night was a 4x Barlow image of Uranus but it had vanished. It was about 3 am and time to call it
quits and warm up before bed.

peterako

All I can say ThatDrGuy is.....

WOW!

Well done!

Peter

Tzetze

Thanks for documenting the session so well, TDG. That was an interesting read. I can certainly relate to things conspiring against you as the session pans out.

Your lunar shots are great, and that was with focal reducer in place.. You have potential to build up some finely detailed mosaics using your barlows!

Collimation can be a pain in the neck, but your images of Jupiter look very well regardless. What focal length are you getting with the 4x barlow?

I can get my Newt to 2400mm with a 2x - must get a modded webcam to try out some planetary stuff.

Kersh

Super write up!

Details exactly one of those sessions where nothing is going right.

Which is usually everytime

For one reason or another.

Super crater pics though.

Rubecula

Brilliant stuff. Maybe one day I will do some photography I can post up. But don't hold your breath. For now though, seeing these wonderful pictures just inspires me.

ZeRoY

Thanks for the report detail, helps a lot!

Tzetze wrote: »

Collimation can be a pain in the neck, but your images of Jupiter look very well regardless.

Was going to say just that! Very good resolution

ThatDrGuy

Thanks a lot guys. Murphys law applies so well to Astronomy.

@Peterako: Thanks, you had some great images over the last few years
esp of Jupiter. Have you got your scope out this winter yet?

@Tzetze: The lunar views through my scope are amazing - feels like your
in orbit watching it drift past you. I must have a go at a mosiac, I hope one
will emerge from the odd scap i take every now and again. The focal length of my scope is 2800mm. When you start putting barlows into it , it gets up to crazy numbers. There is a new version of neximage out (5) which might be worth a look, I see some very nice images being taken with it. Collimation seems to be a dark art; I thought CCD inspector would be good for it. Maybe because i had the LPR and focal reducer in place while doing it, but that is how I image.

I got my orion autoguider in the post yesterday.

Now the only thing I am missing for a full auto guided set up is a cheap refractor. Which is actually proving more of a pain to source than all the rest of the components. Then the horrors of drift aligning and gearing troubles ahead as well as the team of sherpas Im going to need to set it all up.

peterako

Unfortunately the 'scope has only been out briefly for visual observation once since last Winter

But Jupiter's back and getting higher.....

Your pictures are really getting very good!

And loved the report

Clear skies, (hopefully better than last Winter's)

Peter