Getting Back on that Bloomin Bike...

[Psychobilly]

Last night it felt like I had fallen off the bike as I was a bit disappointed with the results... so like when you fall off a bike I had to get straight back on again and the skies looked better tonight... had a few targets in mind...

Where it was the transparency that was the problem last night I had a few issues with the guiding tonight which was a PITA as I was taking 1200s (yes 20 min subs) unattended (trouble with weeknight imaging is I need to try and get some sleep as well so set up 2-3 hour sequences) and I haven't found the cause yet...

These are the first roughs.... both CPC800 @ f6.3 you know all the rest

M101 (no suprise there)

so heres 3x600s ISO800 + 2x600s ISO1600 + 5x1200s ISO800 lost as much again though

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M13 only 5x60s and 5x120s ISO 800 as I am still capturing 5x240s and 5x480s

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Now if only I can work out whats gone wrong with the tracking..... I have an idea but only time will tell....

Sudden descent of mist/drizzle stopped play...

I thing I need to do a 2 or 3 star align each night as the Hibernate isn't putting me on target away from the SOuthern part of the Meridian... I didnt help by trying to replace some of the alignment stars from the night before without reading the manual so only got myself to blame I suppose...

So instead of NGC4088 and SN2009dd I ended up a bit off and got NGC1457 instead.....who wants to image a supernova anyway.... I DO!!!!!

So here it is anyway....

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Peter....

[Aza]

You have done well there despite the problems.

What do you think about the 20 mnutes subs for M101?

Did they help the image?

After all this talk of a maximum DSLR exposure of 10 mins, it has put me off going that long

I am struggling with M101 myself.....do you think the 20 minute subs helped, especially with the colour?

Cheers

[Psychobilly]

Hi Arran,

I must admit that that all this talk about 10 and 20 min subs got me int he mood to try it...the 20 min subs were pretty "noisy" but in a subtle way if that makes any sense whatsover... the background was grainy no ampglow from the 1000D and no really noticeable hot pixels. I wantted to get some long sub data to compare to a load of 5 minute ones which I will have to get the next clear night...

I have run out of attachment space so I'll have to have a clear out and then i'll post single subs for you and anyone else who may be interested to have a look at...

The 20 min subs were also a test on the guiding and until the mount got lost it was working really well... i'll have to go over the full guide logs to see when and then why it happened... I have had an instance before when the guide software locked onto another "object" so wandered off... once it lost teh satr the remiaing subs were useless...

At least Celestrons Support pages confirm what I thought... Hibernate should more accurately called Snooze ...

I hibernated my GOTO mount. When I powered back up and woke up the scope, it did not point as accurately as before. What gives?

Looks like I should be re-aligning every night

Peter....

[Aza]

Thanks for the info Peter.

Shame you didnt manage any 5 minute subs for a comparison with the same conditions. All the time before that I was doing 20 minute subs, I never noticed or seemed to have a problem with excess noise, however if you dont get much more detail that a 5 minute one, the biggest thing is the waste of time and lack of subs.

Shame about the mount needing re-aligning each night, but spare a thought for those of us that have to do the full set up each night

[blinky]

My problem with longer subs is differential problems, it always seems to slightly drift over time.

[jgs001]

Very nice Peter. I wasn't aware of the higher level of noise in DSLR's above 10 minutes until I'd tried 20 , although I've had noisier images at ISO1600 and much shorter subs.

[Tim]

The skies were fairly dire here last night Pete, I have some subs on the Iris (4.5hrs last night) versus 1 hour the night before and they are like chalk and chees as to the number of stars, can barely recognise them as the same piece of sky.

M101 really needs good transparency to get those arms nice, and with that much murk up there, even 20 min subs wouldnt help.

I resigned myself to 15mins last night, and just one target, like you, desperate for SLEEP!!!

[Psychobilly]

I had another reprocess this morning and theres more to come with less noise its just a case of using a slightly different workflow... I pushed the saturation way to early in the one i have posted resulting in excessive chroma noise... so I'll work on it when I'm more "with it"....

The annoying thing is the mist lost me the 240s subs for M13... I know I should have taken them in exposure length order but i wanted to get the longer subs in before the sky lightened up... in the end it wasn't the sky lightening but the mist and drizzle which put a premature end to the proceedings...

I need more sophisticated script based control of the 1000D...

Peter...

[philj]

Despite the problems Peter thats a very nice nights work. Great images. I especially like the colour in you M101.

My CGE throws a wobbler when waking from hibernation. What I have to do is wake up then switch off, then switch on and use last alignment, works a treat. One day I shall load teh new motor firmware which should sort it but I keep forgetting.

20 minute subs!!!!! I dream of 20 minute subs. Im lucky to get 5 minute subs round here, you must have good dark skies.

Phil

[Psychobilly]

The 20 min was a test... I can only do it on a "dry" night and for targets close to the zenith...

With regards to the hibernation what I tried to do was re-sync to a known star replacing one of the alignment stars from the previous night this seemed to be a reasonable idea... maybe it wasn't... I think hibernation is more appropriate for things like changing power sources, "parking" the scope during a shower etc rather than being able to switch on and carry on where you left off so to speak...

I had also been tweaking the settings on PHD guide - effectively resetting them to default and the star shapes even on the 20 min subs were very good from the 8" SCT at f6.3 until the guide software got distracted and wandered off

When i was imaging lulin a few months back I found the guider would sometimes change target if a brighter object entered the star detection box... in that case when the comet passed close to a background star... I'll have to have a good look tonight at the subs and the log files see if i can see whats gone wrong... as soon as I manually rest the guide box to the right star it was happy again all night

Wont it be a boring hobby of everything just behaved itself all the time

Peter...

[blinky]

Peter do you not take dark frames? I dont fancy taking 10 ro so 20min darks each night!

[Psychobilly]

No...

The 10 or 20 min was a one off experiment to see if it could be done and how much benefit I would get ... I find the 1000D doesn't really need darks as it doesn't suffer from any ampglow whatsoever even leaving only 30 secs between exposures of any length up to 20 mins...anby hot or cold pixels are taken care of in DSS's cosmetic tab...

The 350D really does need dark frames but seeing as its relegated to the secondary FOV for any particular target I tend to use "library" darks if at all ...

So to explain the setup...

1000D primary imaging camera - for Small targets its on the 8" for wide fields its on the Megrez 72

350D secondary imaging camera - on the "unused" OTA just to grab some extra data - for use with registar... Its always "useful" in wide field when its on the 72 but often not looking at anything "interesting" when its on the 8"

Guiding is via a DSI IIC on a 500mm f8 telephoto on its own mini guide rings...

I could offset the 3 OTA's but prefer to keep them all as co-aligned as possible.. the FOV of the DSI IIC on the 500mm is a very good match to a DSLR on the 8" @ f6.3 which is handy for rough framing...

Peter....

[jgs001]

Craig I used scaled darks for my 10 and 20 minute exposures, but given your comments Peter about the 1000d, I might try the 450d stack of M51 without the darks also and see how it comes out.

[saturn5]

Great shots Peter,that M101 is a good skies only for me anyway.

You mentioned no amp glow with the longer subs,i noticed that a few days ago at 10 mins i had no amp glow either but at 3-4 mins a couple of months ago it was quite noticable,does the outside temperature have an effect on it?