M81 - First Attempt (Critique Please)

[Pat Curran]

Hi All,

I managed 60 x 2 minute subs on M81 this morning between 00:55am and 02:10am using the Comet Hunter / ASI 533MM rig. No filters and no calibration files - just trying to get used to NINA and the remote operation of the rig.

Camera was cooled to -10°C

 

Processed in Deep Sky Stacker, GraXpert, Siril and Affinity Photo 2

Feedback welcomed and appreciated.

Thanks,

Pat

[Norris Adams]

From one Irishman to another...!

I've previously found Bode's to be a challenge (it always appears to be slightly diffuse and ethereal), but I see you have also managed to capture Holmberg IX into the bargain!

I had a quick look in my last image of the same target but there's nothing comparable there!

It's an accomplishment to be able to pick up these targets so close to the solstice.

Norris

[Pat Curran]

Thanks Norris,

I wanted to post the PHD2 log with it, but can't seem to find it!

Seen some weird (to me) movements on the DEC axis graph which may account for the poor star shapes.

I also have some serious doughnut dust motes in the train - next step is learning to do flat calibration.

Pat

[Norris Adams]

Yes Pat, I noticed the motes, but I guess they'd disappear with the application of Flats.

Funnily enough, I tried my first Flats last night (in SharpCap). I had previously used only Darks, but my daughter bought me a Light Box and I set it up properly for the first time last night. (I'd noticed an increased degree of vignetting recently so I felt it was time)!

It was a bit of a faff, but it seemed to work well. I have yet to process the images to see the full effect, but they looked good on screen during the wee small hours.

I know you can take Flats at the end of a shoot, but since I'm not really post-processing I've got to do it before I take the Lights.

Norris

[900SL]

Where's your location / bortle ? Not bad for a first attempt.  Looks a bit over exposed or stretched, and some odd star shapes. How's your collimation? Is the focuser barrel protruding into the light path? 

[Albir phil]

That a good image considering you are trying out your rig and only two hrs.I always struggle with m81, but I'd say you're on the right track.👍👍

[Pat Curran]

20 hours ago, 900SL said:

Where's your location / bortle ? Not bad for a first attempt.  Looks a bit over exposed or stretched, and some odd star shapes. How's your collimation? Is the focuser barrel protruding into the light path? 

Hi 900SL,

I'm located here in SE Ireland under a Bortal 4 sky with local town 5 Kms to my south.

I haven't adjusted collimation as I have heard Mak-Newts can be troublesome to perform collimation on. You are correct in thinking the focuser barrel does extend into the Comet Hunter tube - not sure if its intruding into the light path however.

...and while I'm confessing, I might as well state  I paid no attention to back focus measurement;  just set the focuser half way in and then added spacers (including an Antila OAG/Filter drawer combo AND another ZWO filter drawer! 

How critical is back focus on a Mak-Newt?

Thanks 900SL,

Pat

 

[Pat Curran]

20 hours ago, Albir phil said:

That a good image considering you are trying out your rig and only two hrs.I always struggle with m81, but I'd say you're on the right track.👍👍

Thanks Albir phil,

There are so many variables which might be impacting on quality that I just need to get a grip on one at a time and deal with that issue before moving on to another.

...speaking of which...does anyone know why my PHD2 Log Files are showing created but no data (1Kb)? I have set the save location in the Advanced 'brain' settings.

Thanks,

Pat

 

[Pat Curran]

Just for info,

I keep the Comet Hunter in the Observatory Shed while not in use on the red test bed, where I can update software (eg 'Orbitals' NINA plugin) via the internet connected WiFi - there is no internet when the Mini-PC /telescope is out on the  CEM70G.

Regards,

Pat

[Pat Curran]

...while at the same time the CEM70G remains on the telephone pole pier under cover from the Irish weather! (hopefully remaining Polar Aligned!)

 

[900SL]

The focuser protrusion is likely causing the diffraction flares around brighter stars. This, and the exposed mirror clips are usually the cause with the Comet Hunter. There's no set backfocus with a Mak Newt as far as I know (no flattener or reducer)

[Pat Curran]

That's good to know 900SL,

I'll re-work the focuser today...the spacer above the OAG in above image seems to be close to the protrusion length, so hopefully it's removal will allow the racking out of the focuser barrel so it's outside the light cone.

Like collimation, I'll leave the mirror clips until I have the easier issues sorted first.

Also one less issue if back spacing is not a factor.

Many thanks for this feedback,

Pat

 

[Pat Curran]

OK,

The 20 mil spacer is removed and I now have little or no protrusion.

I didn't want to go too bare as I am not sure if the focuser quality is good enough to avoid flexing if it's racked out too far.

Now for a clear night to test...

[Elp]

It's a very good result. With a bit more PP you'll be able to eek more difference between the light and dark areas of the galaxy. Add in the RGB data underneath and you'll have an excellent image.

[Pat Curran]

Thanks Elp,

I'm Mono only for now until proficient at handling the gear and processing.

Flats and luminence filter are my next two steps.

Pat

[Elp]

I like that box solution, is it resting on a base of some sort?

[Pat Curran]

Hi Elp,

I welded a angle iron rectangular frame which acts as a floor with flat sheeting to keep out rodents. That frame is the floor of the box when closed and is attached to the wooden telephone pole pier.

I'll post some pics when I get home.

Pat

[TiffsAndAstro]

On 02/06/2024 at 21:11, Pat Curran said:

...while at the same time the CEM70G remains on the telephone pole pier under cover from the Irish weather! (hopefully remaining Polar Aligned!)

 

This is the best idea I've seen for an inexpensive pier. Hopefully in the future I can steal it.

Though im not keen on boring a 10 meter hole in the ground

Paint your mini obsie blue and it will feel like a Tardis inside

Edited June 5 by TiffsAndAstro

[wimvb]

On 02/06/2024 at 21:31, Pat Curran said:

I haven't adjusted collimation as I have heard Mak-Newts can be troublesome to perform collimation on

Easiest way to check collimation is to center a bright star in your fov. Then swing from outside defocus to inside defocus. If the hole in the doughnut that is the defocused star moves, then you need to collimate. You should only need to tweak the primary mirror slightly.

[Pat Curran]

Thanks for the feedback on collimation Wim; will certainly do as you suggest when I see the stars again.

Elp and TiffsandAstro, I've posted a few pics of the box shelter over on the Equipment > DIY Observatories section here.

I used white paint on the outside to keep as much heat as possible reflected off. Combined with the Telegizmos bag, summer heat doesn't seem to be a problem, but then we haven't had summer heat for a while in Ireland. 🤐

Regards,

Pat

[Pat Curran]

4 hours ago, TiffsAndAstro said:

...

Though im not keen on boring a 10 meter hole in the ground

...

I get it now...I was a bit slow off the mark there TiffsAndAstro! 🤣🤣🤣

Pat

[TiffsAndAstro]

20 minutes ago, Pat Curran said:

I get it now...I was a bit slow off the mark there TiffsAndAstro! 🤣🤣🤣

Pat

How far down did you go?

[Pat Curran]

About one foot six in a 2x4ft hole. Filled that with concrete, let it set for a few months and then added the six inch deep floor 12x12ft square on top. Hope to build a proper observatory on that base when funds allow.

[Pat Curran]

The AGPTEK LED Tracing Light Pad arrived today. Purchased it on foot of the good review it received here on CN. The A4 version fits the Comet Hunter nicely. Now just need a clear night to take my first flats!...