Slow Beginnings

[Hemi]

Dear Members,

As I've posted before, im predominantly a visual observer. But have started some imaging. Im interested in near real time imaging to start with as it seems a nice way to learn the basics.
Ive spent 6m getting to grips with my relatively new AZEQ6, polar alignment, ASCOM, EQMOD, Stellarium, Plate solving, Sharp Cap etc etc etc! Here are a number of images i've taken. All are short exposures 4-15s. stacks of 40-60 lights. No Darks,Flats, Biases. A basic stretch (with my limited understanding and processing skill) and very rudimentary sharpening all from just within Sharpcap.

They are terrible images I know, but still have me excited. The reason for posting them, is I thought I better start somewhere (never posted an image before), and hopefully to get some feedback and answers.

Firstly, can someone please tell me what the red and green squiggly lines and streaks are, the ASI 294MC Pro, cooled to the max (in Darwin, Ambient currently is mid 20's at night). Secondly on the over exposed and stretched image, what is the fingerprint like pattern. Sensor, mirror and corrector all look clean and fine.
Does the vignetting mean i've got the spacing incorrect? I have the reducer on the OTA directly, followed by Baader click lock, Click lock 1.25 adapter and then the nose piece of the Camera.

Oh...im using a C925 at f6.3. And a ZWO ASI 294 MC Pro Cooled. I have an ES 102 APO as well, but kind of love my C925, and never shift it!

Sorry for the long thread....and the shameful images :)

Oh....and one last question, I saved the individual frames from the stack as an SER file, is it worth processing these very short exposures in startools or pixinsight etc?

Cheers

Hemi

[xelasnave]

Well I think you should be excited as your images are remarkable given your experience. And if I may suggest grab maybe three times as many and stack the best . . Great post.
Alex

[Hemi]

Thanks Alex for taking the time to have a look.
Im not sure what those lines are from though. What kind of noise and how to get rid of them.

Cheers

Hemi

[Atmos]

For short exposures with a "slow" SCT they've come up really well :thumbsup:

The squiggly lines are hot pixels, these still exist even if you cool the sensor but there is less of them. Darks will remove most of these and also using pixel rejection will remove them too. My understanding is that SharpCap average stacks the images together but doesn't do any kind of pixel rejection. So, what you're seeing is the natural "walk" at the mount is doing. Guiding and dithering will fix that particular issue but I'm not sure whether you can dither through SharpCap or not.

That fingerprint looking thing to me looks like frost on the sensor. This appears in warmer more humid environments (like Darwin) and it can be mitigated a bit if you cool the camera down slower. I've started cooling my ASI094 down over 10 minutes and I've found that works better than letting it do it as fast as it can.

As for processing these in PixInsight, you'll get a better image if you do proper pixel rejection but I'd say if you're going to go through that effort you'd be better off getting some darks and flats first so that you're dealing with the cleanest data you can :)

[Hemi]

Thanks Colin,

I just searched the latest documentation with SharpCap. The latest version 3.2 now does dithering, so will give that a go.
There are options which reject entire subs based on FWHM and brightness filters.
As to pixel rejection, it has several options, none of which I have tried, but will now that you've told me about it. The options are to reject pixels based on sharpness, min and max star size and sigma clipping. Are these what you mean?

Not sure im ready for guiding yet, as my Polar alignment could be way better and I only have one camera. I can't see the SCP, so use ASPA. It reports back that the error is now about 20-30" in both axis. But I thinks its much worse.

How do you gradually cool the camera?

Next step for me is darks and flats.

Thanks again

Hemi

[casstony]

I have marks on tiles set into the ground for the tripod legs; this gets me close to PA when setting up the mount, then PA is fine tuned with ASPA.
I also have a mark on the mount base and tripod head which is lined up.

Up to 600mm focal length, positioning the tripod on the marks is good enough but I do need to fine tune PA for longer focal lengths.

[Hemi]

Thanks Casstony,

I have a semi permanent setup. Im using the AZEQ6 tripod with pier extension. Its on an open air first floor verandah. There is no roof, so I have been leaving the scope mounted outside with a TG 365 cover. Its worked really well for 3 years now. The only effect so far has been some rusting of the OTA screws. Not game enough to change them to marine grade alternatives. I keep re iterating the ASPA, and the error definitely has gotten smaller. But I do get small trails with 2m or so exposures if I pixel peep. The other problem though is with long exposures and minimal gain I still get a white out.

Cheers

H