And Another RASA 8 M31

[tomato]

These must be like buses, you don't see one for a while, then two come along at once.

I was mightily impressed with @gorann's M31 image taken with a RASA 8 and ASI 2600 OSC, especially as it was just 90 mins integration, and coupled with my M31 mosaic project not really getting off the ground due to the miserable UK weather, I took the plunge and spent the annual astro budget on a RASA 8. This was coupled to @Tomatobro's Atik Horizon II OSC, mounted on a Mesu 200 with no guiding.

This is 64 x 45 sec exposures, using Atik's Low setting for gain and offset, full calibration frames and stacked in APP, processed in StarTools 1.6. It's certainly not as crisp or deep as Göran's image, as would be expected, given  the Panasonic sensor is not as high a specification as the Sony chip. The star shapes are also not great, I suspect imprecise spacing or possibly camera tilt. I am not impressed with the squidgy material Celestron have glued to the back of the screw on M42 adapter, I can easily see how it might compress unevenly when tightened down. This was also manually focussed, no Bahtinov or auto focuser available.

However, I am impressed with what was captured in just 48 minutes, this combination really works for me under UK skies, I can't see me buying another CCD camera.

Thanks for looking.

 

[gorann]

That was a quick delivery, especially nowadays! You must have hit a worm hole in corona space-time. Nice first light Tomato! Yes, I have also been wondering a bit about that "squidgy material" since I also have a tilt issue. I just ordered one of these so I could use filters on my ASI2600 (with a 17.5 mm chip distance I cannot use a filter slider for it so I would need to use my ASI1600MM). It hopefully lacks that "squidgy material".

https://www.pierro-astro.com/materiel-astronomique/hyperstar-et-rasa/adaptateur-filtres-pour-rasa-8-compatible-zwo_detail

[tomato]

Yes, I have removed the optical window from the scope as recommended in the manual, I was wondering if 2” filters could be mounted in this holder, but the adapter you have located makes a lot of sense, especially if it is free of any cushioning material.

[gorann]

12 hours ago, tomato said:

Yes, I have removed the optical window from the scope as recommended in the manual, I was wondering if 2” filters could be mounted in this holder, but the adapter you have located makes a lot of sense, especially if it is free of any cushioning material.

Not sure what filters will fit in the optical window. Celestron sells a dedicated one but it is just for light pollution. I assume that you could compare the hight of the optical window to that of any 2" filter you have to see if it could fit (and if it is a normal 2" filter thread). I have not removed the optical window - why is it recommended in the manual? I missed that.

EDIT: I read up a bit and it seems like the optical window should be removed if you put other filters into the lightpath. Baader suggest this for their filter slider (which I have). With the ASI2600MC I did not use any filters and the the optical window can be in place. So tonight I will try Ha imaging with the ASI1600MM and a Baader high speed Ha filter (2") in the slider. I will then remove the optical window and hope I got the spacing just about right (I have a 6.5 mm female to female T2 from Agena Astro between the camera and filter slider) so the total telescope to chip distance will be 29.4 mm which adds a little extra needed when there is a filter in the path.

 

Edited August 30, 2020 by gorann

[tomato]

The manual states that if you are putting any kind of filter in the optical train or if you are using a camera with an optical window (and all astro cameras I have seen have one), then the optical window fitted to to the RASA should be removed. Having said that, there are posts on Cloudy Nights where folks have left it in, with no apparent ill effects, and your images don't appear to have suffered.

The internal thread on the Celestron insert will take a 2" filter, however, the problem is as you point out, that if the filter is too thick, it wont allow the adapter to sit down flat.

Some filters are shorter than others though, the Optolong L-enhance dual NB filter is quite low profile, and might be OK. Another alternative would be  to remove the 2" filter from it's mounting, and mount this in the Celestron holder, assuming the actual glass diameters are similar enough, I need to check this.

Or just go with the adapter you have identified, please let us know how you get on with it.

[gorann]

5 minutes ago, tomato said:

The manual states that if you are putting any kind of filter in the optical train or if you are using a camera with an optical window (and all astro cameras I have seen have one), then the optical window fitted to to the RASA should be removed. Having said that, there are posts on Cloudy Nights where folks have left it in, with no apparent ill effects, and your images don't appear to have suffered.

The internal thread on the Celestron insert will take a 2" filter, however, the problem is as you point out, that if the filter is too thick, it wont allow the adapter to sit down flat.

Some filters are shorter than others though, the Optolong L-enhance dual NB filter is quite low profile, and might be OK. Another alternative would be  to remove the 2" filter from it's mounting, and mount this in the Celestron holder, assuming the actual glass diameters are similar enough, I need to check this.

Or just go with the adapter you have identified, please let us know how you get on with it.

Here is the filter slider I will be using tonight for NB imaging.

https://www.baader-planetarium.co.uk/2019/11/28/baaders-rasa-8-ufc-telescope-side-adaptor/

It cannot be used for cameras with more than 13 mm chip distance, so the ASI1600 is fine (after adding 6.5 mm) but not those with 17.5 mm distance, like ASI2600 and ASI071. For those you need the adapter I linked to in the earlier reply.

[Datalord]

Lovely data! You image seemed green to me, so I took it and added PixInsights SCNR to remove the green tones. Nothing else.

[tomato]

Thanks, a much better colour balance. At some point I will put the data through PI,  I still need more time with this software.

[gorann]

My RASA 8 is ready for some serious Ha collection success (or failure🥴) tonight. Remeber Tomato that you need to put your camera cables in a curve to avoid ugly spikes. I did it with bent steel weire (the type I use for tieing up garden plants) and electric tape. Seems to be no need for heating the front of the scope - enough heat is produced by the cooled camera if you have a dew shield. And you may want to get an extra Losmandy bar on the top - stabilizes the tube and great for firmly attaching a guide scope. Celestron have a dedicated bar that is reasonably priced.

Edited August 30, 2020 by gorann

[tomato]

Yes thanks, , it's on my to do list. I have just finished assembling my triple rig (RASA + 2 Esprit 150s), I need to see how stable the arrangement is and if the Mesu can cope, before applying the finishing touches.

[gorann]

4 minutes ago, tomato said:

Yes thanks, , it's on my to do list. I have just finished assembling my triple rig (RASA + 2 Esprit 150s), I need to see how stable the arrangement is and if the Mesu can cope, before applying the finishing touches.

You are a brave guy! Will be very interesting to see how it goes. I think I wait with fireing up my Esprits on the Mesu until the moon leaves us.

[Datalord]

29 minutes ago, gorann said:

My RASA 8 is ready for some serious Ha collection success (or failure🥴)

You will be amazed. I only had a single quick run one evening with the filter (you have the fast narrowband filters from Baader, right?) and this is the completely unprocessed stack from 42 minutes of 3 min subs:

[gorann]

1 hour ago, Datalord said:

You will be amazed. I only had a single quick run one evening with the filter (you have the fast narrowband filters from Baader, right?) and this is the completely unprocessed stack from 42 minutes of 3 min subs:

Very promising indeed. Yes, I have the fast Ha and am waiting for the fast OIII but Baader seem to be still working on the next batch. 3 minute subs - this is a fast scope! What camera did you use?

Edited August 30, 2020 by gorann

[Datalord]

11 minutes ago, gorann said:

Yes, I have the fast Ha and am waiting for the fast OIII but Baader seem to be still working on the next batch. 3 minute subs - this is a fast scope! What camera did you use?

It took them almost 1½ years to get a batch for me, so do whatever you can to get a hold of one! This is with the QHY247, so a CMOS color.

[gorann]

19 minutes ago, Datalord said:

It took them almost 1½ years to get a batch for me, so do whatever you can to get a hold of one! This is with the QHY247, so a CMOS color.

I ordered it from FLO in June. I can see on the TS site that a new batch is promised by Baader for October so I hope FLO gets some of those too. TS is good in showing expected delivery dates and not just stating "Usually shipped 10-15 working days" like FLO. Sorry FLO but maybe you could also try to be more precise?

[tomato]

Got a few more 45 sec subs added earlier this week, inferior to the first set as a 50% illuminated moon was beginning to intrude. total integration time now 106 minutes. Are the inky black regions in the top right genuinely that dense or is that my processing?

This is it for now, the RASA has to come off the rig so I can image with the dual refractors properly. My plan is to try and get a 24 hr total , 12 panel M31 LRGB mosaic, and see how this compares with this quick and easy result...

 

 

[Datalord]

1 hour ago, tomato said:

Are the inky black regions in the top right genuinely that dense or is that my processing?

I think you went a bit overboard in stretching and contrast on this one. You've also lost some of the colour you had in the first image. 

1 hour ago, tomato said:

My plan is to try and get a 24 hr total , 12 panel M31 LRGB mosaic, and see how this compares with this quick and easy result...

24h data vs 1½h? How will you ever compare those results?

[MarsG76]

Nice Andromeda... wish I could see it from down here.....

 

[tomato]

29 minutes ago, Datalord said:

I think you went a bit overboard in stretching and contrast on this one. You've also lost some of the colour you had in the first image. 

24h data vs 1½h? How will you ever compare those results?

Yes, there is always a big difference between tablets and my calibrated monitor I find. It looked sort of OK on the latter but distinctly yellow and washed out on hand held devices.

As for the comparison, if I make a half decent job of the mosaic it should be better, but 22 hrs of UK dark sky invested better? That’s what I want to find out.

[tomato]

Had another go, toned down the stretch a little.

[Datalord]

20 hours ago, tomato said:

Had another go, toned down the stretch a little

Infinitely better. Very nice.