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mftoet

LDN 1355 & 1358 and surroundings in Cassiopeia

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This is my final image of a week of pursuing astrophotography at @ollypenrice's 'Les Granges' in Southern France. Captured during the last two nights. Unfortunately I had to ditch about 2 hours of subs due to focus drift when I was asleep (resting for the trip back home).  

This is a crop. A larger field of view can be found at https://www.mauricetoet.nl/DeepSky/i-vtgtMB4/A (and a high res of this crop at https://www.mauricetoet.nl/DeepSky/i-KmtWWpX/A

Also seen are LDN 1353 & 1357, VdB 7, 8 & 9 and LBN 643

Exposure time: 7 hours, 30 minutes (5 min. subs) | Optics: Takahashi ε-180ED f/2.8 | Camera: Nikon D810a (ISO 400) | Mount: Astro-Physics Mach1 GTO | Guiding: Lacerta MGEN + Vixen 70S | SQM: 21.3 - 21.5 magnitude/arcsec² | Location: Étoile-Saint-Cyrice, France | Date: August 19 & 20, 2020 | Processing: Astro Pixel Processor, PixInsight and Photoshop CC

i-KmtWWpX-X5.jpg

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A really attractive image with everything just right.

Olly

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Lovely image, all the bright stars nicely backlighting the dark nebulosity.

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Posted (edited)

Lovely image Maurice! I can see some almost squid like objects in there. I notice the reddish tone in the dark nebulosity. I have it in LDN1228 that I recently posted and @vlaiv is trying to convince us that dark nebulosity should be grey and the red is an effect of scattering in our atmosphere. I am still to be convinced about that.

 

Edited by gorann
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Thank you Craig, Olly, Mark and Göran. 
 

@gorann: no the browns have nothing to do with light scattering in Earth’s atmosphere. It are genuine colours in these molecular clouds. You can also see the yellows and browns in dust lanes of other galaxies. I don’t know the exact (physical) reason for the colour, but probably a combination of absorption, reflection and ionisation in relation to the ratio between CO and H2 in these regions.

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Another fabulous image Maurice..    you certainly had a very productive week at Olly's :) ..   

Dave

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Lovely image, I already saw it on Astrobin.

Carole 

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20 hours ago, mftoet said:

Thank you Craig, Olly, Mark and Göran. 
 

@gorann: no the browns have nothing to do with light scattering in Earth’s atmosphere. It are genuine colours in these molecular clouds. You can also see the yellows and browns in dust lanes of other galaxies. I don’t know the exact (physical) reason for the colour, but probably a combination of absorption, reflection and ionisation in relation to the ratio between CO and H2 in these regions.

Good to hear and now Vlaiv has analyzed my raw data and calibrated according to the star colours, and then he actually finds that the dark nebulosity in LDN1228 shall be reddish brown and not gray:hello2:.

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Such a delicate image, the stars are amazing points of blue light.

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21 hours ago, gorann said:

@vlaiv is trying to convince us that dark nebulosity should be grey and the red is an effect of scattering in our atmosphere

I think I remember one program saying that dark nebulosity will only let through some extreme infra red at best, so red/brown gets my vote but I don't think it really matters with nebulosity. Make it purple if you like.

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That's a superb image Maurice. One thing that interests me, I don't see the primary mirror clip reflections around your bright stars that i see in every other Epsilon image. Is yours modified in some way?

Example of mirror clip reflections around Sadr

get.jpg?insecure

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2 hours ago, Allinthehead said:

That's a superb image Maurice. One thing that interests me, I don't see the primary mirror clip reflections around your bright stars that i see in every other Epsilon image. Is yours modified in some way?

Example of mirror clip reflections around Sadr

get.jpg?insecure

Hi Richard. I’ve attached an image I took of M45 couple of nights ago. There is evidence of mirror clips I think, but are there four instead of three on the 180 rather then your 130?

https://stargazerslounge.com/uploads/monthly_2020_09/M45-600s.jpg.13a5c384788fbc86998ff67813b4582f.jpg

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8 hours ago, Allinthehead said:

That's a superb image Maurice. One thing that interests me, I don't see the primary mirror clip reflections around your bright stars that i see in every other Epsilon image. Is yours modified in some way?

Thanks! The primary mirror of the Epsilon-180 has a diameter of 190 mm and has a mask / edge support with an aperture of 180 mm. A simple but clever solution to avoid undesired diffraction patterns like spikes caused by a turned down edge.

(Please don't get upset by the dust on the mirror: this picture was taken just before cleaning...)

epsilon_mirror.jpeg

Edited by mftoet
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That is an absolute beauty Maurice - you must be very pleased with that.

A great advert for @ollypenrice's lovely skies too.  (I hear the wine is pretty good as well!)

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49 minutes ago, mftoet said:

The primary mirror of the Epsilon-180 has a diameter of 190 mm and has a mask / edge support with an aperture of 180 mm. A simple but clever solution to avoid undesired diffraction patterns like spikes caused by a turned down edge.

Thanks, that makes sense. I wonder could I use a black marker around the edge of mine to get a similar result?

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Love the processing on this. The image has a gorgeous, ethereal quality about it. 

Top quality stuff Maurice! 

 

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Yes, you can, Richard. I suppose a 3D-printer can do the job. 

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And thanks again for the nice comments 🙂

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13 hours ago, Allinthehead said:

That's a superb image Maurice. One thing that interests me, I don't see the primary mirror clip reflections around your bright stars that i see in every other Epsilon image. Is yours modified in some way?

Example of mirror clip reflections around Sadr

get.jpg?insecure

Interesting and sorry for intruding on the thread, but I did not know that the Epsilons both have spikes and clip reflections. Here is Sadr in my RASA from two weeks ago (same camera). I was close to getting an Epsilon until a good offer for a RASA 8 came up and I am getting curious about the advantages/disadvantages of these two popular wide field designs. There is certainly a big price difference.

 

Edited by gorann

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58 minutes ago, gorann said:

Interesting and sorry for intruding on the thread, but I did not know that the Epsilons both have spikes and clip reflections. Here is Sadr in my RASA from two weeks ago (same camera). I was close to getting an Epsilon until a good offer for a RASA 8 came up and I am getting curious about the advantages/disadvantages of these two popular wide field designs. There is certainly a big price difference.

 

The 44mm imaging circle is the big one that comes to mind.

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7 hours ago, tooth_dr said:

The 44mm imaging circle is the big one that comes to mind.

Very true. If your goal is widefield then it makes sense to use the largest chip you can. It may be ironic but I do 20x more mosaics with my widefield rig than with my long FL. Once you go wide you want wider!

Olly

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9 hours ago, ollypenrice said:

Very true. If your goal is widefield then it makes sense to use the largest chip you can. It may be ironic but I do 20x more mosaics with my widefield rig than with my long FL. Once you go wide you want wider!

Olly

 

16 hours ago, tooth_dr said:

The 44mm imaging circle is the big one that comes to mind.

Yes, that is true and slipped my mind. However, now thinking about it, the effect is not very large, but very expensive. The Epsilon 180 (that has 80% of the aperture area of the RASA) has a FL of 500 mm (RASA 8 is 400 mm) so with a 36 x 24 mm chip, the Tak only gives 23% wider FOV than a RASA with an APS-C chip. With ASI cameras the cost (FLO prices) for the two set ups will be 1839 (RASA) + 2069 (ASI2600) = 3908 pounds and 4345 (E 180) + 4159 (ASI6200) = 8504 pounds. Maybe it is worth it?

Edited by gorann

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When I acquired the Epsilon-180ED, the RASA systems weren't released by Celestron. In the late analogue / early digital age, a friend of mine used an Epsilon-160. I fell in love with the crisp stars that telescope produced and promised myself I would acquire one some day. About 10 years later I ordered an Epsilon-180ED including the ridiculous expensive tube rings, base plate en 7x50 finder scope (which in the end I only use for star alignment after switching on the mount). Another thing that I like about the Epsilons (and other fast Newtonians for that matter), are the diffraction spikes. I know, you either like them or you don't. 

Would I consider acquiring a RASA instead of a fast Newtonian? Maybe, but probably not. A thing that would bother me is that the camera (and cables) must be placed in front of the corrector plate. I can imagine taking proper flats can be challenge with a RASA. So respect for those who manage to produce excellent images with these astrographs!   

  

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