The "No EQ" DSO Challenge!

[susan-parker]

Final shot taken on the night of the 7th July; this one is centered on Rasalhague, which is a bright magnitude 2.1 star at the top corner of the constellation Ophiuchus.

Two pics; a 1800 pix wide scaled down from the full-frame, and an 1800x1800 pix 1to1 crop from the center.

Stars are down to magnitude 14.8 (according to my star hunting with Stellarium) which shows that there is some benefit to increasing the number of frames for pulling out the background detail, however it is diminishing returns after about 30 frames (with this setup and using the in-camera sensor noise reduction).

This sequence of frames was taken about 23:30 and was at the beginning of astronomical-dark. Notwithstanding this, there was still discernable sky glow from nearby vilages (Goult), towns, and city (Avignon), albeit a small fraction of what there is in West London. Looking carefully at the sky at day or night there always seemed to be a thin vapour layer high up in the stratosphere.

Nikon D800 with Nikkor 105mm f/2.5 at f/2.5, ISO 250. IDAS D1 filter. Image is a stack of 32 exposures of 2.0 seconds each. Camera on fixed mini-tripod, plus IR remote.

[smisy]

At last friday my old dream came true, I took a picture about a comet ? Of course I used my gadgets as usually Huawei P10 smartphone with monochrome camera, 25mm plössl eyepiece, Celestron Nexstar 8 SE, alt-az mount. One frame with 30 sec exposition at ISO 3200. Comet 21P/ Giacobini-Zinner. 

[susan-parker]

The night before the full moon last month on the 26th June; a composite of a set of 17 frames for the stars plus one of the moon itself, plus an original single frame.

Nikon D800 with Nikkor 105mm f/2.5, ISO 800; Stars at f/2.5 at 2 seconds, and moon at f/8.0 at 1/1000sec. Size reduced to 1600 pix wide.

[The Admiral]

As a result of a question on another thread, I've managed to plot (after a fashion) the field rotation rates across the sky. I thought that it was worth posting the map here as well, as it's pertinent to Alt-Az imaging. I've had to use demo software, hence the watermarking, but the overall picture can be seen.

This map shows the number of seconds for a 0.1° field rotation relative to the position in the sky. The physical scale is the wrong way around, i.e. the horizon should be 0° not 90°, but I can't change that with the demo software. The elevation rings are at every 10°. The zenith is at the centre. The N-S axis is horizontal, and the E-W axis vertical. The advantage of imaging in the East or West direction can be clearly seen. There are some mapping artefacts on the RHS which will need to be ignored.

Hope that is of some help.

Ian

[happy-kat]

That is brilliant Ian, well done and thanks for sharing.

[RobertI]

Very useful map, I think the lines should be called ‘Isochrones’! ?

[The Admiral]

34 minutes ago, RobertI said:

Very useful map, I think the lines should be called ‘Isochrones’! ?

And why not! Sounds good to me. Mind you, having just checked on goggle I see that such a word is in use for much the same thing!

Ian

Edited July 31, 2018 by The Admiral

[RobertI]

1 hour ago, The Admiral said:

And why not! Sounds good to me. Mind you, having just checked on goggle I see that such a word is in use for much the same thing!

Ian

Damn.

[matt_baker]

On 31/07/2018 at 10:21, The Admiral said:

As a result of a question on another thread, I've managed to plot (after a fashion) the field rotation rates across the sky. I thought that it was worth posting the map here as well, as it's pertinent to Alt-Az imaging. I've had to use demo software, hence the watermarking, but the overall picture can be seen.

This map shows the number of seconds for a 0.1° field rotation relative to the position in the sky. The physical scale is the wrong way around, i.e. the horizon should be 0° not 90°, but I can't change that with the demo software. The elevation rings are at every 10°. The zenith is at the centre. The N-S axis is horizontal, and the E-W axis vertical. The advantage of imaging in the East or West direction can be clearly seen. There are some mapping artefacts on the RHS which will need to be ignored.

Hope that is of some help.

Ian

If you don't mind me asking, what do the axes represent?

[happy-kat]

The axes not in the text is the right hand coloured axes legend which is exposure length. Hope that helps.

[The Admiral]

2 hours ago, matt_baker said:

If you don't mind me asking, what do the axes represent?

Not at all. Think of it as a sky chart, with N-S parallel to the horizontal axis and E-W parallel to the vertical axis, and vertically above you is the zenith, at the centre of the chart. And as happy-kat says, each of the coloured lines corresponds to an exposure time in seconds to give a 0.1° field rotation; the colour key is shown on the side.

Ian

[matt_baker]

M101 Pinwheel Galaxy

130SLT with nexstar mount

D3200 (unmodified)

93x25s @ 800ISO

20 Darks/Bias/Flats

Processed in DSS and Startools

Had a lot of trouble getting down the noise and properly exposing the galaxy but thats probably due to the lack of exposure time

Once I get my new setup, I'll properly try getting this, minus the noise and coma

The Hi-res flikr link is here if anyone wants to have a go at getting a little more out of it

https://www.flickr.com/photos/129093386@N05/43778258422/in/dateposted-public/

Matt

Autosave00444.tiff

[happy-kat]

That's super and you've got colour in there.

StarTools likes the autosaved FITs file for processing. Re noise I've found better results with my DSLR from doing flats and dark flats and leave out the darks.

[matt_baker]

41 minutes ago, happy-kat said:

That's super and you've got colour in there.

StarTools likes the autosaved FITs file for processing. Re noise I've found better results with my DSLR from doing flats and dark flats and leave out the darks.

I've managed to edit it slightly in lightroom by upping the contrast and highlights to bring out more of the galaxy

 

[happy-kat]

The thing to watch for is clipping the black point. I've been using the latest Startools beta it's been very stable.

Your image reminds and enforces I must take as many images as I can as it really makes a difference to what is captured.

Edited August 3, 2018 by happy-kat

[The Admiral]

6 minutes ago, happy-kat said:

 I've been using the latest Startools beta it's been very stable.

The latest one? Is that v1.4, issued almost a year ago, or has there been a later edition I've not spotted?

Ian

[happy-kat]

There's a newer beta out 1.4.332

Mask action has been added to the log file as well.

Edited August 3, 2018 by happy-kat

[The Admiral]

Thanks happy-kat. This is a bit confusing, as the 'latest version' thread on the ST forum hasn't been updated since Oct 2017. Having looked on the download site though I see Ivo refers to a 1.4.332 alpha version! He really ought to keep his version lists up to date.

Ian

[happy-kat]

I'm using that version and it's been pretty stable really. There's plan for scripts Guy has been working on stuff.

[matt_baker]

Went out last night and added another hour of data for a total of 2 hours

Much less noisy with the extra data and I could bring out more without clipping too far and not having extensive noise reduction

Much more pleased with this result

Matt

 

 

[Filroden]

22 hours ago, matt_baker said:

Much more pleased with this result

Isn't it great seeing an immediate improvement to the image when you add more data? Just the difference of 1 extra hour can really help the image. I can only say the image quality and ease of processing get better and better with more data!

And one tip (it's becoming a mantra for me): there's a lot more colour in your image than you're showing in your processing. I think you may be over exposing your stars so any colour is being washed out. To illustrate, I took you image and applied an "increase star colour" action in Photoshop and then really (over)boosted saturation to show what information is hiding. This isn't the right way to process it. Better not to lose it than to try and recover it!

[Manners2020]

Great image. Question on post processing.  My computer  wont run startool will gimp do the job?

[The Admiral]

Folk do use Gimp though I don't. Best let them advise. But why won't Startools run as a matter of interest?

Ian

[Manners2020]

Well it might now since I added more ram.  I should try but it's not a powerful  pc. It would start and gradually  grind  to a halt. So I tried pixinsight trial which works but I cant justify  the price yet as I dont get many opportunities  to image. Maybe in the future.

[The Admiral]

Pity if you can't get it to work, as it seems to give good results for our sort of imaging, and at a reasonable price. Mind you, Startools and PI have quite different approaches, as I'm sure you are aware.

Ian