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Starlight Live post-processing


richardlawler
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Hello, all.

I acquired an Ultrastar C for EAA last fall. (I only got a few chances to use it over the winter, but we got some desperately needed rain instead. So that's ok.)

The Ultrastar C has been astounding on the few evenings where the fates have yielded to properly working equipment and clear skies.

I'm looking for pointers to tools and techniques for post-processing the color FITs image stacks captured from Starlight Live. I'm on a Mac so that limits some of the software options available. 

The docs for Starlight Live say there is a command line option ('-load-image-rggb') to reload a color FITs file into the program. Does this work from a Mac command line? 

Are there any other Mac programs that can read the Bayer RGGB color FITs files exported from Starlight Live for manipulation. Or something that can demosaic and export the files for manipulation in Photoshop? Maybe Nebulosity4.

TIA.

- Richard

 

 

Edited by richardlawler
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18 minutes ago, richardlawler said:

The docs for Starlight Live say there is a command line option ('-load-image-rggb') to reload a color FITs file into the program. Does this work from a Mac command line? 

 
1

Update: I found this command worked:

/Applications/StarlightLive.app/Contents/MacOS/StarlightLive -load-image-rggb Bodes_17x15s_median_2017.4.21_00.17.34.fit

 

Edited by richardlawler
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I have an Ultrastar and a Lodestar X2C and use Nebulosity on both Mac and PC to post-process EAA captures, which all works well.  Although I confess that this year I'm concentrating on mono rather than colour.

I find the easiest approach is to stick to a single exposure setting for the whole session, say 60s, and just let the FITS capture run, only changing the target name when I slew.  I also use bias and a bad pixel map, both of which Nebulosity supports well and both are independent of exposure.

I posted some comparisons of EAA captures and post-processed FITS recently here: 

 

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2 hours ago, AKB said:

I posted some comparisons of EAA captures and post-processed FITS recently here: 

Thanks, that's exactly the sort of information and experience I'm looking for.

I've been trying out Nebulosity, and it looks like it can do the sorts of things I want to do "the morning after" with the FITS files captured from Starlight Live.

I can't get Nebulosity 4 to see the Ultrastar C camera from the Mac. (I've not tried it on a PC.)  I don't know if that's a bug or just a gap in the supported cameras. But it's probably not necessary with Starlight Live doing the image and dark frame capture. Although Starlight Live doesn't capture bias or light frames AFAIK. 

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46 minutes ago, richardlawler said:

Although Starlight Live doesn't capture bias or light frames AFAIK

No, it uses darks, but I do use it to capture bias frames for use in Nebulosity. 

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Starlight Live has a dark frame mode to capture darks (which are not applied to any of the raw image FITS files - only to the live stack). You can capture a bias with a 1ms exposure (but the bias is reasonably well contained in the dark) and you can capture flat frames by following the same as image capture but turn off live stacking.

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On 4/25/2017 at 11:05, Paul81 said:

Starlight Live has a dark frame mode to capture darks (which are not applied to any of the raw image FITS files - only to the live stack). You can capture a bias with a 1ms exposure (but the bias is reasonably well contained in the dark) and you can capture flat frames by following the same as image capture but turn off live stacking.

 
 

Thanks Paul.

I forgot that with the 3.3 exposure control I can now go down to 1ms. I guess darks encapsulate bias as long as the exposure is the same as the light frames. So I should be good if I standardize on an exposure time for most of my images (as AKB suggests above) and the temperature doesn't vary too much.

Flat fields might still be helpful, depending on the optics. But a few experiments with various optical configurations should determine if there's anything to gain. 

In spite of my desire to post-process, I'm really trying to keep it simple. I've learned the hard way that it's easy to get lost in the details with astro imaging. By focusing on EAA I'm able to keep it fun and interesting and thus not get bogged down. 

Edited by richardlawler
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