Heart Nebula Help

[Rodd]

How do I do that--when I save to Fits, it looks the same as when I save to SBIG uncompressed.  I take a pic, it comes up on screen like the Ha one I posted--stretched apparently, I save it to fits and open it and it looks the same.  How do I save an unstretched version.  As far as I can figure-there is no setting that controls this.  What am I missing?

[Davey-T]

Will have a read of the Starizona guide later to try and see what's going on.

Dave

[Rodd]

Another question arises--if I am supposed to stack very dark-nearly black images, how can I align them?  If I can't see the stars how can I choose the star to use for alignment? In Nebulosity you use 1 star for translation (normal subs taken at the same time), 2 stars for translation and rotation (subs taken on different nights if the mount has been moved) and 3 stars for  translation, rotation and scaling (subs taken on different nights if the mount has been moved with different scopes).

[swag72]

You don't need to see the stars - The software that stacks them does it all. You're not stacking the individual subs manually.

[Rodd]

I guess in Pixinsight the STF gets me through that.    By the way, is it possible that because no data is lost when my camera is auto stretching (according to SBIG), I am simply supposed to manually reverse the stretch to near dark levels before continuing with the processing?  That seems convoluted to me.  I just don't understand how it is possible for me to have gone down such a wrong road, completely unaware of the issue, after doing so much research and watching so many tutorials, reading all the manual and taking so many subs.  Its like a math problem in a text book where the answers are given in the back for all the odd examples, but this problem is an even question and it's different than all the odd ones!  (yes that was my problem back then too--I'm 53 and it still plaguing me.

[Rodd]

You don't need to see the stars - The software that stacks them does it all. You're not stacking the individual subs manually.

I have been--in nebulosity you do that after the images have been aligned, normalized and calibrated (reverse order there) by the software.  My 45 day Pixinsight trial expired last night, so I am perhaps in a spot that most of you will find hard to advise-I think I just made some progress though.  I saved one of my SBIG uncompressed files into FITS and opened it in Nebulosity and it looked very dark indeed.  I swear I tried that before--I'm swimming in files.   Maybe I have not lost any of my data after all.  Learning lessons the hard way is no fun.  

Hopefully this thank you will be the end of this dental visit.  I will try and reprocess the Heart Nebula data to see if it makes a difference.  

I meant no disrespect to anyone if it appeared that was the case.  

Thanks,

Rodd

[Davey-T]

No problem Rodd, please keep us informed of your progress, we all knew nothing when we started, some of us haven't made a lot of progress  

Dave

[Rodd]

No problem Rodd, please keep us informed of your progress, we all knew nothing when we started, some of us haven't made a lot of progress  

Dave

--here is a JPEG of the reprocessed data.  I started with unstretched FITs files, subtrcted a master dark (no flats or biases because I don't have them), matched hsograms for all pics of the same channel (Ha, R, G, , aligned, and stacked the Various channels.  Then I  assigning the R, G, B stacks to the various channels and the Ha to the Lum channel.  I auto color balanced (the thing in Nebulosity), and stretched numerous iterations with small steps.  I can't say the image blows me away.  A tried processing the Ha channel by itself, and it looked pretty good--but Nebulosity would not let me assign a processed (stretched) image to the Lum channel.  The image leaves me no more satisfied then before--though some of the details are better I must say (middle and Ha highs).

[Rodd]

ctually here is a better version--lower compression ration--the previous one looks bad

[Pompey Monkey]

I have an SBIG STF-8300M and I can confirm that all of my subs come out almost black.

Here is a 10 minute sub Ha of IC 405, next to the same sub with STF applied so I can see what's going on:

I use APT, not the CCDops software for capture and it saves the files as raw FITS.

[Rodd]

Yeah--I got that solved now--thankfully.  I didn't loose any data, though I had to open and re-save 75 files in various folders and directories into a new one--not fun.  From now on its FITs for everythjing