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Stellina - How to process the FITS

Astrophotography Imaging
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#1 CptNautilus

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Posted 24 June 2021 - 04:36 PM

 The smart telescope Stellina (by Vaonis) is known for its ease of use and the way it produces automatic images in JPEG format, straight from the beast.

 

  However, it has more to offer. It can be used as an astrophotography station that collects raw images in FITS format (from now on called FITS). Those subs are, at the moment of the writing, 10-second-long subs. Thanks to Stellina's automatic setup, automatic focusing, mechanical derotator and anti-dew heater, those subs are of very good quality. They can be processed in much the same way as subs produced by more regular rigs.

 

  The goal of this thread is to discuss all the tricks of the trade that are particular to the Stellina when it comes to stacking, stretching and processing its FITS.

 

  As a starter, I propose here a kind of tutorial explaining all you have to know to collect light frames and dark frames with Stellina and how to stack them in the free application DeepSkyStacker:

 

How to stack Stellina's FITS with DeepSkyStacker



#2 Brainebula

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Posted 25 June 2021 - 11:14 AM

 The smart telescope Stellina (by Vaonis) is known for its ease of use and the way it produces automatic images in JPEG format, straight from the beast.

 

  However, it has more to offer. It can be used as an astrophotography station that collects raw images in FITS format (from now on called FITS). Those subs are, at the moment of the writing, 10-second-long subs. Thanks to Stellina's automatic setup, automatic focusing, mechanical derotator and anti-dew heater, those subs are of very good quality. They can be processed in much the same way as subs produced by more regular rigs.

 

  The goal of this thread is to discuss all the tricks of the trade that are particular to the Stellina when it comes to stacking, stretching and processing its FITS.

 

  As a starter, I propose here a kind of tutorial explaining all you have to know to collect light frames and dark frames with Stellina and how to stack them in the free application DeepSkyStacker:

 

How to stack Stellina's FITS with DeepSkyStacker

AFAIK, there is no Mac version of DSS. Do you know of any FITS stackers for Mac? Affinity Photo can stack and can handle Stellina's TIFF but I don't think it handles the FITS format. 


Edited by Brainebula, 25 June 2021 - 11:15 AM.


#3 rj144

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Posted 25 June 2021 - 11:48 AM

Appreciate the thread, but once you have the FITS it's the same as processing and stacking and processing discussed ad infinitum here and many places on the net.

 

Also, if you have lots of subs, the average stacking method for light frames, is not the best algorithm to use.


Edited by rj144, 25 June 2021 - 11:58 AM.


#4 jonnybravo0311

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Posted 25 June 2021 - 12:41 PM

AFAIK, there is no Mac version of DSS. Do you know of any FITS stackers for Mac? Affinity Photo can stack and can handle Stellina's TIFF but I don't think it handles the FITS format. 

SiriL is free and works on Mac.



#5 CptNautilus

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Posted 26 June 2021 - 02:41 PM

AFAIK, there is no Mac version of DSS. Do you know of any FITS stackers for Mac? Affinity Photo can stack and can handle Stellina's TIFF but I don't think it handles the FITS format. 

  The latest version of Affinity Photo can read FITS but in my experience, their stacking has problems. For me it crashes all the time.

 

  Many Mac users use SiriL (free) or AstroPixelProcessor (not free).



#6 CptNautilus

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Posted 26 June 2021 - 02:50 PM

Appreciate the thread, but once you have the FITS it's the same as processing and stacking and processing discussed ad infinitum here and many places on the net.

 

Also, if you have lots of subs, the average stacking method for light frames, is not the best algorithm to use.

  That's true. I forgot that I had put that method in the PDF, which I had written very early after my first success with DSS. Nowadays, I use the "Median Kappa-Sigma clipping" algorithm for the light frames, and the "Average" for the dark frames. Is that the algorithm you had in mind?

 

  Besides, Stellina has some peculiarities with the FITS Bayer pattern due to the mechanical derotator, and there is also tricks to know to optimize the collection of light frames and dark frames.


Edited by CptNautilus, 26 June 2021 - 02:55 PM.


#7 CptNautilus

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Posted 26 June 2021 - 02:57 PM

  In my DSS for Stellina tutorial, I mention a Python script that helps sorting out all the FITS created by Stellina. You can download it from here:

 

SortStellinaFITS.py

 

# Name:         SortStellinaFITS
# Version:      1.6
# Purpose:      Sorts Vaonis Stellina's FITS into Lights, Darks and bad images
# Method:       It goes through the FITS produced by Vaonis Stellina telescope
#               and, based on the JSON files, sort them into
#               1. Lights (good images)
#               2. Darks (no star detected, used for sensor's hot pixel removal)
#               3. Bad images (not usable for stacking)
#               FITS in categories 1 and 2 are then copied to the target folder
#               and renamed with a name that allows to sort them in a stacking
#               application (e.g. DeepSkyStacker)
#               The new name contains the following information:
#               - Name of the featured object (or "Dark")
#               - Code of the Bayer pattern
#               - Star roundness (small values are better)
#               - Name of the original FITS
#               - Number of the folder inside the observation folder
#               The last JPG images are also copied to the target folder
#               All the TIFF images are also copied
#               4. Every FITS is then checked and if they are not in BGGR Bayer pattern
#               they will be rotated by 180° to make them in that pattern
#
#               Since version 1.5 the script loops over all the folders
#               that contain the word "capture". It copies the FITS, JPEGS and TIFFs
#               that are in those folders and put them all in the same target folder.
#               If you have reframed the view field, or do not want one of the
#               capture folders to be processed for any reason, delete it before
#               starting the script (or rename it to remove "capture" from its name.
#
#               Since version 1.6, FITS in RGGB Bayer pattern are rotated to BGGR
#               This is done with the astropy.io library, which must be installed
#               beforehand.
#
# Parameters:
#   sourceFolder: Folder of the USB key that contains the "observation.json" file.
#                 This is NOT the folder that contains the FITS.
#                 The original files will neither be deleted nor modified
#   targetFolder: Folder where the sorted FITS will be copied. A new folder will
#                 be created in it, with the date, time and name of the object
#   keepDarks:  Set to True if you have taken darks during this capture
#
# Requirements: There must be JSON files in Stellina's directories. Enable
#               debug mode in Stellinapp to get them (before the capture)
#               The only non-stock library you need is astropy.io, which is free
#
# Author:       Cpt Nautilus
#
# Created:      30/04/2020
# Updated:      23/11/2020
# Copyright:    © CptNautilus 2020
# Licence:      Not for commercial use
#
# New in 1.6:   Convert all FITS with RGGB pattern to BGGR pattern
# New in 1.5:   loops over the entire observation folder
#               gives the JPEG and TIFF more meaningful names
# New in 1.4:   upgraded to work with firmware v20
# New in 1.3:   keepDarks
#
# convertBayerRGGBtoBGGR function derived from HandleFitsFile, developped by Paul de Backer


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