AstroTortilla is software that automates astrophotography tasks like plate solving, polar alignment correction, and syncing a mount based on captured images. It works as a wrapper for other astrophotography tools, using captured images to determine the camera orientation and solve for the object being imaged. The document provides information on installing and configuring AstroTortilla, selecting the appropriate astrometric index files, testing the software using sample images, and the workflow for using it while imaging under the stars.

1. AstroTortilla
Free Plate solving
AstroTortilla is a wrapper around common
astrophotography tools intended to automate basic
tasks such as polar alignment and goto correction.
Mark Casazza
http://Casazza.net
July 2014

2. Important Links
• Home:
– sourceforge.net/p/astrotortilla/home/Home/
• FAQ
– sourceforge.net/p/astrotortilla/home/FAQ/
• Tutorials:
– sourceforge.net/p/astrotortilla/discussion/general/thread/1d35f7ae/
– http://lightvortexastronomy.blogspot.com/2013/08/tutorial-imaging-
setting-up-and-using.html
• User Guide
– file:///C:/Users/Mark/Downloads/AstroTortilla_user_guide%20(1).pdf

3. What Can It Do
• Report back the center point of any image in RA & DEC
– Needed for asteroid, comet and super nova reporting
• Sync a goto mount* to its true orientation
• Slew the mount* to the intended target
• Interface with popular image acquisition tools
– Nebulosity
– Backyard EOS
– Maxim DL
– Astro Photography Tool
– Any other software via image files or screen capture
* ASCOM interface required

4. Any Thing Else?
• Bookmark locations for
– Post meridian flip alignment
– Multi-night exposures
• Assist with Polar alignment
– Not recommended
• Report your real FOV
• Report camera orientation (rotation)

5. Other things to consider
• Creating an all-sky map with each image solved
– Eliminates mount errors (PEC, flexure, etc.)
– Eliminates atmospheric refraction error
– T-Point plus Sky X does this…
• Allow full automation of your setup
– This requires a 100% solve rate
• AT is not yet this good

6. Installation
• This will take a while and will require a large
download
• Follow the prompts; do not deviate from the
default
• Plan what data sets you need before you start
– http://sourceforge.net/p/astrotortilla/home/FAQ/#which-index-files-do-i-need
– 57.3 * sensor_width / focal_length = FOV_degrees
– Download from your largest FoV to 1/5th of your smallest FoV

7. Index Files and Field Width
Index Filename Range of skymark diameters (arcminutes)
index-4219.fits 1400 - 2000
index-4218.fits 1000 - 1400
index-4217.fits 680 - 1000
index-4216.fits 480 - 680
index-4215.fits 340 - 480
index-4214.fits 240 - 340
index-4213.fits 170 - 240
index-4212.fits 120 - 170
index-4211.fits 85 - 120
index-4210.fits 60 - 85
index-4209.fits 42 - 60
index-4208.fits 30 - 42
index-4207-*.fits 22 - 30
index-4206-*.fits 16 - 22
index-4205-*.fits 11 - 16
index-4204-*.fits 8 - 11
index-4203-*.fits 5.6 - 8.0
index-4202-*.fits 4.0 - 5.6
index-4201-*.fits 2.8 - 4.0
index-4200-*.fits 2.0 - 2.8

8. Installation screen shots

11. Astrometric Index Selection
• Shortest FL 18mm 67 degrees
• Longest FL 952mm 1.3 degrees
– 1.3 * 20% * 60 = 15.6 arc minutes
If you backed up the data
you can select 4219 to 4219
and copy the files in later.

12. Check this if you want the icon ->

14. This will take a while!
No avoiding it, you
are downloading a
Linux on Windows
implementation
First it downloads
Then it installs

15. Done!

16. Botched Installation?
• Use Add/Remove programs
– AstroTortilla ver 0.6.0.0
• Backup data files
– C:cygwinusrshareastrometrydata
• Completely remove all files
– C:cygwin
– C:cygdrive (if it exists)
• Use a registry cleaner
– Cclean https://www.piriform.com/ccleaner
– Clean Regstry (backup first)
• Reinstall

17. Configuration
• Equipment
– Camera : via software
• Exposure: 5-15 seconds
– Mount : Normal Ascom setup
• AstroTortilla options – Do not touch
– Backend config
– Cygwin shell
– Hide Cygwyn
– JNow or J2000

18. Configuration
• Options to touch
– Downscaling – 0 (I keep this at 0)
– Scale minimum – 0 (I keep this at 0)
– Scale maximum – 2 (I set this to 2)
– Scale units – degwidth (I leave this alone)
– Scale refinement – 0 (I leave this at 0)
– Search radius – 180 (I leave this at 0)
One final set of parameters that greatly affect the normal usage is the field-of-view
and area restrictions. There are four settings for setting the FOV,
You should set (If you don’t change your setup often):
• Minimum to about half the estimated field size
• Maximum to twice the estimated field size
• Scale refinement to 0.1
• To limit the area of search you can reduce the search radius to 45 degrees

19. Custom options
• --no-plots –N none – r --objs 60 --sigma 10
• Keep --sigma last! It is the one you will edit
• --no-plots
• Do not plot the annotated image
• –N none
• Do not crate a new FITS file with headers added
• -r
• Sort objects by brightness (Limited success)
• --objs 60
• limits objects considered to 60 (also try 50 or 100)
• --sigma 10
• sets noise floor; strong impacts objects found
• Aim for 60 to 500 objects

20. Test Drive
• Find some short exposure images
• Connect to ASCOM Telescope simulator
• Connect planetarium software
• Use “File Open dialog” camera
• With only the “Synch Scope” actions checked
– Click “Capture and Solve”
• Watch the status bar for
– simplexy: Found xxx objects
– This should be greater that 60 and less than 500
– Adjust sigma value if necessary (bigger = less)
• Solved!
– Location will be display & planetarium will point correctly

21. Having trouble?
• Turn on the Log Viewer to see what is going on
• Watch for:
– simplexy: Found xxx objects
• Adjust “sigma” and exposure until you get 100 to 500
• More is okay unless it is noise

22. Workflow under the stars (1 of 3)
• Rough polar align (via pole scope)
• Home mount (no need to be precise)
• Connect Ascom (with guiding software)
• Drift align
• Connect planetarium
• Slew to star for focusing
• Start image acquisition software

23. Workflow under the stars (2 of 3)
• Focus camera
– You can plate solve with your guide scope if you can’t
find a star for focusing
• Slew to target (even between targets)
• Check all 3 “actions”
• Plate Solve (it may take several pictures)
– Watch object count
– Adjust exposure or sigma if needed

24. Workflow under the stars (3 of 3)
• Frame your target
• Check “Sync scope” only
• Plate Solve
• Save Bookmark for meridian flips or next night
– Click “BookMarks”
– Click “Add Current Solution”
– Type in an appropriate name
• Begin imaging