Looking for beta testers of new Polar Alignment utility.

[Merlin66]

AstroArtV5 supports the WCS fits header:

The WCS (World Coordinate Systems) is a standard composed by FITS keywords which permit to share the astrometric calibration on many different platforms.

These keywords are written to the FITS header by Astroart when the image is saved after an astrometric calibration, for future use by any other FITS reader which supports WCS. Here is a brief description of some of the most important WCS keywords:

▪ CTYPE1 and CTYPE2 indicate the coordinate type and projection. The first four characters are RA-- and DEC- in case of equatorial coordinates (other coordinate types like galactic or ecliptic coordinates are not managed by Astroart). The second four characters contain a four-character code for the projection type (-TAN).

▪ CRPIX1 and CRPIX2 are the pixel coordinates of the reference point to which the projection and the rotation refer.

▪ CRVAL1 and CRVAL2 give the center coordinate as right ascension and declination or longitude and latitude in decimal degrees.

There are three options for the scale and rotation:

▪ Historically, CDELT1 and CDELT2 have been used to indicate the plate scale in degrees per pixel and CROTA2 has been used to indicate the rotation of the horizontal and vertical axes in decimal degrees.

▪ The FITS WCS standard uses a rotation matrix, CD1_1, CD1_2, CD2_1, and CD2_2 to indicate both rotation and scale, allowing a more intuitive computation if the axes are skewed. This model has been used by HST and IRAF for several years.

▪ The 1996 proposed FITS WCS standard used PC001001, PC001002, PC002001, and PC002002 to represent the rotation matrix but retained CDELT1 and CDELT2 for the scale. It is also read by this software, but should not be used for new WCS's.

Astroart supports both the approximate standard based on keywords CDELT and CROTA and the more precise system based on keywords CDx_y.

[StuartJPP]

I am assuming that the premise is to take an image in the east then slew in RA only to the west, the error is calculated between the two resolved plates and an adjustment made on alt/azi (based on the arcseconds per pixel of the image)?

I was thinking of something similar a while ago...this helps me to not bother about doing it...a stand alone version would be nice albeit a bit large for the off-line plate solving database.

[Earl]

its clear im poised when is there a release candidate?

[themos]

I'm sorry Earl, there is still no documentation written for it (busy this weekend) , but you could try taking a pair of JPEGs  of the Polaris region with your camera. I don't want you to waste valuable time with a clear sky getting all the python stuff setup. The two images I need must be taken with the camera fixed on the mount with the only difference being a rotation in RA axis. Also, take the 2nd one with the camera sensor oriented n the horizontal direction (like you would normally shoot a snap). Keep them in your drive and you can later try them with the software when the  skies are bad.

[themos]

Merlin66, could you provide some examples of JPEGs and matching WCSs for me to check, please?

[themos]

StuartJPP, I keep to the Polaris region for both images but the RA axis does get swung around by 90 degrees or some similar large angle. 

[Earl]

getting the niper to bed and was welcomed to cloud on return LOL, typical

[themos]

Shame! Do you happen to know what the Field of View is of your imaging setup? That 200mm Canon with a DSLR  would perfect for this method. 

[Earl]

ill be using my zs71 and 314 for this

[Earl]

FOV:

1.54° x 1.15°

Resolution:

3.98"/pixel

Area:

1.77 sq°

Focal length:

334mm

Focal ratio:

f/4.7

From 12dstring

[Merlin66]

Themos,

I'll see what I have.

The electronic finder set-up I have is a Zuiko 200mm f4 lens with an ATiK16ic camera.

FOV = 63 x 84 arc Min

The fits header info:

AVISUMIN=                280.0
AVISUMAX=                426.0
AVISUTYP=                  0.0
APOLY0  =  0.43113530426640000
APOLY1  = -1.01591339168100000
APOLY2  =  1.109754879585E-005
APOLY3  = -3.508152104379E-005
APOLY4  =  0.00500787253995900
APOLY5  = -3.507013049586E-005
APOLY6  = -1.102732033609E-005
APOLY7  =  0.01427973577929000
EQUINOX =               2000.0
CTYPE1  = 'RA---TAN'
CTYPE2  = 'DEC--TAN'
CRVAL1  =  24.7022333335500000
CRVAL2  = -58.2075496941600000
CRPIX1  =  330.514907382500000
CRPIX2  =  247.987018971600000
CD1_1   =  6.358427089425E-004
CD1_2   = -0.00201002309470900
CD2_1   = -0.00200937046438600
CD2_2   = -6.318189145967E-004
CDELT1  = -0.00210757339460800
CDELT2  =  0.00210698552014600
CROTA1  =                  0.0
CROTA2  = -72.4954476428000000
END

It would be much easier to supply the plate solved fits file....drop me an email.

Edited November 22, 2014 by Merlin66

[russellhq]

The mount (or RA or polar) axis! 

After a rough polar alignment, I set the camera somewhere close to declination 90 so I can see Polaris in the field of view. Keeping the camera fixed to the mount, I slew in RA by a large angle (40 degrees say) and watch where Polaris goes. If it goes off the FOV, the RA axis is not close to Polaris. So I adjust the polar alignment, bring Polaris back into the FOV and try again (the details of this iteration need to be worked out). Once it's set so that Polaris stays in FOV after a large RA slew, we are good to fine-tune the polar alignment by PhotoPolarAlign. The first two images give us the position, in pixel coordinates, of the RA axis (the red cross). I take the first image at an RA position so that the sensor is taking a picture of the sky in "portrait mode" and the second image in "landscape mode", with the long side of the sensor horizontal. The plate solving tells me where the NCP is (allowing for precession  since 2000), in pixel coordinates and what the scale is. Now that the camera is horizontal, x and y pixel offsets translate directly into instructions to move the mount RA axis up-down or right-left by so many arcminutes.  After I adjust the polar alignment, I take another image and check for improvement. The RA axis pixel coordinates have not changed, only the NCP pixel coordinates move. With practice, it should take only 3-4 iterations to get it close enough (whatever close enough is for your imaging needs).

Is the aim here simply to find the RA axis in the image and the NCP and get the 2 to overlap?

[themos]

Is the aim here simply to find the RA axis in the image and the NCP and get the 2 to overlap?

Yes, that's the idea.

[russellhq]

Sorry, another question: When you talk about taking a portrait and landscape orientated image, is the intention to achieve this by rotating the mount or rotating the camera in the focuser between shots? It would be slightly cumbersome if it was the latter.

[Merlin66]

Russell,

See message #29 above.

Just the rotation of the mount RA axis until the 2nd image is a horizontal landscape image.....

Edited November 23, 2014 by Merlin66

[themos]

I wish there was more standard terminology! No, you don't rotate the camera in the focuser, there may not even be a focuser. The camera stays rigid with respect to the mount. Now, if I say "rotate the mount", somebody might think that I mean change the direction of the polar axis to the left or right. That is what's making writing the instructions a headache!

[russellhq]

I wish there was more standard terminology! No, you don't rotate the camera in the focuser, there may not even be a focuser. The camera stays rigid with respect to the mount. Now, if I say "rotate the mount", somebody might think that I mean change the direction of the polar axis to the left or right. That is what's making writing the instructions a headache!

I know what you mean. I had trouble just phrasing the question!

[themos]

Maybe I just need to make a YouTube video...

[themos]

Hello,

Please download the installer and run it.

Before running PhotoPolarAlign, you will need to have a Python installation that includes all the modules it needs. (I used the Anaconda distribution)

You will also need to register with http://nova.astrometry.net/  and get an "API key".

AstroPolarAlign can be started by double-clicking the PPA.py file that the installer puts on your file system.

The first thing to do is to add the key you got from nova. Use the File -> Settings menu for that.

The second thing is to try out the supplied test image files. The two big buttons to the left of the Operations panel are used to select image files. Please select the file v.jpg for the top one and the file h.jpg for the bottom one. Hit the Solve button next to the big button, first for one image, then wait until the "Solved" label goes green, then do the second one. This will need an internet connection, o course. Once both "Solved" labels are green, you can hit the Find Polar Axis button and wait for the annotated image to pop up. Your polar alignment is also displayed on the main screen. 

Then select the i.jpg file with the big button on the right side of the Operations panel. Click its Solve button and wait for a solution. Then click on "Show Improvement" button to see a new plot. 

Then, exit the program and restart it to try it with your own images (the reason is that the scale is remembered in a single session but not across sessions and it's unlikely that your image scale will match the examples).

Ok, let's see how this works out! Thanks for your time, hope you will find it useful.

[Earl]

I have downloaded the application, its insatlled, but created no links to access it, how do you use this?

Edited November 25, 2014 by Earl

[Earl]

OK i solved that by opening the file with python (and creating an association, which for some odd reason decided to install in the users directory.... not progrtam files), then create a shot cut to the PPA file on the desktop.

Now the api key does not do anythign when input.

clicking ok doer nothing, however it seem to work by just closing the window with the x in the right corner.

Edited November 25, 2014 by Earl

[themos]

Do you have python 2.7 or some other version, Earl? I should have said we need 2.7 

You mean you can't close the Settings window by clicking Ok? That's odd.

Try restarting the app, and look at File->Settings again. If a key was given it should be there (it gets stored in a PPA.ini file, where PPA.py is).

[Earl]

Looks like im stuck on inptting the api as python is goving me:

Its 2.7

{'parity': None, 'scale_est': None, 'myjobs': None, 'center_dec': None, 'scale_l
ower': None, 'radius': None, 'center_ra': None, 'scale_units': None, 'wcs': u'C:
/Program Files/photopolaralign/v.wcs', 'allow_mod': 'd', 'job_id': None, 'downsa
mple_factor': None, 'public': 'y', 'galex_wcs': None, 'kmz': None, 'scale_err':
None, 'sdss_wcs': None, 'allow_commercial': 'd', 'scale_upper': None, 'crpix_cen
ter': None, 'upload_url': None, 'wait': None, 'apikey': '', 'sub_id': None, 'twe
ak_order': None, 'upload': u'C:/Program Files/photopolaralign/v.jpg', 'server':
'http://nova.astrometry.net/api/' 'jobs_by_exact_tag': None, 'jobs_by_tag': Non
e}
Sending to URL: http://nova.astrometry.net/api/login
{'parity': None, 'scale_est': None, 'myjobs': None, 'center_dec': None, 'scale_l
ower': None, 'radius': None, 'center_ra': None, 'scale_units': None, 'wcs': u'C:
/Program Files/photopolaralign/h.wcs', 'allow_mod': 'd', 'job_id': None, 'downsa
mple_factor': None, 'public': 'y', 'galex_wcs': None, 'kmz': None, 'scale_err':
None, 'sdss_wcs': None, 'allow_commercial': 'd', 'scale_upper': None, 'crpix_cen
ter': None, 'upload_url': None, 'wait': None, 'apikey': '', 'sub_id': None, 'twe
ak_order': None, 'upload': u'C:/Program Files/photopolaralign/h.jpg', 'server':
'http://nova.astrometry.net/api/' 'jobs_by_exact_tag': None, 'jobs_by_tag': Non
e}
Sending to URL: http://nova.astrometry.net/api/login
Exception in Tkinter callback
Traceback (most recent call last):
  File "C:\Users\lappy\Anaconda\lib\lib-tk\Tkinter.py", line 1486, in __call__
    return self.func(*args)
  File "C:\Program Files\photopolaralign\PPA.py", line 593, in settings_destroy
    self.write_config_file()
  File "C:\Program Files\photopolaralign\PPA.py", line 584, in write_config_file

    with open(self.cfgfn, 'w') as cfgfile:
IOError: [Errno 13] Permission denied: 'PPA.ini'
Exception in Tkinter callback
Traceback (most recent call last):
  File "C:\Users\lappy\Anaconda\lib\lib-tk\Tkinter.py", line 1486, in __call__
    return self.func(*args)
  File "C:\Program Files\photopolaralign\PPA.py", line 593, in settings_destroy
    self.write_config_file()
  File "C:\Program Files\photopolaralign\PPA.py", line 584, in write_config_file

    with open(self.cfgfn, 'w') as cfgfile:
IOError: [Errno 13] Permission denied: 'PPA.ini'
 

Edited November 25, 2014 by Earl

[themos]

Hmm, it's trying to save the settings file but you're not allowed to create a file in whatever directory you started python in.  What directory is PPA.py in?

[themos]

Sorry, I can see it's in  C:\Program Files\photopolaralign\PPA.py

Run as administrator, or install it again under C:\Users\lappy