Atik 460 subs orientation question

[gorann]

35 minutes ago, assouptro said:

That camera has an option to rotate the image 180 degrees which can be useful do alignment with a previous imaging session especially after a meridian flip, the problem is, if you forget to uncheck the rotate camera option then the subs will  be “upside down” in relation to your calibration frames. A flipped flat would be a flat taken with the rotate camera option checked so you can calibrate the frames taken “by accident’ the problem I have, as David kindly pointed out, is identifying the images that have been taken in the rotate mode as they look the same as images taken before the meridian. 
I hope that makes sense? 
cheers 

Bryan

Aha, I get it. I assume that what you can do is identify the first image after a flip (it takes some time to flip and align so it should be pretty obvious from the time on the file) and then have a quick look at it if it has been rotated. If you cannot see a star pattern I assume your processing program have a simple function that let you look at a temporary stretch (like the Equalize function in PS). If it is rotated then that presumably goes for the rest of the images that night so you have to rotate them all. After that you should be able to use the same flats and darks for all images (unless you also have some of those rotated)

Good Luck!

[david_taurus83]

30 minutes ago, assouptro said:

Hi David

I am not entirely sure what the FITS header is? I have been referring to the filename or the image properties but if there is more information hidden in the FITS that can possibly help I'd be interested in learning about it!

Cheers 

Bryan

The FITS header contains information like the exposure length, CCD temp, camera gain, your location, RA and DEC information, pixel size etc. Its pretty comprehensive. Each capture software has slightly different formats. I'm wondering if Artemis has put anything in there to indicate the rotation? I use Ekos for capture and Pixinsight for processing and both can display the FITS header. Do you want to post up a sub and I will look to see if Artemis has wrote anything into the header?

[assouptro]

11 minutes ago, david_taurus83 said:

The FITS header contains information like the exposure length, CCD temp, camera gain, your location, RA and DEC information, pixel size etc. Its pretty comprehensive. Each capture software has slightly different formats. I'm wondering if Artemis has put anything in there to indicate the rotation? I use Ekos for capture and Pixinsight for processing and both can display the FITS header. Do you want to post up a sub and I will look to see if Artemis has wrote anything into the header?

Here is one of the subs for your scrutiny 

cheers

rev broom_013_oiii.fit

[carastro]

Fits header tells me:

INSTRUME    = 'ATIK-460ex: fw rev 3.40'                                   
FILTER      = 'Position 7'                                                
EXPTIME     = 1200.000                                                    
DATE-OBS    = '2019-09-21T22:05:51'                                       
XPIXSZ      = 4.540                                                       
YPIXSZ      = 4.540                                                       
XBINNING    = 1                                                           
YBINNING    = 1                                                           
XORGSUBF    = 0                                                           
YORGSUBF    = 0                                                           
XPOSSUBF    = 0                                                           
YPOSSUBF    = 0                                                           
CBLACK      = 495                                                         
CWHITE      = 3868                                                        
CCD-TEMP    = -10.8                                                       
SWCREATE    = 'Artemis Capture'                                           
INPUTFMT    = 'FITS    ' /          Format of file from which image was read        
 

[assouptro]

I have just opened the file myself to check the upload and it opened in ps fits liberator 2 and I can see the tab for image headers!

I'm always learning!

I'm not sure there is anything in there to indicate camera orientation though?

[assouptro]

mage #1
    SIMPLE  =                    T
    BITPIX  =                   16
    NAXIS   =                    2
    NAXIS1  =                 2749
    NAXIS2  =                 2199
    BZERO   =           32768.000000
    BSCALE  =             1.000000
    DATAMIN =             0.000000
    DATAMAX =           65535.000000
    INSTRUME=           'ATIK-460ex: fw rev 3.40'
    FILTER  =           'Position 7'
    EXPTIME =           1200.000
    DATE-OBS=           '2019-09-21T22:05:51'
    XPIXSZ  =           4.540
    YPIXSZ  =           4.540
    XBINNING=           1
    YBINNING=           1
    XORGSUBF=           0
    YORGSUBF=           0
    XPOSSUBF=           0
    YPOSSUBF=           0
    CBLACK  =           495
    CWHITE  =           3868
    CCD-TEMP=           -10.8
    SWCREATE=           'Artemis Capture'

[assouptro]

My FITS header information is displayed slightly differently to Carole's but essentially gives the same numbers.

I can't see anything in there to denote orientation though?

[Xplode]

FITS does actually have header for this use so it must be your software that doesn''t write it.

[david_taurus83]

7 minutes ago, assouptro said:

I can't see anything in there to denote orientation though?

It would appear not

[ApophisAstros]

3 hours ago, ollypenrice said:

I thought you did. It's dead easy from (I think) AA5 onwards. Go to the second page of the Pre-processing window and 1) choose auto alignment, then 2) Star pattern, translation and rotation and then 3) type in 180 for the max rotation. The screen grab is from AA6 but AA5 is almost the same. The third step is easy to identify, it just requires the maximum permitted rotation to be 180 degrees. This will save you an awful lot of faffing about.

A note on terminology: a meridian flip, confusingly, makes a rotated image and not a flipped one. A flipped image is a mirrored one. Some capture software does produce flipped output files, which is rather silly!

Olly

PS Correction: It seems you have to uncheck 'Automatic Settings' to make the third step. I always do so anyway because I prefer to up the number of alignment stars to the maximum allowed.

Wow does this work or what , thanks Olly.

I increased the star detection to 40 as suggested and lost 19 subs out of 77 in Ha (9 before flip rest after)but nice result as below

Processed a little in PS.

Thanks again Olly,

Roger

Edited October 12, 2019 by apophisOAS

[ollypenrice]

1 hour ago, apophisOAS said:

Wow does this work or what , thanks Olly.

I increased the star detection to 40 as suggested and lost 19 subs out of 77 in Ha (9 before flip rest after)but nice result as below

Processed a little in PS.

Thanks again Olly,

Roger

My pleasure. Want to fix that very slight star elongation top to bottom in Ps?

- Create a copy layer.

- Set blend mode to darken.

- Go to Filter - Other - Offset and, in this case, offset vertically by 1 pixel or maybe 2. Slightly too much is best. 

- Then go to Edit - Fade and fade the offset till you have perfectly round stars.

(This one is very well known and not one of mine.)

Olly

[assouptro]

It's good when you ask a question and get an answer! especially when the answer includes information that covers questions you didn't even know you wanted to ask!!

Thanks again for the input.

I think this forum and this community are awesome!!

clear skies 

Bryan

Edited October 13, 2019 by assouptro

[assouptro]

Well, It turns out the camera rotation is actually marked in the FITS header!

I didn't see it as I was opening 'correctly' orientated subs and reviewing the header whereas if I had opened a rotated sub I would have seen the information!

Thanks for all the help

Bryan

 mage #1
    SIMPLE  =                    T
    BITPIX  =                   16
    NAXIS   =                    2
    NAXIS1  =                 2749
    NAXIS2  =                 2199
    BZERO   =           32768.000000
    BSCALE  =             1.000000
    DATAMIN =             0.000000
    DATAMAX =           65535.000000
    INSTRUME=           'ATIK-460ex: fw rev 3.40'
    FILTER  =           'Position 7'
    EXPTIME =           0.100
    DATE-OBS=           '2019-10-16T20:32:10'
    XPIXSZ  =           4.540
    YPIXSZ  =           4.540
    XBINNING=           1
    YBINNING=           1
    XORGSUBF=           0
    YORGSUBF=           0
    XPOSSUBF=           0
    YPOSSUBF=           0
    CBLACK  =           260
    CWHITE  =           386
    CCD-TEMP=           -11.8
    HISTORY =           'Rotate 180'
    SWCREATE=           'Artemis Capture'