Cannot platesolve processed image

[Forum_2017]

Hi,

I took 6 lights each 6 minutes of M31 last month. When centering on M31, I took several short exposures, 10 sec, and platesolved fine in AA6.

However, the other night I wanted to revisit my processed image and wanted to find a certain coordinate (look for the new sn), but I can not get AA6 SP2 to platesolve the image.
Here's a link to the image:
http://b-rasmussen.dk/astro/2017/0827/m31.png

Are there too many stars and to much bright area in the image?

Is there any way to manually set say three known stars coordinates to enable finding coordinates in the image?

PS: I have searched this forum for similar questions, but I didn't find anything similar.

[Forum_2017]

What camera focal length, what pixel size?
I find that All Sky Plate Solver is an excellent fall back

http://www.astrogb.com/astrogb/All_Sky_ ... olver.html

[Forum_2017]

Hi,

Camera: Canon 1000D (unmod)
telescope: F640mm Ø130mm, FOV approximately 117'

The linked image is scaled down from 3906x2602 to 1024x682, using the original image doesn't work either.

[Forum_2017]

Hi,
sometimes it's not possible to plate-solve the 4-5 brightest objects of the sky (e.g. M31, M42, M13, etc) because the extreme brightness of the nebula caused trouble to the catalogs from where the pattern were generated.
You need to use the command "Astrometry", with "Manual" reference stars.

[Forum_2017]

Thanks Fabio - will try that.

[Forum_2017]

I have been trying this plate solve module for several hours with several different images both bright and dim. MOst of the time it does not solve anything. It will never solve for the coordinates even if it plate solves. I have used several of your practice images and mostly they work. I am using a fits but the header information is not completely correct as the RA and Dec are not available to the star finder.
AS regards the coordinates I have placed the object name and the cameras fov. I am disgusted with this entire process. I watched a youtube video on plate solving but it was not a help. Could some please point me in the correct direction. I have read and re read the manual. thanks cjacobson

[Forum_2017]

Remember to set the correct platesolve parameters for your camera (field / rotation, etc) . Post/send by email a sample image and a screenshot of the Find Coordinates window.

[Forum_2017]

thanks I will after I try this again tonight. cjacobson

[Forum_2017]

Problem resolved with help of Fabio by just flipping the orientation. Thanks. cjacobson

[Forum_2018]

Hi again Fabio,

Now I have another image that can-not be platesolved after being processed.

Is it possible to see a log file to investigate why it fails and possibly tweak some of the platesolver parametres?
(nova.astrometry.net solves the image just fine, see http://nova.astrometry.net/user_images/2551314#original)

The image is here (Maffei 1):
http://b-rasmussen.dk/astro/2018/1210/Maffei_ed1.jpg

Horizontal field is 95 arc minutes.

Some of the lights platesolves fine, but not all?

Here's data for one of the successfully solved fit files:

Name ........... #3 Maffei_s4_480s_001.fit
Path ........... C:\CanonTemp\
Size ........... 3906 x 2602
Field of view .. 95.59' x 63.67' , 85.5°
Pixel scale .... 1.47" x 1.47"
Center ......... 02 36 29.8 +59 39 31
Pixels ......... 10163412
Min ............ 15 @ 3016,149
Max ............ 3651 @ 3818,0
Background ..... 407
Average ........ 411.39064
Sum ............ 4181132537
Std.deviation .. 106.55653

[Forum_2018]

In this image the problem is not platesolve, it's the stars.

If you place the mouse over them you'll see that they are not recognized, because the 8 bit JPEG saturated too much (10 pixels of saturation, there are also small "valleys" in the middle). The Astroart star recognizer is maybe too strict about it. In any case a good precision of the centroid is lost.

About some 16 bit files that where not platesolved, verify again the stars, you may increase the FWHM max in the Preferences. If the stars are really extremely saturated you may try a light Gauss filter, then platesolve, the Undo the filter.

Just as a test, that JPEG image can be platesolved reducing the size of saturation (size of the image), for example with the command Binning2x2. Then the image is correctly platesolved (but the N-E marker is not shown immediately, this is a bug on color images, to solve just Copy and Repaste the platesolved image, or just Save and Reopen it).

[Forum_2018]

Hi Fabio,

Thanks for the explanation.

I tried light gauss blurr, several attempts ranging from 0.1 up to 5 in smalle steps, but with no success.

I am using the full fits file:
http://b-rasmussen.dk/astro/2018/1210/Maffei_ed1.fit

The dip is not present in the fit file image, it must be a JPEG artifact.