Plate Solving Question - Forums

Topic starter

Dec 10, 2023 · Edited: Dec 10, 2023

Hi AstroBiners!

Quick question: I have a 4 times binned image, from 9576 x 6382 to 2394 x 1595

In the Camera each pixel is 3.76

So when I try plate solving, Siril is asking me to input FL and Pixel Size. I tried putting in 3.76um but it doesnt work. Could it be that binning changes the pixel size I need to input? If so, what should it be?

Gracias in advance!

FilippoTib

Dec 10, 2023

Interesting.

I've never worked with binning, but from what I understand you group 4x4 pixels together. So I think the pixel size is also scaled by 4 times, so 15.04um.

Take this with a grain of salt. Let's wait for an expert's opinion on the subject

Respectful Concise

Brock Johnston

Dec 10, 2023

The binning you did creates a picture with effective pixel size 4 x 3.76 = 15.04um. The focal length remains the same. The plate solver uses the pixel size, the number of pixels and the focal length to determine the field of view to match the stars to.

Brock

Helpful Concise

Kai Linde

Dec 10, 2023

Hello,

Siril is sometimes very demanding when it comes to plate solving. Have you ever tried a different catalogue? That has often helped me.

CS

Tom Gray

Dec 10, 2023

With the correct focal length and pixel size (as others have said 4 x original value for your bin 4x4, Siril usually does a great job. Another free program you can try is ASTAP.

Oscar

Dec 10, 2023 · Edited: Dec 10, 2023

Tom Gray:
With the correct focal length and pixel size (as others have said 4 x original value for your bin 4x4, Siril usually does a great job. Another free program you can try is ASTAP.

Which one is a good star database for ASTAP? D80, D50, D20, D05, G05, W05, or Hyperlada? I'm guessing D50 or D20 is good enough for most cases?

Alien_Enthusiast

Topic starter

Dec 10, 2023

Interesting.

I've never worked with binning, but from what I understand you group 4x4 pixels together. So I think the pixel size is also scaled by 4 times, so 15.04um.

Take this with a grain of salt. Let's wait for an expert's opinion on the subject

It did work! Thanks a lot!

Tom Gray

Dec 10, 2023

Tom Gray:
With the correct focal length and pixel size (as others have said 4 x original value for your bin 4x4, Siril usually does a great job. Another free program you can try is ASTAP.

Which one is a good star database for ASTAP? D80, D50, D20, D05, G05, W05, or Hyperlada? I'm guessing D50 or D20 is good enough for most cases?

I think I just use H18 - I do most of my plate solving with Stellarmate EKOS during image framing and capture, and Siril in processing. Many databases can be used https://sourceforge.net/projects/astap-program/files/star_databases/

Oscar

Dec 10, 2023 · Edited: Dec 10, 2023

This is sort of unrelated (to my last question), but if I drizzle 2x, does that mean I need to decrease pixel size by half in Siril plate solve?

Tom Gray

Dec 11, 2023 · Edited: Dec 11, 2023

This is sort of unrelated (to my last question), but if I drizzle 2x, does that mean I need to decrease pixel size by half in Siril plate solve

I think so yes - I don’t tend to use drizzle as file sizes to big for my ageing computer.

Alien_Enthusiast

Topic starter

Dec 11, 2023

Tom Gray:
This is sort of unrelated (to my last question), but if I drizzle 2x, does that mean I need to decrease pixel size by half in Siril plate solve

I think so yes - I don’t tend to use drizzle as file sizes to big for my ageing computer.

*Wait but what happens if I first bin by 4 and then drizzle by 3? My initial pixel size is 3.76 - would my final be 3.76x4 = 15.04 - 3.76 = 11.28? Am I correct?

Tom Gray

Dec 11, 2023 · Edited: Dec 11, 2023

~5.01 arc second/px. =(3.76x4)/3
Try it at then platesolve to see the result. https://nova.astrometry.net/upload

Tom Gray

Dec 11, 2023

Another useful calculator https://astronomy.tools/calculators/ccd