Newbie "fits" question
Posted: Fri Nov 09, 2018 4:51 pm
Hi,
I've been using SharpCap for about 6 months and have found it really useful. I'm a retired Lecturer / Professional Engineer, and have some background in Astronomy and Computing. My question concerns some fundamental concepts associated with the fits files saved from the SharpCap "Live Stacking" function. I append some images:
* Image A is a jpg of the png from SharpCap.
* Image B is a jpg of the 32 bit file from SharpCap as portrayed on "Irfanview" (one of the "normal" image viewers that handles fits).
* Image C is a jpg of the same 32 bit file as seen on "avisFT" (a fits viewer that I am trying out).
* Image D is a jpg of the same 32 bit file with the white threshold altered.
Using image A as a reference point being comparable to what I observed in the sky, my questions are these:
1 I can see that image B is vertically flipped, but why is the default rendering so different from image A ?
2 I can see how image B becomes image C, but why are the 4 stars from A portrayed as discs, whereas most of the remaining features are arcs? (I can appreciate that the 4 stars were "locked on to" by SharpCap, but why are the arcs even visible when they are invisible on A? And how can SharpCap generate a visible background between the "locked stars", such as a deep sky object, if non locked entities are permitted to rotate on the image?
3 You will note that 4 stars are circled in red on D. These correspond to stars identified on planetarium software, but which I do not believe were visible by eye at the time of capture. Why are these discs, rather than arcs, and how can one make more arcs become discs?
I apologise for the length of my post, but I am struggling to comprehend what is actually going on, and how I can make use of it.
Many thanks for reading this far, Rfi
I've been using SharpCap for about 6 months and have found it really useful. I'm a retired Lecturer / Professional Engineer, and have some background in Astronomy and Computing. My question concerns some fundamental concepts associated with the fits files saved from the SharpCap "Live Stacking" function. I append some images:
* Image A is a jpg of the png from SharpCap.
* Image B is a jpg of the 32 bit file from SharpCap as portrayed on "Irfanview" (one of the "normal" image viewers that handles fits).
* Image C is a jpg of the same 32 bit file as seen on "avisFT" (a fits viewer that I am trying out).
* Image D is a jpg of the same 32 bit file with the white threshold altered.
Using image A as a reference point being comparable to what I observed in the sky, my questions are these:
1 I can see that image B is vertically flipped, but why is the default rendering so different from image A ?
2 I can see how image B becomes image C, but why are the 4 stars from A portrayed as discs, whereas most of the remaining features are arcs? (I can appreciate that the 4 stars were "locked on to" by SharpCap, but why are the arcs even visible when they are invisible on A? And how can SharpCap generate a visible background between the "locked stars", such as a deep sky object, if non locked entities are permitted to rotate on the image?
3 You will note that 4 stars are circled in red on D. These correspond to stars identified on planetarium software, but which I do not believe were visible by eye at the time of capture. Why are these discs, rather than arcs, and how can one make more arcs become discs?
I apologise for the length of my post, but I am struggling to comprehend what is actually going on, and how I can make use of it.
Many thanks for reading this far, Rfi