Layering (M31 core)

[rottielover]

So I've decided to go after M31 (Andromeda), and I think anyone who's ever shot long exposures of it will have the same experience, if you shoot long exposures you can get great detail in the spiral, but you "blow out" the core. Of course shooting shorter exposures will get you the core, but not the detail in the spiral. So most folks that post about it talk about "layering" in the core by processing 2 images (long exp and short exp) and "compositing" them together.

My questions are: Is there a better way to do this using StarTools? (may or may not be "compositing")...

This is for DSLR. One thing I was wondering about is the LRBG tool for combining CCD data... sorry the hamster is spinning the wheels in my head and I'm probably going down the wrong path here....

EDIT: I found a tutorial on this here: http://forum.startools.org/viewtopic.php?f=7&t=247

Not sure I understand what I'm doing so I'm trying it now. I'm working on my two exposures of Andromeda, when I'm done I'll launch the layer module and see if I can figure this out...

One big question though, if I Bin and Crop these two , then they may not end up the same size ... I'm assuming Layer module has a way to align them?

EDIT 2 - "Dimensions differ" I figure this is because I'm cropping by hand to get rid of the stacking artifacts on the edges. Any suggested easy ways around this?

[micheleorsini]

Hi,
I have followed the same tutorial with success (see my commments in this thread)

You'd better use the layer module with pictures that are already aligned and of the same size

- DSS when stacking: use the same reference frame for both stacks (in one of the two stacks you will use it for reference only, unchecking it to avoid using it in stacking)
- when cropping: same amount in both pictures
- if you are binning: bin both

Michele

[Guy]

Hi,

I have included a description of aligning images using both DSS and Regim in the Background Notes in LRGB Module Use.
However, when I tried to align images using DSS I had problems if I didn't include the reference sub-frame in the stack.
It looks like Michele didn't have the same problem - so perhaps it was something I was doing wrong.

I'd be interested to know how you get on.

Guy

[micheleorsini]

Hi,
my Veil DSS list files

A. this is for RGB:

DSS file list
CHECKED TYPE FILE
1 reflight E:\20170725_Veil\LIGHT_400ISO_240s_28C\L_4271_ISO400_240s__28C.CR2
1 light E:\20170725_Veil\LIGHT_400ISO_240s_28C\L_4272_ISO400_240s__29C.CR2
1 light E:\20170725_Veil\LIGHT_400ISO_240s_28C\L_4273_ISO400_240s__30C.CR2
1 light E:\20170725_Veil\LIGHT_400ISO_240s_28C\L_4274_ISO400_240s__30C.CR2
1 light E:\20170725_Veil\LIGHT_400ISO_240s_28C\L_4275_ISO400_240s__30C.CR2
[...]

B. And this is for Ha

DSS file list
CHECKED TYPE FILE
1 light E:\20170730_Veil_HA\LIGHT_HA_1600ISO_240s_34C\L_4336_ISO1600_240s__30C.CR2
[...]
0 reflight E:\20170725_Veil\LIGHT_400ISO_240s_28C\L_4271_ISO400_240s__28C.CR2

as you can see, the RGB frame is unchecked in Ha list

Beware that if you registered your data and added the reference frame later (and unselected), DSS might not require you to re-register. So be sure to force re-registration

Another suggestion: explicitly set the reference frame in both list and do not rely on DSS "implicit" behaviour (yes, if you do not set one, DSS will do for you and it selects, if I remember well, the one with higher score)

[Guy]

Thanks for the suggestion Michele.
I tried aligning images using DSS again and I had no problem this time - so I expect you are right and it was down to not re-registering all the frames.

Guy