spectro-aras.com

Hello,
My computer crashed last week and took with it all of my apps. Thanks to my backing up almost everything, I have regained pretty much everything I lost. But I am missing my cosme files that I used for processing specs using ISIS. For the life of me I cannot recall how I created those cosme files let alone their importance in processing the specs. I have the ISIS manual and have seen the mention of cosme in the pictures, but I cannot find how to create them.

So, can someone direct me to the place in the manual where cosme files are explained as well as how to go about creating them?
If I recall, I think they have something to do with the darks but that is as far as my mind will let me remember. I did make cosme files for each exposure time I use (i.e 120 sec, 300 sec, etc ) which is why I suspect the darks are used in their creation. Or if it is an easy to explain process perhaps you would not mind simply outlining the process. I also seem to remember someone saying they do not use cosme files, so perhaps I do not even need them. However I suspect if Christian included them in the spec processing that they must have some value.

Thanks,

Keith

Hi Keith,

You just need a master dark and use the ISIS Masters Tab, Compute a cosmetic file. To set the threshold I tried a series of values and found they stayed fairly constant as I reduced the threshold until it rapidly went up. I used the value just before the upturn.

Using this list in IRAF (not ISIS) I found it's Clean routine still left about 10 hot pixels which I added to the list manually.

If the Dark is exposed long enough I don't think you only need multiple cosmetic files. At least I don't with my CCDs as hot pixel is hot although it may not show it in a quick exposure.

Regards Andrew

Thanks some time.

a bunch, Andrew. Just before I read your reply to my request I found the cosme part in the ISIS manual. I did not know that I could use only i dark aster if it was exposed long enough. That would safe some time.

To be clear, when you said "To set the threshold I tried a series of values and found they stayed fairly constant as I reduced the threshold until it rapidly went up. I used the value just before the upturn", does "they" refer to the number of hot pixels? If so, where do you see those hot pixel numbers?

Cheers

Whoops! Just found the answer. Those numbers appear in the box in the lower left of the Masters tab.

Thanks.

Glad you have it sorted Keith. Sorry I was not clear. Yes the "they" referred to the number of hot pixels. I was importing the file into a spreadsheet so I could edit it into the format required by IRAF so I got the number from there but as you found ISIS reports the number.

Regards Andrew