NB NGC 3199 Tutorial

Brent Jaffa

Adam,

I enjoyed your NGC 3199. I might have missed it, but did you use the OIII 1200 sec and the SII 1200 sec images

and if so what stage did you use the 1200 sec. images?

On the download data I did not see any HA  1200 sec images.

Thanks,

Brent

BlockHead

HI Brent,

Sorry..I am a bit confused. I used all of the data provided. The H-alpha images were all 900 sec. The OIII and SI were all 1200sec. There are no 1200sec H-alpha. 

Please ask again so I better understand.

Thanks,

-the Blockhead

Brent Jaffa

Hi Adam, 

I will check again but when I downloaded and unzipped; I had the following images:

HA there are 58 images 900 seconds and no 1200 second images

OIII there are 37 images 900 seconds and 12 images 1200 seconds

SII  there are 37 images 900 seconds  and 14 images 1200 seconds

I will check the fits headers to make sure the OIII and SII file names with 900 seconds are mislabeled.

Brent

Brent Jaffa

Adam,

I downloaded and checked again.

HA there are 58 images 900 seconds and no 1200 second images

OIII there are 37 images 900 seconds and 12 images 1200 seconds

SII  there are 37 images 900 seconds  and 14 images 1200 seconds

I also check the fits header exposure parameter to see that it match the file name. So there 

are 2 different exposure sets (900,1200 sec) O3 an S2. 

Did you treat the 900 exposures of O3 and S2 as 1200 second exposures or

did you use a different dataset?

Brent

BlockHead

Mike Selby provided both 900 second dark frames and 1200 second dark frames. So all of the data files are being used and calibrated for the OIII and the SII (please watch the WBPP section). Then later all of the files (both the 900 second and 1200 second files of OIII and SII) are integrated together after NSG. Proper normalization will give each frame appropriate weight so that the different exposure times are integrated properly. Look at the weights that NSG calculates. for example the  900 sec OIII files are roughly .75 in weight. This is the ratio of the exposure time.

I used exactly the same data set you have in hand.

-the Blockhead

Brent Jaffa

Adam,

Thank you. I didn't understand that in NSG you were using the combined files (900, 1200).

I probably missed it I really appreciate your clarification.

I really enjoy your tutorials as they have been so helpful.

Thanks,

Brent