Image Acquisition Information
Telescope: 16" RCOS Richey Chretien Telescope (ion milled at 6/9)
Camera: SBIG STL-6303 M
Guiding: SBIG AOL, Astrodon MOAG AOG (SBIG 237
with Custom FLR)
Filters: Astrodon Ha, NII, OIII (3 nm filters)
Mount: Software Bisque Paramount ME
Acquisition Programs: The Sky,CCDAutopliot III, CCD Soft.
Processing Programs: CCDStack, Maxim DL, Photoshop
Date: August 26, 2009 -September 20, 2009,
Time: 10 x30 min ( 5
hours) each for each of Ha, NII and OIII:
Total of 15 hours imaging time.
Processing: CCD Stack and PhotoShop CS/3
Image Infornmation: NGC 6781
ia a planetary nebula in the constelation of Aquila. It is 109 arc-secs in size at magnitute 11.4. This object
has distincively different patterns under NII and H-alpha filters, with a large central blue (OIII) component with minimal contribution
in the SII region. It it about 3000 light-years distant. The central star is faint at magnitude 15.5.
This Narrow Band image was obtained using AstroDon 3nm band pass of Ha,
NII and OIII. This object sheds light in the Ha, NII and OIII wavelengths, making it an interesting object for an NII
filter. The Narrow Band image was created by an unequal weighting of Ha/NII/OIII at a ratio of 1:1:4
(the OIII signal is relatively weak, but Ha and NII quite similar in strength, thought the pattern was different).
This was essentially a modified Hubble Palette (RGB as Ha/NII/OIII). This was layered over a modified (enhanced)
H-alpha image to bring out some of the details lost in the assembled narrow band image. Further data stretching,
high pass filtering and background smoothing was performed with Adobe Photoshop CS/4. All data stretching was by minimal
stretching with gamma and DDP in CCD Stack and then further stretching with curves/levels in photoshop.