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Monday, February 9, 2015

Abell 85 (CTB1), a dim Galactic Supernova Remnant in Cassiopeia

I managed to collect some lights for this object between 19.01 - 08.02. 2015. The transparency was poor at all nights and speeding clouds interrupted the imaging session way too soon. Altogether I collected only four hours of H-a and two hours of O-III.

Abell 85 (CTB1) 
SNR G116.9+00.1 in constellation Cassiopeia

A bicolor photo of Abell 85 from an emission of ionized elements,
Oxygen and Hydrogen (O-III and H-alpha)

An experimental starless photo shows the actual SNR better

The ionized oxygen, O-III, can be seen as a blue color. The O-III channel is very weak and I was able to dig it out it only at left side of the shock front.

The supernova remnant in H-alpha light alone


Abell 85 is a very faint supernova remnant in constellation Cassiopeia. It's difficult to image with any details due to extremely low surface brightness. Abell 85 has a largish diameter, about half a degree, it has a same apparent diameter as a full Moon. The physical diameter is about 98 light years across. This SNR locates about 9800 light years from the Earth. CTB1 was originally thought to be a planetary nebula and it was included the Abell catalog of planetary nebulae under a name Abell 85. It was confirmed to be a supernova remnant by Willis & Dickel at 1971.

Technical details

Processing work flow
Image acquisition, MaxiDL v5.07.
Stacked and calibrated in CCDStack2.
Deconvolution with a CCDStack2 Positive Constraint, 33 iterations, added at 50% weight
Color combine in PS CS3
Levels and curves in PS CS3.

Imaging optics
Celestron Edge HD 1100 @ f7 with 0,7 focal reducer for Edge HD 1100 telescope

Cameras and filters
Imaging camera Apogee Alta U16 and Apogee seven slot filter wheel
Guider camera, Lodestar x2
Astrodon filter, 5nm H-alpha
Astrodon filter, 3nm O-III

Exposure times
H-alpha, 12 x 1200s binned 2x2 = 4h
O-II, 6 x 1200s bined 4x4 = 2h

A single un cropped, calibrated and stretched, 20 min. H-alpha frame


JayOutWest said...

You do extremely wonderful work and I hope it is okay, I posted links to your site and images from my blog though I am a visual observer. Keep up the great work!

J-P Metsavainio said...

Thanks to inform me,

It's OK to publish my images as long as credits and a link to an original source are mentioned.