Chi Cygni - Real geek stuff!

[timwetherell]

Got quite interested in Chi Cygni recently. Magnitude varies from about 3 to about 14 which is a crazy range. Apparently it's due to the surface temperature dropping which has the double effect of shifting the emission peak into the infrared and molecules forming in the cooler photosphere that absorb visible light. It's near minima so thought I'd try photographing it in visible and infrared light and sure enough, it's really bright at 1µm and really dim visually. 

[beka]

16 hours ago, timwetherell said:

Got quite interested in Chi Cygni recently. Magnitude varies from about 3 to about 14 which is a crazy range. Apparently it's due to the surface temperature dropping which has the double effect of shifting the emission peak into the infrared and molecules forming in the cooler photosphere that absorb visible light. It's near minima so thought I'd try photographing it in visible and infrared light and sure enough, it's really bright at 1µm and really dim visually. 

Hi timwetherell,

Very interesting. Could I ask the equipment you used? I am especially interested in how you did the 1𝜇m IR.

Best

[timwetherell]

13 minutes ago, beka said:

Hi timwetherell,

Very interesting. Could I ask the equipment you used? I am especially interested in how you did the 1𝜇m IR.

Best

Thanks  I have a infrared modified Sony A7s mounted on a skywatcher black diamond 90mm ED apo. Used a photographic  >950nm pass IR filter. The silicon CCD has some sensitivity out to about 1.1µm so it's recording in the 950nm-1100nm band. The filter is only 77mm diameter (bought it for a regular camera lens) so the 90mm refractor is actually a 77mm with that on the front. I find the Sony a really good astrophotography camera - really excellent CCD!