Canon is planning to introduce a full frame mirrorless camera in EOS R lineup dedicated for astrophotography. This model will be named as Canon EOS Ra, and it is already appeared on an internal Canon roadmap for 2020.
In the past, Canon has released several DSLR models such as EOS 20Da and EOS 60Da for astrophotography. Currently, there is no specs about this EOS Ra full frame astrophotography camera..
Canon also has mentioned the Canon EOS Ra in an EOS R leaflet on one of their official sites. You can download the leaflet here.
Canon EOS Ra leaflet states:
The EOS Ra is a version of the EOS R designed for astrophotography. This camera has approximately four times the transmittance of hydrogen-alpha light (656 nm) as the EOS R. Photographs of subjects that reflect a lot of infrared light will therefore appear redder than they actually are. Also, as it may not be possible to obtain an appropriate color balance or uneven colors may result, shooting normal subjects with this camera is not recommended
Camera operations are essentially the same as for the EOS R. Refer to the included EOS R Getting Started Guide (booklet). Additionally, you can download the EOS R Advanced User Guide (PDF file) from the Canon website.
No specifications are known at this time, as only the model name has appeared on the internal document. There is however a chance that the model name is an internal codename for a different camera.
Canon Camera Deals:
$300 off on Canon EOS R body: $1,999 at Amazon
$500 off on Canon EOS R with 24-105mm Lens: $2,899 at Amazon
$200 off on Canon EOS RP with 24-105mm Lens: $2,199 at Amazon