Macophot IR820c is/was rebadged Efke IR820 (same as Adox selling the Efke films as their CHS line), according to their US distributor who claims to have organised that rebranding arrangement after Maco produced and released a badly uneven batch of their own IR sheet film. The identical spectral sensitivity and use of Aura branding kind of gives it away too.
Originally Posted by tsiklonaut
Same guy also asserts that the 820nm IR sensitiser is now very hard to source because the lab that was making it got bought and raised the MOQ to about $50k.
I guess Ilford is using a different sensitiser for SFX.