GRIS: slit angle
The scanning direction of GRIS should in theory be encoded in the SLITORIE
keyword. While trying to determine the meaning of this angle, I've found that it seems to be very volatile. In the following plot I have plotted the value of the SLITORIE
keyword against the correct angle as determined from cross correlation with HMI. We can see that for 2015, the value was somewhat well-behaved, but for all other years, it seems to be more or less random... The X value is the angle between slit and Y axis measured in mathematically positive direction (counter-clockwise). Even if SLITORIE
doesn't hold the full information, there should at least be some correlation.