Support is actually around 37.88 not 39.60
How do we know that's the support? well-going back to 1990 until now it has acted as support and resistance line.
Also known as axis line has to be tested.
Wait to go long- if planning for short have a good SL around 43
For longs- if cannot wait to go long at least have enough funds to go via multiple entries instead of one big entry.