There was a smooth market at the moment. I bought the RUT double calendar to complete my November income portfolio, according to my plan. As usual, I placed a limit order with $0.05 above mid price and it was filled immediately. After the fill, I found the mid price dropped $0.10 or so for a couple of minutes caused by market activities then backed up. The DC reduced the portfolio vega by 90, almost the amount of that of 2 iron condors. The probability of success at expiration at either break even points is in high 70%.