There is a nice amount of liquidity at 49k. Usually Bitcoin will have some sort of liqiduity purge on this lower timeframe before an impulsive move up. 49.000 is a nice round number, traders almost always act around these round numbers. This equals liquidity.
Next to this, there was a bullish flag formed there with a nice hammer candle. Lots of traders acted at this place. This also equals liquidity.