(Adds transaction details, background on BlackSky)

Feb 18 (Reuters) - Satellite imagery and data company BlackSky Holdings said it had agreed to go public through a merger with blank-check firm Osprey Technology Acquisition Corp

in a deal valuing the combined entity at $1.5 billion.

BlackSky, founded in 2014, uses a constellation of high-resolution small satellites with artificial intelligence and machine learning for real-time Earth observation.

It said it will be listed on the New York Stock Exchange, under the new ticker symbol "BKSY" after the merger, which is expected to provide $450 million in net proceeds.

This includes $180 million from investors including Tiger Global Management, Peter Thiel's Mithril Capital, Hedosophia and Senator Investment Group.

So-called SPACs like Osprey, which raised $275 million in an initial public offering last year, are shell companies which raise funds to acquire private companies.

SPACs have emerged as a popular alternative to a traditional IPO, with at least 144 SPACs collectively raising $45.7 billion so far this year.

Credit Suisse Securities $(USA)$ LLC and Moelis & Company LLC are acting as financial advisers to BlackSky and Osprey respectively.

(Reporting by Sohini Podder in Bengaluru; Editing by Shounak Dasgupta and Anil D'Silva)

((sohini.podder@thomsonreuters.com))