From Eduard Mol 17/6/2026:
Keep in mind masers are variable, so any list will be more of an indication.
W49 is the best one to start out with, because it’s consistently very bright and both Wolfgang and I observe it regularly.
The other ones which I can detect consistently are W75, Cepheus A, Orion KL, W3IRS5/ W3(OH) (these two are located in the same region), and W51. In particular W75 has been quite active in recent years.
Then there is another group of masers which can only be detected with a small dish if they are in an active phase. W31, W44 and NML Cygni fall into this last category.
Brightest water maser list (22 GHz relevant to currently available detection equipment at LRO):
Excel spreadsheet:
https://www.astronomy.me.uk/wp-content/uploads/2026/06/Eduard-Mol-Water-Masers-List-170626.xlsx
ZIP file of Excel spreadsheet above:
https://www.astronomy.me.uk/wp-content/uploads/2026/06/Eduard-Mol-Water-Masers-List-170626.zip
CSV file: