Not listed NICER BRINGS CAPABILITY TO RESOLVE A LONGSTANDING QUESTION IN HYDRODYNAMICS OF ACCRETING PULSARS NAMELY WHETHER THERE OCCURS THE PHOTO-HYDRODYNAMIC PHENOMENON KNOWN AS PHOTON BUBBLES WHEREIN REGIONS OF HIGH RADIATION DENSITY FORM IN THE ACCRETION COLUMN AND ESCAPE GIVING BURSTS OF X-RAYS IN A HIGH-FREQUENCY QUASI-PERIODIC OSCILLATION (QPO) AS HAS BEEN CLAIMED IN RXTE OBSERVATIONS OF TWO SOURCES. CONCERNS HAVE BEEN RAISED THAT THIS COULD BE RXTE SYSTEMATICS. NICER CAN ADDRESS THIS BY BRINGING BOTH NEW OBSERVATIONS OF BRIGHT ACCRETING PULSARS AND A DIFFERENT INSTRUMENTAL DESIGN WITH DIFFERENT CHARACTERISTICS FOR DEAD TIME AND LIVE TIME ON BRIGHT SOURCES. WE PROPOSE OBSERVATIONS AND DATA ANALYSIS TO ACCOMPLISH A NEW SURVEY SEARCH FOR THE PHOTON BUBBLE SIGNATURE. $0 8/19/20 P00001 NICER BRINGS CAPABILITY TO RESOLVE A LONGSTANDING QUESTION IN HYDRODYNAMICS OF ACCRETING PULSARS, NAMELY WHETHER THERE OCCURS THE PHOTO-HYDRODYNAMIC PHENOMENON KNOWN AS PHOTON BUBBLES WHEREIN REGIONS OF HIGH RADIATION DENSITY FORM IN THE ACCRETION COLUMN AND ESCAPE GIVING BURSTS OF X-RAYS IN A HIGH-FREQUENCY QUASI-PERIODIC OSCILLATION (QPO), AS HAS BEEN CLAIMED IN RXTE OBSERVATIONS OF TWO SOURCES. CONCERNS HAVE BEEN RAISED THAT THIS COULD BE RXTE SYSTEMATICS. NICER CAN ADDRESS THIS BY BRINGING BOTH NEW OBSERVATIONS OF BRIGHT ACCRETING PULSARS AND A DIFFERENT INSTRUMENTAL DESIGN WITH DIFFERENT CHARACTERISTICS FOR DEAD TIME AND LIVE TIME ON BRIGHT SOURCES. WE PROPOSE OBSERVATIONS AND DATA ANALYSIS TO ACCOMPLISH A NEW SURVEY SEARCH FOR THE PHOTON BUBBLE SIGNATURE. Other Administrative Action $0 8/19/20 Not listed NICER BRINGS CAPABILITY TO RESOLVE A LONGSTANDING QUESTION IN HYDRODYNAMICS OF ACCRETING PULSARS, NAMELY WHETHER THERE OCCURS THE PHOTO-HYDRODYNAMIC PHENOMENON KNOWN AS PHOTON BUBBLES WHEREIN REGIONS OF HIGH RADIATION DENSITY FORM IN THE ACCRETION CO Not listed $45.0k 9/5/19 Not listed NICER BRINGS CAPABILITY TO RESOLVE A LONGSTANDING QUESTION IN HYDRODYNAMICS OF ACCRETING PULSARS NAMELY WHETHER THERE OCCURS THE PHOTO-HYDRODYNAMIC PHENOMENON KNOWN AS PHOTON BUBBLES WHEREIN REGIONS OF HIGH RADIATION DENSITY FORM IN THE ACCRETION CO $45.0k 9/5/19