NICER observation list: Target ID 468001

Abstract

We propose to use the advanced energy and time resolutions of NICER to search for discrete spectral features during thermonuclear X-ray bursts from 4U 1820-30. During the strong bursts of this source, the photosphere of the neutron star can temporarily be lifted to large radii, ejecting nuclear burning ashes that can imprint the burst spectra. We aim, with the proposed observations, to double the number of bursts detected by NICER from this source. Stacking bursts together does significantly improve the detection of spectral lines, making it possible to track their energy through the burst evolution. By identifying lines related to heavy elements we can explain burst nucleosynthesis processes and probe the equation of state of the neutron star through the measured gravitational redshift.
Obsid RA DEC l b Start End Exposure Number of
Modules		 Number of
Processing		 Status of
Processing		 Date of
Processing		 Public
date
4680010101 275.919 -30.361 2.788 -7.913 59336.2132 59336.9956 3395.0 52 6 VALIDATED 59346.6 59350
4680010102 275.919 -30.357 2.792 -7.912 59337.1188 59337.1245 413.0 52 5 VALIDATED 59346.7 59351
4680010103 275.920 -30.361 2.789 -7.914 59338.6014 59338.8653 1844.0 52 10 VALIDATED 59357.6 59352
4680010104 275.919 -30.362 2.788 -7.914 59344.3091 59344.9627 1651.0 52 7 VALIDATED 59356.6 59358
4680010105 275.919 -30.361 2.789 -7.914 59500.1907 59500.9837 2283.0 52 7 VALIDATED 59510.6 59514
4680010106 275.919 -30.361 2.788 -7.914 59501.1008 59501.7009 536.0 52 7 VALIDATED 59511.6 59515
4680010107 275.919 -30.361 2.788 -7.914 59504.0145 59504.0683 543.0 52 6 VALIDATED 59513.7 59518
4680010108 275.918 -30.362 2.788 -7.913 59505.1788 59505.3169 1273.0 52 6 VALIDATED 59514.7 59519
4680010109 275.919 -30.361 2.788 -7.914 59507.8042 59507.9443 2056.0 52 7 VALIDATED 59518.7 59521
4680010110 275.920 -30.361 2.788 -7.914 59507.9977 59508.3317 3262.0 52 7 VALIDATED 59518.7 59522
4680010111 275.919 -30.361 2.788 -7.914 59509.0308 59509.0419 860.0 52 5 VALIDATED 59518.8 59523
4680010112 275.918 -30.362 2.788 -7.913 59511.3032 59511.3785 1349.0 49 6 VALIDATED 59520.7 59525
4680010113 275.918 -30.362 2.788 -7.913 59512.0648 59512.9979 4022.0 49 6 VALIDATED 59522.7 59526
4680010114 275.919 -30.361 2.788 -7.914 59513.3058 59513.9428 4309.0 49 6 VALIDATED 59523.8 59527
4680010115 275.918 -30.362 2.787 -7.913 59514.0130 59514.9873 2996.0 49 5 VALIDATED 59526.6 59528
4680010116 275.919 -30.361 2.788 -7.914 59515.0456 59515.7726 12000.0 49 4 VALIDATED 59526.7 59529
4680010117 275.919 -30.362 2.788 -7.914 59516.8424 59516.8683 1431.0 49 6 VALIDATED 59527.7 59530
4680010118 275.919 -30.361 2.788 -7.914 59517.3067 59517.8407 4188.0 49 7 VALIDATED 59528.8 59531
4680010119 275.919 -30.361 2.788 -7.914 59518.0926 59518.9387 5472.0 49 9 VALIDATED 59536.9 59532
4680010120 275.919 -30.362 2.788 -7.914 59519.0537 59519.7050 6466.0 49 7 VALIDATED 59534.1 59533
4680010121 275.919 -30.361 2.788 -7.914 59520.5972 59520.6174 1374.0 49 6 VALIDATED 59531.0 59534
4680010122 275.920 -30.362 2.787 -7.915 59521.3626 59521.3882 1740.0 49 5 VALIDATED 59531.1 59535
4680010123 275.920 -30.361 2.788 -7.914 59523.2977 59523.3294 2263.0 47 6 VALIDATED 59533.1 59537
4680010124 275.919 -30.361 2.788 -7.914 59524.1368 59524.1687 2166.0 47 5 VALIDATED 59534.2 59538
4680010125 275.919 -30.362 2.788 -7.914 59525.1722 59525.1928 1387.0 47 5 VALIDATED 59535.1 59539
4680010126 275.919 -30.361 2.788 -7.914 59527.4967 59527.5264 818.0 47 5 VALIDATED 59537.0 59541
4680010127 275.919 -30.362 2.788 -7.914 59528.5447 59528.6238 1201.0 47 5 VALIDATED 59538.8 59542
4680010128 275.919 -30.361 2.788 -7.914 59529.4333 59529.4577 93.0 47 5 VALIDATED 59538.8 59543