NICER observation list: Target ID 560401

Abstract

The persistent neutron star X-ray binary 4U 1820-30 displays a 170 d accretion cycle, evolving between phases of high and low X-ray luminosity. Over this cycle, dramatic changes are observed in both the X-ray spectral-timing properties (related to the accretion flow) and the radio spectral shape (related to the jet). Interestingly, the jet evolution seems to be triggered by the accretion rate rather than the spectral state. The aim of the proposal is to progressively track the spectral and timing evolution of the accretion flow over a cycle with a NICER+NuSTAR monitoring campaign. 9 NICER observations of 10 ks each, 3 of them paired with 20 ks NuSTAR visits, are requested. This campaign will be coupled with radio and IR observations to trace the accretion/ejection coupling mechanism.
Obsid RA DEC l b Start End Exposure Number of
Modules		 Number of
Processing		 Status of
Processing		 Date of
Processing		 Public
date
5604010101 275.919 -30.362 2.788 -7.914 59671.1289 59671.8727 8140.0 52 5 VALIDATED 59681.2 59685
5604010102 275.919 -30.361 2.788 -7.914 59683.1958 59683.6613 4460.0 52 7 VALIDATED 59693.6 59697
5604010103 275.918 -30.360 2.789 -7.912 59685.3324 59685.9192 1135.0 52 7 VALIDATED 59695.7 59699
5604010301 275.919 -30.361 2.788 -7.913 59699.3398 59699.9900 2574.0 52 4 VALIDATED 59709.9 59713
5604010302 275.919 -30.361 2.788 -7.914 59700.1123 59700.9567 6471.0 52 4 VALIDATED 59711.7 59714
5604010303 275.919 -30.361 2.788 -7.914 59701.0161 59701.0213 411.0 52 4 VALIDATED 59711.7 59715
5604010304 275.919 -30.361 2.788 -7.914 59730.5954 59730.9894 9968.0 52 3 VALIDATED 59740.9 59744
5604010305 275.919 -30.361 2.788 -7.914 59731.0224 59731.0537 1963.0 52 4 VALIDATED 59741.0 59745
5604010401 275.918 -30.362 2.787 -7.914 59742.7037 59742.9914 9212.0 52 4 VALIDATED 59753.9 59756
5604010402 275.919 -30.363 2.787 -7.914 59743.0264 59743.0560 1331.0 52 5 VALIDATED 59754.0 59757
5604010501 275.919 -30.360 2.789 -7.913 59756.4481 59756.8458 1240.0 52 4 VALIDATED 59768.2 59770
5604010502 275.918 -30.360 2.789 -7.913 59757.4160 59757.9426 1340.0 52 4 VALIDATED 59782.8 59771
5604010503 275.918 -30.360 2.789 -7.913 59757.9954 59758.3951 3444.0 52 6 VALIDATED 59782.8 59772
5604010601 275.918 -30.361 2.788 -7.913 59768.2692 59768.8618 6253.0 52 4 VALIDATED 59779.2 59782
5604010602 275.919 -30.361 2.788 -7.913 59769.0456 59769.5542 4111.0 52 5 VALIDATED 59782.9 59783
5604010701 275.923 -30.362 2.789 -7.917 59784.4050 59784.7356 2844.0 52 6 VALIDATED 59800.0 59798
5604010702 275.920 -30.361 2.788 -7.914 59785.2437 59785.9769 3981.0 52 5 VALIDATED 59800.1 59799
5604010703 275.920 -30.361 2.789 -7.914 59786.0202 59786.2859 2010.0 52 6 VALIDATED 59800.2 59800
5604010801 275.919 -30.362 2.788 -7.914 59801.3022 59801.9581 9406.5 52 5 VALIDATED 59813.9 59815
5604010901 275.919 -30.361 2.788 -7.914 59812.2037 59812.7495 9805.0 52 4 VALIDATED 59822.8 59826
5604011001 275.919 -30.362 2.788 -7.914 59824.1556 59824.9403 2297.0 52 5 VALIDATED 59836.6 59838
5604011002 275.919 -30.362 2.788 -7.914 59825.1255 59825.9690 3666.0 52 4 VALIDATED 59836.6 59839
5604011003 275.923 -30.364 2.787 -7.918 59826.0133 59826.3549 1138.0 52 3 VALIDATED 59836.7 59840
5604011101 275.918 -30.360 2.789 -7.912 59840.5247 59840.9914 5693.6 52 7 VALIDATED 59850.7 59854