NICER observation list: Target ID 357501

Abstract

We detected periodic X-ray eclipse from a low-mass X-ray binary 1RXS J175721.2-304405 with NICER. It shows a step-function like time variability observed with the X-ray satellite ASCA. NICER monitored it from September 2018 to February 2019. We made the light curve with NICER and ASCA light curves superposed to investigate the time variability, and then we preliminary identified a periodicity of about 14.5 (or 7.3) days. Since the long orbital period suggests a giant companion with a neutron star or a blackhole, 1RXS J175721.2-304405 is likely a new and rare eclipsing low-mass X-ray binary with a giant companion. Future follow-up observation with NICER will find the evidence of a periodic eclipse. we propose one month NICER monitoring (1 ksec x 29 visits).
Obsid RA DEC l b Start End Exposure Number of modules Status of Processing Date of Processing Public date
3575010101 269.343 -30.735 359.75245 -3.10936 58989.3039 58989.3192 1093.00000 52 VALIDATED 59011.8 59003
3575010201 269.343 -30.736 359.75236 -3.10962 58990.2076 58990.2273 1304.00000 52 VALIDATED 59011.8 59004
3575010301 269.342 -30.736 359.75206 -3.10939 58991.1798 58991.1981 1055.00000 51 VALIDATED 58999.7 59005
3575010401 269.341 -30.735 359.75184 -3.10823 58992.0196 58992.0387 1414.00000 52 VALIDATED 58996.6 59006
3575010501 269.341 -30.734 359.75312 -3.10720 58992.9228 58992.9433 1486.00000 52 VALIDATED 58996.7 59006
3575010601 269.342 -30.734 359.75372 -3.10804 58993.9560 58993.9778 1520.00000 52 VALIDATED 58998.9 59007
3575010701 269.341 -30.734 359.75265 -3.10717 58994.9893 58995.0113 1412.00000 52 VALIDATED 58999.7 59009
3575010801 269.341 -30.734 359.75332 -3.10718 58995.8993 58995.9801 1694.00000 52 VALIDATED 59000.7 59009
3575010901 269.339 -30.734 359.75185 -3.10624 58997.1273 58997.6516 2286.00000 52 VALIDATED 59001.7 59011
3575011001 269.342 -30.735 359.75236 -3.10842 58998.0886 58998.1574 438.00000 52 VALIDATED 59002.7 59012
3575011101 269.340 -30.735 359.75194 -3.10708 58998.7324 58998.9961 833.00000 52 VALIDATED 59003.6 59012
3575011102 269.341 -30.735 359.75194 -3.10758 58999.0568 58999.1896 578.00000 52 VALIDATED 59003.7 59013
3575011201 269.339 -30.735 359.75124 -3.10639 59000.4118 59000.6092 1117.00000 52 VALIDATED 59004.7 59014
3575011301 269.339 -30.735 359.75126 -3.10628 59001.1852 59001.3838 854.00000 52 VALIDATED 59008.9 59015
3575011401 269.339 -30.735 359.75120 -3.10612 59002.0981 59002.2326 435.00000 52 VALIDATED 59011.8 59016
3575011501 269.338 -30.735 359.75064 -3.10624 59003.0559 59003.1912 518.00000 52 VALIDATED 59011.9 59017
3575011601 269.338 -30.735 359.75069 -3.10611 59004.0171 59004.0306 929.00000 52 VALIDATED 59012.0 59018
3575011701 269.339 -30.735 359.75082 -3.10653 59005.2423 59005.2579 1244.00000 52 VALIDATED 59012.8 59019
3575012001 269.339 -30.735 359.75120 -3.10612 59008.4123 59008.4352 1396.00000 52 VALIDATED 59026.8 59022
3575012101 269.339 -30.735 359.75112 -3.10607 59009.3803 59009.4035 1410.00000 52 VALIDATED 59026.9 59023
3575012201 269.339 -30.736 359.74984 -3.10680 59010.6650 59010.6750 773.00000 52 VALIDATED 59024.9 59024
3575012301 269.339 -30.735 359.75106 -3.10620 59011.4484 59011.4690 1175.00000 52 VALIDATED 59016.0 59025
3575012401 269.339 -30.735 359.75112 -3.10617 59012.5437 59012.5662 1747.00000 52 VALIDATED 59016.7 59026
3575012501 269.338 -30.735 359.75089 -3.10610 59013.3838 59013.4014 1133.00000 52 VALIDATED 59017.8 59027
3575012601 269.339 -30.735 359.75094 -3.10627 59014.4884 59014.5025 1186.00000 52 VALIDATED 59018.8 59028
3575012701 269.339 -30.735 359.75104 -3.10611 59015.4565 59015.4708 1111.00000 52 VALIDATED 59019.8 59029
3575012801 269.339 -30.736 359.74991 -3.10686 59010.6004 59010.6104 773.00000 52 VALIDATED 59024.9 59024
3575012802 269.339 -30.735 359.75102 -3.10632 59016.4891 59016.5037 1206.00000 52 VALIDATED 59020.8 59030
3575012901 269.339 -30.735 359.75106 -3.10620 59017.3882 59017.4074 1025.00000 52 VALIDATED 59021.7 59031