2S 1553-542
Also known as: H 1553-542 [[1]
Monitoring data: RXTE/ASM Swift/BAT MAXI Fermi/GBM pulsed flux
Coordinates
| RA | 15h 57m 49s | Dec | -54° 24' 54" |
| RA | 239.454167 | Dec | -54.415000 |
| l | 327.9441 | b | -00.8570 |
Binary system
Orbit
| Parameter | Value | Unit | Reference |
|---|---|---|---|
| Porb | 29.56±0.53 | days | [1] |
| Tperiastron | 54488.38±0.51 | JD | [1] |
| a sin i | 168±18 | lt-sec | [1] |
| e | <0.09 | [2] | |
| ωperiastron | ? | ||
| Mass function | 5.3±1.2 | Msol | [1] |
Alternative solution:
| Parameter | Value | Unit | Reference |
|---|---|---|---|
| Porb | 31.303(27) | days | [3] |
| Tpi/2 | 2457 089.421(19) | JD | [3] |
| a sin i | 201.25(84) | lt-sec | [3] |
| e | 0.0351(22) | [3] | |
| ωperiastron | 163.4(35) | [3] |
Spin-down observed. Local spin-up during NuSTAR observations [3]
Optical Companion
Swift XRT found no optical counterpart down to 3-sigma limiting magnitudes 18.4 in V and fainter in other bands. ATel 1371
Available data from pointing instruments
- RXTE: Monitoring from 2008-Jan-06 to 2008-Mar-20
- Swift-XRT: 4081 seconds on 2008 January 24
- NuSTAR: 27 ks on 2015 April 3
Description
2S 1553-542 was discovered by SAS3 in June 1975 (Apparao et al. 1978). It is somewhat peculiar in having a low eccentricity in a wide orbit. After many years of quiescence, Krimm et al. (2007, ATel 1345) observed another outburst, which was then monitored by RXTE/PCA (Pal & Pahari 2008, ATel 1373).
After several more years of quiescence the source has been observed in outburst again in 2015. Results from a NuSTAR observation, including a cyclotron line detection are reported by [3].
References