The progress of Low-Mass X-ray binary monitoring program 陳炳志 許瑞榮 蘇漢宗 成功大學物理系 天文實驗室 周翊 黃崇源 中央大學天文所

2003 年物理年會 2 Outlines Scientific motivation The collaboration with Yale 2002 Summer visiting and 4U Current status at NCKU Monitoring targets and observation Data archive Data reduction and automatic photometry pipeline Web-based photometry database Preliminary result — V616 Mon and GRO J On-going work and perspectives

2003 年物理年會 3 Scientific motivation Sometimes, an X-ray binary star could be ignited dramatically by 8-magnitude which we call “outburst” → Target of opportunity(TOO). Some outbursts will occur repeatedly but almost irregularly, and they were referred as recursive novae. In the outburst state, multi-wavelength light curves are excellent probes to explore the structure of the accretion disk and mass transfer between components.

2003 年物理年會 4 Scientific motivation The luminosity can reach a maximum in few days, but declines gradually to quiescence state in few weeks or few months. → It’s essential to have observation facility to response to the outburst alert and to perform follow-up. Some outbursts occur repeatedly but irregularly. → Need to monitor these known X-ray binaries continuously and globally.

2003 年物理年會 Summer Visiting Go through real observation data before LOT routine operation Discuss the scientific strategy and collaboration platform on this 2-sites monitoring work Major work: 2002 outburst of 4U (observed by MSO 74in reflector which was burned on a wildfire of Jan !)

2003 年物理年會 6

7

8 Targets to be monitored

2003 年物理年會 9 Observation at LOT Observed targets V616 Mon: 12 nights (11/26, 12/1-12/6, 12/13-12/14, 1/1, 1/23, 1/25) XTE J : 10 nights (12/1-12/3, 1/24, 1/29- 1/31, 2/6, 2/9, 2/10) 4U : 1 night (11/09) GRO J : 2 night (11/26, 1/25), 1/25: Fast photometry

2003 年物理年會 10 Data Archive Transfer data to download area by ftp in next morning (30~40KB/s). Copy to archive area and carry out bias/dark/flat calibration, remove matterless files. Backup to DVD-R when download area occupation exceeds 4.5GB. Remove files after backup. Copy into work area to reduce photometry. Clean work area after photometry reduction.

2003 年物理年會 11 Data Reduction Archive area Put "observatory", "RA", "DEC" tags into fits header. (hedit/cl) Calculate "hour angle", "airmass", "mean sideral time", "julian day" and paste into fits header. (asthedit) Do bias/dark/flat calibration on all files. (zerocomb/darkcomb/flatcomb/ccdproc) Keep combined bias/dark/flat std. fields and LMXB observation, remove other files.

2003 年物理年會 12 Data Reduction Work area Crowd field photometry (daophot → AUTOMATIC PIPELINE) Match target and comparison/standard stars (photcal → IDL) Photometry calibration and check (photcal → IDL) Post calibrated photometry to web-based database

2003 年物理年會 13 Automatic photometry pipeline Only one parameter for this pipeline: an estimate of FWHM of the field stars Major tasks: Calculate the deviation of sky background by 3-σ rejection and iteration. Find the coarse center of the stars (daofind task). Carry out fast aperture photometry as as initial value in the following calculation (phot task). Sift bright stars with non-linear central profile, faint and non-stellar objects. Select 35 bright candidates to construct an analytic PSF (pstselect and psf tasks). Solve the magnitudes of the stars (allstar task). Reject bright stars with non-linear central profile from solved objects list. Select 25 bright candidates from solve objects list and construct an PSF (pstselect and psf tasks). Solve the magnitudes of the stars as final results (allstar task).

2003 年物理年會 14 Automatic photometry pipeline Advantages of the pipeline: Only one parameter: Other essential parameters can be estimated by pipeline itself. Accurate photometry: less than magnitude difference compared to the results reduced by manual operation and inspection. Fast reduction: minutes per frame, and the pipeline can be scripted in order to process numerous of images.

2003 年物理年會 15 Web-based photometry database Designed by PHP, MySQL, TCL Data post Web-based interactive input Upload by predefined format text file Output Tabular photometry data On-line light curve A platform for site-to-site collaboration.

2003 年物理年會 16

2003 年物理年會 17

2003 年物理年會 18

2003 年物理年會 19

2003 年物理年會 20

2003 年物理年會 21 Preliminary results — V616 Mon V~18.2 in quiescent state. (R~17.27) 3 minutes exposure, S/N >100 Calibration Done by 2002/12/14 observation 6 Landolt fields and 36 Std. Stars 7 nearby stars were calibrated in V616 Mon field K R =0.097

2003 年物理年會 22

2003 年物理年會 23 Preliminary results — V616 Mon Photometry accuracy : 0.01 mag Δm V616 Mon ~ 0.2 Δm comp. star ≦ 0.02

2003 年物理年會 24 Preliminary results — GRO J fast photometry Photometry accuracy : 0.01 mag Δm V616 Mon < 0.1 Δm comp. star ≦ 0.02

2003 年物理年會 25 On-going works Precise multi-band photometry calibration on XTE J , GRO J and V616 Mon fields. Fast photometry to detect orbital and other related periods and superhump phenomena.

2003 年物理年會 26 Perspectives The improvement on the observation Resident observers? Multi-band photometry → precise calibration Header tags of "RA", "DEC" to help automatic calibration pipeline Increase monitoring targets → 3~5/nights (1 hr/night) Better automatic pipeline? Auto download and bias/dark/flat correction? Photometry calibration script