[vsnet-alert 11065] N LMC 2009 and MACHO

[varposts at Safe-mail.net]

As already noted, Terry Bohlsen has made astrometry available via AVSON 1562

There appears to be nothing in GSC 2.3.2, SAGE, USNO B1.0, 2MASS, DENIS at this position, for quite some distance, about ten arcsecs radius.  Nothing to stop this being double checked though.

There are two MACHO sources within about half an arcsecond of his position though, each source appears to be for the same actual star.

Mean blue and red magnitudes are about 19.5, which given V reports of around twelve and a half from approximate visual and above CCD measures, gives an overall amplitude of around seven magnitudes.  Note MACHO "blue mags" are sometimes referred to as V mags, I've never been clear on this.  The archived plates at the CADC are logged as macho_r and macho_v for instance.

The MACHO magnitudes are also very similar, ie the object is not particularly coloured, white to blue.

There is some structure in the MACHO lightcurves, however the structure range is near the estimated error for each observation range so some serious care will have to be taken in assessing especially any aperiodic variation, and even periodic variation if of low amplitude.

The objects are :-

MACHO Star: 67.9895.257	 RA: 05 40 44.134 DEC: -66 40 11.07
Observations: 307

and

MACHO Star: 66.9895.1200 RA: 05 40 44.103 DEC: -66 40 11.17
Observations: 66

with the former the better coverage

<http://store.anu.edu.au:3001/cgi-bin/clclite?star=67.9895.257&sodset=PhotSS%2FF_67%2Fsodset_67.9895&token=SZAiLQAAAAAAAB2LAAA&bt=83501&pskip=0&pcount=307&punits=instr&pop=2&prmin=-5.56655&prmax=-2.93645&pbmin=-6.0168&pbmax=-2.8532&XFocus=50274.6&RFocus=-4.2515&BFocus=-4.435&Units=calib>

MACHO epoch photometry can be interrogated via

http://store.anu.edu.au:3001/cgi-bin/lc.pl

it looks like there is no other MACHO object within roughly four arcseconds, to limiting magnitude about 20 or so

<http://store.anu.edu.au:3001/cgi-bin/getsod?RA=05:40:44.200&Dec=-66:40:11.30&radius=60&nstars=50&token=SZAiLQAAAAAAAB2LAAA>

Neighbouring objects can be used to assess the normal MACHO epoch photometry behaviour for faint stars in this region, eg

<http://store.anu.edu.au:3001/cgi-bin/clclite?star=67.9895.249&sodset=PhotSS%2FF_67%2Fsodset_67.9895&token=SZAiLQAAAAAAAB2LAAA&bt=84605&pskip=0&pcount=307&punits=instr&pop=2&prmin=-5.67305&prmax=-2.94395&pbmin=-6.8121&pbmax=-3.0479&XFocus=50274.6&RFocus=-4.3085&BFocus=-4.93&Units=calib>

four arcsecs away.

Using CDS Aladin actual field images can be loaded, use Load Image and Select CADC as source, then select MACHO project images under SELECTION drop down input, and select radius as 1' or less to try and ensure you get images containing the object within the field (personally I haven't managed to find one that does yet, but given there's photometry there must be some images).  These are likely sizeable fits files, so take this into account re personal bandwidth.

Cheers

John