Table information for 'plc.rawcands'

General

Table Description: The table of candidate stars. These are objects from highpm that have a PPMXL object within their regions of interest.

This table is not available for ADQL queries and through the TAP endpoint.

Resource Description: A catalogue of candidate stars for observing astrometric microlensing using Gaia.

For a list of all services and tables belonging to this table's resource, see Information on resource 'Candidates for astrometric microlensing'

Citing this table

This table has an associated publication. If you use data from it, it may be appropriate to reference 2011A&A...536A..50P (ADS BibTeX entry for the publication) either in addition to or instead of the service reference.

To cite the table as such, we suggest the following BibTeX entry:

@MISC{vo:plc_rawcands,
  year=2008,
  title={Candidates for astrometric microlensing},
  author={Demleitner, M. and Proft, S.},
  url={http://dc.zah.uni-heidelberg.de/tableinfo/plc.rawcands},
  howpublished={{VO} resource provided by the {GAVO} Data Center}
}

Resource Documentation

The Idea behind this Catalog

We constructed the candidate list to identify stars with large proper motions (>0.15 arcsec/year) that are potential candidates for the astrometric microlensing effect during the Gaia mission [PDW]. With the Gaia mission it will be possible to measure this effect with the required accuracy at best 30 micro-arcsec for a single measurement. The satellite, which is observing since July 2014, surveys the whole sky and has an expected lifetime of five years. It is doing astrometry, photometry and spectroscopy of approximately one billion stars in our galaxy brighter than ~20 mag in visual band [GAIA].

The astrometric microlensing effect allows a precise measurement of the mass of a star that is acting as a lens [PAC]. Ideally, the microlensing event is observed both astrometrically and photometrically. When the unaffected source position is not known or the lens is not visible both measurements are necessary. Photometric microlensing events (with small angular distances of lens and source) are about ten times shorter than the corresponding astrometric event. Hence Gaia will do no or only few photometric measurements. Therefore, an accompanying ground based photometric observations of the events would be advantageous. For this purpose it is very helpful to predict microlensing events.

To predict microlensing events it is essential to have positions and proper motions with a high accuracy (maximal 100 mas in position and 10 mas/year in proper motion). Hence it is important to choose suitable catalogs for the lenses and sources. For the sources, we chose PPMXL [PPMXL], for the lenses the LSPM-NORTH [LSPM] on the northern sky and PPMX [PPMX] and UCAC3 [UCAC3].

Problems

After manual inspection of about one hundred lens proper motions we found out that the majority of the high proper motions in PPMX an UCAC3 are erroneous. While nearly all proper motions from LSPM are correct, only a small fraction of high proper motions (<1%) from PPMX and UCAC3 are physical. This means that a high number of the predicted events from our candidate list is wrong.

Confirmed Microlensing Candidates (2012-2019)

In our previous work the assembled microlensing catalog comprised 910 candidates for the years 2012 to 2017. Their proper motion analysis yielded that 96% of the (high) proper motions of the lensing stars were erroneous. We were thus left with only 43 confirmed microlensing candidates. Due to an improvement of the search width around potential lensing stars, we can predict 50 additional astrometric microlensing events with correct proper motion now between 2014 and 2019. All confirmed astrometric microlensing candidates are marked with true in the "Confirmed?"-column.

References

[PDW]Proft, S., Demleitner, M. and Wambsganss, J. (2011). Prediction of astrometric microlensing events during the Gaia mission. 2011A%26A...536A..50P
[GAIA]Science Performance of the Gaia Satellite. www.cosmos.esa.int/web/gaia/science-performance
[LSPM]Lepine, S. and Shara, M. M. (2005). A Catalog of Northern Stars With Annual Proper Motions Larger Than 0.15 Seconds of Arc (LSPM catalog - North). 2005AJ....129.1483L
[PAC]Paczynski, B. (1995). The Masses of Nearby Dwarfs can be Determined with Gravitational Microlensing. 1995AcA....45..345P
[PPMXL]Roeser, S., Demleitner, M. and Schilbach, E. (2010). The PPMXL catalog of positions and proper motions on the ICRS. Combining USNOB1.0 and 2MASS. 2010AJ....139.2440R
[PPMX]Roeser, S. et al. (2008). PPM Extended (PPMX) - a catalogue of positions and proper motions. 2008A&A...488..401R
[UCAC3]Zacharias, N. et al. (2010). The Third US Naval Observatory CCD Astrograph Catalog (UCAC3). 2010AJ....139.2184Z

Columns

Sorted alphabetically. [Sort by DB column index]

NameTable Head DescriptionUnitUCD
alpha Alpha N/A deg pos.eq.ra;meta.main
alphaErr Alphaerr N/A deg N/A
Bmag m_B B magnitude in Johnson system mag phot.mag;em.opt.B
delta Delta N/A deg pos.eq.dec;meta.main
deltaErr Deltaerr N/A deg N/A
e_lensedde E_lensedde Mean error in Dec at mean epoch deg stat.error;pos.eq.dec;meta.main
e_lensedpmde Err. PM(Dec) Mean error in pmDE deg/yr stat.error;pos.pm;pos.eq.dec
e_lensedpmra Err. PM(RA) Mean error in pmRA*cos(delta) deg/yr stat.error;pos.pm;pos.eq.ra
e_lensedra E_lensedra Mean error in RA*cos(delta) at mean epoch deg stat.error;pos.eq.ra;meta.main
Hmag m_H H magnitude in Johnson system mag phot.mag;em.IR.H
Jmag m_J J magnitude in Johnson system mag phot.mag;em.IR.J
Kmag m_K K magnitude in Johnson system mag phot.mag;em.IR.K
lensedBmag USNO mag (B1) B mag from USNO-B, first epoch [Note 1] mag phot.mag;em.opt.B
lensedde Dec Declination J2000.0, epoch 2000.0 deg pos.eq.dec
lensedepde Lensedepde Mean Epoch (Dec) yr time.epoch;pos.eq.dec
lensedepra Lensedepra Mean Epoch (RA) yr time.epoch;pos.eq.ra
lensedhmag m_H H magnitude in Johnson system mag phot.mag;em.IR.H
lensedid Id Identifier (Q3C ipix of the USNO-B 1.0 object) N/A meta.id;meta.main
lensedImag USNO mag (I) I mag from USNO-B [Note 1] mag phot.mag;em.opt.I
lensedjmag m_J J magnitude in Johnson system mag phot.mag;em.IR.J
lensedkmag m_K K magnitude in Johnson system mag phot.mag;em.IR.K
lensedpmde PM(Dec) Proper Motion in Dec deg/yr pos.pm;pos.eq.dec
lensedpmra PM(RA) Proper Motion in RA*cos(delta) deg/yr pos.pm;pos.eq.ra
lensedra RA Right Ascension J2000.0, epoch 2000.0 deg pos.eq.ra
lensedRmag USNO mag (R2) R mag from USNO-B, second epoch [Note 1] mag phot.mag;em.opt.R
mag Mag Some, source dependent, magnitude mag N/A
pma Pma Proper motion in alpha, cos(delta) applied deg/yr N/A
pmaErr Pmaerr Error in PM(alpha), cos(delta) applied deg/yr N/A
pmd Pmd N/A deg/yr N/A
pmdErr Pmderr N/A deg/yr N/A
pmPA Pmpa Position angle of proper motion deg N/A
pmTotal Pmtotal Total proper motion deg/yr N/A
Rmag m_R calculated Ru magnitude from source mag phot.mag;em.opt.R
roi Roi Region potentially swept over, as alpha, delta points N/A N/A
source Source N/A N/A N/A
sourceId Sourceid N/A N/A N/A
Vmag m_V V magnitude in Johnson system mag phot.mag;em.opt.V

Columns that are parts of indices are marked like this.

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