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AGAPEROS: Searches for microlensing in the LMC with the Pixel Method; 1, Data treatment and pixel light curves production
The presence and abundance of MAssive Compact Halo Objects (MACHOs) towards the Large Magellanic Cloud (LMC) can be studied with microlensing searches. The 10 events detected by the EROS and MACHO groups suggest that objects with 0.5 Mo could fill 50% of the dark halo. This preferred mass is quite s...
| Autores principales: | , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , |
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| Lenguaje: | eng |
| Publicado: |
1998
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| Materias: | |
| Acceso en línea: | https://dx.doi.org/10.1051/aas:1999439 http://cds.cern.ch/record/341780 |
| _version_ | 1780891523119841280 |
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| author | Melchior, A.-L. Afonso, C. Ansari, R. Aubourg, E. Baillon, P. Bareyre, P. Bauer, F. Beaulieu, J.-Ph. Bouquet, A. Brehin, S. Cavalier, F. Char, S. Couchot, F. Coutures, C. Ferlet, R. Fernandez, J. Gaucherel, C. Giraud-Heraud, Y. Glicenstein, J.-F. Goldman, B. Gondolo, P. Gros, M. Guibert, J. Gry, C. Hardin, D. Kaplan, J. de Kat, J. Lachieze-Rey, M. Laurent, B. Lesquoy, E. Magneville, Ch. Mansoux, B. Marquette, J.-B. Maurice, E. Milsztajn, A. Moniez, M. Moreau, O. Moscoso, L. Palanque-Delabrouille, N. Perdereau, O. Prevot, L. Renault, C. Queinnec, F. Rich, J. Spiro, M. Vigroux, L. Zylberajch, S. Vidal-Madjar, A. |
| author_facet | Melchior, A.-L. Afonso, C. Ansari, R. Aubourg, E. Baillon, P. Bareyre, P. Bauer, F. Beaulieu, J.-Ph. Bouquet, A. Brehin, S. Cavalier, F. Char, S. Couchot, F. Coutures, C. Ferlet, R. Fernandez, J. Gaucherel, C. Giraud-Heraud, Y. Glicenstein, J.-F. Goldman, B. Gondolo, P. Gros, M. Guibert, J. Gry, C. Hardin, D. Kaplan, J. de Kat, J. Lachieze-Rey, M. Laurent, B. Lesquoy, E. Magneville, Ch. Mansoux, B. Marquette, J.-B. Maurice, E. Milsztajn, A. Moniez, M. Moreau, O. Moscoso, L. Palanque-Delabrouille, N. Perdereau, O. Prevot, L. Renault, C. Queinnec, F. Rich, J. Spiro, M. Vigroux, L. Zylberajch, S. Vidal-Madjar, A. |
| author_sort | Melchior, A.-L. |
| collection | CERN |
| description | The presence and abundance of MAssive Compact Halo Objects (MACHOs) towards the Large Magellanic Cloud (LMC) can be studied with microlensing searches. The 10 events detected by the EROS and MACHO groups suggest that objects with 0.5 Mo could fill 50% of the dark halo. This preferred mass is quite surprising, and increasing the presently small statistics is a crucial issue. Additional microlensing of stars too dim to be resolved in crowded fields should be detectable using the Pixel Method. We present here an application of this method to the EROS 91-92 data (one tenth of the whole existing data set). We emphasize the data treatment required for monitoring pixel fluxes. Geometric and photometric alignments are performed on each image. Seeing correction and error estimates are discussed. 3.6" x 3.6" super-pixel light curves, thus produced, are very stable over the 120 days time-span. Fluctuations at a level of 1.8% of the flux in blue and 1.3% in red are measured on the pixel light curves. This level of stability is comparable with previous estimates. The data analysis dedicated to the search of possible microlensing events together with refined simulations will be presented in a companion paper. |
| id | cern-341780 |
| institution | Organización Europea para la Investigación Nuclear |
| language | eng |
| publishDate | 1998 |
| record_format | invenio |
| spelling | cern-3417802023-01-31T08:11:46Zdoi:10.1051/aas:1999439http://cds.cern.ch/record/341780engMelchior, A.-L.Afonso, C.Ansari, R.Aubourg, E.Baillon, P.Bareyre, P.Bauer, F.Beaulieu, J.-Ph.Bouquet, A.Brehin, S.Cavalier, F.Char, S.Couchot, F.Coutures, C.Ferlet, R.Fernandez, J.Gaucherel, C.Giraud-Heraud, Y.Glicenstein, J.-F.Goldman, B.Gondolo, P.Gros, M.Guibert, J.Gry, C.Hardin, D.Kaplan, J.de Kat, J.Lachieze-Rey, M.Laurent, B.Lesquoy, E.Magneville, Ch.Mansoux, B.Marquette, J.-B.Maurice, E.Milsztajn, A.Moniez, M.Moreau, O.Moscoso, L.Palanque-Delabrouille, N.Perdereau, O.Prevot, L.Renault, C.Queinnec, F.Rich, J.Spiro, M.Vigroux, L.Zylberajch, S.Vidal-Madjar, A.AGAPEROS: Searches for microlensing in the LMC with the Pixel Method; 1, Data treatment and pixel light curves productionAstrophysics and AstronomyThe presence and abundance of MAssive Compact Halo Objects (MACHOs) towards the Large Magellanic Cloud (LMC) can be studied with microlensing searches. The 10 events detected by the EROS and MACHO groups suggest that objects with 0.5 Mo could fill 50% of the dark halo. This preferred mass is quite surprising, and increasing the presently small statistics is a crucial issue. Additional microlensing of stars too dim to be resolved in crowded fields should be detectable using the Pixel Method. We present here an application of this method to the EROS 91-92 data (one tenth of the whole existing data set). We emphasize the data treatment required for monitoring pixel fluxes. Geometric and photometric alignments are performed on each image. Seeing correction and error estimates are discussed. 3.6" x 3.6" super-pixel light curves, thus produced, are very stable over the 120 days time-span. Fluctuations at a level of 1.8% of the flux in blue and 1.3% in red are measured on the pixel light curves. This level of stability is comparable with previous estimates. The data analysis dedicated to the search of possible microlensing events together with refined simulations will be presented in a companion paper.Recent surveys monitoring millions of light curves of resolved stars in the LMC have discovered several microlensing events. Unresolved stars could however significantly contribute to the microlensing rate towards the LMC. Monitoring pixels, as opposed to individual stars, should be able to detect stellar variability as a variation of the pixel flux. We present a first application of this new type of analysis (Pixel Method) to the LMC Bar. We describe the complete procedure applied to the EROS 91-92 data (one tenth of the existing CCD data set) in order to monitor pixel fluxes. First, geometric and photometric alignments are applied to each images. Averaging the images of each night reduces significantly the noise level. Second, one light curve for each of the 2.1 10^6 pixels is built and pixels are lumped into 3.6"x3.6" super-pixels, one for each elementary pixel. An empirical correction is then applied to account for seeing variations. We find that the final super-pixel light curves fluctuate at a level of 1.8% of the flux in blue and 1.3% in red. We show that this noise level corresponds to about twice the expected photon noise and confirms previous assumptions used for the estimation of the contribution of unresolved stars. We also demonstrate our ability to correct very efficiently for seeing variations affecting each pixel flux. The technical results emphasised here show the efficacy of the Pixel Method and allow us to study luminosity variations due to possible microlensing events and variable stars in two companion papers.astro-ph/9712236FERMILAB-PUB-98-019-AFERMILAB-PUB-98-019-Aoai:cds.cern.ch:3417801998-01-05 |
| spellingShingle | Astrophysics and Astronomy Melchior, A.-L. Afonso, C. Ansari, R. Aubourg, E. Baillon, P. Bareyre, P. Bauer, F. Beaulieu, J.-Ph. Bouquet, A. Brehin, S. Cavalier, F. Char, S. Couchot, F. Coutures, C. Ferlet, R. Fernandez, J. Gaucherel, C. Giraud-Heraud, Y. Glicenstein, J.-F. Goldman, B. Gondolo, P. Gros, M. Guibert, J. Gry, C. Hardin, D. Kaplan, J. de Kat, J. Lachieze-Rey, M. Laurent, B. Lesquoy, E. Magneville, Ch. Mansoux, B. Marquette, J.-B. Maurice, E. Milsztajn, A. Moniez, M. Moreau, O. Moscoso, L. Palanque-Delabrouille, N. Perdereau, O. Prevot, L. Renault, C. Queinnec, F. Rich, J. Spiro, M. Vigroux, L. Zylberajch, S. Vidal-Madjar, A. AGAPEROS: Searches for microlensing in the LMC with the Pixel Method; 1, Data treatment and pixel light curves production |
| title | AGAPEROS: Searches for microlensing in the LMC with the Pixel Method; 1, Data treatment and pixel light curves production |
| title_full | AGAPEROS: Searches for microlensing in the LMC with the Pixel Method; 1, Data treatment and pixel light curves production |
| title_fullStr | AGAPEROS: Searches for microlensing in the LMC with the Pixel Method; 1, Data treatment and pixel light curves production |
| title_full_unstemmed | AGAPEROS: Searches for microlensing in the LMC with the Pixel Method; 1, Data treatment and pixel light curves production |
| title_short | AGAPEROS: Searches for microlensing in the LMC with the Pixel Method; 1, Data treatment and pixel light curves production |
| title_sort | agaperos: searches for microlensing in the lmc with the pixel method; 1, data treatment and pixel light curves production |
| topic | Astrophysics and Astronomy |
| url | https://dx.doi.org/10.1051/aas:1999439 http://cds.cern.ch/record/341780 |
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