Dauban V242


nameDauban V242
constellationLyr
J2000.019 05 31.28 +28 55 24.3
other names2MASS J19053128+2855242
typeEA
mag range14.0 - <15.7 CR
period (days)--
epoch--
colorJ-K = 0.51
remarks--
links--
discovery26/12/2012
DSS2-R
DSS2-IR


Confirmation of variability


Additional observations have been made with a 200mm reflector. The data confirms the occurrence of eclipses.



Photometric data


We provide magnitude data in the tables below. All the images have been carefully checked prior to photometry based on the following criteria: (1) normal value of magnitude zero point, (2) sky background is uniform across the image, (3) air mass < 2.5, (4) stars are sharp and not elongated in the E-W direction, (5) for the 80mm refractor only: accuracy of astrometric reduction is better than 0.5 pixel.

For the 80mm refractor, three 10 sec exposures are taken. The magnitudes are measured on the median of the three images.

For the 200mm reflector, the exposure and number of images taken is changing. The magnitudes values are measured on each individual image. For each night, a median is taken over several consecutive measurements to obtain the final magnitudes reported in the table. The number of values used for the median is indicated in the table third column. If it is greater than 3 the data is very reliable. If only 1 image was used, the data is probably fine but we cannot guarantee it does not contain an error.

Dauban Survey (80mm F/7.5 refractor)
Julian dateCR magnitude
2456190.31706214.059
2456195.34558814.022
2456202.32296514.271
2456205.30303514.081
2456206.29516614.072
2456209.27191215.720
2456210.27240914.012
2456213.25868314.070
2456219.25372214.041
2456225.25043514.182
2456230.24311313.992
2456250.22766114.276
2456254.22643314.152
2456261.22886414.357
2456263.23260414.103
2456271.22258815.313
2456277.22968013.989
2456288.22747114.174
2456401.56553314.072
2456461.37726614.227
2456474.52186314.000
2456501.36727314.223
2456502.35513614.273
2456513.52536614.059
2456516.53684714.365
2456523.34345014.345
2456540.39001113.984
2456549.48727414.090
2456558.37040814.075
2456566.36016713.974
LX200 (200mm F/10 reflector)
Julian dateCR magnitudenumber of images
used for photometry
2456504.34897814.13415
2456504.39150414.14915
2456504.43533714.17215
2456504.47947214.16315
2456505.39955114.1173
2456505.41924714.1073
2456505.43930514.1033
2456505.45929314.1123
2456505.47873414.1353
2456506.35175415.8303
2456506.37033216.2773
2456506.38990916.8123
2456506.42600616.8043
2456507.35140414.1811
2456507.35180014.0781
2456507.35219614.1831
2456508.34970214.1813
2456508.36810714.1483
2456508.38632214.1383
2456508.40484014.1033
2456508.42323814.1513
2456509.35689314.1643
2456509.37921314.1223
2456509.39658214.1543
2456509.40822214.1702
2456510.33860014.1473
2456510.35861814.1283
2456513.34436314.2011
2456513.34476414.1471
2456513.34516714.1951

Period search


Eclipses have been observed at these dates:

Eclipse julian dates
2456209.271912
2456271.222588
2456506.426006


The smallest observed interval between two eclipses is 61.95 days, this is too large for a period search.