Dauban V239
| name | Dauban V239 |
| constellation | Vul |
| J2000.0 | 19 36 08.39 +25 45 10.2 |
| other names | 2MASS J19360839+2545102 |
| type | EA |
| mag range | 13.3 - 14.6 CR |
| period (days) | -- |
| epoch | -- |
| color | J-K = 0.43 |
| remarks | -- |
| links | -- |
| discovery | 24/09/2012 |
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.
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Period search
Eclipses have been observed at these dates:
| Eclipse julian dates |
| 2456225.271875 |
| 2456263.254055 |
| 2456513.353204 |
| 2456516.558486 |
A period search gives the following phase residual:
Possible periods are:
| Possible periods |
| 3.166 days |
| 1.583 days |
| 1.0553 days |