For information on the WISE mission and to access the results visit this web site. In summary WISE used a 40cm telescope to map the sky at 3.4, 4.6, 12, and 22 µm in 2010 with an angular resolution of 6.1" 6.4" 6.5" and 12.0" in the four bands with saturation impacting on photometry for sources brighter than magnitudes approximately 8.0, 6.7, 3.8 and -0.4.
The database contains information on sources where "the source flux measured on the individual WISE exposures was not constant with time." All sources where var_flg > 9799 were downloaded and these were cross referenced against the International Variable Star Index (VSX) using a search radius of 20 arc seconds. Of the 16103 entries 5550 were within 20 arc sec of a VSX entry. What is particularly noteworthy is what types (using the classification used in VSX) of variable stars that can be matched with a WISE source. Overwhelmingly it is short period stars that have been detected.
| VSX VARIABLE STAR CATEGORY | NUMBER / 5550 |
| EW | 983 |
| RRAB | 518 |
| EA | 357 |
| EB | 238 |
Full details of all these known variable stars matching VSX against WISE entries can be found here.
The initial list of candidate variable stars ( that is all stars that could not be matched against a VSX entry) was "cleaned" by deleting all entries where more than one source contributed to a single results (flag nb), where there was contamination or confusion (flag cc_flags) or where the source was extended (flag ext_flg). After the cleaning process 6058 candidate variable stars remained.
| FLAG | SIGNIFICANCE |
| nb |
nb - Number of PSF components used simultaneously in the profile-fitting for this source. This number includes the source itself. |
| cc_flags |
Contamination and confusion flag. Four character strong, one character per band [W1/W2/W3/W4], that indicates that the photometry and/or position measurements of a source may be contaminated or biased due to proximity to an image artifact. |
| ext_flg |
Extended source flag. This flag indicates whether or not the morphology of a source is consistent with the WISE point spread function in any band. 0 - The source shape is consistent with a point-source 1 - The source shape is not consistent with a point-source. |
| ph_qual |
Photometric quality flag. Four character flag, one character per band [W1/W2/W3/W4], that provides a shorthand summary of the quality of the profile-fit photometry measurement in each band, as derived from the measurement signal-to-noise ratio. |
Full details of all these candidate variable stars can be found here.
Over the last few years I have carried out many astronomical data mining or data analysis projects. Most remain unpublished and this series of papers aims to put them all into the public domain. I welcome constructive feedback from readers and encourage colleagues to take the work forward, perhaps as far as peer reviewed publication. I can be contacted by email. and this address is monitored daily.
Martin Piers Nicholson - Shropshire, United Kingdom.
This page was last updated on July 8th 2011.