PUBLIC DATA FOR θ CYGNI RELEASED

Observing Period: June - September 2010
Release Date: Jan 24, 2011

A 42 day segment of the Quarter 6 short cadence light curve for θ Cygni. The inset shows ~5 hours of data at finer temporal resolution. The data were normalized to the mean flux within the displayed time period.

During Quarter 6 the Guest Observer Office targeted the bright star θ Cyg (KIC 11918630), the brightest star located on active pixels within the Kepler field. The GO Office observed this source to develop and refine procedures for constructing dedicated pixel masks for highly-saturated targets. We note that this is a service available to the community through the Director's Discretionary Program.

• Short cadence data was obtained during 3 months of the quarter (June - September 2010). Due to the extensive charge bleed, a dedicated pixel mask was designed to capture the flux from this saturated source while minimizing the size of the mask.

• The pixel level data for this source will be available at MAST after the ingest of Q6 target pixel files in Feb 2011. These data will have no proprietary period; all users are free to analyze the data and publish results. The target pixel file will contain more detailed information on the timestamps and backgrounds derived for this source.

• Software for constructing a light curve directly from the target pixel files will be available here on 1 Feb 2011. As a courtesy, we provide a light curve in the link below.

Download the θ Cygni short cadence light curve here.

• This short cadence light curve data is being released as an ascii file. We will provide a FITS formatted version in the near future.

• The first 19 lines serve as a header with relevant parameters. The light curve is listed in rows containing a timestamp and observed flux. The timestamp is given in units of seconds based on a fiducial time given in the header and has been corrected to the solar system barycenter. Observed flux is listed in electrons per cadence (i.e., per 1-minute observation for short cadence). There are over 129K data points within the entire light curve.

• This light curve was created using all pixels in the aperture mask, uniformly weighted. Unfortunately the assigned mask was too small to capture θ Cygn properly over the full quarter. Observations during only about 40 days captured the target well, with substantial degradation in the signal-to-noise ratio early and late in the quarter and clear evidence of light loss in the observed light curve.

Details about this observation were presented at the Seattle meeting of the American Astronomical Society as presentation 140.07. This presentation can be downloaded here. The abstract is given below:

Public Kepler Data on the Bright Star θ Cygni
Abstract

The bright star θ Cygni (Kepler ID 11918630) has been observed by Kepler in both short (59 sec) and long (29.4 min) cadence for a period of approximately 50 days starting on MJD 55410. These observations were made at the request of the Kepler Guest Observer Office and are intended for immediate public release. The purpose is to demonstrate Keplers exquisite photometric precision on bright, highly saturated targets. Theta Cygni is a F3V/M3V binary with a visual magnitude of 4.9/13.0. The short-cadence data show evidence of granulation (i.e., convection) out to about 1 mHz (~100 c/d) and clear detection of numerous p-modes with a peak near 1.8 mHz (~150 c/d). The high-frequency noise floor has a 3-sigma upper envelope of 0.4 ppm. The amplitude of the p-modes agrees with the stellar effective temperature, indicating that the star has a thin convective layer. Since a custom aperture was employed, the light curves will be constructed manually and placed on the Guest Observer website (http://keplergo.arc.nasa.gov/). The corresponding pixel-level data will be available from the Kepler archive (http://archive.stsci.edu/kepler/). The Kepler mission can accommodate a small number of such bright targets every quarter. Observing proposals can be submitted annually to the peer-reviewed Guest Observer Program, or much less formally on a quarterly basis for Directors Discretionary Time. Kepler was selected as the 10th mission of the Discovery Program. Funding for this mission is provided by NASA, Science Mission Directorate.

Please direct questions about this data to the .

QUICK LINKS

• θ CYG Light curve (ascii file)
• Kepler Data Search and Retrieval form
• Search and Retrieval Form helpage
• Kepler Archive Manual