A new algorithm for differential photometry: computing anoptimum artificial comparison star

Broeg, C.; Fernández, M.; Neuhäuser, R.

doi:10.1002/asna.200410350

Cited by 71 publications

(76 citation statements)

References 10 publications

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“…First we perform aperture photometry by using the IRAF task chphot (see Raetz et al 2009 stars with the best S/N in the field (Broeg et al 2005;Raetz et al 2009). …”

Section: In Generalmentioning

confidence: 99%

Planetary transit observations at the University Observatory Jena: TrES‐2

Raetz¹,

Mugrauer²,

Schmidt³

et al. 2009

Astron Nachr

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We report on observations of several transit events of the transiting planet TrES-2 obtained with the Cassegrain-TeleskopKamera at the University Observatory Jena. Between March 2007 and November 2008 ten different transits and almost a complete orbital period were observed. Overall, in 40 nights of observation 4291 exposures (in total 71.52 h of observation) of the TrES-2 parent star were taken. With the transit timings for TrES-2 from the 34 events published by the TrESnetwork, the Transit Light Curve project and the Exoplanet Transit Database plus our own ten transits, we find that the orbital period is P = (2.470614 ± 0.000001) d, a slight change by ∼ 0.6 s compared to the previously published period. We present new ephemeris for this transiting planet. Furthermore, we found a second dip after the transit which could either be due to a blended variable star or occultation of a second star or even an additional object in the system. Our observations will be useful for future investigations of timing variations caused by additional perturbing planets and/or stellar spots and/or moons.

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“…First we perform aperture photometry by using the IRAF task chphot (see Raetz et al 2009 stars with the best S/N in the field (Broeg et al 2005;Raetz et al 2009). …”

Section: In Generalmentioning

confidence: 99%

Planetary transit observations at the University Observatory Jena: TrES‐2

Raetz¹,

Mugrauer²,

Schmidt³

et al. 2009

Astron Nachr

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“…A problem in differential photometry is the search for a good comparison star. Broeg et al (2005) developed an algorithm which uses as many stars as possible (all available field stars) and calculate an artificial comparison star. The algorithm decides which stars are the best by taking the weighted average of them.…”

Section: Photometry and Detrendingmentioning

confidence: 99%

Planetary transit observations at the University Observatory Jena: XO‐1b and TrES‐1

et al. 2009

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We report on observations of transit events of the transiting planets XO-1b and TrES-1 with a 25 cm telescope of the University Observatory Jena. With the transit timings for XO-1b from all 50 available XO, SuperWASP, Transit Light Curve (TLC)-Project-and Exoplanet Transit Database (ETD)-data, including our own I-band photometry obtained in March 2007, we find that the orbital period is P = (3.941501 ± 0.000001) d, a slight change by ∼3 s compared to the previously published period. We present new ephemeris for this transiting planet. Furthermore, we present new R-band photometry of two transits of TrES-1. With the help of all available transit times from literature this allows us to refine the estimate of the orbital period: P = (3.0300722 ± 0.0000002) d. Our observations will be useful for future investigations of timing variations caused by additional perturbing planets and/or stellar spots and/or moons.

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“…We used the approach of Broeg et al (2005), which consists in comparing each star with an artificial comparison composed of all the other stars in the field. An iterative process allowed us to identify the variable objects and separate them from those that are best suited to construct the artificial comparison, by weighting them down according to their variability.…”

Section: Differential Photometrymentioning

confidence: 99%

REM near-IR and optical photometric monitoring of pre-main sequence stars in Orion

Frasca¹,

Covino

Spezzi

et al. 2009

A&A

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Aims. We aim at determining the rotational periods and the starspot properties in very young low-mass stars belonging to the Ori OB1c star forming region, contributing to the study of the angular momentum and magnetic activity evolution in these objects. Methods. We performed an intensive photometric monitoring of the PMS stars falling in a field of about 10 × 10 in the vicinity of the Orion nebula cluster (ONC), also containing the BD eclipsing system 2MASS J05352184-0546085. Photometric data were collected between November 2006 and January 2007 with the REM telescope in the VRIJHK bands. The largest number of observations is in the I band (about 2700 images) and in J and H bands (about 500 images in each filter). From the observed rotational modulation, induced by the presence of surface inhomogeneities, we derived the rotation periods. The long time-baseline (nearly three months) allowed us to detect rotation periods, also for the slowest rotators, with sufficient accuracy (ΔP/P < 2%). The analysis of the spectral energy distributions and, for some stars, of high-resolution spectra provided us with the main stellar parameters (luminosity, effective temperature, mass, age, and v sin i) which are essential for the discussion of our results. Moreover, the simultaneous observations in six bands, spanning from optical to near-infrared wavelengths, enabled us to derive the starspot properties for these very young low-mass stars.Results. In total, we were able to determine the rotation periods for 29 stars, spanning from about 0.6 to 20 days. Thanks to the relatively long time-baseline of our photometry, we derived periods for 16 stars and improved previous determinations for the other 13. We also report the serendipitous detection of two strong flares in two of these objects. In most cases, the light-curve amplitudes decrease progressively from the R to H band as expected for cool starspots, while in a few cases, they can only be modelled by the presence of hot spots, presumably ascribable to magnetospheric accretion. The application of our own spot model to the simultaneous light curves in different bands allowed us to deduce the spot parameters and particularly to disentangle the spot temperature and size effects on the observed light curves.

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A new algorithm for differential photometry: computing anoptimum artificial comparison star

Cited by 71 publications

References 10 publications

Planetary transit observations at the University Observatory Jena: TrES‐2

Planetary transit observations at the University Observatory Jena: TrES‐2

Planetary transit observations at the University Observatory Jena: XO‐1b and TrES‐1

REM near-IR and optical photometric monitoring of pre-main sequence stars in Orion

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