MBCAA Observatory

SDSS J040714.78-064425.1: an eclipsing cataclysmic

Observed: 30 Nov, 13, 14, 22, 23, 24, 25 Dec 2006, 12, 13 Jan 2007

Michel Bonnardeau
1 Dec 2006
Updated 23, 28 Dec 2006, 13, 25 Jan 2007

Abstract

Time series for this deeply eclipsing cataclysmic system are presented.

Introduction

SDSS J040714.78-064425.1 is a cataclysmic system, that is a binary system with an accreting white dwarf. Its discovery was reported in 2003. It has a 4-hr orbital period with mag 2 deep eclipses.

This is a CBA target for Nov 2006-Jan 2007.

Observations

The observations were carried out with a 203mm f/6.3 SC telescope, a Clear filter and a SBIG ST7E camera (KAF401E CCD). Each exposure has a duration of 200s. 265 images were obtained.

The comparison star is GSC 4731-00077 with an assumed unfiltered magnitude of 15. The check star is UCAC2 29-394-440 at RA=04h07mn19.58s DEC=-06°45'23.2" with an observed magnitude of 15.66 and a standard deviation of 0.10.

An example of an image:

Blue circle: SDSS J0407, Yellow square: comparison star, Blue tick: check star. From my location, SDSS J0407 is observed through the geostationary orbit, then the 5 satellite trails. Actually a number of observations were lost because of trails on the variable or on the comparison star.

An example of a light curve:

Red: SDSS J0407; Blue: the check star, shifted by +4 mag. The error bars are +/- the 1-sigma statistical uncertainties. The 4 spikes for the check star are due to the many geostationary satellites visible from my location in the direction of SDSS J0407.

All the light curves are HERE.

Eclipse ephemeris

Ak et al (2004) observed 12 eclipses and derived the ephemeris:
T(HJD) = 2,452,949.1504(6) + 0.17017(3)*E

I observed the following 5 eclipses at HJD - 2454000:

70.453 70.625 92.410 95.4735 113.346
This can be used to improve the ephemeris:
T(HJD) = 2452949.1503(6) + 0.1701785(2)*E

The resulting phase plot:

Red: Session 30 Nov 2006
Blue: 22 Dec 2006
Shifted by +3 magnitudes:
Brown: 25 Dec 2006
Magenta: 12 Jan 2007
Cyan: 13 Jan 2007