Observing Campaign to Monitor
the White Dwarf V1412 Aquilae
for Planetary Transits

Dr. Arlo Landolt (Louisiana State University) has requested a campaign to perform long-term photometric monitoring of the suspected white dwarf binary V1412 Aql (== G 24-9), a carbon white dwarf (spectral type DQ7; V=15.75) which has undergone deep (3-4 magnitude) fadings on at least two occasions. The depth of the changes suggest eclipses by an unseen object. Observations in the near infrared by Zuckerman and Becklin (1988) showed no sign of a secondary, which suggests that any single eclipsing body is substellar, with an effective temperature less than 1200 K. If the causes of the fadings are eclipses as suspected, then this could be a white dwarf with a transiting exoplanet.

The fadings have been observed twice: V=18.29, 1985 October 7.11 UT (JD 2446345.61; Landolt, IAUC #4125), and R < 19, 1988 July 15.3 UT (JD 2447357.8; Carilli and Conner, IAUC #4648). This constrains the period to be no longer than 1012 days, but the fact that two pointed observations scheduled by chance showed the white dwarf was faint suggests that the period may be much shorter. Both of those observations were single data points, and there is no indication of how long the eclipses lasted. In addition, the white dwarf may also be an intrinsic variable with a range of nearly 0.1 mag, although this is also not certain; there is no suggested timescale for the suspected intrinsic variability, but pulsating white dwarfs have periods of tens of minutes.

Observers are asked to perform nightly observations of V1412 Aql during the next year to search for variability in this star. Both filtered and unfiltered observations are useful; time-series are not required at this time. Because the interval between and duration of eclipses are unknown, this is largely an exploratory project. Nightly monitoring by a number of observers around the world should be able to provide sufficient coverage to detect eclipses with a period shorter than one year. Please submit your data as promptly as possible; please contact the AAVSO after submitting your observations to WebObs if there is any indication of an eclipse.

Observers should note that V1412 Aql has a very high proper motion of more than 0.6"/year, and both DSS and plotted (NOMAD) charts will not reproduce the current position of this star on the sky. Observers are asked to obtain comparison star magnitudes and positions from VSP; a current, 8.7'x8.7' finder chart showing the proper position of the variable is below:

Finder chart for V1412 Aql. Note this is a high proper motion star. This image is epoch 2008.9 -- the coordinates below are the same epoch, referenced to J2000. (Chart by A. Henden, taken with the SRO 0.3m)

V1412 Aql (AUID 000-BDF-742) is located at the following coordinates (J2000, epoch 2008.9, from A. Henden):

Charts for the field of V1412 Aql may be plotted using VSP:

Please refer to the current finder chart given above for the location of the variable, and note it will move slightly during the course of the year.

Please report all observations to the AAVSO as "V1412 AQL".

Observations requested

This campaign begins now (February 26, 2009) and continues indefinitely until an eclipse is detected or until sufficient data is collected to reject the eclipse hypothesis.

Both visual and CCD observations are requested. Visual observers should rapidly report any substantial deviation (more than 0.5 magnitudes) from its typical range; fainter-than estimates are valuable if you can clearly determine V1412 Aql is fainter than 16.5. CCD observers are asked to obtain photometry with signal to noise of 10 or better. Filtered photometry is not required but is encouraged if possible. Time-series observations are not required unless the star has faded or is in decline. We request that any indication that V1412 Aql is significantly fainter than normal be reported to the AAVSO immediately. Please submit all data via the WebObs feature of the Blue & Gold section of our website.

Update: September 2009

Michel Bonnardeau recently posted a link to his personal website on the V1412 Aql campaign, which presents a statistical analysis of the past eclipses and gives predictions of future ones. You can view his webpage here, and view some of the follow-ups in the discussion here.