Alert Notice 641: V1490 Cyg multiwavelength campaign

July 24, 2018: Dr. Dirk Froebrich (University of Kent) has requested AAVSO observations to support their upcoming observations of V1490 Cyg. He writes:

"Background: We have recently discovered that the young star V1490 Cyg (situated in the Pelican Nebula IC 5070) is periodically occulted by material in its circumstellar disk(*). Our light-curves indicate a period of about 32 days, and the obscurations are comparable to UX-Ori type eclipses.

"We will be conducting a [six-week], high cadence, multi-wavelengths optical monitoring campaign (in BVRI) of this source to map out in high resolution the azimuthal distribution of the material in the disk around this young star. Our campaign will run from [1 August 2 018] to [15 September 2018] and we will use three 'observatories':

i) Daily observations with the LCO (in particular the 1m telescope at the McDonald Observatory (longitude ~104deg West).

ii) Daily observations with the University of Kent's Beacon Observatory (longitude ~1deg East).

iii) The observations will be supported by UK amateur astronomers who work with us as part of our HOYS-CAPS(**) citizen science project and are distributed across the entire UK.

"We estimate the the optimal cadence to fully map the azimuthal distribution of material in this object is about 6-8hrs. Thus we would like to request assistance from AAVSO observers to cover longitudinal gaps and to account for potential bad weather at our observing sites.

"Observations: We request CCD or DSLR observations of the target as often as possible and in as many optical filters as are available. In particular we would like BVRI observations, but U and Halpha are welcome as well if the equipment is available and the object can be detected.

"The brightness of the object outside occultations is: B~16.4, V~15.3, R~14.3, I~13.3; during the occultations the object will be up to 1.5mag fainter in all filters. Thus, all the observations should be deep enough to detect the target star at all states with good signal to noise, as we do not know the exact behavior of the object during this period.

"All images should be dark and flat-field corrected. The field of view should be large enough to ensure a sufficient number of comparison stars is available to perform an accurate relative photometric calibration.

"Please stack individual images taken in the same filter per night for an improved signal to noise before submission, but only if they are taken no further apart than 2hrs. Images taken over a longer duration should be stacked seperately.

"Data Submission: As this object is in IC 5070, and thus part of our HOYS-CAPS citizen science project, the reduced images should be submitted in FITS format via our web-upload system (***). Once they are processed the photometry of all the stars in the images will be available immediately publically via our web interface.

"To ensure accurate processing, the FITS header should contain information of the filter used, the total exposure time of the stacked images and the mid-point of the integrations in each stack."

Observations should also be submitted to the AAVSO International Database using WebObs and the name V1490 CYG.

"In case of any questions please contact the PI at or use the HOYS-CAPS facebook group(****)".


Coordinates (2000):  RA  20 50 53.6   Dec  +44 21 01   (from VSX)

Charts with a comparison star sequence for V1490 Cyg may be created using the AAVSO Variable Star Plotter (VSP).

V1490 Cyg is the topic of the AAVSO Campaigns and Observation Reports forum thread

This AAVSO Alert Notice was compiled by Elizabeth O. Waagen.

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