Alert Notice 660: Targets modified for LPV Maser campaign

Note: This campaign has been extended to October 2020 and the list of targets has been revised. Please see AAVSO Alert Notice 687 for details. - Elizabeth O. Waagen, December 4, 2019

January 25, 2019: Further to AAVSO Alert Notice 645, Michael Stroh (Ph.D. candidate, University of New Mexico) informs us that two of the VLA targets on his list of 19 long period variables for his SiO maser study that is underway have been removed and two other targets added.

The stars removed from the campaign are V1301 Cyg and V1659 Cyg. The stars taking their places are V657 Cas and V850 Cas. Below is a revised list of the targets for this campaign.

Stroh writes: "We have an approved Karl G. Jansky Very Large Array (VLA) monitoring campaign beginning in October of 2018 lasting for one year and observations from AAVSO would be invaluable. In particular, we believe that the strengths of the SiO maser lines we observe at 43 GHz in the radio are correlated with the phase of the stars in our sample and may allow us to probe the density in the stellar envelopes. Our VLA observations will likely occur about once every 3 weeks, thus AAVSO sampling of targets ranging from 2 to 4 weeks [through October 2019] will guide our interpretation of the radio observations."

However, the usual cadence for LPVs is one observation every 10 days, and this cadence is requested by the AAVSO. It is asked that more frequent observations not be made.

Stroh continues: "We prefer Johnson V photometry for all stars to standardize our measurements. If this is not possible, redder filters are preferred (if possible), and are considered a bonus if performed in addition to observations in V since these are very red stars." Visual observations are welcomed and encouraged.

Please see Alert Notice 645 for more details on the campaign.

Charts with comparison star sequences for each of the targets above may be created using the AAVSO Variable Star Plotter (VSP).

Please submit observations to the AAVSO International Database using the names given in the table.

AAVSO Forums: This campaign is the topic of the AAVSO Campaigns and Observation Reports forum thread https://www.aavso.org/lpv-maser-2018-campaign and the Long Period Variables forum thread https://www.aavso.org/lpv-maser-2018-campaign-01

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