Alert Notice 847: Monitoring requested for PSN J12355230+2755559 (Com)

January 23, 2024

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Dr. Mojgan Aghakhanloo (University of Virginia) has requested AAVSO observers' assistance in monitoring the very interesting SDOR variable PSN J12355230+2755559 (= AT 2016blu) (Com) to document its next outburst.

Dr. Aghakhanloo writes: "AT 2016blu has experienced at least 19 outbursts from 2012 to 2022. We have observed that AT 2016blu's outbursts occur approximately every 113 days. Based on this estimated period, we predict that its next outburst will occur around February 2024. As the light curve of AT 2016blu shows brief, multi-peaked outbursts that sometimes occur before or after the expected periastron time, it is crucial to monitor it for about a month before and after the proposed timeline."

Beginning immediately and continuing for a month after the next outburst has concluded, R band (Cousins or Sloan) CCD photometry is requested. Unfiltered observations reduced to an R zero-point (CR) are also welcome. Nightly observations are requested, with a higher cadence (several observations per night) if the target is in outburst. DSLR and visual observations are not requested.

Dr. Aghakhanloo continues: "This target could be in a bright state, indicating an ongoing outburst, which should be observed. Alternatively, if it appears faint, this suggests it is in a dormant phase [but also needs to be monitored]."

PSN J12355230+2755559 has a range of 16.6 r - 20.4 G, and shows 2-3 magnitude outbursts. It is a challenging target not only because of its magnitude but also because of its location - in NGC 4559C (= IC 3550), an HII region of NGC 455 with consequent nebulosity.

Coordinates (2000.0):  R.A. 12 35 52.28  Dec. +27 55 55.5  (from VSX page for PSN J12355230+2755559)

Charts with comparison stars for PSN J12355230+2755559 may be created using the AAVSO Variable Star Plotter (VSP). It is recommended to use the 'F' scale chart to see the nearby comparison stars.

Please submit observations to the AAVSO International Database using the name PSN J12355230+2755559.

This AAVSO Alert Notice was compiled by Elizabeth O. Waagen using information provided by Mojgan Aghakhanloo.


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